Class 9

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.1B Mineral Nutrition offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.1B Question Answer – Mineral Nutrition

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which type of nutrients mainly take part in the structural formation of protoplasm?
Answer:
Macronutrients take part mainly in the structural formation of protoplasm.

Question 2.
Which type of elements act mainly as cofactors of enzymes?
Answer:
Micro elements mainly act as cofactors of enzymes.

Question 3.
What is the functional similarity between Fe and Cu in the life process of an organism?
Answer:
Both Fe and Cu take part in oxidation reduction process of photosynthesis and respiration.

Question 4.
What is the functional similarity between Zn and Mg in biochemical activities?
Answer:
Both Zn and Mg act as cofactors of enzymes.

Question 5.
What is chlorosis?
Answer:
The yellowing of leaves due to disintegration of chlorophyll, as a result of the absence of one or more essential elements, is called chlorosis.

Question 6.
Which metallic element is actively present in electron carriers like cytochrome and ferredoxin?
Answer:
Iron (Fe) is actively present in electron carriers like cytochrome and ferredoxin.

Question 7.
Mention a deficiency symptom of sulphur in patients.
Answer:
In case of sulphur deficiency, young twigs become weak.

Question 8.
Mention one metallic macronutrient and one micronutrient, essential for plants.
Answer:
Magnesium is a metallic macronutrient and iron is a metallic micronutrient, essential for plants.

Question 9.
Name any two gaseous macroelements essential for all living organisms.
Answer:
Oxygen and nitrogen are two gaseous macroelements essential for all living organisms.

Question 10.
Which macroelements take part in the structural formation of protoplasm?
Answer:
The macroelements which take part in the structural formation of protoplasm are C, H, O, N, P, Mg, and S.

Question 11.
Which macronutrient is essential for the formation of plasma membrane?
Answer:
Calcium is an essential macronutrient which helps in the formation of plasma membrane.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by macronutrients?
Answer:
The elements, that are required in larger quantities for growth, development and normal physiological activities of plants, are called macronutrients. Example-Carbon (C), Nitrogen (N), Phosphorus (P) etc.

Question 2.
What is meant by micronutrients?
Answer:
The elements, that are required in minute quantities for normal physiological activities of plants, are called micronutrients. Example – Molybdenum (Mo), Boron (B), Zinc (Zn) etc.

Question 3.
How are mineral nutrients associated with survival of plants?
Answer:
For normal growth, proper formation of cells and tissues and proper operation of all physiological functions, plants need different minerals. Minerals act as structural components of protoplasm, cofactors of various enzymes controlling several bio-chemical reactions within the cells etc. That is how mineral nutrients are associated with the survival of plants.

Question 4.
How do different elements take part in the formation of a plant cell?
Answer:
Various elements, such as C, H, O, S, Mg, P, N and Fe, play a prominent role in the formation of protoplasmic chemical constituents of a cell. All cellular matters are basically composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). Proteins need sulphur (S), nucleic acids need phosphorus (P), chlorophylls need magnesium (Mg) and middle lamella of cell needs calcium (Ca) other than C, H, O, and N.

Question 5.
Which elements play role in maintaining osmotic balance in plant cells?
Answer:
Different inorganic salts of potassium (K)and sodium (Na) play an important role in maintaining the osmotic balance of the cells in plants. The elements remain as chloride \(\left(\mathrm{Cl}^{-}\right)\), phosphate \(\left(\mathrm{PO}_4^{3-}\right)\), sulphate \(\left(\mathrm{SO}_4^{2-}\right)\) etc. which help to maintain the osmotic concentration within the plant cells.

Question 6.
How do salts play role in maintaining the pH of a cellular fluid?
Answer:
Certain ions, like phosphate \(\left(\mathrm{PO}_4^{3-}\right)\), bicarbonate \(\left(\mathrm{HCO}_3^{-}\right)\) and carbonate \(\left(\mathrm{CO}_3^{2-}\right)\) may act as buffers and thus resist marked change in pH. Thus, inorganic salts help to regulate pH of any cellular fluid.

Question 7.
What are the main functions of potassium in a plant body?
Answer:
The main functions of potassium in a plant body are as follows-

• It takes part in protein and carbohydrate synthesis.
• It acts as co-enzyme and helps in stomatal movement.
• Maintains normal growth and colour of the leaves.

Question 8.
What are the symptoms that occur due to the deficiency of potassium?
Answer:
The distinct symptoms that occur due to the deficiency of potassium are-

• discolouration of leaves,
• slow growth of roots and seeds
• curling of older leaves.

Question 9
Mention three importance of phosphorus in a plant body.
Answer:
Three importance of phosphorus in a plant body are as follows-

• It plays an important role in protein synthesis.
• It acts as component of ATP, NADP and membrane of cells and other organelles.
• It prevents premature shedding of leaves and blackening of fruits and leaves.

Question 10
Mention the importance of calcium in a plant body.
Answer:
The importance of calcium in a plant body are as follows-

• It helps in cell division by spindle formation and formation of middle lamella of the cell wall.
• It helps in nitrogen and carbohydrate metabolism.
• It maintains normal blooming of flowers.

Question 11.
What are the major roles of magnesium in a plant body?
Answer:
The main roles of magnesium in a plant body are as follows-

• It acts as the metallic constituent of chlorophyll.
• It acts as an enzyme activator.
• Prevents scorching and discolouration of the leaves.

Question 12.
What are the significance of boron in a plant hody?
Answer:
The significance of boron in a plant body are as follows-

• It helps in the formation and growth of leaves and flowers.
• It takes part in calcium and potassium metabolism and protein synthesis,
• It helps in the elongation of pollen tube.

Question 13.
What are the functions of zinc in plant body?
Answer:
The functions of zinc in plant body are as follows-

• It helps in the synthesis of auxins and certain proteins.
• It activates various enzymes as cofactors.
• It also maintains normal growth of the stems and roots.

Question 14.
What are the symptoms that occur due to deficiency of zinc?
Answer:
The distinct symptoms that occur due to deficiency of zinc are-

• retarded growth of roots, stems and leaves,
• delayed seed formation,
• discolouration of leaves.

Question 15.
What is the importance of manganese in a plant body?
Answer:
Importance of manganese in a plant body are as follows-

• It acts as an enzyme activator.
• It takes part in the chlorophyll and protein synthesis.
• It helps in the normal growth of shoots and prevents necrosis of leaves.

Question 16.
Mention the significance of sulphur as a mineral nutrient.
Answer:
The significance of sulphur are as follows:

• It acts as a major constituent of amino acids, vitamins and co-enzyme A.
• It helps in the formation of chlorophylls and development of roots.
• Sulphur prevents hardening of stems and helps in metabolism.

Question 17.
What is necrosis?
Answer:
The death of cells of certain areas of the plant body, due to the deficiency of any particular mineral nutrient (mainly Cl, Mn, Cu ) resulting in the drying up of those affected areas, is called necrosis.

Question 18.
Name the metallic elements which are essential for plants.
Answer:
The metallic elements which are essential for plants are-Magnesium (Mg), Potassium (K), Calcium (Ca), Manganese (Mn), Iron (Fe), Zinc (Zn), Copper (Cu), Molybdenum (Mo), Cobalt (Co), Nickel (Ni), Sodium (Na) etc.

Question 19.
Write the source of carbon (C), oxygen (O) and hydrogen (H) in plants.
Answer:
In plant body, source of carbon is the CO₂ gas, present in atmosphere. Hydrogen is obtained from the water vapour present in atmosphere and also from the water present in soil. Oxygen is taken up by plants directly from the air.

Long Questions and Answers : (5 marks for each question)

Question 1.
Mention the general characteristic features of macronutrients. Write the characteristic features of micronutrients.
Answer:
Characteristic features of macronutrients
The general characteristic features of macronutrients are as follows-

• These elements are present in larger quantities (1-10 mg per g dry weight of plants, or more).
• They are mainly involved in the synthesis of structural components of the plant cells.
• They also participate in maintaining the osmotic potential of the plants.

Characteristic features of micronutrients
The characteristic features of micronutrients are as follows-

• The elements are present in minute quantities ( 0.1mg per g) dry weight of plant, or less).
• High concentrations of micronutrients may prove to be toxic for the plants.
• They mainly participate in electron transport mechanisms and act as cofactors for various enzymes.

Question 2.
Mention the general functions of different nutrients in plants.
Answer:
Functions of different nutrients in plants
The general functions of different nutrients in plants are as follows-

1. Formation of protoplast: Various nutrients, such as C, H, O, S, N, P, Mg and Fe play a prominent role in the formation of chemical constituents of protoplasm.

2. Structure of enzyme: Nutrients, such as Ca, Mg, K, Zn, Cl, Cu, Ni etc. are involved in the formation of various enzymes or act as co-factors.

3. Oxidation-reduction reaction: Flement such as Fe and Cu, take part in electron transfer and thus, bring about oxidation-reduction reaction.

4. Osmotic balance: Presence of inorganic salts (such as \(\mathrm{Cl}^{-}, \mathrm{PO}_4^{3-}, \mathrm{SO}_4^{2-}\) etc.) in the cell sap are involved in maintaining the osmotic balance of the cell.

5. Formation of chlorophyll: Elements, such as O, N, H, C and Mig play a prominent role in the formation of chlorophyll. Iron (Fe) helps in this process.

6. Buffer effect: Certain salts, like phosphates, bicarbonates and carbonates may act as buffers and thus, resist marked change in pH.

7. Growth: Mineral elements, such as Zn, Mn, B etc, maintain normal growth of stem and root.

Question 3.
Mention the importance of any five macronutrients in plants.
Answer:
Importance of any five macronutrients in plants
The importance of any five macronutrients in plants have been discussed below.

1. Phosphorus (P):

• Plays an important role in protein synthesis.
• It acts as a component of ATP, NADP and membrane of cells & other organelles.
• It prevents premature shedding of leaves, blackening of fruits & leaves.

2 Sulphur (S) :

• It is the major constituent of certain amino acids, vitamins & co-enzyme A.
• It helps in the formation of chlorophyll & development of roots.
• It also prevents hardening of stems and plays important role in growth and metabolism.

3. Potassium (K):

• It takes part in protein & carbohydrate synthesis.
• It acts as co-enzyme & helps in the stomatal movement.
• Potassium maintains normal growth & colour of leaves.

4. Calcium (Ca):

• It helps in cell division by spindle formation,
• It helps in nitrogen & carbohydrate metabolism.
• It helps in formation of cell membrane and the middle lamella of cell wall in plants.

5. Magnesium (Mg):

• It acts as primary metallic constituent of chlorophyll.
• It helps in enzyme activation.
• It prevents scorching discolouration of leaves.
• It helps in nucleic acid synthesis and controls fat and carbohydrate metabolism.

Question 4.
Mention the deficiency symptoms of the macronutrients phosphorus, sulphur and magnesium in plants. Mention the deficiency symptoms of the micronutrients copper, manganese and boron in plants.
Answer:
Symptoms due to deficiency of P, S and Mg:
The deficiency symptoms of phosporus, sulphur and magnesium are as follows-
1. Phosphorus (P):

• Leaves and stems turn bluish-green in colour,
• necrosis occurs in leaves,
• plants become weak and stunted.

2. Sulphur (S):

• Curling of leaves occurs followed by necrosis,
• nodule formation in leguminous plants is hampered,
• overall growth of plant is hampered.

3. Magnesium (Mg):

• Chlorosis of matured leaves occurs.
• retarded growth of plants is seen,
• carbohydrate formation is hampered.

Symptoms due to deficiency of Cu, Mn and B.

The deficiency symptoms of copper, manganese and boron are as follows-
1. Copper (Cu):

• Necrosis occurs in tender leaves
• nitrogen metabolism is hampered
• dieback disease (rotting) occurs in the tender portions of stems.

2. Manganese (Mn):

• Necrosis of leaves occurs
• leaves become yellowish, and intervenous chlorosis takes place.

3. Boron (B):

• Rotting of apical portions of stems and roots, followed by necrosis
• margins of leaves dry up and as a result the leaves curl up
• drought spot disease occurs in apples.

Question 5.
Mention the importance of different micronutrients in plants.
Answer:
Importance of different micronutrients in plants
The importance of different micronutrients in plants have been mentioned below.

1. Iron (Fe):

• It helps in the formation of chlorophyll & chromatin reticulum.
• It acts as structural element of electron carriers & helps in ion absorption.

2 Copper (Cu):

• It acts as structural component of some enzymes & helps in reduction of nitrates.
• It takes part in electron transportation in photosynthesis.
• It prevents necrosis of leaves in cereals & pulses.

3. Molybdenum (M0):

• It helps in the fixation & assimilation of nitrogen.
• It acts as cofactor for enzymes involved in nitrogen fixation.
• It helps in normal flowering & colouration of leaves.
• [It also helps in protein synthesis.

4. Zinc (Zn):

• It helps in the synthesis of auxins & certain proteins,
• It activates various enzymes by acting as cofactor.

5. Manganese (Mn):

• It acts as enzyme activator.
• Takes part in chlorophyll & protein synthesis.
• Prevents necrosis of leaves.

6 Boron (B):

• It helps in the formation and growth of flowers & leaves.
• Takes part in protein synthesis.
• Boron helps in the metabolism of calcium and potassium.
• It also helps in the elongation of pollen tube.

7. Chlorine (CI):

• Chloride ions, in the cell sap, helps in maintaining the osmotic balance of the cell,
• Helps in the opening and closing of stomata.
• takes a passive role in photosynthesis.

8 Nickel (Ni):

• Nickel is a component of some plant enzymes, most notably urease, which metabolises urea into ammonia.
• It also acts as a catalyst of enzymes, that help legumes to fix nitrogen.

Question 6.
Distinguish between macronutrients and micronutrients.
Answer:
Differences between macronutrients and micronutrients

Features	macronutrients		micronutrients
1. Necessity	These are needed in larger quantities for growth, development and different physiological activities of the cell		These are needed in very small quantities for growth, development and different physiological activities of the cell
2. General function	Building ceil and different protoplasmic components		Mainly help in catalytic activities
3. Effect of deficiency	Deficiency symptoms are very distinct and plants are adversely affected		Deficiency symptoms are often indistinct and plants are slightly affected
4. Effect of excess intake	Excess nutrients are disposed without causing serious harm		Often cause harm to the plant
5. Example	Oxygen, nitrogen, carbon etc.		Boron, molybdenum, manganese etc.

Question 7.
What is ‘hydroponics’? Explain in a few sentences.
Answer:
Hydroponics
Hydroponics is defined as the subset of hydroculture and a method of growing plants using mineral nutrient solution, in water, but without soil.

Explanation:
Plants require several metallic and non-metallic elements for their normal healthy growth. Plants acquire these essential elements usually from the soil. But, scientists have experimentally proved that soil is not essential for the growth of plants. Only solutions, rich in mineral nutrients, are enough for this process. Thus, the process of cultivation of plants by placing roots in liquid nutrient solution, rather than in soil, and then observing their growth, is called ‘hydroponics.’ It is also called soilless growth of plants.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.3 Nutrition offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.3 Question Answer – Nutrition

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which physiological process provides potential energy to living organisms?
Answer:
Nutrition provides potential energy to living organisms.

Question 2.
Which two steps are involved in the nutrition of green plants?
Answer:
Photosynthesis and assimilation are involved in the nutrition of green plants.

Question 3.
How much energy is necessary for a healthy adult to perform the daily life activities?
Answer:
To perform all life activities, a healthy adult requires 2500-3000 kcal energy.

Question 4.
How much heat is liberated by complete oxidation of one gram of glucose?
Answer:
About 4.1 kcal energy is liberated by the complete oxidation of one gram of glucose.

Question 5.
How much heat is liberated by complete oxidation of one gram of protein?
Answer:
About 4.1 kcal energy is liberated by complete oxidation of one gram of protein.

Question 6.
How much heat is liberated by complete oxidation of one gram of fat?
Answer:
About 9.3 kcal energy is liberated by complete oxidation of one gram of fat.

Question 7.
Which component of food develops disease resistance?
Answer:
Vitamins develop disease resistance.

Question 8.
What is the similarity between Rafflesia and louse?
Answer:
Both Rafflesia and louse are parasitic in nature.

Question 9.
What is the similarity between Mycorrhiza and Rhizobium?
Answer:
Both Mycorrhiza and Rhizobium develop symbiotic association with flowering plants.

Question 10.
In which type of nutrition is one member benefited at the expense of another?
Answer:
In parasitic nutrition one member is benefited at the expense of the another.

Question 11.
What is the similarity between dung beetle and pig?
Answer:
Both dung beetle and pig show coprophagy.

Question 12.
What is the nutritional dissimilarity between louse and tapeworm?
Answer:
Louse is an ectoparasite but tapeworm is an endoparasite.

Question 13.
In which nutritional association both associates are benefited?
Answer:
In symbiotic nutrition both associates are benefited.

Question 14.
Why do some plants capture insects for nutrition?
Answer:
Some plants capture insects to fulfil the nutritional needs of nitrogen.

Question 15.
Which type of food is not digested in the stomach?
Answer:
Starch is not digested in the stomach.

Question 16.
Which type of carbohydrate is hydrolysed in stomach?
Answer:
Sucrose is hydrolysed in the stomach.

Question 17.
Which digestive juice is alkaline in nature?
Answer:
Bile is alkaline in nature.

Question 18.
Which acid makes the chyme acidic inside stomach?
Answer:
HCl makes the chyme acidic inside stomach.

Question 19.
Which digestive enzymes prefer lower pH to act properly?
Answer:
Pepsin and gastric lipase prefer lower pH to act properly.

Question 20.
By which process does food bolus reach stomach through oesophagus?
Answer:
Food bolus reaches the stomach through oesophagus by peristalsis.

Question 21.
From which gland is ptyalin secreted?
Answer:
Ptyalin is secreted from the salivary glands.

Question 22.
Which proteolytic enzyme is secreted from the pancreas?
Answer:
Trypsin is a proteolytic enzyme, secreted from the pancreas.

Question 23.
Which is the widest portion of the human GI tract?
Answer:
Large intestine or colon is the widest portion of the human GI tract.

Question 24.
What do bile salts do in digestion?
Answer:
Bile salts emulsify fat to help its enzymatic hydrolysis.

Question 25.
Which is the primary centre for protein digestion?
Answer:
Stomach is the primary centre for protein digestion.

Question 26.
Which, other than digestive enzymes, are secreted from pancreas?
Answer:
Other than digestive enzymes, hormones like insulin and glucagon are secreted from the pancreas.

Question 27.
From which cells HCl is secreted in stomach?
Answer:
HCl is secreted from oxyntic cells of inner lining of the stomach.

Question 28.
Which cells secrete digestive enzymes in small intestine?
Answer:
Digestive enzymes are secreted from Brunner’s gland cells inside the small intestine.

Question 29.
Which cells in stomach secrete digestive enzymes?
Answer:
The peptic cells or chief cells in the stomach, secrete digestive enzymes.

Question 30.
Which cells in intestine secrete mucus?
Answer:
Goblet cells in intestinal lining secrete mucus.

Question 31.
Name an enzyme, which prefers neutral or slightly alkaline pH for better action.
Answer:
Trypsin prefers neutral or slightly alkaline pH for better action.

Question 32.
Which enzyme hydrolyses protein into peptone?
Answer:
Pepsin hydrolyses protein into peptone.

Question 33.
Which enzyme hydrolyses fats into fatty acids and glycerol?
Answer:
Lipases hydrolyse fat into fatty acids and glycerol.

Question 34.
Which intestinal enzyme hydrolyses lower peptides into amino acids?
Answer:
Erepsin hydrolyses lower peptides into amino acids.

Question 35.
On which substrate does ptyalin act?
Answer:
Ptyalin acts upon boiled starch.

Question 36.
Which is the site for absorption of digested food?
Answer:
Villi inside the small intestine act as the site of absorption of digested food.

Question 37.
End products of which type of food are absorbed in blood capillaries of villi?
Answer:
End products of protein and carbohydrate digestion are absorbed in blood capillaries of villi.

Question 38.
End products of which type of food are absorbed in lacteals or fine lymph ducts of villi?
Answer:
End products of fats are absorbed in lacteals or fire lymph ducts of villi.

Question 39.
Which portion of human GI tract is responsible for absorption of excess water from residue of digestion?
Answer:
Colon is responsible for the absorption of excess water from the residue of digestion.

Question 40.
Which type of food does one need the most to fulfill the daily requirement of energy?
Answer:
Carbohydrate is needed the most to fulfill the daily requirement of energy.

Question 41.
Which nutritional insufficiency is the cause of hypothyroidism?
Answer:
Nutritional insufficiency of iodine is the cause of hypothyroidism.

Question 42.
Insufficiency of which hormone causes diabetes mellitus?
Answer:
Insufficiency of insulin from the beta-cells of the Islets of Langerhans of pancreas causes diabetes mellitus.

Question 43.
Which disease is caused due to impaired carbohydrate metabolism?
Answer:
Diabetes mellitus is caused by impaired carbohydrate metabolism.

Question 44.
Which disease is caused due to abnormal intake of high calorie diet?
Answer:
Obesity is caused due to abnormal intake of high calorie diet.

Question 45.
Which disease results into thickening of walls of arteries due to deposition of fat?
Answer:
In atherosclerosis, walls of arteries become thick and rigid due to deposition of fat.

Question 46.
Which disease results into transformation of liver cells into fibrous tissue?
Answer:
In liver cirrhosis, cells of liver are transformed into fibrous tissue.

Question 47.
Name an organism which performs both intracellular and extracellular digestion.
Answer:
Hydra performs both intracellular and extracellular digestion.

Question 48.
What is the function of lipids in blood?
Answer:
Lipids help to dissolve and transport vitamin A, D, E and K in blood.

Question 49.
What is bile comprised of?
Answer:
Bile is comprised of water, various inorganic salts, bile salts, bile pigments, fatty acids, cholesterol etc.

Question 50.
Name the bile salts.
Answer:
Sodium taurocholate and sodium glycocholate are the bile salts.

Question 51.
Name the two bile pigments.
Answer:
The two bile pigments are bilirubin and biliverdin.

Question 52.
Name the hormone secreted by the stomach.
Answer:
The hormone secreted by stomach is gastrin.

Question 53.
Name two lipolyitc enzymes present in human body.
Answer:
Two lipolytic enzymes present in human body are pancreatic lipase and gastric lipase.

Question 54.
Give two examples of pro-enzymes.
Answer:
Pepsinogen and trypsinogen are two examples of pro-enzymes.

Question 55.
Define apoenzyme.
Answer:
The protein part of a holoenzyme is known as apoenzyme.

Question 56.
What is a coenzyme?
Answer:
The organic non-protien part, which combines with the apoenzyme, thus forming a holoenzyme, is called coenzyme.

Question 57.
Name two coenzymes.
Answer:
NADP and NAD are two coenzymes.

Question 58.
Which process results in vomiting?
Answer:
Reverse peristalsis results in vomiting.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is nutrition?
Answer:
Nutrition is a combination of processes, by which living organisms obtain the substances necessary for growth, developing resistance against diseases and acquiring potential energy for life by intake of food, digestion, absorption, assimilation and egestion (in animals) or by synthesis and assimilation (in plants).

Question 2.
What is food?
Answer:
The edible matters, which a living organism consumes for growth, replenishing physical loss, developing resistance against diseases and acquiring energy for performing all life activities, are called food.

Question 3.
What is meant by autotrophic nutrition?
Answer:
The nutrition in which green plants and other phototrophic or chemoautotrophic organisms synthesize their own organic food from inorganic matters within their body cells is called autotrophic nutrition.

Question 4.
What is meant by heterotrophic nutrition?
Answer:
The nutrition in which organisms take in complex organic or inorganic matters as food, digest it before absorption and assimilation or absorb organic matters from dead and decaying plant and animal products is called heterotrophic nutrition. Example-All animals and nonphotosynthetic plants perform heterotrophic nutrition.

Question 5.
What is meant by holophytic nutrition?
Answer:
The physiological process in which autotrophic organisms perform nutrition by synthesising their own food and assimilating it within the body is called holophytic nutrition. Example-All green plants and photosynthetic organisms perform this type of nutrition.

Question 6.
What is meant by holozoic nutrition?
Answer:
The physiological process, which involves intake of complex organic or inorganic matter as food, followed by their digestion, absorption of endproducts of digestion, assimilation of essential nutrients within the protoplasm and finally egestion of undigested matters, is called holozoic nutrition. Example-All animals perform holozoic nutrition.

Question 7.
What is meant by saprophytic nutrition?
Answer:
The nutrition in which organisms absorb organic matter from dead and decaying plant and animal products is called saprophytic nutrition. ExampleDifferent fungi like Agaricus, Mucor, Penicillium, Saccharomyces etc. perform saprophytic nutrition.

Question 8.
What is meant by parasitic nutrition?
Answer:
The nutrition in which an organism (parasite) collects food from the body of another organism (host) for its growth and nourishment is known as the parasitic nutrition. In this process the parasite is benefited at the expense of the host. ExampleAmong plants, Cuscuta, Rafflesia, Puccinia perform parasitic nutrition. In animals, louse, tapeworm, roundworm show this type of nutrition.

Question 9.
What is meant by symbiotic nutrition?
Answer:
The nutritional process where two different organisms depend upon each other to get nutrition and in this process both are benefited, is called symbiotic nutrition. Example-Rhizobium forms symbiotic relationship with roots of legumes.

Question 10.
What is meant by insectivorous nutrition?
Answer:
Certain plants capture insects with their specialised organs, dissolve it enzymatically and then absorb the nitrogen-rich sap to fulfil the need for extra nitrogen. This type of nutrition is called insectivorous nutrition. Example-Venusflytrap, sundew, pitcher plant etc.

Question 11.
How many types of parasitic nutrition are found among parasitic animals? Give example of each.
Answer:
Two types of parasitic nutrition are seen among parasitic animals-
1. Ectoparasitic nutrition: In this nutrition, parasites collect food from outside the body of the host. Example-Louse performs this type of nutrition.
2. Endoparasitic nutrition: In this process, parasites collect nutrients from inside the body of the host. Example-Tapeworm, germs of malaria perform this type of nutrition.

Question 12.
What is meant by coprophagy?
Answer:
The faeces of animals contain a number of nutrients. Certain animals get these nutrients by consuming its own faeces or of other animals. This type of nutrition is called coprophagy. Example-Guinea pigs, rabbits consume their own faeces whereas pigs and dung beetle consume faeces of others to perform this type of nutrition.

Question 13.
What is sanguinivory?
Answer:
Certain animals perform nutrition by sucking blood from warm-blooded animals, this type of nutrition is called sanguinivory. ExampleMosquitoes, leeches, bedbugs, vampire bats perform this type of nutrition.

Question 14.
Mention the function of human tongue?
Answer:
Human tongue has many taste buds on it to taste different food. The taste buds at the tip are for tasting sweet food. The lateral buds are for tasting salty and sour food. The buds at the posterior region of tongue are for tasting bitter food. Besides tasting food, tongue helps in movement of food inside mouth to mix it with saliva. Tongue also helps in swallowing the bolus. It also takes part in articulation of speech.

Question 15.
What is meant by diphyodont teeth?
Answer:
In mammals teething occurs twice in the life time. The first set of teething occur after the age of six months. These are called milk teeth, which are 20 in number. These teeth fall at the age of six years which are replaced by 32 permanent teeth. This type of teeth of mammals are called diphyodont teeth.

Question 16.
What is meant by heterodont teeth?
Answer:
‘Hetero’ means different and ‘dont’ means teeth. In mammals, teeth are of different sizes and shapes according to their respective functions. Sharp and flat incisors are for cutting food. Pointed canines are used to tear, premolars and molars are used for rough and fine grinding. This type of teeth are called heterodont teeth.

Question 17.
What is meant by thecodont teeth?
Answer:
In mammals and in crocodiles the roots of teeth remain tightly embedded in the socket of jaws. This type of socketted teeth are called thecodont teeth.

Question 18.
Mention the dental formula of an adult person and a three year old baby.
Answer:
Dental formula of an adult individual-

I \(\frac{2}{2}\), C \(\frac{1}{1}\), PM\(\frac{2}{2}\), M \(\frac{3}{3}\)

Dental formula of a three year old child-

I \(\frac{2}{2}\), C \(\frac{1}{1}\), M\(\frac{2}{2}\)

Question 19.
What is pharynx? Mention its function.
Answer:
Pharynx: The posterior portion of the buccal cavity from where larynx and oesophagus start, is called pharynx.
Function: Pharynx helps in the flow of bolus into oesophagus and the passage of inspired and expired air through larynx.

Question 20.
What is oesophagus? What does it do?
Answer:
Oesophagus: Oesophagus is a 10-12 cm long tube, which comes down vertically from the base of pharynx to the stomach along the mid chest line.
Function: Oesophagus carries food bolus to stomach from the mouth.

Question 21.
Briefly mention the structure of stomach.
Answer:
Human stomach is a ‘J’ shaped highly extensible muscular sac. The upper portion of it, approaching the heart, is called the cardiac end. The body of stomach is known as fundus. The posterior end, approaching duodenum is called the pyloric end. Inner wall of stomach has many longitudinal ridges, called rugae.

Question 22.
Write a brief description of human smail intestine.
Answer:
Small intestine of an adult human is a 6 metre long tube, which remains inside abdominal cavity in a densely coiled manner. It has three portions, the first one starts from the pyloric end of stomach, called duodenum. The next highly convoluted portion is known as jejunum. The last portion is called the ileum.

Small intestine is the site of final digestion and absorption of the digested food matters.

Question 23.
Write a brief description of human colon.
Answer:
Colon or large intestine is the wider tube situated at the posterior portion of the human GI tract. It has four portions ascending colon, transverse colon, descending colon and sigmoid colon. The ascending arm emerges from the base of the caecum and the sigmoid colon ends at rectum. Colon is the site of water absorption and the formation of faeces from the undigested food.

Question 24.
How many types of salivary glands are found in human body? Mention their location.
Answer:
There are three pairs of salivary glands in human mouth-

1. Parotid gland-Located at the base of the ears.
2. Sub-maxillary or submandibular gland-Located on two sides of lower jaw.
3. Sub-lingual gland-Located below the tongue under the floor of mouth.

