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-
- Parotid gland-Located at the base of the ears.
- Sub-maxillary or submandibular gland-Located on two sides of lower jaw.
- 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
- Alkaline bile, secreted from liver, neutralizes acidic chyme from stomach.
- Bile salts emulsify fat to facilitate its digestion.
- Bile helps in the absorption of fat.
- 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 :
- HCl, secreted from oxyntic cells of the stomach wall, activates pepsinogen to active pepsin which helps in protein digestion.
- HCl helps in the hydrolysis of sucrose inside the stomach.
- 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-
- Chewing helps in the grinding of food materials. Enzymes can act better or finely ground food particles.
- In the course of chewing, profuse salivary secretion occurs, which makes the bolus softer to ease swallowing.
- 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-
- Stomach holds the food for some time.
- HCl secreted from the stomach acidifies the food to kill germs, which enter along with it.
- 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
- Building up of organs and tissues.
- Growth and differentiation of cells.
- 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-
- Providing kinetic energy for life activities.
- Releasing chemical energy for the synthesis of adenosine triphosphate (ATP).
- 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-
- It should help to maintain the growth and perfect shape of the body.
- It should perfectly meet the calorific demand of a body.
- 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.
- Body surface area: BMR is directly proportional to the body surface area.
- Age: Children have greater body surface area as compared to their body weight, therefore, in children BMR is more than in adults.
- Sex: Males have greater BMR than females.
- Nutritional status: Long term malnutrition causes decrease in BMR.
- Weather: People living in temperate regions have greater BMR than people living in warmer areas.
- 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 |