Question 25.
Give a brief structural account of human liver.
Answer:
Liver is the largest gland of the human body. It is a dark reddish brown coloured triangular gland with two distinct lobes. Liver is lodged at the right side of the abdominal cavity just below the diaphragm. A club-shaped, thin-walled gall bladder is present on the lower side of the right hepatic lobe.

Question 26.
Mention the functions of human liver.
Answer:
The functions of human liver are as follows

1. Alkaline bile, secreted from liver, neutralizes acidic chyme from stomach.
2. Bile salts emulsify fat to facilitate its digestion.
3. Bile helps in the absorption of fat.
4. Kupffer cells of liver kill germs by phagocytosis.

Question 27.
What is common bile duct?
Answer:
Hepatic ducts from right and left lobes of liver join to form a common hepatic duct. The cystic duct from the gall bladder comes to unite with the common hepatic duct to form a wider descending bile duct, called common bile duct.

Question 28.
Mention the functions of pancreas.
Answer:
The functions of pancreas are as follows :
1. Pancreas secretes both enzymes and hormones. Pancreatic juice contain amylolytic, lipolytic and proteolytic enzymes, which help in the hydrolysis of carbohydrate, fat and proteins respectively.
2. From α and β cells of islets of Langerhans two important hormones are secreted, which are glucagon and insulin respectively. These two hormones jointly regulate the sugar level of blood.

Question 29.
Mention the role of HCl in stomach.
Answer:
Role of HCl in stomach are as follows :

1. HCl, secreted from oxyntic cells of the stomach wall, activates pepsinogen to active pepsin which helps in protein digestion.
2. HCl helps in the hydrolysis of sucrose inside the stomach.
3. HCl kills many germs, which enter into the stomach with the food.

Question 30.
Why should one chew food for some time before swallowing?
Answer:
One should chew food for some time before swallowing, because-

1. Chewing helps in the grinding of food materials. Enzymes can act better or finely ground food particles.
2. In the course of chewing, profuse salivary secretion occurs, which makes the bolus softer to ease swallowing.
3. Chewing causes excess salivation, which helps in killing different bacteria by the action of lysozyme present in it.

Question 31.
Nams three proteolytic enzymes, their sources, substrates and the end products of hydrolysis.
Answer:
The following table shows sources, substrates and end products of three proteolytic enzymes.

Question 32.
Name three amylolytic enzymes, their sources, substrates and the end products of hydrolysis.
Answer:
The following table shows sources, substrates and end products of three amylolytic enzymes.

Question 33.
Mention the functions of stomach.
Answer:
The functions of stomach are as follows-

1. Stomach holds the food for some time.
2. HCl secreted from the stomach acidifies the food to kill germs, which enter along with it.
3. HCl activates inactive proenzymes to active enzymes.

Question 34.
What is peristalsis?
Answer:
A wave of contraction and relaxation movement proceeds all along the alimentary tract from oesophagus to rectum. This typical movement is called peristalsis.
Peristalsis pushes the contents of the GI tract downwards.

Question 35.
What is meant by absorption? Where does it occur?
Answer:
Absorption: The process by which end products of digestion are taken into blood and lymph from intestine is called absorption.
Site: Though absorption mainly occurs in the ileum of small intestine, certain matters like some drugs, alcohol, salts etc., are also absorbed in the stomach and large intestine.

Question 36.
What are villi? What do they do?
Answer:
Villi: Villi are numerous tiny cylindrical fingerlike projections emerging from the inner wall of the small intestine.
Function: The blood vessels inside the villi absorb amino acids, simple sugars and glycerols from the small intestine. The lymph ducts or lacteals absorb all other end products of fat digestion.

Question 37.
What is meant by assimilation? Mention its significance.
Answer:
Assimilation: Assimilation is the process by which all essential ingredients of food are integrated in the protoplasm of living cells.
Significance: By assimilation, cells get necessary raw materials from which they synthesize essential cellular macromolecules as well as get necessary fuel, in the form of glucose and fats, to generate metabolic energy.

Question 38.
What is meant by egestion? What is its importance?
Answer:
Egestion: Egestion is the disposal of undigested food matter from rectum in the form of faeces.
Importance: By egestion, the post-digestive waste matter are removed from the GI tract to make it clear for normal functioning.

Question 39.
What is meant by metabolism?
Answer:
A series of constructive and destructive biochemical reactions continue in the protoplasm of all living cells to run the life activities, which are collectively called metabolism. The constructive reactions of metabolism are called anabolism and the destructive ones are known as catabolism.

Question 40.
What is anabolism?
Answer:
Anabolism is a metabolic process, by which some new molecules are synthesized or integrated within the protoplasm to increase the dry weight of an organism. ExamplePhotosynthesis and nutrition.

Question 41.
Mention the significance of anabolism in a living organism.
Answer:
Significance of anabolism are as follows

1. Building up of organs and tissues.
2. Growth and differentiation of cells.
3. Synthesis and storage of complex molecules within the protoplasm.

Question 42.
What is catabolism?
Answer:
Catabolism is a metabolic process by which certain materials from protoplasm are utilized or broken down and as a result, the dry weight of an organism decreases. Example-Respiration and excretion.

Question 43.
Mention the significance of catabolism.
Answer:
Significance of catabolism are as follows-

1. Providing kinetic energy for life activities.
2. Releasing chemical energy for the synthesis of adenosine triphosphate (ATP).
3. Disposal of harmful waste materials, produced in the body from different physiological reactions.

Question 44.
What is meant by balanced diet?
Answer:
The diet consisting of different food items including carbohydrates, proteins, lipids, vitamins, minerals and water in perfect quantities and proportions, in order to meet the requirement of the body for normal growth, replenishing physical loss, developing resistance against diseases and collecting potential energy necessary to perform all life activities, is called a balanced diet.

Question 45.
What is meant by basal metabolic rate? Mention the normal BMR of a healthy adult male and female individual.
Answer:
Basal metabolic rate: Basal metabolic rate is defined as per hour energy output of an individual, who is at complete physical and mental rest in a comfortable environment, 12 to 18 hours after taking a light meal.
Normal BMR values: BMR of a healthy adult male is 40 kcal / hour / sq.metre body surface.
BMR of a healthy adult female is 37 kcal / hour / sq.metre body surface.

Question 46.
Mention the calorific demand of a healthy adult man and a woman, performing normal job.
Answer:
The following table shows the calorific demand of a healthy adult man and a woman, performing normal job.

Class	Body weight	Calorific demand
Healthy adult male	60 kg	2730 kcal
Healthy adult female	55 kg	2230 kcal

Question 47.
Mention the diet of an adult individual according to daily energy requirement.
Answer:
The following table shows the diet of an adult individual according to daily energy requirement.

Question 48.
What is meant by metabolic disorder?
Answer:
Within all the living cells several metabolic reactions go on continuously day and night. If any of these reactions go out of order due to insufficiency of any reactant (nutrients or substrates), enzyme or any physical factor, the effect is seen as abnormal life activity in an organism. This abnormality is known as metabolic disorder. Example- Diabetes mellitus, obesity, arthritis are some common metabolic disorders.

Question 49.
What is meant by hyperthyroidism? Mention its symptoms.
Answer:
Hyperthyroidism:The disorder related to increased secretion of thyroxin hormone from thyroid gland, is known as hyperthyroidism.
Symptoms: Symptoms of hyperthyroidism are-

• Irregular heart rate
• Hypertension
• Increased BMR
• Exophthalmic goitre.

Question 50.
What is diabetes mellitus? Mention its symptoms.
Answer:
Diabetes mellitus: The metabolic disorder in which blood sugar level is elevated above normal (140 mg/100 ml blood) after two hours of taking full meal, due to insulin deficiency, is called diabetes mellitus.

Symptoms: Symptoms of diabetes mellitus are-

• Frequent urination
• Fatigue
• Excessive urge for sweet food
• Weight loss
• Delayed healing of wounds
• Boils and sores.

Question 51.
What is meant by obesity? Mention the problems related to obesity.
Answer:
Obesity: The metabolic disorder, noticed as very high body mass index (above 30), caused mainly due to intake of high calorie food beyond normal requirement of the body, is known as obesity.
Problems: Problems of obesity-

• Loss of normal agility
• Fatigue
• Breathlessness
• Hypertension
• Cardiac disorder.

Question 52.
What is meant by atherosclerosis?
Answer:
The metabolic disorder in which fatty materials and WBCs accumulate on the inner wall of arteries to make it rough, non-elastic and reduce the diameter of arterial lumen, is known as atherosclerosis.

Question 53.
What is meant by liver cirrhosis?
Answer:
The metabolic disorder in which normal hepatic cells are transformed into fibrous scar tissues hindering normal secretory activities of liver and finally inactivating the liver function as a whole, is known as liver cirrhosis.

Question 54.
What is meant by arthritis?
Answer:
Arthritis is a metabolic disorder that involves painful inflammation and impaired movement of bone joints due to deposition of metabolic wastes in it or degradation of bones and cartilages.

Question 55.
What is caecotrophy?
Answer:
Certain mammals like rabbits, guinea pigs, etc. eject the semi-digested food of the caecum in the form of faeces or pellets, and engulf it again for complete digestion. This type of nutritional process is called caecotrophy. It is also known as coprophagy.

Question 56.
What do you understand by protein sparing foods?
Answer:
Protein sparing foods are foods other than proteins from which the body derives energy, obtain raw materials to synthesise cellular components as well as replenish physical loss. Generally carbohydrates are known as protein sparing foods and this type of function of carbohydrates is known as protein sparing action of carbohydrates.

Question 57.
All foods are nutrients but all nutrients are not food-Explain.
Answer:
All substances required for the overall nutrition and metabolism of the body, either directly or indirectly, are known as nutrients. Among them only the energy yielding nutrients such as carbohydrates, proteins and fats are generally considered as food. The others such as vitamins, mineral salts and water are incapable of yielding energy but are essential for growth, developing resistance against diseases, replenishing physical loss and thus, are called protective nutrients. Therefore, we can say that all foods are nutrients but all nutrients are not food.

Question 58.
Why milk cannot be considered as a balanced diet?
Answer:
Milk is generally deficient in vitamin C and iron (Fe) and therefore, an adult individual cannot obtain his/her required nutrients from milk. Thus, milk is not considered as a balanced diet in adults.
State the location and function of gall bladder.
Location: Gall bladder is located on the right side of the abdomen just beneath the right lobe of the liver.
Function: Its function is to store, concentrate and release bile which is produced by the liver.

Question 60.
Distinguish between anabolism and catabolism.
Answer:

Features	Anabolism	Catabolism
1. Nature	Constructive metabolism	Destructive metabolism
2. Dry weight	Increases	Decreases
3. Nature of transformation	Simple molecules are transformed into complex organic matter	Complex organic matters are broken down to simpler form
4. Example	Photosynthesis and nutrition	Respiration and excretion

Long Questions and Answers : (5 marks for each question)

Question 1.
Mention the different types of plant nutrition with example.
Answer:
Different types of plant nutrition with examples
Plants perform nutrition in different ways, which are mentioned below.
1. Autotrophic nutrition: In this process, plants perform nutrition by synthesising their own food from simple inorganic matters by photosynthesis followed by assimilation of the simple sugars produced in this process.
Example-All green plants, certain blue-green algae cyanobacteria, protists like Euglena, Chrysamoeba and photosynthetic bacteria like Rhodopseudomonas, Rhodospirillum etc.

2. Heterotrophic nutrition: The plants which cannot carry out photosynthesis due to the lack of photosynthetic pigments and depend on other living or dead or decaying organic matter of food, are called heterotrophs. Their mode of nutrition is called heterotrophic nutrition. These are discussed below.
Parasitic nutrition: In this process, some plants grow on other plants (called hosts) and draw nutrition from them.
Example-Plants like Cuscuta, Rafflesia, etc. show parasitic nutrition.

Saprophytic nutrition: In this process, some plants draw nutrition from dead organisms and decaying organic matters.
Example-All types of fungi, like Agaricus, Mucor, Penicillium etc. perform saprophytic nutrition.

Symbiotic nutrition: In some cases, two different plants live in close association and are mutually benefited by that association. This mode of nutrition is called symbiotic nutrition. Example-Lichen is a symbiotic association of algae and fungi. Here, the fungal part provides the settling platform and water to the algal part. In return, the algae synthesise and supply food.

Insectivory: Certain plants draw nitrogenous nutrients from small insects. These plants have special organs, typically modified for trapping insects. This mode of nutrition is called insectivory.
Example-Pitcher plant, sundew, bladderwort are some plants which show insectivory.

Question 2.
Mention the different types of animal nutrition with example.
Answer:
Different types of animal nutrition
Animals cannot synthesise their own food like plants. For nutrition, they depend on food from plants or other animals. Animals perform three types of heterotrophic nutrition-holozoic, symbiotic and parasitic. These are discussed below.
1. Holozoic nutrition: This is a type of heterotrophic nutrition in animals, which is characterised by the intake and internal processing of the whole food. This is of the following types.
Herbivory: The mode of nutrition of animals, feeding on plants or plant parts is called herbivory.
Example-Cow, goat, monkey etc.
Carnivory: The mode of nutrition of animals feeding on the flesh of other animals is called carnivory.
Example-Tiger, lion, etc.
Coprophagy: Faeces of many animals contain nutritionally important substances. Some animals draw nutrients by consuming their own faeces, or of other animals. This type of nutrition is called coprophagy.
Example-Rabbits, guinea pigs, dung beetles etc. show coprophagy.

Omnivory: The mode of nutrition of animals feeding on all types of food, of both plant or animal origin, is called omnivory.
Example-Man, dog, crows.

Carrion feeding: A few animals exclusively feed on flesh of dead animals for their nutrition. This is known as carrion feeding nutrition. Such animals are called scavengers.
Example-Vultures, hyenas etc.

2. Symbiotic nutrition: Sometimes, two animals develop a close association between them, from which both are nutritionally benefited. This type of nutrition is called symbiotic nutrition. Example-Escherichia coli (a bacterium) gets shelter and food in human intestine. In return, they synthesise vitamin.

3. Parasitic nutrition: Some animals draw nutrients from other living organisms (hosts);:thereby benefiting itself and harming the other. This mode of nutrition is called parasitic nutrition. Example-Plasmodium, Entamoeba, tapeworm, round worm etc. live inside the body of the host and are called endoparasites. Lice, ticks etc. live on the body surface of the host and are called ectoparasites. Some animals draw nutrients from blood of other animals. This mode of parasitic nutrition is called sanguinivory. Leeches, vampire bats etc. show this type of nutrition.

Question 3.
Briefly discuss the different phases of holozoic nutrition.
Answer:
Phases of holozoic nutrition
Holozoic nutrition involves five different phases, which are mentioned below.
1. Ingestion: In this step, food materials are taken into the mouth, chewed by teeth and are pushed into the food pipe or cesophagus. Besides teeth, tongue also helps in this process. Salivary secretion makes the food bolus softer to facilitate this process.

2. Digestion: This step involves mouth, stomach, liver, pancreas and small intestine. Several enzymes are secreted inside these organs from the glandular cells. In the presence of water, these enzymes act upon respective food materials and help in the breakdown of the matters into simple and absorbable forms. This step is known as hydrolysis or digestion of food.

3. Absorption: Mainly small intestine is involved in this process. Stomach and large intestine also play some role in it. End products of digestion are taken into the blood capillaries, where they are absorbed.

4. Assimiation: All tissues of the body are involved in this process. In this penultimate phase of holozoic nutrition. various nutritionally important compounds and ions, absorbed in the blood frum GI tract, enter into cells and become a part of the protoplasm.

5 Egestion: this process involves the rectum and anus of large intestine. In this last phase, undigested food matters are temporarily stured and then discharged as faeces.

Question 4.
Briefly describe the structure of human alimentary canal.
Answer:
Structure of human alimentary canal
The long tube or passage exiending from mouth to anus through which food passes during digestion is calied the alimentary canal. It is composed of the following parts-
1. Mouth: It is the opening of the alimentary canal, guarded by a pair of lips. The inner chamber is known as the buccal cavity, which consists of a muscular tongue at the base. The cavity also consists of an upper and a lower jaw, fitted with a maximum of 32 teeth (16 on each jaw).

2. Pharynx: It is slightly swollen, muscular chamber behind the buccal cavity.

3. Oesophagus: It is a straight, vertical, muscular tube, that carries food from the pharynx to the stomach.

4. Stomach: It is J-shaped muscular sac, present on the left side of the upper abdominal cavity. It consists of four regions-the cardiac stomach (upper portion, close to the heart), fundic stomach (wide middle portion), the body (portion between fundic stomach and pyloric stomach) and pyloric stomach (lower portion, attached to duodenum).

5. Small intestine: It is a very long, narrow and highly convoluted tube, that extends from the stomach to the large intestine and occupies maximum portion of the abdominal cavity. It has three portions-duodenum (emerging from stomach), jejunum (the middle region) and ileum (meets the large intestine).

6. Large intestine: This tube is less coiled and broader than small intestine. It consists of three parts-caecum (the dilated portion, where small intestine meets), colon (the tubular part consisting of four regions–ascending colon, transverse colon, descending colon and sigmoid colon), rectum (a wide tube, next to the sigmoid colon, that proceeds downward and opens through the anus).

Question 5.
raw a labelled diagram of the human alimentary system.
Answer:
A labelled diagram of the human alimentary system

Question 6.
Briefly describe the different digestive glands of human alimentary system.
Answer:
Different digestive glands of human alimentary system
Human alimentary system consists of different types of digestive glands. These are discussed below.
1. Salivary glands: Three pairs of salivary glands are present in the buccal cavity.

• Parotid glands: Situated at the base of two ears.
• Submaxillary or submandibular glands: Situated on the two sides below the lower jaw.
• Sublingual glands: Situated on either sides of the base of the tongue.

2. Gastric glands: Numerous, unicellular gastric glands present in the inner wall of the stomach.
3 Liver: It is the largest gland of the human body, placed below the diaphragm at upper right portion of the abdominal cavity. It has two distinct lobes-left lobe and right lobe. A balloonshaped gall bladder is present on the right lobe.
4. Pancreas: Leaf-shaped organ, transversely placed below the stomach within the duodenal arch.
5. Intestinal glands: Numerous unicellular glands are arranged in the inner wall of the intestine.

Question 7.
Mention the names, sources and roles of the different amylolytic enzymes in digestion.
Answer:
Different amylolytic enzymes in digestion
The names, sources and roles of different amylolytic enzymes that take part in digestion are given below.

Question 8.
Mention the names, sources and roles of different proteolytic and lipolytic enzymes in digestion. 3 + 2
Answer:
Different proteolytic enzymes in digestion
The names, sources and roles of different proteolytic enzymes are given below.

Different lipolytic enzymes in digestion
The names, sources and roles of different lipolytic enzymes are given below.

Question 9.
How does absorption of digested food matters occur in the human GI tract? Briefly explain the method of assimilation of nutrients in the human body. 3 + 2
Answer:
Method of absorption of food
Absorption mainly occurs in the small intestine. The inner wall of the intestine develops many small finger-like projections called villi (singular-villus). Each villus has a central lymph duct called lacteal, and a few blood capillaries. Monosaccharides, amino acids and glycerol are absorbed in the blood capillares. Fatty acids are taken into the lacteals. Besides small intestine, a few materials are absorbed through the epithelial lining of the stomach and large intestine. These include water, alcohol, few salts and drugs.

Method of assimilation of food From the intestine, blood carries glucose, fructose, amino acids and a few fatty acid molecules to liver, through hepatic portal vessels. After supplying nutrients in the liver, this blood moves to systemic circulation. Lymph ducts carry simple fat molecules and finally transfer them to systemic circulation. As a result, all nutrients reach every tissue and cell through blood. Finally, these essential molecules are incorporated in the protoplasm of the cells.

Question 10.
Briefly explain the fate of the nutrients in a living cell. Mention the features of a balanced diet. 3 + 2
Answer:
Fate of nutrients in a living cell
The absorbed nutrients get assimilated within the cells and carry out different functions.
Monosaccharides participate in the cellular respiration as respiratory substrates. These are oxidised to generate energy, which is necessary for different life activities. Proteins help in building body cells and lipids are kept as stored matters. Vitamins act as coenzymes and minerals act as cofactors of various enzymes, or as fundamental components of some cellular molecules. Almost all end products of digestion undergo necessary changes within the cells by the process of metabolism.

Features of a balanced diet Foods, that we take everyday, do not always make a balanced diet. Moreover, any single food material cannot be treated as a balanced diet. It should have certain features which are as follows-

1. It should help to maintain the growth and perfect shape of the body.
2. It should perfectly meet the calorific demand of a body.
3. It should help to develop resistance against infection.

Question 11.
What do you understand by the term mechanical digestion? Mention the different types of mechanical digestion. 2+3
Answer:
Mechanical digestion
The process by which dry and semi-solid foods are converted into smaller fragments in the Gl tract and also the process by which the food is pushed forward along the G1 tract, is called mechanical digestion.

Different types of mechanical digestion
Generally mechanical digestion is of three types-
1. Mastication or chewing: Food matters taken into the buccal cavity undergo mechanical processing. Different types of teeth help to cut, tear and masticate the food matters into small particles. Saliva moistens it to form a soft and smooth dough-like matter. This whole process is known as mastication or chewing of food.

2. Swallowing: The process by which the food passes from the mouth to the pharynx and then enters the oesophagus by shutting the epiglottis, is known as swallowing or deglutition.

3. Movements of the GI tract: Movements of the gastro-intestinal tract occur which help in the forward movement of food. Generally two types of movements are seen-peristalsis and segmentation movement.

Question 12.
State the differences between small and large intestines. Distinguish between stomach and small intestine. 3 + 2
Answer:
Differences between small and large intestines

Features	Small intestine	Large intestine
1. Location in the gastrointestinal tract	After the stomach	After the small intestine
2. Structural parts	Duodenum, jejunum and ileum	Caecum, colon and rectum
3. Length	6-7 metres	1-1.5 metres
4. Diameter of the tract	Smaller in diameter	Larger in diameter
5. Function	Digestion and absorption	Absorption of water and mineral salts of and formation and storage of faeces

Differences between stomach and small intestine

Features	Stomach	Small intestine
1. Location	After the oesophagus	After the stomach
2. Shape	Bag-shaped	Tube-shaped
3. Parts	4 parts-cardiac, fundus, body and pyloric	3 parts-duodenum, jejunum and ileum
4. Function	Temporary storage of food and partial digestion	Complete digestion and absorption

Question 13.
Describe the different phases of protein digestion with the help of a suitable schematic diagram.
Different phases of protein digestion
Digestion of protein occurs stepwise, mostly in the stomach and small intestine. Several proteolytic enzymes (enzymes that break down protein) influence the process of protein digestion. The different phases of protein digestion are as follows-
1. Digestion in the buccal cavity: Since no proteolytic enzyme is present in the buccal cavity, protein digestion does not occur here.

2. Digestion in the stomach: This is the site where protein digestion starts. Upon entering the stomach, the food is converted into chyle after it gets mixed with the gastric juice secreted from the gastric glands of the stomach. Presence of HCl in the gastric juice, makes the chyle acidic and activates the proteolytic enzyme pepsin. Pepsin converts proteins into peptones. However, pepsin is unable to execute the complete digestion of proteins into peptones and therefore, incomplete digestion of proteins occur in the stomach.

3. Digestion in the small intestine: Upon entering the small intestine, the undigested proteins and peptones mix with the pancreatic and the enteric juices. Proteolytic enzymes, named trypsin and chymotrypsin present the pancreatic juice hydrolyse peptones and undigested proteins into small peptides. After that, these small peptides are broken down into amino acids by the action of another enzyme, called erepsin, which is present in the enteric juice. These amino acids are then absorbed into the blood with the help of villi present in the small intestine.

Question 14.
Explain the different steps of carbohydrate digestion with the help of a suitable schematic diagram.
Answer:
Different steps of carbohydrate digestion
Carbohydrate digestion occurs mainly in the buccal cavity and in the small intestine.
Digestion in the buccal cavity: Carbohydrates’ specially boiled starch’ present in the food, mix with ptyalin present in the salivary juice and is converted to maltose and isomaltose. Maltase’ present in saliva’ converts maltose into 2 molecules of glucose. The quantity of maltase in the saliva is very low and therefore, small amounts of glucose is formed in the buccal cavity by the action of the salivary enzymes.

2. Digestion in the stomach: Digestion of carbohydrates does not occur in the stomach due to absence of amylolytic or carbohydrate digesting enzymes. Only a small amount of sucrose is hydrolysed into glucose and fructose with the help of HCl.

3. Digestion in the smail intestine: In the small intestine, both boiled and unboiled starch get converted into maltose by the action of pancreatic amylase. Maltase present in enteric juice then breaks down maltose into 2 molecules of glucose. Majority of the ingested starch is broken down by pancreatic amylase. But if any portion of the starch is still left unbroken, then intestinal amylase will act on it to break it down into simpler components. Moreover, intestinal lactase and sucrase hydrolyse lactose into glucose and galactose and sucrose into glucose and fructose respectively. In this way, complex carbohydrates are broken down into simple monosaccharide units which are then absorbed in the body.

Question 15.
What do you mean by fat digestion? Briefly describe the different sieps involved in fat digestion. 1 + 4
Answer:
Fat digestion
The process by which fats or lipids are broken down into fatty acids and glycerol in the alimentary canal with help of the enzyme lipase and bile salts present in the digestive juice is called fat digestion.

Different steps of fat digestion
Fat digestion mainly occurs in the stomach and in the small intestine. The different steps of fat digestion are described below.

1. Digestion in the buccal cavity: Fat digestion does not occur in the buccal cavity due to insufficient amount of fat digestive enzymes.
2. Digestion in the stomach: When the ingested food enters the stomach, it gets mixed with the gastric juice. Gastric lipase, present in the gastric juice, breaks down fats into fatty acids and glycerol.
3. Digestion in the small intestine: As the lipid molecules enter the duodenum of the small intestine, they get mixed with the bile, pancreatic and intestinal juices. The bile salts present in the bile juice emulsify the lipid molecules. Then pancreatic and intestinal lipases act on the emulsified fats and break them into fatty acids and glycerol. In this way, fat is broken down into fatty acids and glycerol which are then absorbed in the bloodstream.

Question 16.
What is basal metabolic rate? Mention the factors that regulate basal metabolic rate. 2 + 3
Answer:
Basal Metabolic Rate (BMR)

Basal metabolic rate is the amount of energy given out per hour and per square metre of body surface area of a person who is awake, but at complete mental and physical rest in comfortable environment and in a post-absorptive state, i.e. 12 to 18 hours after meal. It is the minimum amount of energy required to maintain vital physiological functions such as breathing, blood circulation etc. BMR of a healthy adult man is 40 kcal/hour/sq. metre body surface area and BMR of a healthy adult female is 37 kcal/hour/sq. metre body surface area. It is generally measured with the help of Benedict Roth apparatus.

Factors regulating basal metabolic rate
The factors which regulate the basal metabolic rate are discussed below.

1. Body surface area: BMR is directly proportional to the body surface area.
2. Age: Children have greater body surface area as compared to their body weight, therefore, in children BMR is more than in adults.
3. Sex: Males have greater BMR than females.
4. Nutritional status: Long term malnutrition causes decrease in BMR.
5. Weather: People living in temperate regions have greater BMR than people living in warmer areas.
6. Endocrine giands: Hormones secreted from thyroid, adrenal glands and anterior pituitary, increase BMR.
   Body temperature: BMR increases or decreases with increase or decrease of body temperature.

Question 17.
State the significance of metaholism. What do you mean by metabolic disorders? State the reasons for metabolic problems in humans. 2+1+2
Answer:
Significance of metabolism
The significance of metabolism are as follows-
1. Maintenance of body homeostasis: Metabolism is essential for the normal functioning of all biochemical reactions taking place in the body.
2. Generation of energy: Metabolism provides energy, which is needed for the normal functioning of various body processes.

Metabolic disorders/problems
The condition in which normal body metabolism is altered, is called metabolic disorders or problems. Generally, metabolism decreases or sometimes halts in such conditons.

Reasons for metabolic disorders in humans
The reasons for metabolic disorders in humans are as follows-

1. Insufficient enzymes: A decrease in the functional enzymes is one of the main reasons of metabolic problems.
2. Insufficient hormones: Hormones generally regulate several metabolic processes. In absence of such hormones, these metabolic processes are altered leading to metabolic problems.
3. Genetic problems: Generally mutations of genes, involved in different metabolic pathways, lead to metabolic disorders.

Question 18.
Distinguish between autotrophic nutrition and heterotrophic nutrition.
Answer:
Differences between autotrophic nutrition and heterotrophic nutrition

Features	Autotrophic nutrition	Heterotrophic nutrition
1. Nutritional dependence	Can synthesise own food hence, nutritionally independent	Cannot synthesise their own food, hence nutritionally dependent upon other organisms
2. Chlorophyll	Possess chlorophyll	Do not possess chlorophyll
3. Nature of food	Simple carbohydrate in solution	Solid and complex organic and inorganic matters
4. Phases	Two phases-synthesis and assimilation	Five phases-ingestion, digestion, absorption, assimilation and egestion
5. Occurrence	Occurs in green plants and some bacteria	Occurs in all animals

Question 19.
Compare among parasitic, saprophytic and symbiotic nutrition.
Answer:
Comparison among parasitic, saprophytic and symbiotic nutrition

Question 20.
Distinguish between holophytic and holozoic nutrition.
Answer:
Differences between holophytic and holozoic nutrition

Features	Autotrophic nutrition	Heterotrophic nutrition
1. Nutritional dependence	Can synthesise own food hence, nutritionally independent	Cannot synthesise their own food, hence nutritionally dependent upon other organisms
2. Chlorophyll	Possess chlorophyll	Do not possess chlorophyll
3. Nature of food	Simple carbohydrate in solution	Solid and complex organic and inorganic matters
4. Phases	Two phases-synthesis and assimilation	Five phases-ingestion, digestion, absorption, assimilation and egestion
5. Occurrence	Occurs in green plants and some bacteria	Occurs in all animals

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.1A Plant Physiology: Photosynthesis offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.1A Question Answer – Plant Physiology: Photosynthesis

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Name the scientist who coined the term ‘photosynthesis’.
Answer:
Barnes coined the term ‘photosynthesis’.

Question 2.
Name a vascular land plant, which photosynthesises through its roots.
Answer:
Stylites andicola is a vascular land plant, which photosynthesises through its roots.

Question 3.
What does NADP stand for?
Answer:
NADP stands for Nicotinamide Adenine Dinucleotide Phosphate.

Question 4.
From which of the raw materials does glucose get its oxygen during photosynthesis?
Answer:
Glucose, the end product of photosynthesis, gets its oxygen from CO₂

Question 5.
Which element is taken up by green plants from environment in the form of an oxide?
Answer:
Carbon is absorbed by green plants from the environment in the form of an oxide, namely carbon dioxide.

Question 6.
Which biocatalyst is essential for photosynthesis?
Answer:
Chlorophyll is the biocatalyst, which is essential for photosynthesis.

Question 7.
Which pigments are necessary for photosynthesis, other than chlorophyll?
Answer:
Other than chlorophyll, carotenoids are the pigments which are necessary for photosynthesis.

Question 8.
Name two members under kingdom Protista, which are capable of synthesising their own food by photosynthesis.
Answer:
Euglena sp. and Chrysamoeba sp. are the two members under kingdom Protista, which are capable of synthesising their own food by photosynthesis.

Question 9.
Name an enzyme, necessary for the assimilation of carbon during the lightindependent phase of photosynthesis.
Answer:
The enzyme RuBisCO is necessary for the assimilation of carbon during the lightindependent phase of photosynthesis.

Question 10.
What is the full form of the enzyme RuBisCO?
Answer:
The full form of RuBisCO is Ribulose Bisphosphate carboxylase/oxygenase.

Question 11.
Which of the raw materials of photosynthesis is oxidised during the process?
Answer:
Water molecule is oxidised during the process of photosynthesis.

Question 12.
Which of the raw materials of photosynthesis is reduced during the process?
Answer:
Carbon dioxide is reduced during photosynthesis.

Question 13.
In case of terrestrial plants, which process reduces the content of CO₂ and increases the content of O₂ in the atmosphere?
Answer:
In case of terrestrial plants, the process of photosynthesis reduces the content of CO₂ and increases the content of O₂ in the atmosphere.

Question 14.
Where do plants generally store their food?
Answer:
Plants generally store their food in roots, stems and fruits.

Question 15.
What are the end products of photosynthesis?
Answer:
Glucose, oxygen and water are the end products of photosynthesis.

Question 16.
Name the following reaction:
Answer:
This reaction is named as photolysis of water.

Question 17.
Name the following reaction:
Answer:
This reaction is called photophosphorylation.

Question 18.
Who discovered that oxygen, evolved during photosynthesis, comes from water?
Answer:
British scientist Robin Hill discovered that oxygen, evolved during photosynthesis, comes from water.

Question 19.
Who discovered the reaction path of carbon assimilation?
Answer:
Scientist Blackman discovered the reaction path of carbon assimilation.

Question 20.
Who discovered the reaction path of glucose synthesis and regeneration of RuBP from PGA?
Answer:
Scientist Melvin Calvin and his co-workers discovered the cyclic reaction path of glucose synthesis and regeneration of RuBP from PGA.

Question 21.
How many phosphoglyceraldehyde (PGAld) molecules are required to produce a glucose molecule?
Answer:
Two phosphoglyceraldehyde (PGAld) molecules are required to produce one molecule of glucose.

Question 22.
Which co-enzyme carries hydrogen for the reduction of PGA?
Answer:
NADP carries hydrogen for the reduction of PGA.

Question 23.
Which compound supplies chemical energy for the reduction of PGA?
Answer:
Adenosine triphosphate (ATP) supplies chemical energy for the reduction of PGA.

Question 24.
Out of 12 PGAld molecules, how many take part in the synthesis of RuBP in Calvin cycle?
Answer:
Out of 12 PG.Ald molecules, 10 molecules take part in the synthesis of RuBP in Calvin cycle.

Question 25.
Which are the end products of light-dependent phase of photosynthesis?
Answer:
Oxygen, ATP and NADPH+H⁺ are the end products of light-dependent phase of photosynthesis.

Question 26.
Which of the end products of light-dependent phase take part in the reactions of light-independent phase of photosynthesis?
Answer:
ATP and NADPH+H⁺ are the end products of light-dependent phase, which take part in the reactions of light-independent phase of photosynthesis.

Question 27.
Which reactant of light-independent phase of photosynthesis is received from the environment?
Answer:
CO₂ is the only reactant of the light-independent phase of photosynthesis which is received from the environment.

Question 28.
Which are the essential components, necessary for light-independent reactions of photosynthesis?
Answer:
CO₂, ATP, NADPH₂, and RuBP are the essential components, which are necessary for the light independent reactions of photosynthesis.

Question 29.
Which instrument is used to measure the absorption spectrum of chlorophyll?
Answer:
The absorption spectrum of chlorophyll is measured with the help of spectrophotometer.

Question 30.
Due to excessive heat from the sun, the process of photosynthesis stops. What is this condition called?
Answer:
The condition, in which the process of photosynthesis stops due to excessive heat from the sun, is called solarisation.

Question 31.
Under what temperature does photosynthesis occur at its best?
Answer:
Photosynthesis occurs at its best at an optimum temperature ranging between 25°C – 35°C

Question 32.
Name a bacteria which can prepare its own food without performing photosynthesis.
Answer:
Thiobacillus sp, is a bacteria which can prepare its own food without performing photosynthesis.

Question 33.
In green plants, what percentage of the total stored water is used during photosynthesis?
Answer:
During photosynthesis, only 1% of the total stored water is used up by green plants.

Question 34.
Name the co-pigment present in green plants which helps in photosynthesis.
Answer:
In green plants, carotenoids act as co-pigment, which help in photosynthesis.

Question 35.
What is the absorption spectrum of carotenoid?
Answer:
Absorption spectrum of carotenoid is blue-green.

Question 36.
Name two carotenoids.
Answer:
Carotene and xanthophyll are two carotenoids.

Question 37.
Why photosynthesis does not occur in animal cells?
Answer:
Photosynthesis does not occur in animal cells because they lack chloroplast and hence the photosynthetic pigment chlorophyll.

Question 38.
Which compound is both a raw material and a by-product, in the process of photosynthesis?
Answer:
Water is both a raw material as well as a byproduct, in the process of photosynthesis.

Question 39.
How do completely submerged aquatic plants absorb necessary CO₂ for photosynthesis?
Answer:
Completely submerged aquatic plants absorb necessary CO₂ through their entire body surface by the process of diffusion.

Question 40.
Give an example of a natural and an artificial Hill reagent?
Answer:
An example of natural Hill reagent is NADP, and an example of artificial Hill reagent is potassium ferric oxalate.

Question 41.
What are the two types of photophosphorylation?
Answer:
The two types of photophosphorylation are-

• cyclic photophosphorylation and
• non-cyclic photophosphorylation.

Short Questions and Answers : (2 marks for each question)

Question 1.
Define photosynthesis.
Answer:
Photosynthesis is a photochemical process in which green plants and certain chlorophyll containing organisms utilise water and carbon dioxide as raw materials to synthesise monosaccharide (glucose) in their body by entrapping light energy (especially sunlight) within it and releasing oxygen as a by-product in the environment.

Question 2.
Mention the components, necessary for photosynthesis.
Answer:
The materials required for photosynthesis are as follows-

• Raw material- Water and carbon dioxide,
• Pigments – Chlorophyll and carotenoids (carotene and xanthophyll),
• Energy- Light (sunlight or bright artificial light).

Question 3.
Where does photosynthesis occur?
Answer:
Photosynthesis occurs in the chloroplast-containing parenchyma (chlorenchyma) tissues known as mesophyll tissue of higher green plants. These tissues are distributed in leaves and all other green parts of the plants, like stems (in herbs), sepals of flowers, petals (water lily and custard apple flower), bracts (vasak plant), stipule (pea plant), root (orchid, Tinospora) etc.

Question 4.
How do plants absorb water for photosynthesis?
Answer:
Terrestrial plants absorb water from the soil with the help of their roots. Aquatic plants absorb water from the surrounding water medium through their body surface by the process of simple diffusion. Epiphytes (plants growing on other plants) like orchids, have aerial roots, called velamen, with thick hygroscopic outer coating, which absorb rain water and moisture from air to fulfill the plant’s need of water.

Question 5.
How do plants absorb CO₂ for photosynthesis?
Answer:
All terrestrial plants absorb CO₂ from the atmosphere through stomata of the leaves. Aquatic plants absorb dissolved CO₂ from surrounding water by simple diffusion through body surface. Partially submerged plants absorb CO₂ through stomata of the aerial portion of their body and the submerged portion get it by diffusion from the surrounding water medium.

Question 6.
What do photosynthetic pigments in plants do?
Answer:
In plants, there are two types of photosynthetic pigments, namely, chlorophyll and carotenoids. Chlorophyll helps in the dissociation of water and formation of energy packed ATP molecules. Carotenoids (carotene and xanthophyll) trap light energy and transfer it to chlorophylls for further reaction.

Question 7.
What is meant by absorption spectrum of photosynthesis?
Answer:
The specific wavelength of visual spectrum, which is absorbed by certain plant pigments and used in photosynthesis, is called absorption spectrum of that particular pigment.

Question 8.
What is meant by action spectrum of chlorophyll?
Answer:
Out of the seven colours of the visible spectrum of light, chlorophyll molecules strongly absorb red (650-760nm) and blue (430-470nm) light which is most effective for photosynthesis. Therefore, this region of the visible spectrum denotes the action spectrum of chlorophyll.

Question 9.
Mention the events occurring during the light-dependent phase of photosynthesis.
Answer:
Five different events occur during the light dependent phase of photosynthesis. These are–

• activation of chlorophyll,
• ionisation of water (photolysis of water),
• reduction of NADP⁺
• production of oxygen and
• photosynthetic phosphorylation.

Question 10.
What is meant by activation of chlorophyll?
Answer:
Light from the sun comes to earth in the form of energy-rich particles, called photons. When photons hit a chlorophyll molecule, it gets excited and releases an energised electron. This event is known as activation of chlorophyll.

Question 11.
What is meant by photolysis or ionisation of water?
Answer:
Being hit by photons, chlorophyl molecules get excited and dissociates water molecules into protons H⁺ and hydroxyl ions OH^–. This lightdependent dissociation of water molecule is called photolysis of water. This reaction is popularly known as Hill reaction.

Question 12.
What is meant by reduction of NADP⁺ ?
Answer:
NADP⁺ is a proton acceptor, which is present in chloroplast. During light-dependent phase of photosynthesis, proton (H⁺) is produced during photolysis of water, electron (e^–) is released from an excited chlorophyll molecule and NADP⁺, present in the photosynthetic cells, react to produce NADPH+H⁺. This reaction step is known as reduction of NADP⁺.
\(\mathrm{NADP}^{+}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{NADPH}+\mathrm{H}^{+}\)

Question 13.
How is O₂ produced during photosynthesis?
Answer:
During photolysis of water, protons (H⁺) and hydroxyl ions (H^–) are produced. These hydroxyl ions then release one electron each and are transformed into hydroxyl radicals [OH]. These radicals combine to form water H₂O and oxygen O₂ molecules. Thus, O₂ is produced during light-dependent phase of photosynthesis, which is a by-product.
\(4 \mathrm{OH}^{-} \rightarrow 4[\mathrm{OH}]+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_2 \mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O}+\mathrm{O}_2 \uparrow\)

Question 14.
What is meant by photophosphorylation?
Answer:
During light-dependent phase of photosynthesis, the energised electrons released from photon hit chlorophylls, help to combine adenosine diphosphate (ADP) and inorganic phosphate (IP) to produce an energy-rich compound, adenosine triphosphate (ATP). This reaction is known as photosynthetic phosphorylation or photophosphorylation.

Question 15.
Why is it better to designate the second phase of photosynthesis as light-independent phase rather than dark phase?
Answer:
The term dark phase apparently indicates events occurring in dark, but reactions of photosynthesis never occur in the absence of light. The second phase of photosynthesis does not need direct light but some by-products of light phase like ATP and NADPH₂, come to act here. Therefore, it is better to designate this phase as light-independent phase rather than dark phase.

Question 16.
Which reactions take place in the light-independent phase of photosynthesis?
Answer:
During light-independent phase of photosynthesis four different reactions occur. These are

• carbon assimilation,
• reduction of PGA,
• resynthesis of RuBP and
• glucose synthesis.

Question 17.
What is meant by carbon assimilation?
Answer:
The CO₂ absorbed by photosynthetic plants from the atmosphere, reacts with RuBP, a five carbon compound, present in the stroma of chloroplast, to produce phosphoglyceric acid (PGA) in the presence of an enzyme, called RuBisCO. In this reaction, carbon atom of CO₂ is assimilated within the cellular organic compounds. This reaction is known as carbon assimilation. Here, 2 molecules of PGA are produced.

Question 18
How does reduction of PGA occur in lightindependent phase of photosynthesis?
Answer:
After the production of PGA during the assimilation of carbon, two products of light-dependent phase, namely NADPH+H⁺ and ATP come into action. NADPH+H⁺ reacts with PGA and reduces it to produce phosphoglyceraldehyde (PGAld). ATP supplies the necessary chemical energy for this reaction.

Question 19.
How is glucose synthesised in the lightindependent phase of photosynthesis?
Answer:
During the light-independent phase of photosynthesis, RuBP is carboxylated to form PGA, which is reduced to phosphoglyceraldehyde (PGAld) with the help of NADPH+H⁺ and ATP. Out of the total PGAld, 5/6th part undergoes a cycle of reactions and resynthesises RuBP. And the rest 1/6th portion of the total PGAld produced, then undergoes a series of reactions to produce glucose. Two molecules of PGAld produce 1 molecule of glucose.

Question 20.
Why are green plants considered as the food producers of the environment?
Answer:
By the process of photosynthesis, inorganic materials like water and carbon dioxide combine to produce a monosaccharide, called glucose. It is the basic component of all food matters on earth. From this glucose, all other carbohydrates, proteins and lipids are produced through various metabolic processes within the plant body, which is consumed by the other organisms. This is why, green plants are considered as food producers of the environment.

Question 21.
How does solar energy enter in the living organisms?
Answer:
During photosynthesis, light energy from the sun is trapped by the chlorophyll molecules. This energy is then transformed into chemical potential energy by the formation of glucose. At the end, this energy is transferred to different consumers or heterotrophic organisms and decomposers through food chain. This is how solar energy enters in the living organisms.

Question 22.
What are the sources of the components of carbon assimilation?
Answer:
The sources of the components of carbon assimilation are-

• CO₂ – Source of CO₂ is air,
• RuBP- Source of RuBP is the mesophyll tissue of leaf,
• NADPH+H⁺ Source of NADPH+H⁺ is NADP⁺ present in chlorophyll of leaf.
  NADP+ reacts with the H⁺ ion produced by the photolysis of water to form NADPH +H⁺and
• ATP – ATP is formed by the combination of ADP and inorganic phosphate in leaf during photophosphorylation.

Question 23.
Write the differences between light-dependent and light-independent phase of photosynthesis.
Answer:

Features	Light-dependent phase.	Light-independent phase
1. Role of sunlight	Sunlight is necessary	Sunlight is not necessary
2. Site of occurrence	It takes place in the grana of chloroplast	It takes place in the stroma of chloroplast
3. Production of oxygen	Oxygen is given out during this phase	Oxygen is not given out during this phase
4. Fate of NADP	NADP+ is reduced in this process, to form NADPH + H+	NADPH+ + H+ is oxidised in this process, to form NADP+

Long Questions and Answers : (5 marks for each question)

Question 1.
Briefly describe the reactions of light-dependent phase of photosynthesis.
Answer:
Reactions of light-dependent phase of photosynthesis
The reactions of light-dependent phase of photosynthesis occur in the stroma of chloroplastids. Five different reactions occur in this phase, which are mentioned below.

1. Activation of chlorophyll: Light from sun reaches the earth in the form of energy-packed particles, called photons. When these photons hit the chlorophyll molecules present in the chloroplast of green leaves, they get excited and release energised electrons. This event is known as activation of chlorophyll.

2. Photolysis of water: Activated chlorophyll dissociates water molecules into protons H⁺ and hydroxyl ions H^–. This light-dependent dissociation of water molecule is called photolysis or ionisation of water.

3. Reduction of NADP+ NADP⁺ is a proton acceptor, present in the chloroplasts. Proton H⁺ produced during the photolysis of water, reacts with NADP⁺and reduces it to NADPH+H⁺. In this reaction, necessary electrons for the subsequent reactions are emitted from the excited chlorophylls.

4. Production of oxygen: Hydroxyl ions H^–, produced during the dissociation or lysis of water, release electrons and are transformed into hydroxyl radicals OH. These radicals combine to form water H₂O and oxygen O₂ molecules.

5 Photosynthetic phosphorylation: The energised electrons, released from the photon-hit chlorophylls, help to combine adenosine diphosphate (ADP) and inorganic phosphate (iP) to produce an energy-rich compound, called adenosine triphosphate (ATP). This reaction is known as photosynthetic phosphorylation or photophosphorylation.

Question 2.
‘Green plants entrap solar energy and convert it into potential energy’- explain the sentence along with a diagram.
Answer:
Entrapping of solar energy and its conversion to potential energy by green plants. The source of every form of energy on earth is sunlight. The chlorophyll present in palisade cells of green plants absorbs the photon particles of the sunlight and stores it in the form of chemical energy in ATP through various chemical reactions.

This is known as the ‘entrapping of solar energy’. Later, the chemical energy of ATP is converted into the potential energy which remains stored within the glucose which is formed by the combination of CO₂ and H₂. This is known as the ‘conversion of solar energy into potential energy’.

Question 3.
Briefly describe the steps of light-independent phase of photosynthesis along with a diagram.
Answer:
The steps of light-independent phase of photosynthesis:

The reactions of light-independent phase occurs in stroma of chloroplastids. Four different reactions occur in this phase of photosynthesis. These are as follows-

1. Carbon assimilation: Photosynthetic plants absorb CO₂ from the atmosphere. This CO₂ reacts with RuBP in the stroma of chloroplast to produce phosphoglyceric acid (PGA). The enzyme RuBisCO catalyses this reaction. In this reaction, carbon atom (C) of CO₂ is assimilated within the cellular organic compounds. This reaction is known as carbon assimilation.

2. Reduction of PGA: In this step, two products of light-dependent phase, namely NADPH+H⁺and ATP come into action. NADPH + H⁺reacts with phosphoglyceric acid and reduces it to produce phosphoglyceraldehyde (PGAld). ATP supplies the necessary chemical energy for this reaction.

3. Re-synthesis of RuBP: Out of the total PGAld produced, 5/6th part undergoes a cycle of reactions and resynthesises RuBP. This reaction cycle is named Calvin cycle. In this cycle, several intermediate compounds are produced in subsequent steps.

4. Glucose synthesis: Out of the total PGAld produced, 1/6th part takes part in the synthesis of glucose. Within the stroma of chloroplasts, PGAld molecules undergo a series of reactions to synthesise glucose.

Question 4.
Write the significance of light-dependent phase of photosynthesis. What is the significance of light-independent phase of photosynthesis?
Answer:
Significance of light-dependent phase of photosynthesis:

The significance of light-dependent phase of photosynthesis are as follows-

• During photophosphorylation of the light-dependent phase, solar energy is converted into chemical energy and is stored as ATP.
• ATP, produced during photophosphorylation and NADPH₂, produced during reduction of NADP⁺, in the light-dependent phase, help in the reduction of PGA to PGAld, later in the light-independent phase.
• During the photolysis of water, it gets dissociated to liberate oxygen. This oxygen helps in respiration of all living organisms present in the environment.

Significance of light-independent phase of photosynthesis
The significance of light-independent phase of photosynthesis are as follows –

• Solar energy gets stored in glucose as potential energy. This energy helps the living world, either directly, or indirectly, to perform all metabolic functions.
• The CO₂ released into the environment by all organisms during respiration, is taken up by plants during the light-independent phase. As a result, the balance of CO₂ and O₂ is maintained in the environment.
• During this phase, assimilation of carbon takes place and carbohydrate, in the form of glucose, is produced as an end product. This glucose, either actively, or passively, forms the source of food for all living organisms.

Question 5
What are the significance of photosynthesis?
Answer:
Significance of photosynthesis
The significance of photosynthesis are mentioned below.

1. Trapping and transformation of solar energy: Light energy from the sun is trapped by chlorophyll and transformed into chemical potential energy by the synthesis of glucose. This energy is then passed on from the plants to the consumers through food chain.

2. Production of food: By photosynthesis, inorganic materials like water and CO₂ combine to produce glucose, which is the basic component of all food matters on earth. Not only plants but other animals also obtain this food, either directly or indirectly, to survive.

3. Maintenance of O₂ and CO₂ balance in the environment: During respiration, all living organisms release CO₂ and absorb O₂ .On the other hand, green plants release O₂ and absorb CO₂ during photosynthesis. Thus, photosynthesis along with respiration, helps to maintain the balance between O₂ and CO₂ in the environment.

4. Production of fuel: Due to natural disasters, like earthquake, plants get trapped under the soil and in due course of time get converted into coal and mineral oils. The energy obtained from these coal and mineral oils, is the solar energy which was entrapped by the plants in the past. This is how photosynthesis helps in the production of fuel.

5. Source of human welfare: We get different types of important materials from plants, like food, wood, paper, cloth, rubber, gum, paint etc. Apart from these, we get different alkaloids like morphine, quinine, reserpine etc. and various medicines from plants. Therefore, plants, more specifically photosynthesis, is very important for human welfare.

Question 6.
Write the role of chlorophyll in photosynthesis. How is photosynthesis related to the flow of energy in the environment?
Answer:
Role of chlorophyll in photosynthesis:
Chlorophyll gets excited by the absorption of photon particles of sunlight and dissociates the water absorbed by the root hairs into H⁺ and OH^– ions. Chlorophyll also converts the solar energy into the chemical energy which remains stored within ATP in the form of potential energy.

Relation of photosynthesis with energy flow in the environment The green plants trap solar energy and store it within ATP in form of chemical energy by photosynthesis. Later, this energy is converted to potential energy and remains stored within glucose, which is the end-product of photosynthesis.

On the other hand, a large part of potential energy, stored in glucose, is used up for performing various metabolic activities and is released as heat energy. The remaining potential energy enters the body of the primary consumers (herbivores), then secondary consumers carnivores. In this way, the energy reaches the ultimate consumers.

Decomposers, like various bacteria, fungi etc. act on the dead bodies of these consumers and the energy, thus, is recycled back into the environment through their decomposing activities. Thus, the solar energy returns to the environment after passing through producers and various consumers and decomposers. In this way, photosynthesis is related with energy flow in the environment.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.4 Circulation offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.4 Question Answer – Circulation

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which system of animal body can be treated as the system of transport?
Answer:
Circulatory system of animal body can be treated as the system of transport.

Question 2.
Which components of human circulatory system do act as vehicle?
Answer:
Blood and lymph of the human circulatory system act as vehicle of transport.

Question 3.
Which gases are transported through blood?
Answer:
Oxygen and carbon dioxide are transported through blood.

Question 4.
Which type of secretory products are transported through blood.
Answer:
Hormones are the main secretory products, transported through blood.

Question 5.
What does pulse rate indicate?
Answer:
Pulse rate indicates the rate at which the heart beats.

Question 6.
In which type of circulation different organs bathe in blood?
Answer:
In open circulatory system different organs bathe in blood.

Question 7.
From which body cavity blood enters into the heart of a cockroach?
Answer:
Blood enters into the heart of a cockroach from the pericardial sinus.

Question 8.
Why does blood of earthworm appear red?
Answer:
Blood plasma of earthworm contains haemoglobin, so it appears red.

Question 9.
Which is the largest sinus of insect body?
Answer:
Visceral sinus is the largest sinus of insect body.

Question 10.
How many ventricles does insect heart possess?
Answer:
Insect heart possesses thirteen ventricles.

Question 11.
Name an invertebrate animal, which possesses closed circulatory system.
Answer:
Earthworm possesses closed circulatory system.

Question 12.
Name an animal, in which blood does not take part in the transportation of the respiratory gases.
Answer:
In cockroach, blood has no role in the transportation of the respiratory gases.

Question 13.
Name a nutritionally important plasma protein.
Answer:
Albumin is a nutritionally important plasma protein.

Question 14.
Name an immunologically important plasma protein.
Answer:
Globulin is an immunologically important plasma protein.

Question 15.
Which disease is caused due to deficiency of red blood cells?
Answer:
Anaemia is caused due to the deficiency of red blood cells.

Question 16.
Which part of human circulatory system has the highest immunological importance?
Answer:
The lymph glands of human circulatory system have the highest immunological importance.

Question 17.
Which type / types of blood can be transfused to a person carrying ‘O’ blood group?
Answer:
A person with ‘O’ blood group can receive the ‘O’ group of blood only.

Question 18.
Which is the largest cell in the human blood?
Answer:
Monocyte is the largest cell in the human blood (Diameter. 12-18 μ m)

Question 19.
Which is the smallest cell in human blood?
Answer:
Platelet is the smallest cells in human blood. (Diameter, 2.5 μ m)

Question 20.
Which blood cells of human blood prevent blood coagulation inside blood vessels?
Answer:
Basophils prevent blood coagulation inside the blood vessels.

Question 21.
Which are the non-nucleated cells of the human blood?
Answer:
Platelets and matured red blood cells are the non-nucleated cells of the human blood.

Question 22.
Which blood cells of human blood take part in antibody formation?
Answer:
Lymphocytes take part in antibody formation.

Question 23.
Increase of which blood cell indicates blood cancer?
Answer:
Excessive and uncontrolled increase of WBC indicates blood cancer.

Question 24.
Who discovered the ABO blood grouping technique?
Answer:
Dr. Karl Landsteiner discovered the ABO blood grouping technique.

Question 25.
A baby is suffering from erythroblastosis foetalis. His father carries Rh⁺ blood. Which type of blood is expected in his mother?
Answer:
Mother of the baby is expected to carry Rh^– blood.

Question 26.
Which blood cell prevents allergy?
Answer:
Eosinophils prevent allergy.

Question 27.
Which blood cells are involved in transportation of respiratory gases?
Answer:
Erythrocytes (RBC) are involved in the transportation of the respiratory gases.

Question 28.
Which blood cell is the most abundant in human blood?
Answer:
RBC is the most abundant in human blood.

Question 29.
Which blood coagulating factor is possessed by platelets?
Answer:
Thromboplastin is the blood coagulating factor possessed by platelets.

Question 30.
Which element is essential for activating thromboplastin?
Answer:
Calcium ion is essential for activating thromboplastin.

Question 31.
Which two valves are commoniy called semilunar valves?
Answer:
Aortic valve and pulmonary arterial valves are commonly called semilunar valve.

Question 32.
How many heartbeats are generated by a healthy sinoatrial node?
Answer:
Sinoatrial node generates 70-80 heartbeats per minute.

Question 33.
Which junctional tissue supplements the function of a defective SA node?
Answer:
AV node or atrioventricular node supplements the function of a defective SA node.

Question 34.
Which part of special cardiac junctional tissue supply impulse to ventricular wall?
Answer:
Purkinje fibres supply impulse to the ventricular wall.

Question 35.
Which blood vessels carry oxygenated blood towards heart?
Answer:
Pulmonary veins carry oxygenated blood towards heart.

Question 36.
Which chamber of human heart receives deoxygenated blood?
Answer:
The right atrium receives deoxygenated blood.

Question 37.
How long does RBC survive?
Answer:
Normal life span of RBC is 120 days.

Question 38.
What is pericardium?
Answer:
Pericardium is the membranous outer covering of the heart.

Question 39.
What are systole and diastole?
Answer:
Contraction of the heart is called systole and relaxation of the heart is called diastole.

Question 40.
Which instrument is used to measure haemoglobin in blood?
Answer:
Haemoglobinometer is used to measure haemoglobin in blood.

Question 41.
What is haemoglobin made up of?
Answer:
Haemoglobin is made up of an iron part, called haem, and a protein part, called globin.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by circulation?
Answer:
Circulation is the physiological process by which nutrients, respiratory gases, hormones, minerals etc. are supplied to all the tissues of the body and the metabolic waste matters, produced inside the cells are transported to the respective excretory organs through fluid medium.

Question 2.
What is heart?
Answer:
Heart is a muscular, multi-chambered (2 in fishes, 3 in amphibians and reptiles, 4 in birds and mammals and 13 in insects) sac-like structure, which continuously pumps blood in a rhythmic manner into arteries and receives blood from the veins and in this process, helps the blood to flow through the network of vessels to every part of the human body.

Question 3.
What are arteries?
Answer:
Arteries are thick-walled blood vessels with roundish lumen, which carry oxygenated blood (exception-pulmonary arteries) from heart to the tissues with continuous rhythmic pulsation.

Question 4.
What are veins?
Answer:
Veins are the blood vessels with thinner wall and flattish lumen, which carry deoxygenated blood (exception-pulmonary vein) from the tissues to the heart and possess valves to maintain unidirectional blood flow.

Question 5.
What are capillaries?
Answer:
Capillaries are the finest of blood vessels with very thin wall, present in between arteries and veins. These fine vessels reach deep in the tissues to supply nutrients, oxygen etc. to the tissue fluid through diffusion and to collect the excretory materials and hormones from the tissues and the glands respectively.

Question 6.
What is meant by circulatory system?
Answer:
The system of organs, involved in supplying nutrients, respiratory gases, hormones to different tissues of the body and removing metabolic wastes from the body, is known as circulatory system.

Question 7.
What is meant by open circulation?
Answer:
The type of circulation, where body fluid does not remain confined within vessels, but pumped by the heart into open body cavity (haemocoel) to come in direct contact with the tissues, is called open circulation. This type of circulation is seen in molluscs, arthropods etc.

Question 8.
What is meant by closed circulation?
Answer:
The type of circulation, where blood flows through heart and network of blood vessels within the body and never opens in the body cavity, is called closed circulation. This type of circulation is noticed in all vertebrates and a few invertebrates like earthworm, leech etc.

Question 9.
What is blood?
Answer:
Blood is a red coloured, thick, faintly salty and alkaline, opaque, vascular connective tissue, composed of different types of cells suspended in a liquid matrix (plasma), which is pumped by the heart to flow through vessels for the transport of nutrients, respiratory gases, hormones, excretory substances and several other materials to all the parts of body.

Question 10.
What is haemolymph?
Answer:
Haemolymph is a colourless fluid, composed of a watery matrix and a few cells, flowing through the body cavity (haemocoel) of insects and other arthropods.

Question 11.
What is lymph?
Answer:
Lymph is a yellowish, transparent, modified tissue fluid, involved in absorption and transportation of nutrients, dissolved gases, immunologically important materials and different secretory and excretory substances into the tissues of higher animals.

Question 12.
Where do you find lymph in human body?
Answer:
Lymph is present in lymph vessels and lymph glands. Lymph glands are localised in certain regions of the body viz. around neck, breasts, armpits, groin etc. of a human body.

Question 13.
What is CSF? Where is it found?
Answer:
CSF: CSF or cerebrospinal fluid is a typical fluid, present in the central nervous system (CNS) of vertebrates.
0ccurrence of CSF: CSF is present in the ventricles of brain and in the central canal of the spinal cord. This fluid is also present in the subarachnoid space (between the second and third covering layers of brain or meninges).

Question 14.
What is synovial fluid? What does it do?
Answer:
Synovial fluid: Synovial fluid is a slightly viscous, colourless body fluid typically present in the membrane-bound synovial cavities in between movable bone joints.
Function: Synovial fluid protects bone ends against frictional damage and supplies nutrients.

Question 15.
What is tissue fiuid? What is its function in animal body?
Answer:
Tissue fluid: Tissue fluid is the extracellular fluid present in the tissues of multicellular animals.
Function: Tissue fluid helps in the transportation of nutrients, respiratory gases, hormones and metabolic waste materials.

Question 16.
What is meant by cytosol?
Answer:
Cytosol is a bulk of intracellular fluid present in the cytoplasm. Different types of intracellular fluids are present in different cell organelles like mitochondria, Golgi body, plastid, endoplasmic reticulum, lysosome, vacuoles etc. performing their respective functions.

Question 17.
How is water utilised in human body?
Answer:
Water is utilised in the human body in different ways as follows-

• It acts as the main component of the protoplasm
• Helps in hydrolysis of food matters in digestion
• Acts as the medium of diffusion and osmosis for nutrients, respiratory gases, metabolic wastes and hormones.

Question 18.
Mention the characteristic features of matured human RBC.
Answer:
Matured human RBC is a round shaped anucleated biconcave, membrane-bound cell. It contains haemoglobin within cytoplasm but devoid of mitochondria and nucleus. The cell is 7.2 μ m in diameter and 2.6 μ m in thickness. Number of RBC is 5 million / ml in male & 4.5 million / ml in female. Its average life span is 120 days.

Question 19.
Mention the functions of RBC.
Answer:
Functions of RBC are as follows-

1. RBCs transport respiratory gases.
2. They maintain acid-base balance in the plasma.
3. They maintain ionic equilibrium.
4. They help in the formation of colour of faeces.

Question 20.
From where do RBCs originate in human body?
Answer:
RBCs originate from-

• Vasculosa region of early embryo.
• Spleen and liver of matured foetus, about one month before birth
• Red bone marrow after birth.

Question 21.
Mention the structural features and function of neutrophils.
Answer:
Structural features: Neutrophils are amoeboid WBC with a diameter of 10-12 μ m. Its cytoplasm is granular and the nucleus has 2-7 lobes.
Function: Neutrophils kill germs by the process of phagocytosis.

Question 22.
Mention the structural features and function of eosinophil.
Answer:
Structural features: Eosinophils are amoeboid WBC with a diameter of 10-12 μ m. Its cytoplasm is granular and the nucleus has 2-3 lobes.
Function: Eosinophils play important role in preventing allergy.

Question 23.
Mention the structural features and function of basophil.
Answer:
Structural features: Basophil is a granulocytic WBC with a diameter of 8-10 μ m. The nucleus of basophil is bean-shaped.
Function: Basophils secrete an anti-coagulant to prevent coagulation of blood within blood vessels.

Question 24.
Mention the structural features and function of monocytes.
Answer:
Structural features: Monocytes are agranulocytic WBC with a diameter of 7.5-12 μ m. It contains a round or kidney-shaped nucleus and homogenous cytoplasm.
Function: Monocytes kill germs by the process of phagocytosis.

Question 25.
Mention the structural features and function of lymphocytes.
Answer:
Structural features: Lymphocytes are agranulocytic WBC with a diameter of 14-18 μ m. It contains a horse-shoe shaped nucleus and homogenous cytoplasm.
Function: Lymphocytes prepare antibody to maintain immunity.

Question 26
Mention the structural features and function of platelets or thrombocytes.
Answer:
Structural features: Platelets or thrombocytes have oval or water droplet-like cell without nucleus. This blood cell is only 2.5 μ m in diameter, treated as the smallest cell in human body.
Functions: When platelets are broken, thromboplastin is released from them to initiate the reactions of blood coagulation.

Question 27.
What is meant by ABO blood group?
Answer:
In 1901, Karl Landsteiner classified human blood into four groups, on the basis of distribution of agglutinogens (antigens) on RBC & agglutinins (antibodies) in plasma. There are two types of agglutinogens (A and B) & two types of agglutinins (α and β) found in blood. Based on this distribution human blood is classified into A, B, AB and O groups. This system of classification of blood is called ABO blood group.

Question 28.
Mention the distribution of agglutinins and agglutinogens in different blood groups in a tabular form.
Answer:
The following table shows the distribution of agglutinins and agglutinogens in different blood groups.

Blood group	Agglutinogens in RBC	Agglutinins in plasma
Group A	A	β
Group B	B	α
Group AB	A and B	Agglutinin absent
Group O	Agglutinogen absent	α and β

Question 29.
What is meant by universal donor of blood?
Answer:
Due to absence of agglutinogen in RBC, a person having blood group ‘ O ‘ can donate blood to any group. In this case, chance of haemagglutination does not arise. Therefore, an individual having blood group ‘O’ is called universal donor.

Question 30.
What is meant by universal recipient of blood?
Answer:
Due to absence of any agglutinin in plasma, people having blood group ‘AB’ can receive blood from any group. In this case, chance of haemagglutination does not arise. Therefore, an individual having blood group ‘AB’ is called universal recipient.

Question 31.
What is Rh factor?
Answer:
Rh factor is an antigenic protein present in the RBC of most of the world’s population, which has close similarity with a factor present in RBC of Indian monkey Rhesus macaques. The people having this factor are treated as Rh⁺whereas those do not having it are regarded as Rh^–

Question 32.
Mention the importance of Rh factor in blood transfusion.
Answer:
If a person without Rh factor (Rh^–) is transfused with blood from a person carrying Rh factor (Rh⁺), after 12 days, an antibody, called anti-Rh factor, develops in the recipient’s blood. In case the same person gets a second transfusion with Rh⁺blood, a reaction will take place between Rh factor (antigen) and anti-Rh factors (antibody) in his blood. This will lead to a fatal consequence due to agglutination and haemolysis of RBC.

Question 33.
What is erythroblastosis foetalis?
Answer:
If an Rh^–mother carries a Rh⁺foetus, the Rh antigen enters into mother’s blood from the foetus. In this situation, anti-Rh factor (antibody) develops in mother’s blood, which comes back to Rh⁺foetus and destroys the foetal RBC. As a result, the baby is born with serious anaemia. This is called erythroblastosis foetalis.

Question 34.
What is meant by blood transfusion? Mention its importance.
Answer:
Blood transfusion: Blood transfusion is a technique of intravenous infusion of blood to a person who is deficient of blood or blood components.
importance: Blood is something, which cannot be prepared by any means. Therefore, a patient, suffering from severe anaemia or excessive blood loss has to be transfused with blood to replenish the need.

Question 35.
What is meant by blood clotting? Mention its importance.
Answer:
Blood clotting: Blood clotting is a physiochemical process by which blood turns into a semisolid jelly-like mass or clot.
importance: Blood clots at the opening of a wound within a few minutes, hereby, stops bleeding and prevents excessive blood loss.

Question 36.
Mention different layers of the the walls of human heart.
Answer:
The wall of heart has three layers. These are-

• Epicardium (outermost layer)
• Myocardium (middle layer)
• Endocardium (innermost layer)

Question 37.
What is mitral valve? What does mitral valve do?
Answer:
Mitral valve: Mitral valve or bicuspid valve is the double cusped valve present at the left atrioventricular opening of the human heart.
Function: Mitral valve allows blood to flow from left atrium to left ventricle but prevents its backflow.

Question 38.
What is tricuspid valve? What does it do?
Answer:
Tricuspid valve: Tricuspid valve is the triplecusped valve present at the right atrioventricular opening of the human heart.
Function: Tricuspid valve allows blood to flow from right atrium to right ventricle but prevents the backflow.

Question 39.
What do semilunar valves do?
Answer:
In heart, the atrial semilunar valve allows the flow of oxygenated blood from the left ventricle through the aorta and prevents the backflow of blood. The pulmonary semilunar valve allows deoxygenated blood from the right ventricle to flow through the pulmonary artery and prevents the backflow.

Question 40.
What are papillary muscles?
Answer:
The inner surface of the ventricular wall of heart gives off many inwardly directed columnar muscular projections. These projections are called papillary muscles.

Question 41.
What are chordae tendineae?
Answer:
From the tip of the papillary muscles, inside ventricle, some strong cord-like tendons arise, these are called chordae tendineae.

Question 42.
Mention the role of chordae tendineae?
Answer:
The chordae tendineae attach to the ventricular face of the cusps of right and left atrioventricular valves. When the ventricles contract, these strong cords prevent the valves against opening towards the atria.

Question 43.
Distinguish between open and closed circulation.
Answer:

Features	Open circulation	Closed circulation
1. Body cavity	Blood opens in the body cavity	Blood remains confined in the blood vessels
2. Capillaries	Capillaries absent	Capiliaries present
3. Blood cells	Very few cells are present in the matrix	Different cells are present in liquid matrix Exception – Invertebrates
4. Occurrence	Arthropods and molluscs	Annelids and vertebrates

Question 44.
Distinguish between human blood and lymph.
Answer:

Features	RBC, all types of WBCs and platelets	Lymph
1. Cellular components	Red	Lymphocytes only
2. Colour	Does not come in direct contact with the tissue fluid	Faintly yellow
3. Relation with tissue fluid	Coagulates faster	Comes in direct contact with the tissue fluid
4. Coagulation	RBC, all types of WBCs and platelets	Coagulates slowly

Question 45.
Distinguish between plasma and serum.
Answer:

Features	Plasma	Serum
1. Nature	Matrix of blood	Watery portion of clotted blood
2. Fibrinogen	Present	Absent
3. Coagulating factors	Present	Absent
4. Coagulation	Occurs slowly	Does not coagulate

Question 46.
Distinguish between haemoglobin and haemocyanin.
Answer:

Features	Haemoglobin	Haemocyanin
1. Metallic component	Iron	Copper
2. Colour	Red	Faintly bluish
3. Occurrence	Plasma of some invertebrates and in RBC of vertebrates	Body fluid of crustacean, arthropods and molluscs
4. Transportation of respiratory gases	Carries O2 and CO2	Carries O2 only

Question 47.
Distinguish between universal donor and universal recipient.
Answer:

Features	Universal donor	Universal recipient
1. Blood group	group	AB group
2. Agglutinin	α and β	Absent
3. Agglutinogen	Absent	A and B
4. Compatibility	Can donate blood to any group but can receive the same blood group only	Can receive blood from any group but can donate to the same group only

Question 48.
Distinguish between artery and vein.
Answer:

Features	Artery	Vein
1. Origin and termination	Originates from the heart and terminates into the capillaries	Originates from the capillaries and terminates in the heart
2. Walls and lumen	Walls thick, lumen roundish	Walls thinner, lumen flattish
3. Valves	Absent	Present
4. Pulsating movement	Occurs	Does not occur
5. Function	Carries oxygenated blood (except pulmonary artery)	Carries deoxygenated blood (except pulmonary vein)

Question 49.
Distinguish between auricle and ventricle.
Answer:

Features	Auricle	Ventricle
1. Position	Upper portion of the heart	Lower portion of the heart
2. Wall	Thinner and less muscular	Thicker and highly muscular
3. Inner surface	Smooth	Projects papillary muscles
4. Function	Receives blood from the veins (superior and inferior vena cava, and pulmonary vein)	Circulates blood through the arteries (pulmonary artery, aorta)

Question 50.
Distinguish between systemic circulation and pulmonary circulation.
Answer:

Features	Systemic circulation	Pulmonary circulation
1. Course of circulation	From the heart to different organs (except lungs) and back	From the lungs to heart and back
2. Nature of blood	Oxygenated blood	Deoxygenated blood
3. Size of vessels	Long and elaborate	Short and compact
4. Connection to lymphatic ducts	Lymphatic ducts join to it	Lymphatic ducts do not join to it

Question 51.
Distinguish between CSF and synovial fluid.
Answer:

Features	CSF	Synovial fluid
1. Occurrence	In ventricles and lumens of the central nervous system	In spaces of movable bone joints
2. Function	Transportation of nutrients, respiratory gases and excretory matters, and acts as a shock absorber	Protection against frictional damage

Question 52.
Distinguish between tissue fluid and intercellular fluid.
Answer:

Features	Tissue fluid	Intercellular fluid
1. Occurrence	Inside the spaces within the tissues	In the spaces between the cells
2. Function	Keeps tissue-cells alive by supplying nutrients	Helps in the diffusion and osmosis of important materials

Long Questions and Answers : (5 marks for each question)

Question 1.
What is circulation? Mention the importance of circulation in living organisms. 1 + 4
Answer:
Circulation
Circulation is the physiological process by which nutrients, respiratory gases, hormones and metabolic waste matters are transported within a body through a fluid medium.

Importances of circulation
Circulation is important for the living organisms for the following purposes.

1. Movement of nutrients and minerals: Water, essential minerals, food materials are transported to all tissues of a living body by means of circulation.
2. Transport of respiratory gases: Respiratory gases, such as O₂ and CO₂, are transported within the body through the process of circulation.
3. Removal of metabolic wastes: The unwanted matters, produced in the cells from metabolic activities are transported from the tissues to excretory organs for elimination.
4. Movement of synthesized materials: Hormones, synthesized in cells, are transported to their target organs by means of circulation.
5. Maintenance of heat: Circulatory fluid maintains the body heat in warm-blooded animals.
6. Storage: Amino acids are stored in the circulatory fluid (blood) to form an amino acid pool. Some lipids (cholesterol) are also stored in the blood.

Question 2.
Give a brief account of the different components of human circulatory system.
Answer:
Components of human circulatory system
Human circulatory system is composed of three major components-

• circulating fluids.
• vessels.
• a pumping organ (heart).

1. Circulating fluids: Blood and lymph are the circulating fluids of human circulatory system.

Blood: Blood is the red coloured fluid connective tissue, which carries different important materials through the blood vessels.
Lymph: Lymph is a special tissue fluid that flows through the lymphatic ducts and lymph glands and acts as another transporting medium.

2. Vessels: Blood flows through three types of vessels, which form an intricate network in the human body. These are-arteries, veins and capillaries.
Arteries: Arteries are thick-walled vessels with roundish lumen. They carry oxygenated blood (exceptionpulmonary arteries) from the heart to the tissues. Arteries show rhythmic pulsation.
Veins: Veins have thinner wall and flattish lumen. Veins carry deoxygenated blood (exception-pulmonary vein) from the tissues to the heart. They have valves to maintain the unidirectional blood flow.
Capillaries: These are very thin-walled blood vessels present in between the arteries and the veins. These fine vessels reach deep in the tissues.

3. Heart: It is a muscular, four-chambered sack-like structure, which pumps blood continuously into arteries and helps blood to flow through the network of vessels in the human body.

Question 3.
Schematically mention different types of blood corpuscles of human body.
Answer:
Different types of blood corpuscles or cells of human body

Question 4.
Mention the functions of lymph, cerebrospinal fluid and sweat. 2 + 2 + 1
Answer:
Functions of lymph
The functions of lymph are as follows-

1. It supplies nutrients and oxygen deep into the tissues,
2. Lymphocyte cells and antibodies present in the lymph, kill germs
3. Absorbs fat from the intestine
4. It collects the metabolic wastes from the tissue fluid
5. Lymph maintains pressure, volume and composition of the tissue fluids.

Functions of cerebrospinal fluid
The functions of cerebrospinal fluid are mentioned below.

• Acts as a shock absorber for the brain & spinal cord
• Supplies nutrition and oxygen to the brain tissue
• Helps in the removal of metabolic wastes from the CNS.

Functions of sweat
The functions of sweat are as mentioned below.
1. It maintains the acid-base balance, water balance and the body temperature.
2. Some salts, urea and many other materials are excreted through sweat.

Question 5.
What is plasma? Briefly represent the composition of plasma. 1 + 4
Answer:
Plasma :
Plasma is the yellowish, slightly alkaline, transparent watery matrix of blood.

Composition of plasma :
Plasma contains water (91-92%) and solid matters (8-9%). These solid matters include different inorganic and organic materials.
1.  Inorganic matters of plasma (0.9 %) : Compounds of sodium, potassium, calcium, magnesium, phosphorus, iron, copper, chlorine, iodine etc.
2 Organic matters of plasma (7-8 %) : Organic matters of plasma are mentioned below.

• Sugar-glucose
• Protein-serum albumin, serum globulin, prothrombin, fibrinogen etc.
• Fat-cholesterol, lecithin, phospholipids, neutral fat molecules.
• Non-protein nitrogenous compounds-urea, uric acids, ammonia, creatinine, creatine etc.
• Pigments-bilirubin, biliverdin, β-carotene etc.
• Secreted materials-hormones, enzymes etc.
• Gases-oxygen, carbon dioxide etc.

Question 6.
Mention the functions of blood plasma? How is water utilised in human body? 3 + 2
Answer:
Functions of blood plasma –
The functions of blood plasma are mentioned below.

1. Plasma helps in transportation of nutrients, metabolic waste matters, hormones etc.
2. It maintains acid-base balance of the body.
3. Plasma proteins develop immunity and provide protection against many diseases.
4. Plasma proteins, like prothrombin and fibrinogen, help in blood clotting.

Utility of water in human body
Water is utilised in the human body in different ways which are mentioned below.

1. Water acts as the main component of the protoplasm.
2. It helps in the hydrolysis of food matters in digestion.
3. Water acts as the medium of diffusion and osmosis for nutrients, respiratory gases, metabolic wastes and hormones.

Question 7.
Briefly describe the role of blood in human body.
Answer:
Functions of blood in human body
For human life, blood is an ultimate essentiality. We need blood for-
1. Iransportation of O₂, CO₂ and nutrients: Blood carries O₂ and nutrients to different tissues and carries CO₂ to lungs.
2. Removal of the metabolic wastes: Blood collect excretory matters from the tissues and carries those materials to respective excretory organs.
3. Movement of hormones from glands to target organs: Hormones, secreted from the hormone glands are transported to the tissues or other glands by blood.
4. Maintenance of body temperature: Blood carries glucose to all the tissues, which generate heat by oxidation to maintain the body temperature.
5. Resistance against infections: Neutrophils and monocytes kill germs by phagocytosis. Lymphocytes produce antibody. Thus, blood resists infection.
6. Preventing blood loss: Excessive loss of blood from wounds is restricted by its coagulating ability.

Question 8.
Explain the significance of blood grouping. How do you inspire somebody for blood donation? 2 + 3
Answer:
Significance of blood grouping
Due to the presence of various agglutinogens and agglutinins, transfusion is not possible among all groups. If donor’s and recipient’s blood react to cause agglutination (antigen-antibody reaction i.e. coagulation of RBC), their blood groups will be treated as mismatch or incompatible. There will be no agglutination if the blood groups are compatible. In case of incompatible transfusion, agglutinogen of donor’s RBC reacts with agglutinin of recipient’s plasma to cause agglutination.

Ways to inspire somebody for blood donation
To inspire somebody for blood donation, I shall try to eliminate his on her misconceptions regarding blood donation by saying that-

1. Blood donation causes no harm to the donor.
2. The donated blood is replenished within a week.
3. Blood donation reduces the chance of heart attack and hypertension.
4. Blood can not be created artificially. So donated blood can save any needy patients life.
5. It is a noble gesture of a person towards the society.

Question 9.
Mention the mechanism of blood coagulation in brief.
Answer:
Mechanism of blood coagulation
The components involved in the main steps of blood clotting are enzyme thrombokinase or thromboplastin, calcium ion, plasma proteins like prothrombin and fibrinogen. The main steps of blood clotting are mentioned below.
1. Some blood platelets break near the wounds. From broken platelets enzyme Platelet-thromboplastin and from damaged tissue, tissuethromboplastin are secreted.

2. These two enzymes, with other proteins and Ca²⁺ prepare another enzyme named prothrombinase. This enzyme inactivates heparin and activates prothrombin into thrombin. This reaction is helped by calcium ions (Ca²⁺).

3. This thrombin then reacts with another plasma protein, fibrinogen, to produce fine thread-like fibrin molecules. In this reaction also calcium ions play a supporting role. The fibrin molecules form a dense network at the opening of the wound. The blood cells get trapped in that net. Within a few minutes blood at that point is transformed into a thick, viscous, jelly-like mass, called thrombus. This thrombus plugs the wound and stops bleeding.

Question 10.
Briefly describe the structure of human heart.
Answer:
Structure of heart
Human heart is a hollow, muscular, blunt-ended conical sac-like structure. It is externally covered with a bilayered coating called pericardium.
If a human heart is cut longitudinally, we can see the following anatomical features in it.

1. Chambers of the heart: Human heart has four chambers. The upper two are called auricles or atria and the two, at the lower side are the ventricles.
Auricles or atria: Auricles have comparatively thinner wall. According to the relative position, these are denoted as left and right atria. The two atria are separated by inter-atrial septum.

Ventricles: These two chambers are located lower to the auricles. Ventricular walls are more thick and muscular. A thick inter-ventricular septum separates the two ventricles.

2. Valves of heart: The left and the right atria are connected to respective ventricles with two openings, called left and right atrioventricular apertures. These two apertures are fitted with two valves. The right atrioventricular valve has three cusps (flaps), so it is called tricuspid valve. The left one has two cusps, so it is called bicuspid valve or mitral valve.

The exits of aorta and pulmonary trunk are fitted with two outwardly directed valves. These are known as aortic valve and pulmonary valve respectively. These are commonly called semilunar valves because of their half moon-shaped cusps.

Question 11.
Describe the structure of pacemaker system of human heart.
Answer:
Structure of pacemaker system of human heart
The pacemaker of human heart is made up of a few cardiac muscle cells, specialized to generate spontaneous impulse within the heart. This impulse is spread all over the heart and makes it beat continuously in a rhythm. These tissues are called the junctional tissues or pacemaker of the heart.

The main impulse generating centre of the heart is called sinoatrial node (SA node), located near the junction of superior vena cava and right auricle. It can generate 70-80 beats / min. The next centre is atrioventricular node (AV node), positioned at right atrioventricular wall. It can take over the charge from an inactive SA node and can generate 60-70 beats/ min. SA node and AV nodes are interconnected by three pairs of internodal connectors. From AV node a bundle of junctional tissues comes down through the interventricular septum. This is called bundle of His. This bundle is also capable of generating about 50 beats / min. This bundle then ramifies into several branches and spread in the ventricular wall as Purkinje fibres.

Question 12.
Briefly describe the course of circulation through human heart.
Answer:
Course of circulation through human heart
Human heart beats spontaneously in a rhythmic fashion. Due to this contraction and expansion movement, blood is pumped through the blood vessels and circulates in the body. The contraction and expansion of the heart is called systole and diastole respectively. During systole and diastole following events occur in different chambers of the heart.
1. Diastole of auricles: In this phase the auricles expand and auriculoventricular valves close. Pressure decreases in the auricles. Soon deoxygenated blood from superior and inferior vena cava and coronary sinus enters into right auricle. At the same time oxygenated blood from pulmonary veins enters into left auricle.

2. Systole of auricles: As the auricles get completely filled, they contract. Pressure increases in the auricle. With this pressure, both tricuspid and bicuspid valves open towards right and left ventricles respectively.

3. Diastole of ventricles: Diastole of ventricles starts with the systole of auricles. With the opening of tricuspid and bicuspid valves deoxygenated blood enters into right ventricle and oxygenated blood rushes into left ventricle respectively.

4. Systole of ventricles: When the two ventricles get filled with blood, ventricular systole starts. So pressure increases inside these chambers. With this pressure tricuspid and bicuspid valves close with a jerk. With maximum ventricular pressure the pulmonary and aortic valves open at a time. Then deoxygenated blood from right ventricle and oxygenated blood from left ventricle are pumped out through pulmonary trunk and aorta respectively.

In human heart, blood flows through two separate circuits. The right portion of it carries deoxygenated blood and oxygenated blood flows through the left portion. In a normal human heart, mixing of two different types of blood never happens. Therefore, human heart acts as a perfectly double circuit heart.

Question 13.
Draw a line diagram of L.S. of human heart to show the course of circulation through it, with labelling.
Answer:
Diagram of human heart
Following is a labelled diagram of L.S. of human heart showing course of circulation through it.

Question 14.
What is meant by double circulation? Show the path of double circulation with a schematic diagram. 2 + 3
Answer:
Double circulation
In higher vertebrates like birds and mammals, heart is four chambered. Here blood flows in two separate circuits, one through systemic path and the other through pulmonary path. This type of circulation is known as double circulation. It is called a double circulatory system, since it has two loops. The one is from the heart to the lungs and the other is from the heart to the rest of the body.

Diagram of double circulation path –
The following labelled diagram shows the path of double circulation.

Question 15.
Comparison among human RBC, WBC and platelets.
Answer:

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 2.4 Major Organs of Human Body and Their Function offer valuable context and analysis.

WBBSE Class 9 Science Chapter 2.4 Question Answer – Major Organs of Human Body and Their Function

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which two layers constitute our skin?
Answer:
Epidermis and hypodermis constitute our skin.

Question 2.
Which is the largest sense organ of our body?
Answer:
Skin is the largest sense organ of our body.

Question 3.
Which organ of our body carries the sensory cells for perception of heat and pressure?
Answer:
Skin of our body carries the sensory cells for perception of heat and pressure.

Question 4.
Which organ of our body can store the food for some time during digestion?
Answer:
Stomach of our body can store the food for some time during digestion.

Question 5.
Which gland of human body is called a mixed gland?
Answer:
Pancreas is called the mixed gland.

Question 6.
Which organ of the human digestive system acts as the killing field for most of the microbes, taken with food?
Answer:
Stomach of human digestive system acts as the killing field for most of the microbes, which are taken with food.

Question 7.
Besides killing germs within the consumed food, what other function does HCl do inside stomach?
Answer:
Besides killing germs within the consumed food, HCl activates pepsinogen into pepsin inside the stomach.

Question 8.
Name the paired organs which are protected by ribbones from all sides.
Answer:
The lungs are the paired organs which are protected by ribbones from all sides.

Question 9.
Name the organ of human body which helps in neutralising the acidic food mass, coming into duodenum from the stomach.
Answer:
Liver, of our body secretes bile, which neutralises the acidic food mass, coming into duodenum from the stomach.

Question 10.
Which organ is located just below the stomach at the left side of the abdomen?
Answer:
The organ located just below the stomach at the left side of the abdomen is the spleen.

Question 11.
Name the largest gland of human body which is composed of densely packed tissues.
Answer:
Liver is the largest gland of human body composed of densely packed tissues.

Question 12.
Name a highly extensible sac-like structure located at the left side of the upper abdomen.
Answer:
Stomach is a highly extensible sac-like structure located at the left side of the upper abdomen.

Question 13.
Which organ removes dead RBCs from blood?
Answer:
Spleen removes dead RBCs from the blood.

Question 14.
This elongated cord-like structure acts as the centre for reflex action of our body. What is it?
Answer:
Spinal cord is the elongated cord-like structure, which acts as the centre for reflex action of our body.

Question 15.
The lumen of which organ always remains in acidic state?
Answer:
The lumen of stomach always remains in acidic state.

Question 16.
Which two organs of our body contract and expand continuously throughout our lives?
Answer:
Heart and lungs contract and expand continuously throughout our lives.

Question 17.
Which organ of our body remains protected in a roundish bony case known as cranium?
Answer:
Brain remains protected in a roundish bony case known as the cranium.

Question 18.
Which paired structures keep our blood clean from metabolic wastes?
Answer:
The kidneys keep our blood clean from metabolic wastes.

Question 19.
Name the organ of our body, through which blood passes along two different paths.
Answer:
Heart is the organ of our body, through which blood passes along two different paths.

Question 20.
What is the position of heart in human body?
Answer:
Hear is located in the chest cavity, in between the two lungs, slightly inclined towards the left.

Question 21.
Name the cells from which testosterone is secreted inside the testes of male.
Answer:
Testosterone is secreted from the leydig cells of the testes in male.

Question 22.
Name two hormones secreted by the corpus luteum in female.
Answer:
Two hormones secreted by the corpus luteum in female, are oestrogen and progesterone.

Question 23.
What is the process of production of ovum called?
Answer:
The process of production of ovum is called oogenesis.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by organ?
Answer:
An organised group of various specialised tissues which carry out a specific function of the body, is called an organ. Example-Heart, brain etc.

Question 2.
Mention the functions of skin of our body.
Answer:
The functions of skin are as follows-

• Skin protects our body from mechanical injuries.
• Enzymes and salts, secreted through sweat, kill bacteria and other germs.
• Sensory cells in skin help us to feel heat, touch, pressure etc.
• Skin absorbs sun rays to synthesise vitamin D for the body.

Question 3.
What is a sebaceous gland?
Answer:
The gland present in the dermis layer of the skin, that secretes an oily substance called sebum, which keeps the skin smooth, is called the sebaceous gland.

Question 4.
Mention the function of human heart.
Answer:
The functions of human heart are as follows —

• Pumping of heart helps the blood to flow through blood vessels of the body.
• It drives oxygenated blood from left ventricle through systematic circulation to different organs and tissues of the body.
• Deoxygenated blood from right ventricle goes out to lungs through pulmonary circulation.
• Heart receives deoxygenated and oxygenated blood into its right auricle and left auricle respectively.

Question 5.
Name a hormone and the major enzyme secreted by the stomach.
Answer:
Gastrin is a hormone secreted by the stomach and pepsin is the major enzyme secreted by the stomach.

Question 6.
Mention the location and function of human lungs.
Answer:
Location: The two lungs are situated at the two sides of chest cavity within the rib cage.
Function:

• Lungs help in the intake of O₂ rich air by inspiration and expulsion of CO₂ rich air by expiration.
• Lungs also help in the excretion of few other toxic materials by expiration.

Question 7
Name the two major blood vessels of the kidney and name the protective layer of kidney.
Answer:
The two major blood vessels of the kidney are the renal vein and renal artery and the protective layer of kidney is called capsule.

Question 8.
Mention the functions of the human brain.
Answer:
The functions of human brain are as follows —

• Brain processes all sensory informations like vision, smell, hearing, taste, touch etc. and generate responses accordingly.
• It acts as the centre for memory, intelligence, thinking and all other mental activities.
• Coordination among all organs of our body and their activities are maintained by the brain.

Question 9.
What is spinal cord? Mention the functions of spinal cord.
Answer:
Spinal cord: The long, hollow, cylindrical structure extending from the posterior parts of medulla oblongata upto first lumber vertebra in the neural canal of vertebral column, is known as spinal cord.

Function:

• Spinal cord receives the nerve impulses from brain and conducts it to the muscles and visceral organs.
• Spinal cord controls different types of unconditioned reflexes.

Long Questions and Answers : (5 marks for each question)

Question 1.
Describe the location of human stomach. Mention its functions.
Answer:
Location of human stomach
Stomach is situated on the left side of the upper abdomen, just below the muscular diaphragm.

Functions of human stomach
The functions of human stomach are as follows-

• Stomach is a large ‘J’ shaped sac-like structure that receives food from the oesophagus, stores it for some time and acts as a site of digestion of protein and fat.
• HCl, secreted from the oxyntic cells of stomach, helps in activating the gastric enzymes.
• Activated pepsin, present in gastric juice, acts upon proteins to break it into smaller derivatives, called peptones.
• Lipase, present in gastric juice, helps in the hydrolysis of fat.
• As the pH inside the stomach is acidic, microbes find it difficult to survive within it. Therefore, most microbes of the digestive flora remain within the gut and not in the stomach.

Question 2.
Mention the location of human liver. Mention its functions.
Answer:
Location of human liver
Liver is present on the right ventral side of upper abdomen, just below the diaphragm.

Functions of human liver:
The functions of human liver are as follows-

• Liver secretes bile, which neutralises the acidic contents of the stomach.
• Bile salts emulsify fat and help in its digestion.
• Liver primarily absorbs nutrients from blood before supplying it to different parts of the body.
• It acts as the site of several metabolic activities.
• Urea is synthesised within the liver.
• Liver detoxifies various harmful components of the blood, like urea.
• It helps in the synthesis of blood-coagulating components like prothrombin, fibrinogen, etc.

Question 3.
Mention the location and functions of human kidney. Mention the location and functions of the pancreas in the human body.
Answer:
Location of kidney
Kidneys are held at the back wall of abdominal cavity on either sides of the vertebral column. Right kidney is positioned slightly lower than the left one.

Functions of kidneys
The functions of kidneys are as follows-

• Formation of urine by filtration of blood.
• Maintains the water and electrolyte balance of our body.
• Regulates blood pressure by secretion of renin.
• Controls formation of RBC by secretion of erythropoietin.

Location of pancreas : Pancreas is located transversely on the posterior side of the abdomen, extending from the duodenum to the spleen.

Functions of pancreas
The functions of pancreas are as follows-

• It secretes different digestive enzymes for the digestion of proteins, carbohydrates and fats. The enzymes are trypsin, amylase and lipase.
• The pancreas produces essential hormones like insulin, glucagon and somatostatin in the body.

Question 4.
Mention the location of spleen in human body. Mention the functions of spleen.
Answer:
Location of spleen : Spleen of human body is located on the upper far left side of the abdomen, below the left side of the stomach.

Functions of spleen
The functions of spleen are mentioned below.

• In embryonic state, spleen acts as the site of RBC formation.
• In adults, it produces lymphocytes (B-cells and T-cells) to help the proper functioning of immune system.
• Spleen separates out and removes damaged, inactive and aged RBC from the blood stream.
• It stores large quantity of RBC and leucocytes and releases it into the blood stream according to the need of the body.

Question 5.
What is ovary? Mention the position of human ovary and its functions.
Answer:
Ovary: The primary sex organ or gonad of female body is called ovary.

Location of human ovary:
Human ovaries are located at the two sides of lower abdominal cavity in females. Each ovary is an almond shaped structure, which is held in the abdominal wall with a thin membranous structure, a fibrous cord, known as the ovarian ligament.

Functions of human ovary:
The functions of human ovary are mention below.

• Several primordial germ cells are present in the ovary, which ultimately mature as ovum or female reproductive cells.
• Ovary secretes hormones like oestrogen and progesterone. These two female hormones help to maintain the feminine features and reproductive cycle in female.
• Hormone relaxin, secreted from the ovary, facilitates labour during childbirth.

Question 6.
What is testis? Mention the location and functions of testis.
Answer:
Testis : The primary sex organ or gonad of male body is called testis.

Location of testis
Human testis are paired structures, which are held in a sac-like structure, called scrotum, outside the lower abdomen in males. These are placed in between the penis and anus.

Functions of testis
The functions of testis are mentioned below.

• Male gametes (spermatozoa) are formed within the seminiferous tubules of testis.
• Spermatozoa are nourished and stored inside the testis.
• Testis secretes a hormone, named testosterone, which controls the development of masculine features like formation of beard, muscular body etc. in adult male. It also controls the maturity of spermatozoa.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.5 Excretion offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.5 Question Answer – Excretion

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Name a tree, which removes excretory materials by exfoliation of bark.
Answer:
Guava tree removes excretory materials by exfoliation of bark.

Question 2.
Name a plant, which stores most of its excretory matters in leaves.
Answer:
Tea plant stores most of its excretory matters (tannin, theine) in leaves.

Question 3.
Which type of plant excretory substance is disposed through skin of orange?
Answer:
Volatile oil or essential oil is disposed through skin of orange.

Question 4.
What is clove oil?
Answer:
Clove oil is an essential oil excreted by cloves.

Question 5.
Name a medicinally important plant, which disposes its excretory matters through bark.
Answer:
Arjun (Terminalia arjuna) tree disposes its excretory matters through bark.

Question 6.
Which economically important material is excreted from Hevea brasiliensis?
Answer:
Latex of Hevea brasiliensis is the economically important excretory material used to prepare commercial rubber.

Question 7.
Name the plant, whose latex is taken as a supplement of milk.
Answer:
Latex of Brosimum galactodendron is taken as a supplement of milk by the people of Venezuela.

Question 8.
Name a water-soluble non-nitrogenous excretory material of plant.
Answer:
Gum is a water-soluble non-nitrogenous excretory material of plant.

Question 9.
Which part of Rauvolfia plant is the source of reserpine?
Answer:
Root of Rauvolfia plant is the source of reserpine.

Question 10.
From which part of cinchona plant is quinine extracted?
Answer:
Quinine is extracted from the bark of cinchona plant.

Question 11.
What is the source of atropine?
Answer:
Leaves and roots of Atropa belladonna are the sources of atropine.

Question 12.
Which type of plant excretory matters are insoluble in water but most have great medicinal importance?
Answer:
Alkaloids are insoluble in water but most have great medicinal importance.

Question 13.
Name the plant whose excretory material is used for preparing varnish.
Answer:
Excretory material of pine tree is used for preparing varnish.

Question 14.
Name an edible plant excretory matter.
Answer:
Camphor is an edible plant excretory matter.

Question 15.
Name a plant excretory matter used as a common nerve stimulant.
Answer:
Caffeine is used as a common nerve stimulant.

Question 16.
Which alkaloid is used to control hypertension?
Answer:
Reserpine is used to control hypertension.

Question 17.
Name the excretory organ of Amoeba.
Answer:
Contractile vacuole is the excretory organ of Amoeba.

Question 18.
Which is the excretory organ of annelids?
Answer:
Nephridia is the excretory organ of annelids.

Question 19.
From where do malpighian tubules collect excretory materials?
Answer:
Malpighian tubules collect excretory materials from haemolymph.

Question 20.
What is the excretory organ of prawn called?
Answer:
The excretory organ of prawn is called green gland or antennary gland.

Question 21.
What is the structural and functional unit of kidney called?
Answer:
The structural and functional unit of kidney is called nephron.

Question 22.
Which is the site of ultrafiltration in a nephron?
Answer:
Malpighian corpuscle is the site of ultrafiltration in a nephron.

Question 23.
Which portion of human excretory system stores urine for sometime inside the body?
Answer:
Urinary bladder stores urine for sometime inside the body.

Question 24.
In which organ of vertebrate animals is urine prepared?
Answer:
Urine is prepared in the kidneys of vertebrates.

Question 25.
Which branch of artery forms the glomerulus?
Answer:
Afferent renal arteriole forms the glomerulus.

Question 26.
Which arteriole comes out from the glomerulus of nephron?
Answer:
Efferent renal arteriole comes out from the glomerulus of nephron.

Question 27.
Which region of kidney possesses more number of nephrons?
Answer:
Cortical region of kidney possesses more number of nephrons.

Question 28.
Name two materials which are reabsorbed in blood from renal tubule.
Answer:
Amino acids and glucose are two materials reabsorbed in blood from renal tubule.

Question 29.
Name a vitamin which is reabsorbed from glomerular filtrate to blood.
Answer:
Vitamin C is reabsorbed from glomerular filtrate to blood.

Question 30.
Name a hormone, which controls the reabsorption of water from renal tubule.
Answer:
Antidiuretic hormone or ADH controls the reabsorption of water from renal tubule.

Question 31.
Name an excretory material, which is disposed through faeces.
Answer:
Bilirubin is excreted through faeces.

Question 32.
Which main excretory material is eliminated through lungs?
Answer:
Carbon dioxide is the main excretory material, eliminated through lungs.

Question 33.
Through which glands are the fatty excretory materials eliminated from human body?
Answer:
The fatty excretory materials of human body are eliminated through sebaceous glands of the skin.

Question 34.
How much glomerular filtrate is produced in the two kidneys of a healthy adult individual in 24 hours?
Answer:
In 24 hours, about 170 L of glomerular filtrate is produced in the two kidneys of a healthy adult individual.

Question 35.
How much urine is excreted by a healthy adult individual in 2 4 hours?
Answer:
In 24 hours, a healthy adult individual excretes about 1.5 L of urine.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by excretion?
Answer:
Excretion is the process by which harmful metabolic waste products are eliminated from the body of an organism in order to keep it fit and healthy.

Question 2.
Why is excretion treated as a catabolic reaction?
Answer:
By the process of excretion, different metabolic waste matters are eliminated from the body of an organism. This process reduces the dry weight of the organism. Therefore, excretion is treated as a catabolic process.

Question 3.
What is gum?
Answer:
The highly viscous, non-nitrogenous, watersoluble, carbohydrate-rich plant excretory material, produced within the plant body by conversion of cellulose, is called gum.

Question 4.
What are resins?
Answer:
Resins are solid, amorphous or semi-solid, inflammable plant excretory material, which are usually transparent or translucent and yellowish to brown in colour and are soluble in organic solvents (as ether) but not in water. Resins are secreted from injured parts of plants like pine, sal etc.

Question 5.
What are volatile oils or essential oils?
Answer:
Volatile oils or essential oils are quickly evaporating plant excretory materials having a typical odour. Volatile oils are stored in the leaves of lemon, eucalyptus, citronella, etc. and fruits of lemon, orange, etc.

Question 6.
What are alkaloids?
Answer:
Alkaloids are generally colourless, complex nitrogenous organic bases with bitter taste, occuring especially in flowering plants. Example-Morphine, quinine, reserpine etc.

Question 7.
What is latex?
Answer:
A thick, milky white fluid, excreted by many flowering plants (angiosperms), composed of a complex emulsion of proteins, alkaloids, starches, sugars, oils, tannins, resins and gums which coagulate on exposure to air, is called latex. Example-Para-rubber (Hevea brasiliensis), rubber (Ficus elastica), banyan (Ficus benghalensis), different cacti etc.

Question 8.
Mention the sourse and medicinal importance of reserpine.
Answer:
Source: Root extract of Rauvolfia serpentina or ‘sarpagandha’ plant.
Medicinal importance:

1. It is used to control hypertension.
2. Reserpine is a good nerve soother.
3. It is a good medicine for insomnia.

Question 9.
Mention the source and medicinal importance of morphine.
Answer:
Source: Fruit coat of Papaver somniferum or poppy plant.
Medicinal importance:
1. Morphine is used to treat severe pain.
2. It is a strong sedative.

Question 10.
Mention the source and medicinal importance of quinine.
Answer:
Source: Bark of cinchona plant.
Medicinal importance:
1. it is used to treat malaria.
2. It is a good medicine for intestinal disorder.

Question 11.
Mention the source and medicinal importance of caffeine.
Answer:
Source: Seeds of Coffea arabica or coffee plant.
Medicinal importance:
1. It is a good nerve stimulant.
2. It is a moderate pain killer.

Question 12.
Mention the source and medicinal impertance of daturine.
Answer:
Source: Seeds of Datura stramonium or ‘dhutura’ plant.
Medicinal importance:
1. It is used as a medicine for asthma.
2. It is used to prepare narcotic drug.

Question 13.
Mention the source and medicinal importance of atropine.
Answer:
Source: Leaves and roots of Atropa belladonna.
Medicinal importance:
1. It is used to dilate the pupil before ophthalmological investigation.
2. It also used to treat certain inflammatory conditions of the eye.

Question 14.
Mention the source and medicinal importance of theine.
Answer:
Source: Leaves of tea plant.
Medicinal importance: It is consumed as a mild nerve stimulant.

Question 15.
What is tannin? What are its sources?
Answer:
Tannin: Tannin is a bitter tasting carbon-rich material excreted by plants.
Sources of tannin: Tea leaves, haritaki and bohera fruits, stems of Acacia catechu etc.

Question 16.
Mention the source and medicinal importance of azadirachtin.
Answer:
Source: Leaves, stems and fruits of Azadirachta indica or neem plant.
Medicinal importance:
1. It is used as a good medicine to treat various skin problems.
2. It is also used as an effective pesticide.

Question 17.
Mention the source and medicinal importance of strychnine.
Answer:
Source: Seeds of Strychnos nux-vomica.
Medicinal importance: It is used as homeopathic medicine to treat digestive enzyme.

Question 18.
Mention the economic importance of gum.
Answer:
The economic importances of gum are as follows-

1. Gum is used as glue in book-binding industry.
2. It is used as a fixative of lime-based paints, inks and water-based paints.
3. Gums of some plants are used to prepare chocolates.

Question 19
Mention the economic importance of latex.
Answer:
The economic importances of latex are as follows-

1. Latex of rubber plants is the raw material used in industrial rubber, which is used to prepare all rubber material starting from vehicle tyres to pencil erasers.
2. Latex of papaya plant is a source of the protein-digesting enzymepapaine.
3. Latex of Brosimum galactodendron is consumed as a supplement of milk.

Question 20.
Mention the economic importance of resin.
Answer:
The economic importances of resin are as follows-

1. Hard resin is used as a sealing material.
2. Liquid resin is used to prepare turpentine oil.
3. Asafoetida is used as an essence for cuisines.
4. Resin of sal is used to as ‘dhuna’.

Question 21.
Mention the economic importance of tannin.
Answer:
The economic importances of tannin are as follows-

1. It is used in tannery to tan leather.
2. Tannin is used to prepare certain type of ink.
3. It is used as ‘kattha’ or ‘khair’ in betel leaf.

Question 22.
How do unicellular organisms perform excretion?
Answer:
Unicellular organisms like Amoeba, Paramoecium, Euglena etc. carry out excretion with the help of contractile vacuoles. In this process, excess water from cytoplasm enters into a small vacuole. Gradually, it swells and moves towards the periphery. Finally, it bursts and expels water and dissolved waste materials outside the body.

Question 23.
Mention the economic importance of essential oil or volatile oil.
Answer:
The economic importances of essential oil are as follows-

1. It is used to prepare essence for soap, body or hair oil and several other cosmetic items.
2. Essential oil is used to add flavour to different preparations of sweets.
3. Essential oil obtained from eucalyptus is used in pain balms.

Question 24.
How does excretion help in maintaining water balance in a living body?
Answer:
Due to the deposition of waste matters, osmotic pressure in cells changes. As a result, more water enters into the cells, that hampers their normal biological processes. By excretion, waste matters are eliminated from the cells along with water. Thus, excretion helps to maintain water balance and osmotic pressure within cells and tissues of a living body.

Question 25.
How are the metabolic wastes of plants eliminated?
Answer:
In plants, some metabolic wastes are stored in specialised cells or tissues, that are eliminated during any physical injury. Some other excretory matters are deposited in organs like leaves, fruits, barks, which plants shed naturally.

Question 26.
How do animals dispose excretory matter?
Answer:
In animals, toxic excretory products are transported from tissues to specific excretory organs by circulatory system. From these organs, metabolic wastes are eliminated from the body.

Question 27.
How do flame cells work as excretory organ?
Answer:
In animals like tapeworm, liver fluke, etc, the main excretory tube spreads fine branches inside the body, called excretory tubule. Free end of each excretory tubule bears a flame cell, with a tuft of long cilia. These cells collect metabolic wastes and release those matters in the excretory tubule. The entire excretory matters, from all those tubules, reach the main excretory duct and are disposed finally through excretory pore.

Question 28.
Mention the role of nephridium in excretion.
Answer:
Nephridium is the excretory organ of annelids, such as earthworm, leech, etc. Each nephridium (piural nephridia) has three portionsnephritides, tubule and nephridiopore. Nephrostome is a ciliated funnel-shaped end of nephridium, which collects metabolic wastes from coelomic fluid. The coiled tubule collects excretory substances from surrounding blood capillaries.
All these materials are then released outside through nephridiopore, present on the skin.

Question 29.
How do malpighian tubules work as an excretory organ of insects?
Answer:
Malpighian tubules are present as a tuft of very fine tubules, at the junction of mid-gut and hind-gut of insects. These tubules absorb nitrogenous waste matters from haemolymph (insect blood) and dispose it inside the alimentary canal. Finally, the excretory products are eliminated along with faeces of insects.

Question 30.
Distinguish between latex and alkaloid.
Answer:

Features	Latex	Alkatoid
1. General nature	Milky white fluid	Colourless, faintly yellow to dark brown, non-secretory matter
2. Chemical nature	Non-nitrogenous	Nitrogenous
3. Medicinal importance	Insignificant	High medicinal value

Question 31.
Distinguish between maipighian corpuscle and malpighian tubule.
Answer:

Features	Malpighian copuscle	Malpighian tubule
1. Occurence	At the free end of nephron of all vertebrates	At the junction of mid-gut and hind-gut of insects
2. Structure	Knob-like corpuscular structure	Fine tubular structures
3. Components	Glomerulus and Bowman’s capsule	Only a close-ended tubular structure
4. Function	Ultrafiltration of blood	Absorption of excretory matters from haemolymph

Long Questions and Answers : (5 marks for each question)

Question 1.
What is the significance of excretion?
Answer:
Significance of excretion
Excretion is an important physiological process which helps to lead a healthy life. Its significance is discussed below.
1. Maintenance of fit and healthy life: Excretion removes all toxic and harmful matters produced in the cells by various metabolic activities.
2. Maintenance of water balance: Excretion removes excess water from the cells to maintain water balance in the body.
3. Recycling of matters: By excretion, many elements, present in the waste materials, are disposed in nature. These are made available for reuse by action of decomposers.
4. Economic importance: Many plant excretory products, especially alkaloids, have certain medicinal importance. Gums, resins, tannins, latex etc. are used for industrial purposes. Some nitrogen-rich animal excretory products are used as fertilisers.

Question 2.
How do plants dispose excretory materials?
Answer:
Excretion in plants
Plants eliminate excretory products by the following processes.
1. Shedding of leaves: Trees, such as hog palm, Albizia, silk cotton etc. store excretory substances in leaves. These trees shed leaves once a year to dispose those excretory substances.

2. Exfoliation of barks: Some trees, such as guava, arjun etc. deposit waste matters in their bark. These plants naturally peel off their bark to eliminate those waste matters from time to time.

3. Shedding of fruits: Plants like lemon, apple, tamarind etc. store excretory matters, like different organic acids (eg, citric acid, tartaric acid, malic acid, etc.) or essential oils in their fruits. These matters are removed from these plants by shedding of fruits.

4. Shedding of flowers: In some plants, excretory products are stored in their flowers. These products are excreted when different parts of the flowers are shedded off. Example-Clove flower.

5. Aikaloids: Sometimes alkaloids are stored in the stems and leaves of some plants like banyan, Calotropis etc. In alkaloids different types of excretory products remain solubilised. In case of injury, these alkaloids are released outside and in this way other soluble excretory products are also relaeased.

6. Resin secretion: In the resin ducts of stem and leaves of some plants, like pine, a complex insoluble excretory product called resin is present.

7. Gum excretion: In some plants such as babul, soluble wastes are excreted in the form of gum.

8. Excretion of water: Potato, tomato etc. solubilise different excretory products in water and then excrete them with the help of hydathodes.

Question 3.
Name the non-nitrogenous excretory products of plants. Compare them. Non-nitrogenous excretory products of plants
Answer:
The non-nitrogenous excretory products of plants are gum, latex and resin.
Comparison among gum, latex and resin

Question 4.
Distinguish between excretion in plants and animals.
Answer:
Differences between excretion in plants and animals

Features	Plants	Animals
1. Definite excretory organ and excretory system	Absent	Present
2. Amount of excretory products formed	Less	More
3. Nature of excretory products	Simpler and less harmful	More complex and more harmful
4. Fate of excretory products	Mostly stored	Generally excreted from the body and partially stored in some cases
5. Reutilisation of the excretory products	Some excretory products are used in metabolism	Generally not used
6. Nitrogenous excretory product	Less	More
7. Toxicity	Less	More

Question 5.
Briefly describe the structure of human excretory system.
Answer:
Structure of human excretory system
Human excretory system consists of a pair of kidneys, two ureters, a urinary bladder and a urethra.
1. Kidneys: The kidneys are brown coloured, bean-shaped structures, positioned at either side of vertebral column, just below the ribs. The concave face of the kidney is called the pelvis. The section of kidney shows two distinct regions-outer cortex and inner medulla. A renal artery enters and a renal vein leaves each kidney through the pelvis. Numerous fine tubular structures, called nephrons, are present in kidneys, which filters blood from the specially designed renal capillaries.

2. Ureter: Ureters are two in number. Each ureter is a 35 cm long, slightly curved tube, emerging from the renal pelvis. Ureters are usually 2-4 mm in diameter. The ureters connect kidneys to the urinary bladder, present at the lower portion of the abdominal cavity.

3. Urinary bladder and urethra: Urinary bladder is a muscular sac, located at the front lower portion of the abdominal cavity. Urethra is a muscular tube that descends from the floor of the bladder. The base of urethra is equipped with sphincter muscles, which help to hold the urine inside urinary bladder.
Urine enters the urinary bladder via the ureters and leaves via urethra. The capacity of a typical human bladder is 300-500 ml.

Question 6.
Briefly describe the structure of nephron.
Answer:
Structure of nephron
A nephron has two parts-malpighian corpuscles and renal tubule.
1. Malpighian corpuscles: It is situated at the free and blind end of a nephron. This portion is composed of Bowman’s capsule and glomerulus. The free and blind end of nephron forms a cup-shaped double-walled structure, called the Bowman’s capsule. A fine branch of renal artery enters into the Bowman’s capsule as afferent arteriole. It ramifies to form a capillary network inside the capsule, where these capillaries reunite and return as efferent arteriole. It is comparatively narrower than the afferent arteriole. This capillary network is called glomerulus.

2. Renal tubule: It is a convoluted tubule, extending from the base of the Bowman’s capsule and ending in the collecting tubule. Renal tubule has three parts-proximal convoluted tubule, which starts from the base of the Bowman’s capsule; loop of Henle, which is a ‘U’-shaped loop-like structure, and distal convoluted tubule, which ultimately meets a comparatively wider collecting tubule. Several collecting ducts finally unite to form thicker ducts, called the duct of Bellini.

Question 7.
Describe the steps of urine formation in human kioney.
Answer:
Steps of urine formation in human kidney
The mechanism of urine formation in nephron involves four different phases, which are mentioned below.
1. Glomerular ultrafiltration: Due to increased blood pressure in the glomerular capillaries, water from blood plasma enters into Bowman’s capsule. This water carries different excretory materials like urea, uric acid, etc. and many essential substances like glucose, amino acids, smaller protein molecules, salts, ions, vitamins, etc. This process is known as glomerular ultrafiltration and the dilute fluid, collected in the Bowman’s capsule, is called glomerular filtrate.

2. Reabsorption: Glucose and different ions (K⁺, Na⁺. etc.) are reabsorbed in cells of renal tubule from the glomerular filtrate by active transport. Cells of proximal convoluted tubules reabsorb the small protein molecules by phagocytosis. Ions like phosphates, bicarbonates, chlorine, etc., vitamin C, amino acids and many other substances are reabsorbed by renal tubule. All these reabsorbed essential materials then return to the blood.

3. Secretion: Creatine, creatinine, hippuric acid, etc. are some excretory materials, which are secreted from the renal tubule.

4. Passive absorption of water: Excess water from the glomerular filtrate is reabsorbed by passive transport in the loop of Henle and distal convoluted tubule. Reabsorption of water is controlled by a posterior pituitary hormone, named Antidiuretic Hormone (ADH).
After these four steps, normal concentrated urine is formed in nephron, which is received by the collecting tubule and finally reach the duct of Bellini.

Question 8.
Write about the roles of the accessory excretory organs other than the kidney.
Answer:
Roles of excretory organs other than kidney

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 2.3B Tissue: Animal Tissue and its Distribution offer valuable context and analysis.

WBBSE Class 9 Science Chapter 2.3B Question Answer – Tissue: Animal Tissue and its Distribution

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which tissue has liquid matrix?
Answer:
Blood has liquid matrix.

Question 2.
Which tissue has rigid calcified matrix?
Answer:
Bone tissue has rigid calcified matrix.

Question 3.
Where does connective tissue originate from?
Answer:
Connective tissue originates from mesoderm.

Question 4.
Where does nervous tissue originate from?
Answer:
Nervous tissue originates from ectoderm.

Question 5.
Which tissue is responsible for absorption of nutrients from intestinal tract?
Answer:
Epithelial tissue of intestinal lining is responsible for absorption of nutrients from intestinal tract.

Question 6.
Activity of which tissue or tissues directly controls the batting skill in the game of cricket?
Answer:
Activity of muscular and nervous tissues controls the batting skill in the game of cricket.

Question 7.
Name a type of cell that is present in bones.
Answer:
Osteocyte is a type of cell that is present in bones.

Question 8.
Which tissue plays the major role in circulation of blood through blood vessels?
Answer:
Muscular tissue, especially the cardiac muscles and muscular layer of blood vessels play major roles in circulation of blood through blood vessels.

Question 9.
Which proteins are responsible for muscular contraction?
Answer:
Contractile proteins, namely actin and myosin are responsible for muscular contraction.

Question 10.
Which is the other name of voluntary muscle?
Answer:
The other name of voluntary muscle is skeletal muscle.

Question 11.
Why voluntary muscles are called striated muscles?
Answer:
Under microscope, alternate dark and light striations are seen across the voluntary muscle fibres. Therefore, these are called striated muscles.

Question 12.
Which type of cells is present on the inner lining of the respiratory tract?
Answer:
Epithelial cells are seen on the inner lining of the respiratory tract.

Question 13.
Which type of muscles never get fatigued?
Answer:
Cardiac muscles never get fatigued.

Question 14.
Which tissue helps us to respond to the changes in the environment?
Answer:
Nervous tissue helps us to respond to the changes in environment.

Question 15.
Which are the receiving projections of neurons?
Answer:
Dendrons are the receiving projections of a neuron.

Question 16.
What are muscle fibres?
Answer:
The fine elongated contractile components of muscular tissues are called muscle fibres.

Question 17.
Which type of muscles are branched?
Answer:
Cardiac muscles are branched.

Question 18.
Which is the short and well-branched projection of a neuron?
Answer:
Dendrons is the short and well-branched projections of a neuron.

Question 19.
Name the longer and less branched projection of a nerve cell.
Answer:
Axon is the longer and less branched projection of a nerve cell.

Question 20.
Name the lipid-rich insulating coating present on the axon.
Answer:
The lipid-rich insulating coating present on the axon is known as myelin sheath.

Question 21.
Name the neuron, which does not have any lipid-rich insulating coating on the axon.
Answer:
A neuron without any lipid-rich insulating coating on the axon, is known as nonmyelinated neuron.

Question 22.
Name the specialised nerve cells having lipidrich insulating coating on the axon.
Answer:
The nerve cells, which have lipid-rich insulating coating on the axon, are called myelinated neuron.

Question 23.
Which is the most flexible connective tissue of our body?
Answer:
Cartilage is the most flexible connective tissue of our body.

Question 24.
Which is the most rigid connective tissue of our body?
Answer:
Bone is the most rigid connective tissue of our body.

Question 25.
Name the fluid connective tissues of human body.
Answer:
Blood and lymph are the two fluid connective tissues of human body.

Question 26.
What type of tissue is tendon?
Answer:
Tendon is a connective tissue.

Question 27.
Which two connective tissues are built for bearing weight of the body?
Answer:
Bones and cartilages are the two connective tissues, built for bearing weight of the body.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by epithelial tissue?
Answer:
The tissue, which typically covers the outer surface of the body as well as the inner and outer lining of internal organs, is known as epithelial tissue. It consists of one or more cell-layers.

Question 2.
What is basement membrane? What does it do
Answer:

• Basement membrane: Basement membrane is a typical acellular layer of epithelial tissue, composed of materials, somewhat similar to matrix of connective tissue.
• Functions: Basement membrane holds the epithelial cells on it. It also helps the epithelium to remain attached to the surface of the connective tissue layer below it.

Question 3.
Mention the types of epithelial tissues.
Answer:
There are 3 major types of epithelial tissues. They are-

• simple epithelial tissue
• pseudostratified epithelial tissue and
• stratified epithelial tissue.

Question 4.
Mention the types of simple epithelial tissues.
Answer:
Simple epithelial tissue are of different types. These are-

• squamous epithelium
• cuboidal epithelium
• columnar epithelium
• glandular enithelinm and
• ciliated epithelium.

Question 5.
Mention the distribution of epithelial tissue.
Answer:
Epithelial tissue is present on the outer surface of the body (skin) and the inner lining of oral cavity, intestine, blood vessels, nasal passage, respiratory tracts, alveoli, renal tubules, urinary bladder, uterus, fallopian tube and different glands.

Question 6.
Give two roles of glandular epithelium.
Answer:
Two roles of glandular epithelium are as follows-

• Glandular epithelium present in the inner lining of gastro-intestinal tract secretes various digestive enzymes.
• In endocrine glands, glandular epithelium secretes hormones.

Question 7.
What is meant by cennective tissue?
Answer:
The tissue of mesodermal origin, composed of less cells and more acellular matrix, connecting different tissues is known as connective tissue.

Question 8.
Schematically represent different types of connective tissues.
Answer:
Schematic representation of different types of connective tissue is given below—

Question 9.
What is meant by muscular tissue?
Answer:
The tissue, which has ability to contract and relax and is associated with the movement, is known as muscular tissue.

Question 10.
Mention one function of tendon and ligament each.
Answer:
Function of tendon is to connect muscles to bones. Function of ligament is to connect a bone to another bone.

Question 11.
How many types of muscular tissues are found in higher animals?
Answer:
In higher animals three types of muscular tissues are found, these are-

• voluntary or skeletal muscles,
• smooth muscles and
• cardiac muscles.

Question 12.
Mention the distribution of muscular tissue.
Answer:
The distribution of muscular tissue is as follows-

• Voluntary muscles are attached to bones.
• Smooth involuntary muscles are present in the vital visceral organs, such as oesophagus, intestine, urinary bladder, stomach etc.
• Cardiac muscles are present in the heart.

Question 13.
Write down the functions of different types of muscles.
Answer:
The functions of different muscles are as follows-

• Skeletal muscles help in movement & locomotion.
• Smooth muscles control the movement of the visceral organs like stomach, intestine, urinary bladder, etc.
• Cardiac muscles are responsible for rhythmic contraction and relaxation of heart.

Question 14.
What is nervous tissue?
Answer:
The tissue, which is responsible for receiving and transmitting impulses and thereby coordinating different parts of the body, is known as nervous tissue.

Question 15.
Which are the cellular components of nerve tissue? Where do you find those components?
Answer:

• Cellular components of nerve tissue: Neuron and neuroglia are the two cellular components of the nerve tissue.
• Distribution of neuron and neuroglia: Neurons are present in brain, spinal cord, sense organs and nerves. Several neurons, surrounded by connective tissue, form a nerve. Neuroglia cells are found in brain and spinal cord as packing material of neurons, providing them with necessary support and insulation.

Question 16.
Write the functions of nerve tissue.
Answer:
The functions of nerve tissue are as follows-

• Nerve tissue receives external and internal stimuli and responds to them.
• It carries impulses and makes the body aware of the changes in environment.
• It helps to maintain coordination among all organs within the body.

Question 17.
Why blood is called fluid connective tissue?
Answer:
Blood is mesodermal in origin, has less cells and more matrix, and it maintains connection among various parts of the body. On the other hand, the matrix of blood, i.e., plasma, is fluid in nature. Therefore, blood is called fluid connective tissue.

Question 18.
Classify different types of animal tissue.
Answer:
Classification of animal tissue is given below-

Question 19.
What are nodes of Ranvier?
Answer:
The continuity of myelin sheath on myelinated axon is interrupted by several constrictions. These are called nodes of Ranvier.

Long Questions and Answers : (5 marks for each question)

Question 1.
Describe the structure of epithelial tissue. Mention its main functions.
Answer:
Structure of epithelial tissue

The structure of epithelial tissue is as follows-

• The cells are present on a basement membrane made up of collagenous materials.
• Cells are densely packed and are joined together by mucoproteins (special type of glycoprotein).
• Cells of this tissue are either arranged in a single layer or in multi-layers.
• Cells do not get direct blood supply. They receive oxygen and nutrients from underlying tissues.

Functions of epithelial tissue
The functions of epithelial tissue are as follows —

• Epithelial tissue provides protection to animal body and its various organs.
• Epithelial tissue like squamous epithelium, takes part in gaseous exchange.
• Columnar epithelial cells help in absorption and secretion.
• Certain cuboidal and glandular epithelial cells secrete enzymes and hormones.

Question 2.
Mention the distribution of connective tissue. Briefly mention the structure of connective tissues.
Answer:
Distribution of connective tissue
The distribution of connective tissue is as follows-

• Areolar tissue is present below skin, between muscles, outer coatings of nerves and walls of blood vessels.
• Fibrous tissues are present in tendons, ligaments, walls of artery, trachea and larynx.
• Adipose tissue is found below skin, mammary glands, surrounding vital organs like heart, kidney etc.
• Bones and cartilages are found in the skeletal parts.
• Blood and lymph are present in the circulatory system.

Structure of connective tissue

The structure of connective tissue is as follows-

• Connective tissue originates from the mesoderm layer of the embryo.
• It possesses fewer cells, which remain loosely placed in the intercellular matrix.
• Cells of connective tissue are of various types with different size, shape, intra and intercellular components and functions.
• Some fibrous materials like collagen, elastin etc. may be present in the matrix.
• The matrix may be soft, jelly-like (areolar and adipose tissue), liquid (blood, lymph), rigid (bone), elastic (cartilage).

Question 3.
Briefly describe the structure of muscular tissue. Distinguish between muscular tissue and nervous tissue.
Answer:
Structure of muscular tissue
The structure of muscular tissue is mentioned below.

• Muscle cells are commonly called muscle fibres. These are thin, elongated, cylindrical or spindle shaped.
• Bundles of muscle fibres, surrounded by connective tissue, constitute a muscle.
• Muscle fibres may be uninucleated, multinucleated, unbranched or branched.
• The cytoplasm of muscle cell is called sarcoplasm, which remains surrounded by sarcolemma. Within sarcoplasm, several longitudinal contractile proteins are present, which help in the contraction and relaxation of muscles.

Differences between muscular tissue and nervous tissue:

Features	Muscular tissue	Nervous tissue
1. Origin	Mesoderm	Ectoderm
2. Distribution	With skeleton, visceral organs and heart	Brain, spinal cord and nerves all over body
3. Cell membrane	Sarcolemma	Axolemma
4. Number of nucleus	One or more	One
5. Processes	Absent	Present viz. axon and dendron
6. Function	Helps in movement and locomotion of organs and limbs	Transmission of nerve impulse

Question 4.
Describe the structure of a neuron.
Answer:
Structure of a neuron

Nerve cell or neuron has a typical structure as mentioned below.

• Neuron has two parts, the cell body or neurocyton and some processes.
• Neurocyton or cell body is covered by a typical cell membrane surrounding the protoplasm.
• Protoplasm has a distinct nucleus and cytoplasm with various cell organelles.
• Apart from mitochondria, Golgi body, ER etc., cytoplasm of a neuron has some nucleoprotein granules, known as nissl granules.
• Processes of a neuron are axon and dendron.
• Axon is the longer part with fewer branching. Few axons have an extra thick insulating cover on it, called myelin sheath.
• Myelin sheath is interrupted by several constrictions. These are called nodes of Ranvier.
• A special type of cell called Schwann cell, is also found along the length of the axon.
• The axon ends with few branches, commonly called as end brush.
• The dendron is shorter and well-branched. These branches are known as dendrites.

Question 5.
Mention the functions of different types of connective tissues. Distinguish between epithelial tissue and connective tissue.
Answer:
Functions of connective tissue
The functions of connective tissue are are follows-

• Areolar tissue acts as packing material between the organs.
• Adipose tissue stores fat for future use, keeps the body warm and acts as a cushion to protect the body against mechanical injury.
• Bones and cartilages form the skeleton, give mechanical support to the body of the vertebrates.
• Fibrous tissue provides elasticity and mechanical support.
• Blood and lymph act as transporting fluid, carrying nutrients, hormones, respiratory gases etc. and distributing them in all parts of the body.

Differences between epithelial and connective tissue

Features		Epithelial	Connective tissue
1. Origin		Ectoderm, mesoderm or endoderm	Mesoderm
2. Cellular arrangement		Densely packed and arranged in a layer	Scattered in a matrix
3 Quantity of intercellular matrix		Very little or completely absent!	Much more than the cellular components
4. Holding material		Basement membrane	Matrix
5. Function		Preparing a protective lining on external and internal organs	Connecting different parts, providing mechanical support and circulation

Question 6.
Compare the features of voluntary, involuntary and cardiac muscle.
Answer:
Comparison among voluntary, involuntary and cardiac muscle:

Features	Voluntary muscle	Involuntary muscle	Cardiac muscle
1. Striations	Present	Absent	Present
2. Number of nucleus	More than one	One	One
3. Arrangement of myofibrils	Longitudinal	Longitudinal	Longitudinal and transverse
4. Occurrence	With skeletal parts	Visceral organs	1 Heart
5. Branching	Unbranched	Unbranched	Branched
6. Nature of contraction	Voluntary	Involuntary	Involuntary
7. Working ability	Gets fatigued quickly	Gets fatigued slowly	Does not get fatigued

Question 7.
Distinguish between (i) Axon and dendron, (ii) Sarcolemma and neurlerama.
Differences between axon and dendron
Answer:

Features	Axon	Dendron
1. Comparative size	longer	Shorter
2. Branching	Less branched	Well branched
3. Myelin sheath	Present	Absent
4. Nodes of Ranvier	Present	Absent
5. Processes	Present	Absent
6. Function	Sending nerve impulse	Receiving nerve impulse

Differences between sarcolemma and neurolemms

Features	Sarcolemma	Neurolemms
1. Associated structures	Muscle fibres	Axon of neuron
2. Structural features	Plasma membrane of muscle cells	Outermost covering of axons
3. Function	Transmits nerve impulse to nerve cells from muscle cells	Serves a protective function for nerve cells

 

 

 

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 4.2 Microbes in Human Welfare offer valuable context and analysis.

WBBSE Class 9 Science Chapter 4.2 Question Answer – Microbes in Human Welfare

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Who is known as the father of microbiology?
Answer:
Louis Pasteur is known as the father of microbiology.

Question 2.
Give an example of a species of bacteria that is used for biological control of insect pest?
Answer:
Bacillus thuringiensis is used for biological control of insect pest.

Question 3.
Name a symbiotic bacterium, which can trap atmospheric nitrogen for its plant partner.
Answer:
Rhizobium leguminosarum can trap atmospheric nitrogen for its plant partner.

Question 4.
Which soil-living bacterium is applied in crop fields to increase nitrogen content of the soil?
Answer:
Azotobacter is a soil-living bacterium, which is applied in crop fields to increase nitrogen content of the soil.

Question 5.
Name a common viral bio-control agent against insect pest.
Answer:
Nuclear Polyhedrosis Virus is a common viral bio-control agent against insect pest.

Question 6.
Crystalline protein from which bacterium is popularly known as ‘cry protein’?
Answer:
Crystalline protein is produced from Bacillus thuringiensis bacteria, which is popularly known as ‘cry protein’.

Question 7.
Which bacterium is used to kill the larvae of Anopheles mosquito?
Answer:
Members of the Bacillus sphaericus bacteria are used to kill the larvae of Anopheles mosquito.

Question 8.
Name a bacterial species dwelling in the root nodules of leguminous plants.
Answer:
Rhizobium leguminosarum is a bacterial species dwelling in the root nodules of leguminous plants.

Question 9.
Name an endomycorrhiza, used as biofertiliser.
Answer:
VAM is an endomycorrhiza used as biofertiliser.

Question 10.
What is vermiculture?
Answer:
Vermiculture is the process in which earthworms are reared in a portion of soil to prepare organic manure to enhance the productivity of soil.

Question 11.
Name two fungal associates of mycorrhiza.
Answer:
Amanita and Boletus are two common fungal associates of mycorrhiza.

Question 12.
How does mycorrhiza help in reducing soil pollution?
Answer:
Mycorrhiza helps in reducing soil pollution removing harmful heavy metals like lead, mercury etc. from soil.

Question 13.
What is the full form of VAM?
Answer:
Full form of VAM is Vesicular Arbuscular Mycorrhiza.

Question 14.
Which types of mycorrhiza are found in nature?
Answer:
Three different types of mycorrhiza are found in nature, which are ectomycorrhiza, endomycorrhiza and ectendomycorrhiza.

Question 15.
Give examples of two fungi, which form ectomycorrhiza.
Answer:
Boletus and Amanita form ectomycorrhiza.

Question 16.
Give examples of two fungi, which form VAM or endomycorrhiza.
Answer:
Glomus and Acaulospora form VAM or endomycorrhiza.

Question 17.
Give exampies of two fungi, which forms ectendomycorrhiza.
Answer:
Clavaria and Endagon form ectendomycorrhiza.

Question 18.
Name two plants in which ectomycorrhiza grows on the roots.
Answer:
Ectomycorrhiza grows on the roots of oak and pine.

Question 19.
What is the full form of NPV?
Answer:
Full form of NPV is Nuclear Polyhedrosis Virus.

Question 20.
What is the full form of CPV?
Answer:
Full form of CPV is Cytoplasmic Polyhedrosis Virus.

Question 21.
Mention of the importance of NPV and CPV as bio-control agent.
Answer:
NPV and CPV are used to destroy several caterpillar pests of vegetable plants, hence, are bio-control agents.

Question 22.
Which type of phage virus is used to kill Salmonella bacteria in water bodies?
Answer:
Caudovirales is a group of phage virus used to control Salmonella build-up in water bodies.

Question 23.
Name a protozoan microbe, used to control insect pest.
Answer:
Nosema locustae is a protozoan microbe, used to control insect pests.

Short Questions and Answers : (2 marks for each question)

Question 1.
What are microhes?
Answer:
Microscopic organisms (less than 0.1 mm in diameter) present in air, water and soil are commonly known as microbes.

Question 2.
Which organisms are called bacteria?
Answer:
Prokaryotic microbes, having cellular diameter less than 3 μ m with cell wall typically made up of peptidoglycan and cytoplasm carrying a circular DNA and scattered 70 S ribosomes are called bacteria. Example-Bacillus, Salmonella etc.

Question 3.
Which organisms are called protozoa?
Answer:
Eukaryotic, unicellular microorganisms, carrying well-defined nucleus with chromosomes and membrane-bound cell organelles, are known as protozoa. Example-Amoeba, Plasmodium etc.

Question 4.
What is meant by bio-control agents?
Answer:
Different virus, bacteria, protozoa and insects can reduce the population growth of various insect pests of crops significantly, by causing disease, parasitism and predation. These biological agents are commonly called biocontrol agents.

Question 5.
What is meant by biological control?
Answer:
The technique by which abundance of pests and harmful organisms is controlled by application of their specific natural enemies is known as biological control.

Question 6.
Name two bacterial and two cyanobacterial species, commonly used as bio-fertilisers.
Answer:
The two bacterial species commonly used as bio-fertilisers are Rhizobium and Azotobacter. The two cyanobacterial species commonly used as bio-fertilisers are Anabaena and Nostoc.

Question 7.
What is meant by GM0?
Answer:
Full form of GMO is Genetically Modified Organism. By application of modern biotechnology, in recent days, plants and animals are produced with tailor made features. For this purpose unwanted genes of the organisms are replaced by desired genes, from outer source. Such organisms show desired features, and are popularly called genetically modified organism.

Question 8.
What are viruses?
Answer:
Viruses are ultra-microscopic, nucleoproteinated, acellular intermediate entity between living and non-living. Examples-HIV, Rotavirus etc.

Question 9.
What is biomagnification?
Answer:
The chemical fertilisers, insecticides, pesticides, which are used in conventional farming, enter into the food chain through producers. As these toxic chemicals pass along food chain from lower to higher trophic levels, the concentration increases step-by-step. This biological event is known as biomagnification. Biomagnification results into a number of diseases amongst the members of the higher trophic levels.

Question 10.
What is bioaccumulation?
Answer:
Bioaccumulation refers to accumulation of toxic substance in a organism. It occurs when an organism absorbs a toxic substance at a rate faster than that at which substance is lost by catabolism or excretion.

Question 11.
How do GMO help in bio-control of insect pests?
Answer:
Bacillus thuringiensis can produce a toxin, called Bt-toxin, which is fatal for insect pests. Biotechnologists have singled out the toxinproducing gene from the bacterium and placed it in the plant cells. Such GMO or Genetically Modified Crop plants synthesise the Bt-toxin, which potentially kill insect pests feeding on it.

Question 12.
Mention the role any of two viruses as biocontrol agents.
Answer:
1. Nuclear Polyhedrosis Virus can potentially kill the larvae of moths and beetles.
2. Granulosis virus destroys larvae of Spodoptera litura, an insect pest.

Question 13.
Mention the role of Caudovirales in controlling water pollution.
Answer:
Caudovirales is a group of phage viruses which kill Salmonella (bacteria) from water bodies. This phage virus can be used to eliminate Salmonella from drinking water to protect us from severe diarrhoea.

Question 14.
Mention the roles of any two protozoa as biocontrol agents.
Answer:
1. Nosema locustae is a protozoan microbe, which is used to control some insect pests.
2. Mattesia grandis, another protozoa, effectively controls cotton ball weevils.

Question 15.
Mention the role of a symbiotic bacteria as bio-fertiliser.
Answer:
Rhizobium leguminosarum is a symbiotic bacteria present in the root nodules of leguminous plants. These bacteria trap atmospheric nitrogen and convert it into nitrates. Ultimately this nitrate is transferred to their plant partners as an essential nutrient.

Question 16.
What is Azolla? Mention its importance.
Answer:
Azolla: Azolla is an aquatic floating fern which is commonly known as ‘mosquito fern’.

importance of Azolla: Azolla leaves give shelter to a nitrogen-fixing cyanobacteria named Anabaena azollae. Azolla is gown in water of paddy fields, Anabaena absorbs nitrogen from air. When water gets absorbed, Azolla decays and nitrogen gets mixed in soil to increase its fertility.

Question 17.
Why Azolla is an effective bio-fertiliser for paddy fields but not effective in wheat and vegetable fields?
Answer:
Azolla grows in water. Paddy plants also grow in wet soil. So, Azolla is grown in water of paddy fields. On the other hand, wheat and vegetables grow in drier soil. Therefore, application Azolla as bio-fertiliser is not effective for wheat and vegetable cultivation.

Question 18.
How do bacteria increase soil fertility?
Answer:
Bacteria can increase soil fertility in two different ways. One type increases nitrogen level in soil by trapping atmospheric nitrogen. Another type makes soil-borne phosphorus, soluble and absorbable to root system.

Question 19.
How Azotobacter can be applied in a crop field as bio-fertiliser?
Answer:
Agricultural laboratories prepare mixture of live Azotobacter cells and charcoal powder. This mixture can be applied in fields during soil preparation in the form of dust. This powder can also be mixed in water to prepare a bacterial solution. The seeds or roots of saplings may be given a dip in it before sowing and plantation.

Question 20.
How do phosphobacteria act as bio-fertiliser?
Answer:
Soil contains some phosphate salts, which are not absorbable by roots. Phosphobacteria make these salts soluble and absorbable to root system of plants. Thus, phosphobacteria act as a biofertiliser. Example-Bacillus megaterium is a phosphobacterium.

Question 21.
Mention the role of Bacillus thuringiensis as bio-control agent.
Answer:
Bacillus thuringiensis produces a toxin, called Bt-toxin, which can destroy larvae of many insect pests. In recent days Bt-toxin, popularly known as ‘thuricide’ is commerciallv prepared and applied in cotton and vegetable crop fields to control caterpillar and grub.

Question 22.
How do different bio-fertilisers work?
Answer:
Nitrogen-fixing bacteria and cyanobacteria propagate in soil and absorb atmospheric nitrogen, which ultimately mix in soil to make it fertile. Phosphobacteria convert phosphate salts into soluble and absorbable forms. Mycorrhiza removes harmful heavy metals (Pb, Cu, Hg, Cd etc.) from soil to reduce soil pollution and promotes plant growth. Certain microorganisms remove weeds.

Question 23.
What is the full form of IPM? Mention its objective.
Answer:
Full form of IPM: Integrated Pest Management.
Objective of IPM: The concept of Integrated Pest Management is developed in view of sustainable development of agriculture. Its main objective is to reduce the use of chemical fertilisers, insecticides, herbicides, fungicides by using bio-control agents or protect the future generation from harmful effects of these harsh chemicals and to keep the world as much pollution free as possible.

Question 24.
Mention the advantages of bio-control or biological controi.
Answer:
The advantages of biological control procedure are as follows-

1. Bio-control is more eco-friendly, because it does not pollute environment.
2. In bio-control, only the target pests are killed, the crop plant and other organisms remain unharmed.
3. This method is less expensive, therefore, reduces the production cost of crops.

Question 25.
Define mycorrhiza.
Answer:
Mycorrhiza is a symbiotic relationship between fungi and root systems of vascular plants. Mycorrhiza is formed in plants like pine, orchids etc. The fungi involved in the formation of the mycorrhiza are Glomus, Boletus etc.

Question 26.
Mention the disadvantages of bio-control measures.
Answer:
The disadvantages of bio-control procedures are-
1. Many bio-controlling organisms cannot adapt themselves with the new environment and often die.
2. The effectiveness of a bio-control agent on a pest cannot be assumed before application.

Question 27.
Describe the importance of VAM as biofertiliser.
Answer:
VAM or Vesicular Arbuscular Mycorrhiza is the most popular bio-fertiliser that enhances phosphorus, sulphur and copper absorption by root systems of plants with which it is associated.

Long Questions and Answers : (5 marks for each question)

Question 1.
Give a brief account of different microbial bio-control agents.
Answer:
Different microbial bio-control agents
Different bacteria, virus, fungi and protozoa can be used as bio-control agents.
1. Bacteria as bio-control agent: Bacillus thuringiensis produces a poison, called Bt-toxin, which is used to control growth of larvae of moths, beetles and flies. Scientists have introduced some genetic materials of these bacteria in corn, vegetables and cotton plants. As a result, Bt-toxin is synthesized in it, so that insect parasites cannot attack these plants. Pseudomonas fluonescena has been commercially used as fungicide. Bacillus popillae is used to control Japanese beetle, a pest of maple and rose plants.

2. Virus as bio-control agent:
Caudovirales is a group of phage virus, which kill Salmonella (bacteria) from water bodies. This phage virus can be used to eliminate Salmonella from drinking water to protect us from severe diarrhoea.

Nuclear Polyhedrosis Virus (NPV) or Cytoplasmic Polyhedrosis Virus (CPV) can kill larvae of moths and butterflies. These viruses are used to destroy some harmful insects like pine sawflies, gypsy moths, tussock moths etc.

3. Protozoa as bio-control agent:

• Nosema locustae is a protozoan microbe, which is used to control some insect pests.
• Mattesia grandis, another protozoa, effectively controls cotton ball weevils.

4. Fungus as bio-control agent: Beauveria bassiana is a fungus, which can control mosquito population effectively. It can be used in those areas, where mosquitoes have developed resistance against chemical insecticides. It can also control termites, whiteflies and many other insects.

Question 2.
What is meant by bio-fertiliser? Mention the roles of bacteria as bio-fertiliser. 1 + 4
Bio-fertiliser
Certain microorganisms, have the ability to promote plant growth by increasing the supply or availability of primary nutrients to plants. These are applied in crop fields to increase soil fertility. These are known as bio-fertiliser.

Roles of different bacteria as bio-fertilisers

1. Rhizobium leguminosarum is a symbiotic bacteria present in the root nodules of leguminous plants. These bacteria trap atmospheric nitrogen and convert it into nitrates. Ultimately this nitrate is transferred to the plant body as an essential nutrient.
2. Frankia is another symbiotic bacteria, which dwell in the root nodules of plants like Casuarina, Rubus, Alnus etc.
3. Some soil-living, aerobic bacteria can absorb atmospheric nitrogen into the cells. After death, this nitrogen is released in soil as nitrates and increases its fertility. Azotobacter sp., Azomonas sp., Derxia sp., Azospirillum sp. etc., are some examples.
4. Among the anaerobic nitrogen-fixing bacteria Clostridium sp., Chromatium sp., Chlorobium sp. are mentionable.
5. Some bacteria like Thiobaccilus, Micrococcus, Acrobacter are capable of solubilizing inorganic phosphorus from insoluble compounds in the soil. Use of these bacteria as bio-fertilisers enhance phosphate-nutrition of plants.

Question 3.
What do you mean by nitrogen fixation? Mention the roles of cyanobacteria as bio-fertiliser. 2 + 3
Answer:
Nitrogen fixation
Nitrogen fixation is a process in which nitrogen (N₂) in the atmosphere is converted into ammonia (NH₃). Nitrogen fixation process occurs naturally in the soil by nitrogen-fixing bacteria.

Roles of cyanobacteria as bio-fertilisers

Some cyanobacteria can trap atmospheric nitrogen. These include Anabaena sp., Nostoc sp., Aulosira sp., Stigonema sp., Plectonema sp., etc. These are now cultured in water of paddy fields. When these organisms die and decompose, nitrates get absorbed in soil and increase its fertility. Recently Azolla is being cultivated in the irrigated paddy fields. Azolla is an aquatic fern. Nitrogen-fixing cyanobacteria Anabaena azollae live in the leaves of this fern.

These cyanobacteria fix nitrogen from atmosphere and supply it to Azolla. Azolla die and get decomposed in the soil. By this process soil get nitrogen from the decomposed body of this fern. In Southeast Asian countries, cultivation of Azolla in paddy fields is a regular practice now. It has reduced the need for chemical fertilisers and has cut down the cost of paddy cultivation. Beside this, cyanobacteria secrete ascorbic acid, Vit. B and auxin in the soil.

Question 4.
Mention the roles of mycorrhiza as a bio-fertiliser. Why are bio-fertilisers and bio-control agents getting more acceptance all over the world? 2 + 3
Answer:
Roles of mycorrhiza as bio-fertiliser :
Mycorrhiza is a symbiotic association between roots of some vascular plants and some fungi. In this association, the fungi develop hyphae (fine filaments of fungal vegetative body) around the root-tip or inside the cortex of roots of the vascular plants. The fungal hyphae can absorb phosphorus and nitrogenous nutrients from soil very efficiently. It can also remove harmful heavy metals like lead, mercury etc., from the soil to reduce soil pollution. Mycorrhiza is formed in oaks, pines, orchids and some crop plants. The fungi involved in the formation of mycorrhiza are Boletus sp., Amanita sp., Glomus etc.

Reasons behind acceptance of bio-fertilisers and bio-control agents :

Chemical fertilisers are expensive. Production of these fertilisers need large infrastructure and power. Chemical fertilisers reduce natural soil fertility and change soil pH. Same is applicable in case of pesticides, these are very expensive and all of these materials increase environmental pollution. However, in comparison with chemical fertiliser production cost of bio-fertilisers is negligible.

Pest control by biological agents do not need any infrastructure at all. Bio-fertiliser does not need heavy infrastructure and power. Moreover bio-control is an eco-friendly procedure and bio-fertilisers do not cause soil pollution. Bio-fertiliser and pest control by biological agents not only retain the natural resources of earth, but also prevent it from getting amalgamated with chemical precipitations. So bio-fertilisers and bio-control agents are getting more acceptance all over the world.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 4.1 Immunity and Human Diseases offer valuable context and analysis.

WBBSE Class 9 Science Chapter 4.1 Question Answer – Immunity and Human Diseases

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which type of immunity develops by birth?
Answer:
Innate immunity develops by birth.

Question 2.
Which characteristic ability of antigen activates the immune system of the body?
Answer:
Immunogenicity of antigen activates the immune system of the body.

Question 3.
Which characteristic ability of antigen makes it compatible to the antibody?
Answer:
Antigenicity of an antigen makes it compatible to the antibody.

Question 4.
What is the name of the reaction shown by the body against any pathogen?
Answer:
The reaction shown by the body against any pathogen is commonly called immuneresponse.

Question 5.
What are allergens?
Answer:
The substances which trigger allergies are called allergens.

Question 6.
What is the name of the chemical, which is produced inside the body to resist a toxin?
Answer:
Antitoxin is produced inside the body to resist a toxin.

Question 7.
Which is the most abundant antibody present in human blood?
Answer:
Immunoglobulin G is the most abundant antibody present in human blood.

Question 8.
Which type of antiborly is present in ditierent body fluids and secretory materials in human body?
Answer:
Immunoglobulin A is present in different body fluids and secretory materials in the human body.

Question 9.
Which is the largest antibody present in our body?
Answer:
Immunoglobulin M is the largest antibody present in our body.

Question 10.
In which antibody five molecules stay as a ciuster?
Answer:
In Immunoglobulin M, five molecules stay as a cluster.

Question 11.
Where do B-lymphocytes mature?
Answer:
B-lymphocyte or B-cells mature in red bone marrow.

Question 12.
Which type of immunity is provided by neutrophils?
Answer:
Neutrophils provide innate immunity to the body.

Question 13.
How does an immunoglobulin G molecule appear?
Answer:
Immunoglobulin G molecules appear like English letter ‘Y’.

Question 14.
How many globulin chains combine to prepare an immunoglobulin G molecule?
Answer:
Two heavy and two light globulin chains combine to prepare an immunoglobulin G molecule.

Question 15.
How do the globulin chains remain tied together in an immunoglobulin G molecule?
Answer:
In an immunoglobulin G molecule the heavy and light chains remain tied together by di-sulphide bonds.

Question 16.
Which type of antibody can penetrate the placental barrier to reach the foetal blood from mother’s body?
Answer:
1gG can penetrate the placental barrier to reach the foetal blood from mother’s body.

Question 17.
Which antibody is present in tears?
Answer:
IgA is present in tears.

Question 18.
Which antibody is synthesised first in human foetus?
Answer:
The antibody synthesised first in human foetus is IgM.

Question 19.
Which antibody protects our body against allergens?
Answer:
IgE protects our body against allergens.

Question 20.
Which is the first line of defence in our immune system?
Answer:
Skin and mucus membrane provide the first line of defence in our body’s immune system.

Question 21.
Which is the second line of defence in our immune system?
Answer:
Phagocytic white blood cells like neutrophils and monocytes provide the second line of defence in our body’s immune system.

Question 22.
Which is the third line of defence of human immune system?
Answer:
Acquired immunity provided by different types of T and B-lymphocytes provides the third line of defence to human immune system.

Question 23.
What is meant by vaccination?
Answer:
Inoculation of the body with vaccines to develop active acquired immunity against specific disease-causing germs or toxins is called vaccination.

Question 24.
What is the full form of DPT vaccine?
Answer:
Full form of DPT is Diphtheria, Pertussis (whooping cough), Tetanus.

Question 25.
What is the full form of TT?
Answer:
Full form of TT is Tetanus Toxoid.

Question 26.
What is the full form of BCG?
Answer:
Full form of BCG is Bacillus CalmetteGuerin.

Question 27.
What is the full form of MMR?
Answer:
Full form of MMR is Mumps, Measles, Rubella.

Question 28.
What is the full form of ATS?
Answer:
Full form of ATS is Anti-Tetanus Serum.

Question 29.
What is the full form of OPV?
Answer:
Full form of OPV is Oral Polio Vaccine.

Question 30.
Give example of attenuated viral vaccines.
Answer:
Vaccines of mumps, measles, rubella, chicken pox belong to attenuated viral vaccines.

Question 31.
What is sub-unit vaccine?
Answer:
The vaccine which is prepared by certain molecular part of a pathogen, a viral protein for instance, is called sub-unit vaccine.

Question 32.
Give example of a sub-unit vaccine.
Answer:
Vaccine of Hepatitis B is a sub-unit vaccine.

Question 33.
To which kingdom of the living world does malaria pathogen belong?
Answer:
Malaria pathogen belongs to kingdom Protista.

Question 34.
What is full form of AIDS?
Answer:
Full form of AIDS is Acquired Immune Deficiency Syndrome.

Question 35.
Which day is observed as World Health Day?
Answer:
Every year 7th April is observed as the World Health Day.

Question 36.
Which day is observed as World AIDS Day?
Answer:
Every year 1st December is observed as the World AIDS Day.

Question 37.
Which disease is commonly known as Lock Jaw disease?
Answer:
Tetanus is commonly known as Lock Jaw disease.

Question 38.
What is the other name of ‘Break Bone fever’?
Answer:
The other name of ‘Break Bone fever’ is dengue.

Question 39.
Which type of hepatitis is transmitted through contaminated food and drink?
Answer:
Hepatitis A is transmitted through contaminated food and drink.

Question 40.
Which vaccine did Calmette and Guerin discover?
Answer:
Calmette and Guerin discovered the vaccine against tuberculosis.

Question 41.
Who discovered the vaccine of polio?
Answer:
Jonas Salk discovered the vaccine of polio.

Question 42.
Who discovered the Oral Polio Vaccine?
Answer:
Albert Sabin discovered the Oral Polio Vaccine.

Question 43.
Name a viral disease which is transmitted by mosquito.
Answer:
Dengue is a viral disease which is transmitted by mosquito.

Question 44.
Mention the full form of ‘WASH’ programme as proposed by UNICEF.
Answer:
The full form of WASH programme isWater and Sanitation Hygiene programme.

Question 45.
Name a virus, which causes severe diarrhoea.
Answer:
Rotavirus causes severe diarrhoea.

Question 46.
Name a bacterial disease, which causes fever, severe chest pain, cough and distressed breathing.
Answer:
Pneumonia causes fever, severe chest pain, cough and distressed breathing.

Question 47.
Name a disease caused by retrovirus.
Answer:
AIDS is caused by retrovirus.

Question 48.
Name two common household disinfectants.
Answer:
Phenyl and bleaching powder are two common household disinfectants.

Question 49.
How can you disinfect your hands without using water?
Answer:
Alcohol-based hand sanitisers can disinfect hands without water.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is immunology?
Answer:
The branch of science, that deals with the study of antigens, antibodies and the overall immune system of the body, is known as immunology.

Question 2.
What is immunity?
Answer:
Immunity is defined as the defence mechanism of the body against a specific infection or toxin or any harmful foreign material, entering the body by the action of specific antibodies or specialised cells or agents.

Question 3.
What is an antigen?
Answer:
Antigens are foreign materials that stimulate the immune system of the body by inducing the synthesis of specific antibodies and sensitising immunologically significant white blood cells.

Question 4.
Mention the characteristic features of antigens.
Answer:
Characteristic features of antigens are as follows-

1. Antigens are commonly proteins, or polysaccharides in nature
2. Antigens are generally of high molecular weight. Minimum molecular weight of an antigen is 10000 Dalton.
3. An antigen induces the synthesis of a specific antibody.

Question 5.
What are the common sources of antigens?
Answer:
The common sources of antigens are as follows-

1. Surface proteins of bacteria and viral capsid are the common sources of antigens.
2. Different toxins, snake venom, sting poisons of bees, wasps, scorpions act as antigens.
3. Secretory or excretory materials of bacteria or parasites contain antigens.
4. Some chemicals, drugs, pollen grains even food materials contain allergic antigens (allergens).

Question 6.
What are exogenous antigens?
Answer:
The antigens, which enter into the body from outside, are called exogenous antigens. Exogenous antigens include different diseasecausing germs, certain allergic food materials, chemicals, pollen grains.

Question 7.
What is endogenous antigen?
Answer:
The antigenic materials, which are synthesised inside the body and are capable of inducing immune response are called endogenous antigens. Certain proteins present on the surface of RBC, cardiolipin of mammalian heart, prostate specific antigen of prostate gland are the examples of endogenous antigens.

Question 8.
What is an antibody?
Answer:
Antibodies are immunoglobulin molecules, which are produced or remain in blood to counteract and inactivate specific antigens and thereby protect the body against their harmful effects.

Question 9.
Mention the characteristic features of antibodies.
Answer:
Characteristic features of antibodies are as follows-

1. Antibodies are glycoproteins commonly called immunoglobulins.
2. Molecular weight of an antibody ranges from 150000 to 950000 Dalton.
3. Antibodies are antigen-specific.

Question 10.
How do antibodies work?
Answer:
Antibodies work through following methods-

1. Antibodies or immunoglobulins bind to specific antigens to agglutinate and precipitate them.
2. Some antibodies bind to antigens to let those to be phagocytized by macrophage cells.
3. Some antibodies immobilize and dissolve antigens.

Question 11.
How many types of antibodies are found in human body?
Answer:
Human body contains five different types of antibodies or immunoglobulins. These are IgA, Ig D, Ig E, Ig G and IgM.

Question 12.
What is primary immune response?
Answer:
The reactions in the body in response to an antigen for the first time is called primary immune response. This response takes a little more time (10-17 days) for recognition of the antigen.

Question 13.
What is secondary immune response?
Answer:
The reactions in response to an antigen, already known to the body’s immune system, is known as secondary immune response. This response is very fast (2-7 days) because memory cells, already produced in the body, recognise the antigen and respond instantaneously.

Question 14.
What is meant by cell-mediated immunity?
Answer:
The immune response, which involves activity of the cytotoxic T-lymphocytes and different phagocytic cells in destroying the pathogens or pathogen infected cells within the body, is called cell-mediated immunity.

Question 15.
What is meant by innate immunity?
Answer:
The innate immunity refers to non-specific defence mechanisms that come into play immediately or within hours of an antigen’s appearance in the body.

Question 16.
What is meant by acquired immunity?
Answer:
The immunity, which develops within the body of an organism by any infection, vaccination or by introduction of antibody artificially, is called acquired immunity.

Question 17.
Schematically represent different types of acquired immunity.
Answer:
Schematic representation of different types of acquired immunity is given below-

Question 18.
What is meant by active acquired immunity?
Answer:
The immunity, which is developed in the body of an organism by introduction of an antigen, naturally or artificially, is called active acquired immunity.

Question 19.
What is artificial active immunity?
Answer:
The active immunity, which develops in an organism after vaccination is called artificial active immunity. Examples-Vaccines like DPT, OPV, BCG etc. develop artificial active immunity.

Question 20.
What is passive acquired immunity?
Answer:
The immunity which is developed in the body of an organism by introduction of an antibody, naturally or artificially, is called passive acquired immunity.

Question 21.
What is natural active immunity?
Answer:
The active immunity, which is developed in an organism after natural infection by any pathogen (virus, bacteria etc.) is known as natural active immunity. Example-After infection of chicken pox, a person develops natural active immunity against this disease and is not attacked by the same disease in future.

Question 22.
What is natural passive immunity?
Answer:
The passive immunity, which is developed by the inflow of antibodies from mother to the foetus through placental circulation is known as natural passive immunity. Example-Immunoglobulin A, acquired by a baby through colostrum of breast milk of the mother, develops natural passive immunity.

Question 23.
What is artificial passive immunity?
Answer:
The passive immunity, which develops in an animal by introduction of antibodies from outside by injection, is known as artificial passive immunity. Example-Antitoxin serum, produced from horse’s blood, is injected to save the life of a person suffering from snake bite.

Question 24.
What is the importance of vaccination?
Answer:
Importance of vaccination are as follows-
1. By means of vaccination specific antibody develops within our body. Memory cells develop in the body, which remain stored in lymphatic system to counter any chance of infection by the same pathogen in future.
2. Certain vaccines develop immunity for lifetime and some others immunize the body for a certain period.

Question 25.
What is meant by attenuated vaccine?
Answer:
The vaccines, which are prepared by living but inactivated pathogens (bacteria or virus) are called attenuated vaccines. Examples-Vaccines of tuberculosis, mumps, influenza, and Oral polio vaccine (Sabin vaccine) belong to attenuated vaccine.

Question 26.
What is meant by killed vaccine?
Answer:
The vaccines, which are prepared with dead or inactivated bacteria or virus, are known as killed vaccines. Examples-Vaccines of typhoid, cholera, whooping cough (pertussis), rabies, hepatitis B and Salk vaccine belong to killed vaccine category.

Question 27.
What is a toxoid?
Answer:
Toxins collected from pathogenic microorganisms, are chemically detoxified keeping their antigenic property intact. These preparations are used as vaccines, which are called toxoids. Examples-Tetanus and diphtheria vaccines are of this type.

Question 28.
What is meant by combination vaccines?
Answer:
Certain vaccines are prepared with different antigens to immunize individuals against more than one disease by a single inoculation. These vaccines are called combination vaccines. Examples-DPT (Diphtheria, Pertussis, Tetanus) vaccine, MMR (Mumps, Measles, Rubella) vaccine are of this type.

Question 29.
What is booster dose of vaccine?
Answer:
To maintain a steady stock of memory cells in the immune system certain vaccines are applied at regular intervals. These slots of vaccines are known as booster dose. Example-Booster dose of tetanus toxoid must be given after every ten years.

Question 30.
Mention the causative agents of diarrhoea. How is the disease transmitted?
Answer:
Causative agents of diarrhoea: Diarrhoea is caused by ETEC- Enterotoxigenic E. coli, Salmonella sp. (bacteria), Rotavirus (virus).
Mode of transmission of diarrhoea: This disease is transmitted through contaminated food and water.

Question 31.
What in meant by primary lymphoid organ?
Answer:
The organs, within which T and B lymphocytes attain maturity, are called primary lymphoid organs. Example-Thymus gland, the site of maturity of T-cells and red bone marrow, the tissue where B-cells mature, are the two primary lymphoid organs.

Question 32.
What is secondary lymphoid organ?
Answer:
Matured T and B-lymphocytes are transferred to some other organs for further proliferation. These organs are known as secondary lymphoid organs. Example-All lymph glands, especially tonsils and spleen are the examples of secondary lymphoid organs.

Question 33.
Write the common symptoms of diarrhoea.
Answer:
Common symptoms of diarrhoea are –

1. frequent watery stool,
2. abdominal pain and cramps,
3. disability to hold bowel movement,
4. nausea and fatigue,
5. thirst and dehydration.

Question 34.
Mention the names of different malaria causing pathogens. How is malaria transmitted?
Answer:
Causative agents of malaria: Malaria is caused by different species of Plasmodium, a parasitic protozoan. They are Plasmodium vivax, P. falciparum, P. malariae and P. ovale.
Transmission of malarial parasite: Female Anopheles mosquito carries Plasmodium from a diseased individual to a healthy person.

Question 35.
Write down the different symptoms of malaria.
Answer:
The symptoms of malaria are-

1. chilled feeling with severe shivering
2. severe headache, [3] very high fever (104 °F or more)
3. remission of fever with profuse sweating
4. fatigue
5. nausea.

Question 38.
Name the causative agent of diphtheria. How is the disease transmitted?
Answer:
Causative agent of diphtheria: Causative agent of diphtheria is a bacterium named Corynebacterium diphtheriae.
Mode of transmission of diphtheria: Diphtheria is transmitted mainly through respiratory droplets. This disease also spread by touching the body of an infected person and from contaminated materials like telephone, utensils, towels, handkerchiefs etc.

Question 37.
Mention the symptoms of diphtheria.
Answer:
The symptoms of diphtheria are-

1. thick, gray coating over pharyngeal wall and tonsils
2. sore throat and hoarseness
3. swelling of lymph glands near the neck
4. distressed breathing and swallowing
5. nasal discharge
6. high fever.

Question 38.
Name the causative agent of pneumonia. How is the disease transmitted?
Answer:
Causative agent of pneumonia: Causative agent of pneumonia is a bacterium named Streptococcus pneumoniae.
Mode of transmission of pneumonia: The pathogens of pneumonia are transmitted through respiratory droplets from the nose and mouth of a sick person.

Question 39.
Mention the symptoms of pneumonia.
Answer:
The symptoms of pneumonia are

1. severe cough
2. distressed breathing
3. chest pain, especially with cough
4. fever
5. breathlessness
6. fatigue.

Question 40.
Name the causative agent of tetanus. How is the disease transmitted?
Answer:
Causative agent of tetanus: Causative agent of tetanus is Clostridium tetani.
Mode of transmission of tetanus: Pathogen of tetanus is transmitted directly from soil through open wounds or injuries. Injuries from contaminated nails, knives, razors, surgical instruments etc. also transmit this disease.

Question 41.
Mention the symptoms of tetanus.
Answer:
The symptoms of tetanus are-

1. fever followed by jaw cramping,
2. spasm in stomach,
3. stiffness of muscles with severe pain,
4. trouble in swallowing,
5. high blood pressure and fast heart rate.

Question 42.
Name the causative agent of tuberculosis. Mention the symptoms of tuberculosis.
Answer:
Causative agent of tuberculosis: Causative agent of tuberculosis is a bacterium named Mycobacterium tuberculosis.
Symptoms of tuberculosis:

1. Night fever with sweating,
2. Dry cough with blood-tinted sputum,
3. Significant weight loss,
4. Fatigue.

Question 43.
How is tuberculosis transmitted?
Answer:
Tuberculosis is transmitted through respiratory droplets from nose and mouth of a diseased person. Exhaled air of the patient carries pathogens of this disease. Inhaling this air from a distance of a few metres, may infect another person with the same disease.

Question 44.
Name the causative agent of dengue. How is dengue transmitted?
Answer:
Causative agent of dengue: Causative agent of dengue is Flavivirus.
Mode of transmission of dengue: Female Aedes aegepti mosquito (which is a blood sucking ectoparasite) carries dengue virus from a diseased person to a healthy individual.

Question 45.
Mention the symptoms of dengue.
Answer:
The symptoms of dengue are-

1. high fever with severe headache
2. pain behind the eyes
3. severe body ache and joint pain
4. rash over skin
5. moderate bleeding from gums.

Question 46.
Name the causative agent of hepatitis A. How is hepatitis A transmitted?
Answer:
Causative agent of hepatitis A: Causative agent of hepatitis A is HAV or Hepatitis A Virus.
Mode of transmission of hepatitis A: This virus comes out through faeces of a person, infected with hepatitis A. The pathogen is then transmitted through contaminated food (raw vegetables) or drinks (water) in a healthy person.
Therefore, in other words it can be stated that this infection is transmitted through faecal-oral route.

Question 47.
Mention the symptoms of hepatitis A.
Answer:
The symptoms of hepatitis A are –

1. nausea and vomiting
2. liver pain
3. loss of appetite
4. darkish urine
5. yellowing of skin and eye.

Question 48.
Name the causative agent of hepatitis B. How is hepatitis B transmitted?
Answer:
Causative agent of hepatitis B: Causative agent of hepatitis B is HBV or Hepatitis B Virus.
Mode of transmission of hepatitis B: This virus is carried by blood or other body fluids. It is transmitted through transfusion of contaminated blood, and sharing same injection needle with a patient. This virus may pass through placenta, therefore, infect a foetus of a diseased mother. It may be transmitted by sexual contact also.

Question 49.
Mention the symptoms of hepatitis B.
Answer:
The symptoms of hepatitis B are-

1. nausea and vomiting,
2. abdominal pain,
3. loss of appetite,
4. darkish urine,
5. yellowing of skin and eye,
6. severe fatigue.

Question 50.
Name the causative agent of AIDS. How is AIDS transmitted?
Answer:
Causative agent of AIDS: The causative agent of AIDS is HIV or Human Immunodeficiency Virus.
Mode of transmission of AIDS: The virus of AIDS is transmitted by transfusion of contaminated blood, sharing same injection needle with a patient, through unsafe sexual contact, from mother to foetus through placental circulation.

Question 51.
Mention the symptoms of AIDS.
Answer:
The symptoms of AIDS are-

1. recurrent fever
2. common cold-like symptoms
3. frequent diarrhoea
4. quick loss of weight
5. swelling of glands in groin
6. fatigue
7. joint pain
8. persistent skin rashes.

Question 52.
What is meant by washing?
Answer:
The process of disinfecting hand and other body parts, garments, utensils, raw food matters, like fish, meat, vegetables and fruits with clean water, soap, detergents or germicidal lotions is known as washing.

Question 53.
Mention the role of different washing materials?
Answer:
The role different washing materials are as follows-

1. Water is used to wash all items.
2. Detergents are used to wash garments, beddings and utensils.
3. Floor cleaners are used to clean floors of room and toilet.
4. Soap, shampoo and shower gels are used in bathing.
5. Hand is washed with soap and disinfecting lotion.

Question 54.
Briefly describe the importance of brushing teeth.
Answer:
Unhygienic oral condition leads to different problems like tooth decay, gum disease, bad breath, pyorrhoea, loosening and falling of teeth. Proper brushing with toothpaste helps in reducing plaque and germ build up in the mouth and reduces the chances of oral problems. For this purpose brushing of teeth is to be done essentially before going to bed.

Question 55.
Why is bathing important for good health?
Answer:
Population of different bacteria, fungi and ectoparasites grow fast on unclean body surface. Sweat and sebum provide the germs a good medium for nutrition and growth. Unclean body surface leads to several skin infections. By regular bathing, these germs are washed off. Therefore, bathing is important to maintain a good health.

Question 56.
What should be the proper bathing technique?
Answer:
To clean the body surface shower with clean water is necessary. Then soap or bathing gel is to be applied and then rubbed with a scrubber to create rich foam. More attention is to be given at the hidden parts like armpits, groins, as these regions provide good places for germ build-up. Finally, the foam is to be cleared with adequate water to get a clean and hygienic skin.

Question 57.
Why are washing and sun drying of garments, beddings, bathing towels, handkerchiefs essential for maintaining hygiene?
Answer:
Pathogens of scabies, ringworm, eczema and a number of allergens spread through contaminated garments, beddings, bathing towels and handkerchiefs. Washing can reduce the population of pathogens from these materials. Therefore, washing and sun drying of these items is essential for maintaining a good hygiene.

Question 58.
Why is washing of hand essential before taking food?
Answer:
We commonly take food by hand. A contaminated hand may carry the pathogens of various diseases like diarrhoea, dysentery, hepatitis A, cholera, gastroenteritis. By washing hand before taking food, the occurrence of these diseases can be reduced to a great extent.

Question 59.
Why an open wound should be washed with germicidal lotion?
Answer:
Skin acts as a great barrier against the entry of germs into our body. However, open wounds become a good entry point for various germs. Therefore, any open wound is to be washed with germicidal lotions to kill the germs in the wound and at its periphery. After washing, the wound must be covered with sterilised bandage, gauge or cotton to resist the entry of germs through it.

Question 60.
What are ‘paratope’ and ‘epitope’?
Answer:
The part of antibody that adheres to antigen is known as ‘paratope’ and the part of the antigen, attached to the paratope is known as ‘epitope.’

Question 61.
What is interferon (IFN)?
Answer:
Interferon is a group of proteins that is formed and released by the host cells in response to pathogens specially virus. These are highly effective in combating hepatitis, influenza etc.

Question 62.
What is MALT?
Answer:
The full form of MALT is Mucosa Associated Lymphoid Tissue. These types of lymphoid tissues are located within the lining of respiratory tract, digestive tract and urino-genital tract and it constitutes 50 % of lymphoid tissues in human body.

Question 63.
What is the main objective of vaccination?
Answer:
Generating memory cells in the blood to recognise a specific antigen for quick triggering of immunological response in case of infection by the same pathogen in future is the main objective of vaccination.

Question 64.
Distinguish between innate and acquired immunity.
Answer:

Features	Innate immunity	Acquired immunity
1. Activation	Becomes active with birth	Becomes active in presence of antigen
2. Specificity	It is nonspecific immune response	It is specific immune response

Question 65.
Distinguish between active acquired immunity and passive acquired immunity.
Answer:

Features	Active acquired immunity	Passive acquired immunity
1. Source of antibody	Originates inside the body with introduction of any antigen	Enters into the body from mother’s body or from other animal source
2. Span of action	Develops slowly but remains active for a long time	Acts instantaneously

Long Questions and Answers : (5 marks for each question)

Question 1.
Briefly describe the structure of the most common antibody present in human plasma. Distinguish between antigen and antibody. 3 + 2
Answer:
Structure of antibody

Immunoglobulin G or IgG is the most common antibody present in human plasma. Its structure is mentioned below.
1. Immunoglobulin G molecule is a ‘Y’ – shaped structure.
2. Each molecule has a specific antigen-binding site, by which it attaches with a specific antigen to inactivate it.
3. The immunoglobulin molecule is composed of 4 polypeptide chains of which two are heavier and two others are lighter in weight. These chains remain attached with di-sulphide bonds.
4. The two forked arms are made up of one light and one heavy chain each. The stem arm of IgG molecule is composed of two heavy chains.

Differences between antigen and antibody

Features	Antigen	Antibody
1. Occurrence	Enters into body from outside (rarely synthesised inside body)	Occurs within the body in the presence of antigen
2. Effect	Causes harm to the body	Protector of the body
3. Chemical nature	Glycoprotein, lipoprotein or polysaccharide	Generally glycoprotein
4. Function	Activates the immune system of the body	Inactivate or destroy antigens

Question 2
Briefly describe the mechanism of immune response against viral attack in human body. Mechanism of immune response against a viral attack
Answer:
Immune response is a complex process involving various cells and biochemical components inside the body.

The steps of immune response against viral antigen are as follows –

1. As any virus reaches blood or attacks any body cells, large phagocytic macrophages engulf those infected cells. Soon viral antigens appear on the cell surface of macrophages.
2. High concentration of viral antigens on macrophage activates helper Tlymphocytes in blood.
3. Helper Tcells immediately initiate the production of cytotoxic killer T-cells, memory T-cells and B-lymphocytes.
4. B-lymphocytes proliferate very fast to produce plasma cells and memory B-cells.
5. Plasma cells produce specific antibodies to bind and inactivate virus before they get chance to infect a cell.
6. Killer Tcells destroy the infected body cells along with viruses.
7. T and memory B- cells stay in the body to recognize the same pathogen in case of further infection and to develop quicker response.

Question 3
What is humoral immunity? How does humoral immunity work?
Answer:
Humoral immunity
The immune response, which involves the action of different B-lymphocytes, like plasma cells, for producing antigen-specific antibodies and memory cells for neutralizing or eliminating toxins and pathogens in the blood and lymph is called humoral immunity.
Mechanism of humoral immunity –
Humoral immunity works for both primary and secondary immune response.
In primary response B-lymphocytes develop typical antibody-producing plasma cells. These cells produce antigen

specific antibodies. Antibodies work in following four ways.

1. Agglutination: By this process antibodies agglutinate pathogens into clusters, which are then collectively phagocytized by macrophages.
2. Precipitation: Some antigen molecules are clamped by antibodies and are precipitated.
3. Opsonisation: Antibodies form a covering on the antigens so that the phagocytic cells ingest packed antigens.
4. Neutralisation: Certain toxic antigens are detoxified and inactivated by the antibodies.

In secondary response memory B-cells play the major role. These cells are produced during primary immune response and remain stored in the secondary lymphoid tissues for keeping the immunological behaviour of the pathogen in memory of the body’s immune system. In case of another attack, these cells help in quick activation of body’s immune system.

Question 4.
Mention the roles of different T-cells in immune response? Mention the roles of different B-cells in immune response? 3 + 2
Answer:
Roles of different T-cells
Different T-cells or T-lymphocytes play different roles in immune response of the body. They are as follows-
1. Cytotoxic T-cells or T_C-cells kill the infected cell, to destroy antigen carrying pathogens within it.
2. Helper T-cells or T_H-cells enhance the activity of killer cells (a type of T_C – cells), antibody producing B-cells and phagocytic macrophages.
3. Suppressor T-cells or T_S-cells destroy T_C-cells, T_H-cells and B-cells to stop immune response after the elimination of the antigens.

Roles of different B-cells :
Different B-cells or B-lymphocytes play different roles in immune response of the body. They are as follows-
1. Plasma cells originated from B-cells produce specific antibodies to inactivate antigens.
2. Memory B-cells remain in lymph glands, keeping the nature of antigens in memory, take quick action in case of any further attack.

Question 5.
Mention the differences between B-cells and T cells.
Answer:
Differences between B-cells and T-cells

Features	B-cells	T-cells
1. Maturation	Lymphoid tissue or bone marrow	Thymus
2. Longivity	Short (few days to a week)	Long (months to years)
3. Surface immunoglobulins	Present	Absent
4. Type of immunity	Humoral immunity	Cell mediated immunity
5. Secretary product	Antibodies	Lymphokines
6. Defence mechanism	Defend against pathogens that enter the blood and lymph	Defend against pathogens that enter the cells
7. Inhibition	Have no inhibitory effect on immune system	Suppressor cells inhibit immune system

Question 6.
Give a brief historical account of the discovery of small pox vaccine.
Answer:
Discovery of small pox vaccine
The scientific concept of vaccination was developed in the later half the of 18th century when a number of scientists and physicians were working hard to develop a vaccine against small pox, the most deadly and contagious disease of that time. Scientists noticed that most individuals, who once suffered from cow pox safely bypassed small pox. But the search was on for long 25 years. Then Dr. Edward Jenner (1798) broke through the concept of vaccination. He collected a little pus from a cow pox vesicle on the hand of Sarah Nelmes, a milkmaid, and introduced it into the arm of James Phipps, an eight year old boy.

After two months, the boy was inoculated with small pox virus, but he did not develop the disease. The modern concept of vaccination is standing on this story. After this discovery, the practice of vaccination took the correct route. After a long battle for about two centuries, small pox has now been eradicated from the world.

Question 7.
What is a vaccine? Mention the basic working principles of vaccines to develop immunity in the body. 2 + 3
Answer:
Vaccine
Vaccine is an antigenic material that is prepared with killed or weakened pathogens, part of pathogens, bacterial toxins or microbial proteins, which do not cause illness but provide active acquired immunity against those pathogens when introduced into the body.

Working principle of vaccines
By vaccination, a killed germ, attenuated (weakened) germ, toxoids (toxins collected from germs) or subunits (fragments of proteins from germs) are introduced into the body of an individual. These may be injected or administered orally. As soon as the substance enters the body, antigens present in it, activate the immune system and initiate an immune response. T-cells and B-cells take a little time to inactivate such little quantity of antigens and this process is known as primary immune response.

However, in this case, main function is done by memory B-cells. These cells, produced during the immune response, are retained in lymph nodes such as spleen, thymus etc.. for a long time. In case of any future infection by the same germ, these memory cells recognize those antigens instantly and inactivate or destroy the attacker very fast. This process is recognized as secondary immune response. Thus, a successful vaccination immunizes a person effectively.

Question 8.
Give a brief account of different types of vaccines.
Answer:
Types of vaccines

With the development of science, new and advanced varieties of vaccines are being developed. Till date World Health Organisation (WHO) has licensed vaccines for 25 diseases. Different types of vaccines are:
1. Killed vaccine: These vaccines contain killed pathogens. Vaccines of cholera, plague, influenza are of this type.

2. Live attenuated vaccine: By some laboratory techniques virulence of the pathogens are reduced to prepare this type of vaccines. Vaccines of mumps, measles, and rubella are of this type.

3. Toxoid vaccine: This type of vaccine is prepared by inactivated toxins from pathogens. Vaccines of tetanus, diphtheria are of this type.

4. Conjugate vaccine: Generally polysaccharide of bacterial capsule is attached with a protein to prepare this vaccine. Body’s immune system can recognise this conjugated protein and keep it in memory for future immune response. Vaccine against Haemophilus influenzae type-B is of this type.

5. Sub-unit vaccine: This type of vaccine is prepared by small fragments of pathogenic protein. Vaccine against Hepatitis B is of this type.
Heterotypic vaccine: This is prepared by pathogens, causing disease to other animals but less or non-virulent to human. Vaccines of small pox and tuberculosis are of this kind.

Question 9.
Why and when should an individual wash hands? Write down the proper method of washing hand. 1 + 2 + 2
Answer:
Reason of washing hand
We take food with hand. We often touch our lips, face and nose with our hands. By contaminated hands, germs or toxins may enter our body through mouth, eyes and nose. Therefore, one must wash the hands to stay healthy.

Time of washing hand
Hands must be washed before –

1. taking food
2. cooking
3. serving food
4. feeding and attending a baby or a patient.

Proper washing of hand is a must after using toilet, cleaning raw vegetables, fish and meat, attending a patient, sweeping and cleaning rooms and toilets, polishing shoe and tying shoe-laces, checking air pressure of cycle tyre, coming home from outside, etc.

Proper method of washing hand :
Proper method of washing hand is mentioned below.

1. Wet the hands with clean water.
2. Take liquid hand-wash or soap in wet hands and rub it for one or two minutes to make rich foam.
3. Carefully rub in between all fingers.
4. Place the hands under running water and continue rubbing until the foam clears.
5. Close tap with clean cloth and wipe the hand with dry and clean towel.

Question 10.
Wilte a short note on ‘WASH’ programme of UNICEF.
Answer:
‘WASH’ programme of UNICEF
Percentage of healthy children in a population is the index of development of a nation. But it is unfortunate that even in the 21 st century, millions of children suffer from diarrhoea and several other water-borne diseases. This happens because of contaminated water, which occurs mostly due to lack of proper sanitation. 44 % of global population defecate in open areas. Faeces contain numerous germs, which easily contaminate water, especially during rainy season.

In view of that, UNICEF (United Nations International Children’s Emergency Fund) has developed a global strategy to lift the standard of health of school children by providing them adequate drinking water, infrastructure for proper sanitation and sense of hygiene. This programme is popularly known as ‘WASH’ (Water Sanitation Hygiene programme). United Nations has set a goal for sustainable development of the standard of living of world population in this millennium. To reach the target, UNICEF has developed a strategy to maximise child survival rate by providing an access to adequate drinking water, sanitation facilities to schools all over the world along with education and nutrition

Question 11.
Describe the WASH strategy taken by UNICEF to improve hygiene behaviour among school children. How can the WASH programme be made successful? 3 + 2
Answer:

WASH strategy to improve hygiene behaviour among school children Schools are the places where a child spends most of the time of his or her life all through the development period. So UNICEF has developed the plan to make every school a child-friendly place. In view of that UNICEF has extended both monetary and strategic support to all developing countries of the world to develop infrastructure for child-friendly schools. The strategy to enhance child survival and development, UNICEF has encouraged a three pillar approach. The first is enabling a child-friendly environment in the school. Next is to improve hygiene behaviour among the students and the third one is to build infrastructure for water supply and sanitation services.

Points to make WASH successful :
The points to make WASH successful are as follows-

1. Wash your hands with adequate water and soap before taking food and after using toilets.
2. Always use sanitary toilets.
3. Clean raw fruits and vegetables before consuming.
4. Keep a close vigilance on drinking water sources to reduce contamination to zero.
5. Clean water storage containers every day.
6. Keep your domestic and school toilets clean.
7. Clip your nails regularly and do not let any filth to deposit under it.

Question 12.
Mention different hygienic practices to secure good health of a person as well as of the society.
Answer:
Different types of hygienic practices
The conditions or practices helpful to maintain health and to prevent diseases, especially through cleanliness are known as hygiene. Hygiene can be practiced in three different levels, i.e., personal, household and social levels, which are mentioned below.
1. Personal level hygiene:

• Cleaning hands before taking food, after using toilet and handing any unclean material.
• Brushing teeth after taking meal and before going to bed.
• Taking bath once or twice a day.
• Trimming hair and clipping nails regularly.

2. Househoid level hygiene:

• Washing and sun-drying clothing and bedding at regular intervals.
• Cleaning utensils, kitchen equipment, raw vegetables, fish and meat.
• Cleaning toilet, basins and sinks.
• Cleaning and disinfecting water reservoirs.

3. Social level hygiene:

• Cleaning of sewage system at regular interval.
• Maintaining general cleanliness in hospitals, educational institutions, market places, railway stations, bus terminus,
• auditoriums, theaters and other community places.
• Regular cleaning and disinfecting public toilets.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 2.3A Tissue: Plant Tissue and its Distribution offer valuable context and analysis.

WBBSE Class 9 Science Chapter 2.3A Question Answer – Tissue: Plant Tissue and its Distribution

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Which type of parenchyma is involved in it aiding photosynthesis within it?
Answer:
Chlorenchyma is involved in holding photosynthesis within it.

Question 2.
Which type of tissue in fruits form roughage a our food diet?
Answer:
Fruits containing sclerenchyma tissue, form roughage of our food diet.

Question 3.
Which tissue is also known as leptome?
Answer:
Phloem tissue is also known as leptome.

Question 4.
Which type of simple permanent tissue has evenly thick cell wall around dead cells?
Answer:
Sclerenchyma has evenly thick cell wall around dead cells.

Question 5.
Which type of scierenchyma cells make the fruits like guava, pear etc. harder?
Answer:
Sclereid cells make the fruits like guava, pear etc. harder.

Question 6.
How do the large air-filled intercellular spaces of parenchyma tissue in petioles of lotus plant help it?
Answer:
The large air-filled intercellular spaces of parenchyma tissue in petioles of lotus plant help it to maintain its buoyancy and to float on water.

Question 7.
Which is the non-living component of phloem?
Answer:
Phloem fibre is the non-living component of phloem tissue.

Question 8.
Which type of tissue is the cork cambium?
Answer:
Cork cambium is a secondary meristematic tissue.

Question 9.
From which type of tissue does permanent tissue develop?
Answer:
Permanent tissues develop from meristematic tissue.

Question 10.
Name the cells of parenchyma tissue in which plants store their excretory matter.
Answer:
Plants store their excretory matter in idioblast cells of parenchyma tissue.

Question 11.
Which type of meristem occurs along the longitudinal plane of the plant body?
Answer:
Lateral meristem occurs along the longitudinal plane of the plant body.

Question 12.
Which type of meristem is seen in the leatbase of pine?
Answer:
Intercalary meristem is seen in the leaf-base of pine.

Question 13.
Which simple permanent tissue is totally devoid of intercellular space?
Answer:
Sclerenchyma tissue is totally devoid of intercellular space.

Question 14.
Which cells do not directly take part in transportation of food in plants but help in this process?
Answer:
Companion cells do not directly take part in food transport but help sieve tubes to do so.

Question 15.
Which simple permanent tissue is responsible for adding mechanical strength to the plant body?
Answer:
Sclerenchyma tissue is responsible for adding mechanical strength to the plant body.

Question 16.
Which plant tissue is involved in ascent of sap?
Answer:
Xylem is involved in the ascent of sap.

Question 17.
Which plant tissue is involved in the transportation of food within the plant body?
Answer:
Phloem is involved in the transportation of food within the plant body.

Question 18.
Which type of cambium is also known as fascicular cambium?
Answer:
Vascular cambium is also known as fascicular cambium.

Question 19.
Which cell of phloem takes part in transportation of food?
Answer:
Sieve tubes take part in transportation of food.

Question 20.
Which cell is accompanied by companion cells?
Answer:
Companion cells accompany the sieve tube of plant cells.

Question 21.
Which is the only living member of xylem tissue?
Answer:
Xylem parenchyma is the only living member of xylem tissue.

Question 22.
Which meristem helps in increasing girth of the plant?
Answer:
Leteral meristem helps in increasing girth of the plant

Question 23.
Which cells of zylem exclusively provide mechanical support to the plant body?
Answer:
Xylem fibres exclusively provide mechanical support to the plant body.

Question 24.
Which tissue is predaminant in a hard woody plant part?
Answer:
Sclerenchyma tissue is predominant in a hard woody plant part.

Question 25.
What is the other name of cork cambium?
Answer:
The other name of cock cambium is phellogen.

Question 26.
What do companion cells do?
Answer:
Companion cells play supporting role in the conduction of food through sieve tubes.

Question 27.
Identify the main types of tissue present in pith of stem and husk of coconut.
Answer:
In the pith of stem, parenchyma tissue and in husk of coconut, sclerenclyma tissue is present.

Question 28.
What is chlorenchyma?
Answer:
The parenchyma tissue, carrying chloroplastids and acting as the site of photosynthesis is known as chlorenchyma.

Short Questions and Answers : (2 marks for each question)

Question 1.
Mention the correlation amongst cells, tissues, organs and body.
Answer:
Cells are the structural and functional unit of living body. Cells of same origin and function having similar or dissimilar structures constitute a tissue. One or more types of tissue when unite to perform a specific function, form a tissue system. Several tissue systems constitute an organ and various organs form a body.

Question 2.
For which type of plant tissue the phrase ‘Three in one’ is appropriate? Justify your answer.
Answer:
1. The phrase ‘Three in one’ is appropriate for the three types of meristem, based on their function.

2. Based on their function, meristems can be of three types-protoderm, procambium and ground meristem. Protoderm gives rise to epidermal layer of different plant parts, procambium gives rise to vascular tissues and ground meristem produces cortex, pith etc. Thus, the total plant body is made from these three meristems. So the statement is justified.

Question 3.
What do you mean by wood fibre? What is bast fibre?
Answer:
Wood fibre: Sclerenchyma fibre associated with xylem tissue is called wood fibre. It provides mechanical strength to the plant.

Bast fibre: Sclerenchyma fibre associated with phloem tissue is called bast fibre. It is responsible for making plant parts strong and also stores food.

Question 4.
What is the utility of tissues in multicellular organisms?
Answer:
Different utility of tissues in multicellular organisms are as follows-

• Tissue brings division of labour to increase efficiency.
• Tissues become organised to form organs and organ systems.
• Decreases the work load of individual cells.
• Chances of survival of these organisms increase due to higher efficiency and better organisation.

Question 5.
Why are some specific types of sclereids called stone cells?
Answer:
The deposition of lignin, cutin and suberin on the cell wall of some short and oval or spherical shaped sclereids, makes them hard like stones. The lumen of such cells are almost squeezed due to deposition. That is why, these special type of sclereids are called stone cells. Stone cells are responsible for mechanical support.

Question 6.
Mention the functions of cork cambium and vascular cambium.
Answer:

• Functions of cork cambium: It takes part in the growth of outer part of plant body beyond vascular bundle, to produce cortex and bark to replace ruptured epidermis.
• Functions of vascular cambium: It takes part in the formation of xylem and phloem within vascular bundle.

Question 7.
Mention the occurrence of parenchyma cells.
Answer:
The occurrence of parenchyma tissue is as follows-

• It is seen in the epidermis of all plant parts.
• It is present in ground tissue of plants including cortex, medulla and medullary rays.
• Mesophyll tissue of leaves is composed of parenchyma.
• It occurs in endosperm of seeds.

Question 8.
Where do you find xylem tissues?
Answer:
Components of xylem tissues are found in the following parts of plant-

• Tracheids and trachea occur in vascular bundle of root, stem and leaf.
• Xylem fibres are seen in vascular and cortex region of woody plants.
• Xylem parenchyma cells are present in vascular region of gymnosperms and dicot plants.

Question 9.
Where do you find collenchyma tissue?
Answer:
Collenchyma tissue is mainly found in the hypodermis of stem. Mid-rib and petiole the of leaves and peduncle of flowers are made up of collenchyma.

Question 10.
Mention the features of different types of collenchyma.
Answer:
Features of different types of collenchyma are as follows-

• Angular collenchyma cells have thickened corners.
• Lacunate collenchyma cells have thick walls near the intercellular spaces.
• Lamellate collenchyma cells have thick walls at the point of contact with adjacent cells.

Question 11.
Mention the different types of sclerenchyma, based on their features?
Answer:
Features of different types of sclerenchyma are as follows-

• Sclerenchyma fibres are long and narrow cells with pointed ends.
• Sclereids are broad with thick walled cells which occur singly or in small groups.

Question 12.
Where do you find sclerenchyma tissue in a plant?
Answer:
Components of sclerenchyma are found in the following parts of plant-

• Sclerenchyma fibres are present in the hypodermis, cortex, vascular bundles and pericycle.
• Sclereids are found in seed coats.

Question 13.
Mention the differences between prokaryotic and eukaryotic cells.
Answer:
Differences between prokaryotic and eukaryotic cell

Question 14.
Distinguish between meristematic tissue and permanent tissue.
Answer:

Feature	Meristematic tissue	Permanent tissue
1. Nature	Always living	Living or dead
2. Cell wall	Very thin and soft	Comparatively thick and rigid
3. Cytoplasm	Dense and spread all over the cell	Reduced as primordial utricle or totally absent
4. Vacuoie	Absent or very small	Very large
5. Divisibility	Divisible	Indivisible

Question 15.
Distinguish between simple permanent tissue and complex permanent tissue.
Answer:

Feature	Simple permanent tissue	Complex permanent tissue
1. Ceil types	Composed of similar types of cells	Composed of different types of cells
2. Cell wall	Thin, evenly or unevenly thickened	Evenly thickened
3. Vascular bundle formation	Does not form vascular bundle only helps to form it	Directly takes part in vascular bundle formation
4. Function	Formation of plant body, synthesis and storage of food	The absorbed materials from the roots are transported throughout the plant body

Question 16.
Distinguish between xylem and phloem.
Answer:

Feature	xylem	Phloem
1. Structural components	Tracheid, trachea, xylem parenchyma and xylem fibre; except xylem parenchyma, other components are dead	Sieve tube, companion cell, phloem parenchyma and phloem fibre; except pholem fibre, other components are living
2. Elements for transportation	Tracheid and trachea	Sieve tube
3. Direction of transportation	Against gravity	Transportation occurs irrespective of gravity
4. Function	Ascent of sap	Transportation of food

Question 17.
Distinguish between tracheid and trachea.
Answer:

Features	Sieve tube	Companion cell
1. Nucleus	Absent	Present
2. Shape	Cylindrical	Lens shaped
3. Cell plate	Porous, produces sieve like structure	Intact, no pore can be seen
4. Function	Transportation of food	Storage of food and helping in transportation of food through sieve tube

Question 18.
Distinguish between xylem fibre and phloem fibre.
Answer:

Features	Sieve tube	Companion cell
1. Nucleus	Absent	Present
2. Shape	Cylindrical	Lens shaped
3. Cell plate	Porous, produces sieve like structure	Intact, no pore can be seen
4. Function	Transportation of food	Storage of food and helping in transportation of food through sieve tube

Question 19.
Distinguish between xylem fibre and phloem fibre.
Answer:

Features	Xylem fibres	Phloem fibres
1. Occurrence	Sclerenchyma cells present in xylem	Sclerenchyma cells present in phloem
2. Shape	Narrower lumen, ends tapered to a point	Wider lumen, ends are blunt
3. Wall thickness	More thickened due to lignification	Less thickened, either lignified or non-lignified
4. Rigidity	More rigid	Comparatively flexible

Question 20.
Distinguish between trachea and seive tube.
Answer:

Features	Trachea	Sieve tube
1. Nature of cell	Dead	Living
2. Sieve plate	Absent	Present, perforations clogged with callose
3. Cell wall	Thickened with secondary thickening of lignin	Comparatively thin, primary wall lignified
4. Function	Ascent of sap against gravity	Transportation of food occurs irrespective of gravity

Long Questions and Answers : (5 marks for each question)

Question 1.
What is meant by tissue? How plant tissues can be classified into different types?
Answer:
Tissue
Tissue is the assemblage of a number of structurally similar or dissimilar cells having same origin and function.
Classification of different plant tissues:

Question 2.
What is meant by meristem or meristematic tissue? Describe the characteristic features of the meristematic tissue with a simple diagram.
Answer:
Meristem or meristematic tissue

Meristems or meristematic tissues are cells or group of cells that are capable of undergoing cell division.

• Cells are living, undifferentiated, polygonal, spherical or oval in shape.
• Cells are densely packed and without intercellular spaces.
• Cell wall is thin, made up of cellulose.
• Nucleus is large and distinct.
• Cytoplasm is dense, vacuoles generally absent.
• The cells are capable of undergoing cell division.

Question 3.
Describe the distribution of different meristematic tissues.
Answer:
Distribution of meristematic tissues:
Based on occurrence, meristematic tissues can be sub-divided into three types, which are as follows-

1. Apical meristem: It occurs at the tip of roots and shoots. This tissue helps the plant to grow in length.

2. Intercalary meristem: It occurs near the nodes of growing shoots, in between two layers of permanent tissues. This makes the young internodes longer and also helps in the growth of leaves.

3. Lateral meristem: It occurs along the lateral position of roots and stems of higher plants. It divides laterally and makes the plant thicker. It is of two types

• Vascular cambium (fascicular cambium): It occurs within vascular bundle to form new xylem and phloem.
• Cork cambium (phellogen): It occurs outside vascular bundle and takes part in the growth of outer layers of the stem and root.

Question 4.
What is meant by permanent tissue? Mention the characteristic features of permanent tissues.
Answer:
Permanent tissues.
The plant tissues in which cells have lost their capability of undergoing cell division are known as permanent tissues.

Characteristic features of permanent tissue:
The characteristic features of permanent tissue are as follows-

• Cells of these tissues do not divide and have no role in plant growth.
• Cells are differentiated into definite size, shape, structure and function.
• Cells have larger vacuoles. Cell walls may be thin or thick. Often ornamentations are seen on cell wall. Intercellular spaces are often present.
• These tissues comprise of either dead or living cells. In living cells, protoplasm is reduced with smaller nucleus.
• These tissues are involved in protection, support, transportation or secretion. Metabolic rate is slower in comparison to meristematic cells.

Question 5.
Describe the characteristic features of parenchyma tissue with simple diagram. Mention its functions in a plant body.
Answer:
Characteristic features of parenchyma tissue

The characteristic features of parenchyma tissue are as follows:

• Cells are living and thin walled, almost equal in size and shape.
• Cells are loosely packed with distinct intercellular spaces.
• Vacuoles are large. Cytoplasm becomes peripheral, forming primordial utricle with a distinct nucleus.

Functions of parenchyma tissue:
The functions of parenchyma tissue are as follows-

• Simple parenchyma cells occur in the ground tissue and store food.
• Aerenchyma maintains buoyancy in floating and submerged aquatic plants.
• Chlorenchyma takes part in photosynthesis.
• Idioblasts store mineral crystals, oil, excretory matter etc.
• Parenchyma allows movement of gases and gaseous exchange because of the presence of intercellular spaces in it.
• As epidermis or epiblemma, parenchyma protects all plant parts.

Question 6.
Describe the characteristic features of collenchyma tissue with diagram. Mention the function of this tissue.
Answer:
Characteristic features of collenchyma tissue

The characteristic features of collenchyma tissue are as follows-

• Cells are living and are of almost identical size. They are cylindrical, but in cross-section appear polygonal.
• Cell wall is made up of cellulose, hemicellulose and pectin, unevenly thickened at the corners.
• Intercellular space is reduced.
• Vacuole is large. Cytoplasm present as primordial utricle. Chloroplast may be present.

Functions of collenchyma tissue
The functions of collenchyma tissue are as follows-

• Provides mechanical strength.
• Provides flexibility to plant parts and Labelled diagram of collenchyma tissue prevents from breaking.
• This type of tissue helps to store food.
• It also carries out photosynthesis.

Question 7.
Describe the characteristic features of scierenchyma tissue with diagram. Mention the functions of this tissue.
Answer:
Characteristic features of sclerenchyma tissue

The characteristic features of sclerenchyma tissue are as follows-

• Cells are dead when mature, devoid of protoplasm and have narrow lumen.
• Cells are without inter-cellular space.
• Cell wall is evenly thickened and highly lignified.
• At some points, pits are present on the cell wall.
• Some cells are thin, elongated and pointed. These are called sclerenchyma fibres. Some are wide with very thick cell wall, which are called sclereids.

Functions of sclerenchyma tissue
The functions of sclerenchyma tissue are as follows-

• Provides mechanical strength.
• Makes the plant parts rigid.
• Sclereids especially form tough seed coat of legume fruits and endocarp of drupe.
• This tissue also protects plant parts from getting wet.

Question 8.
Name the componants of xylem. Describe the characteristic features of these components.
Answer:
Components of Xylem

Xylem has four typical components, these are tracheid, tracheae or vessels, xylem parenchyma and xylem fibres.

Characteristic features of xylem components
The characteristic features of xylem components are as follows-

• Tracheids are dead, elongated cells with pointed ends. Uneven lignified thickening of walls create different patterns. Pits are present in the cell wall. These cells take part in water transportation through the unthickened parts.
• Vessels or tracheae are long, tubular dead cells without end walls. Lumen is wider than in tracheids. The wall of the vessels possess many pits. These cells also carry sap. Numerous cells are arranged in a row to form long continuous vessels.
• Xylem fibres are dead cells, very thin & long with pointed ends. Cell wall is thick with a narrow lumen. These cells provide mechanical strength and rigidity to the plant body.
• Xylem parenchyma is the only living member of the xylem tissue. It has thin cell wall and it contains protoplasm.

Question 9.
Name different components of phloem. Describe the characteristic features of these components.
Answer:
Components of phloem

Phloem has four typical components, these are sieve tube, companion cell, phloem parenchyma and phloem fibre.

Characteristic features of phloem components
The characteristic features of phloem components are as follows-

• Sieve tubes are living cylindrical cells with perforated end walls, called sieve plates. Nucleus is absent in matured cells. Several sieve tubes are arranged in a row forming a long tube. These help in transportation and storage of food.
• Companion cells are lens-shaped cells with prominent nucleus and dense cytoplasm. They are present on either side of sieve tube. These help sieve tube in tranporation of food.
• Phloem parenchyma has granular cytoplasm and thin cell wall made up of cellulose. This component of phloem stores organic and ergastic materials.
• Phloem fibre is the only non-living component. It is elongated with lignified wall. Pits are present in the cell wall. Fibres provide mechanical support to plant parts.

Question 10.
What is sclerenchyma fibre? Where does it occur? Give a brief description of its structure.
Answer:
Sclerenchyma fibre
Long and fine sclerenchyma cells, with pointed ends and pitted wall, are known as sclerenchyma fibres.

Occurrence of sclerenchyma cells
Sclerenchyma cells occur in the hypodermis and pericycle of stem. These are seen in vascular bundle and bundle cap of dicot plants.

Structure of sclerenchyma fibres
The structure of sclerenchyma fibres is described as follows-

• Sclerenchyma fibres are very fine and long with two pointed ends.
• Cells are without intercellular spaces and are compactly arranged sidewise to form bundle.
• Cell wall is evenly thickened with bordered pits and lumen is narrow.
• Cells are dead and appear polygonal in cross-section.
• The sclerenchyma fibres occurring in xylem are called wood fibres. These fibres, when occur in phloem are called bast fibres.

Question 11.
What are trachea or vessels? Give a brief description of their structure. Mention the occurrence and functions of trachea.
Answer:
Tracheae or vessels:
Tracheae or vessels are the non-living, elongated, tubular xylem cells having highly lignified and evenly thick cell wall with bordered pits.

Structure of tracheae or vessels:
The structure of tracheae is as follows-

• These cells are dead, long and tubular in shape with completely or partially open ends.
• The wall is lignified with bordered pits. Ornamentations are often found on the wall due to uneven thickening.
• The lumen is the widest amongst all xylem components.
• Several tracheal cells remain arranged one after another to form a continuous tube due to the dissolution of end walls.

Occurrence of tracheae or vessels
These xylem components occur in all angiosperms and a gymnosperm named Gnetum.

Functions of trachea
The functions of trachea are as follows-

• It transports sap from root to leaves.
• Trachea provides mechanical support to the plant body.

Question 12.
What is xylem parenchyma? Give a brief description of its structure. Mention the occurrence and functions of xylem parenchyma.
Answer:
Xylem parenchyma
The only living cell of xylem with protoplasm, guarded by thin, cellulose-rich cell wall, is known as xylem parenchyma.

Structure of xylem parenchyma
The structure of xylem parenchyma is as follows –

• These are living cells with cytoplasm and small nucleus inside.
• Cell wall is thin and composed of cellulose.
• The cells are almost isodiametric and lateral walls have few simple pits.

Occurrence of xylem parenchyma
Xylem parenchyma is present in the vascular bundle of all angiosperms and most of the gymnosperms, except pines.

Functions of xylem parenchyma
The functions of xylem parenchyma are as follows-

• It helps in transportation of sap and also helps in lateral transportation.
• It stores nutrients like carbohydrates, fats and excretory matters like tannin, inorganic crystals etc.

Question 13
What are xylem fibres? Give a brief description of their structure. Mention the occurrence and
functions of xylem fibres.
Answer:
Xylem fibres
The dead and fine sclerenchyma cells of xylem are known as xylem fibres.

Structure of xylem fibres
The structure of xylem fibres is as follows-

• Xylem fibre cells are dead, very fine with pointed ends.
• Cells have very narrow lumen.
• Cell wall is very thick due to heavy lignification and rigid with both simple and bordered pits.
• Fibres are to two types-libriform fibre and tracheid fibre.

Occurrence of xylem fibres
Xylem fibres are present in vascular bundle of all angiosperms and most of the gymnosperms, except pines.

Functions of xylem fibres
The functions of xylem fibres are a follows-

• These provide mechanical support to plant body.
• These also store food material and certain excretory matters.

Question 14.
What is sieve tube? Give a brief description of its structure. Mention the occurrence and functions of sieve tubes.
Answer:
Sieve tube : Living elongated tubular phloem cell with sieve plates at two terminal ends and cytoplasm without nucleus is known as sieve tube.

Structure of sieve tube

The structure of sieve tube is as follows-

• Sieve tubes are tubular in shape, arranged longitudinally one after another to form a continuous pipe.
• The matured cells have cytoplasm but no nucleus inside.
• The wall is thin and composed of cellulose.
• The two terminal walls are well perforated and are called sieve plates.
• Connection between two sieve cells are made by cytoplasmic strands through sieve pores.

Occurrence of sieve tubes
Sieve tubes are present in pteridophytes and all flowering plants.

Functions of sieve tubes
The functions of sieve tubes are as follows–

• These help in transportation of food.
• These also occasionally store food.

Question 15.
What are companion cells? Give a brief description of their structure. Mention the accurreace and functions of companion cells.
Answer:
Companion cells : The living, nucleated, lens-shaped cells typically present at two sides of a sieve tube are known as companion cells.

Structure of companion cells
The structure of companion cells is as follows –

• The cells are living, full of dense cytoplasm and with a distinct nucleus inside.
• The cells have thin wall, made up of cellulose and appear triangular in cross-section.
• Laterally, these cells are lens-shaped.
• These cells keep a close association with the sieve tube through pits and plasmodesmata on lateral wall.

Occurrence of companion cells
Companion cells occur in phloem of all angiosperms and in a single gymnosperm, called Gnetum sp.

Functions of companion cells
The functions of companion cells are as follows –

• These help in transportation of food through sieve tube.
• These also store carbohydrate and help in lateral transport.

Question 16.
What is phloem parenchyma? Give a brief description of its structure. Mention the occurrence and functions of phloem parenchyma.
Answer:
Phloem parenchyma : Thin-walled, living, cylindrical cell of phloem tissue is known as phloem parenchyma.

Structure of phloem parenchyma
The structure of phloem parenchyma is as follows-

• The cell wall is thin and made up of cellulose. Rarely lignified and pitted.
• Shape of the cells are elongated, cylindrical and radially arranged with the plant axis.
• Cytoplasm of these cells stores starch, resin, tannin etc.

Occurrence of phloem parenchyma
It is seen in all dicot plants but monocot plants never possess phloem parenchyma. Pteridophytes and gymnosperms also have these cells in phloem.

Functions of phloem parenchyma
The functions of phloem parenchyina are as follows-

• It helps in food transport.
• It stores different organic matter and excretory substances.
• It helps in lateral transport of organic food matter.

Question 17.
What is phloem fibre? Give a brief description of its structure. Mention the occurrence and functions of phloem fibres.
Answer:
Phloem fibre
Phloem fibre is the only non-living component of phloem with thin, elongated shape and two pointed ends.

Structure of phloem fibre
The structure of phloem fibre is as follows-

• These cells are non-living, with very fine and hollow lumen.
• The cells are long with pointed ends.
• Cell wall is thick, well lignified and commonly have simple pits.
• The cells remain arranged one after another along the length.
• Fibres are overlapped above one another to form bundle.

Occurrence of phloem fibres
Phloem fibres are present in angiosperms only.

Functions of phloem fibres
The functions of phloem fibres are as follows-

• These provide mechanical support to the plant body.
• These also store food matter like starch.

Question 18.
Compare the characteristic features of parenchyma, collenchyma and sclerenchyma.
Answer:
Comparison among parenchyma, collenchyma and sclerenchyma

Features	Parenchyma	Coilenchyma	Sclerenchyma
1. Nature	Living	Living	Non-living
2. Cell wall	Evenly thick	Unevenly thick	Evenly thick
3. Shape of cells	Spherical or oval	Elongated, polygonal in cross-section	Elongated and polygonal
4. Main component of cell wall	Cellulose	Cellulose and hemicellulose	Lignin, cutin, suberin
5. Inter-cellular space	Present	May or may not be seen	Absent
6. Ornamentation on cell wall	Absent	Absent	Absent
7. Angular thickening of ceil wall	Absent	Present	Absent
8. Function	Synthesise and store food	Synthesise food and provide mechanical support	Provide mechanical support