Prasanna

Well structured WBBSE Class 9 Life Science MCQ Questions Chapter 1.1 Basic Properties of Life can serve as a valuable review tool before exams.

Basic Properties of Life Class 9 WBBSE MCQ Questions

Multiple Choice Questions & Answers

Question 1.
One of the basic properties of a living organism is- …………………….
A. To intake oxygen
B. To move
C. To reproduce
D. To absorb water
Answer:
A. To intake oxygen

Question 2.
All reactions of life take place within the- …………………….
A. Nucleus
B. Mitochondrion
C. Chromosome
D. Protoplasm
Answer:
D. Protoplasm

Question 3.
All the biochemical processes occurring within a living organism in order to sustain life, are collectively known as- …………………….
A. Energy
B. Metabolism
C. Nutrition
D. Digestion
Answer:
B. Metabolism

Question 4.
The concept of spontaneous generation of life was first proposed by- …………………….
A. Haldane and Oparin
B. Aristotle
C. Urey and Miller
D. Melvin Calvin
Answer:
B. Aristotle

Question 5.
The concept of origin of life from inorganic matter is known as-…………………….
A. Special creation
B. Chemosynthesis
C. Biogenetic concept
D. Pangenesis
Answer:
B. Chemosynthesis

Question 6.
The first step of chemical origin of life was the-…………………….
A. Origin of coacervates
B. Origin of complex organic compounds
C. Origin of simple organic compounds
D. Origin of proteinoids
Answer:
C. Origin of simple organic compounds

Question 7.
The essential gaseous ingredient of present atmosphere, which was absent in the primitive atmosphere before the origin of life, is-…………………….
A. Carbon dioxide
B. Nitrogen
C. Oxygen
D. Carbon monoxide
Answer:
C. Oxygen

Question 8.
The concept of chemosynthesis of life on earth was proposed by-…………………….
A. Aristotie
B. Miller and Urey
C. Oparin and Haldane
D. Sidney Fox
Answer:
C. Oparin and Haldane

Question 9.
According to Cosmozoic theory or Panspermia, the reason of origin of life is-…………………….
A. Extraterrestrial objects, such as comet
B. Biochemical reactions
C. Spontaneous creation
D. None of these
Answer:
A. Extraterrestrial objects, such as comet

Question 10.
The simple compound present in the primitive earth, was-…………………….
A. H₂O
B. NH₃
C. CH₄
D. All of these
Answer:
D. All of these

Question 11.
The simple organic matter produced from the inorganic compounds during chemosynthesis of life was-…….
A. Fatty acids
B. Amino acids
C. Both A& B.
D. None of these
Answer:
C. Both A& B.

Question 12.
Coacervate, as proposed by Oparin, was mainly composed of-…………………….
A. Lipids
B. Proteins
C. Carbohydrates
D. All of these
Answer:
A. Lipids

Question 13.
‘Hot dilute soup’ produced in the primitive ocean contained-…………………….
A. Amino acids and fatty acids
B. Purines and pyrimidines
C. Simple sugars
D. All of these
Answer:
D. All of these

Question 14.
Formation of proteinoids, before the origin of primordial cell, was explained by-…………………….
A. A I Oparin
B. J B S Haldane
C. Stanley Miller
D. Sidney Fox
Answer:
D. Sidney Fox

Question 15.
The term ‘biodiversity’ was coined by-…………………….
A. Norman Myers
B. Alexander Oparin
C. Gaylord Nelson
D. W G Rosen
Answer:
D. W G Rosen

Question 16.
In the laboratory experiment of chemosynthesis of organic matters from simple inorganic compounds, Urey and Miller used-…………………….
A. NH_{3 ,}CH₄ ,H₂O
B. H₂O, NH₃,CH₄, H₂
C. NH₃, CH₄, H₂O, O₂
D. All of these
Answer:
B. H₂O, NH₃,CH₄, H₂

Question 17.
The energy required for the chemical reactions, which occur during chemosynthesis of life, was obtained from-…………………….
A. Extreme heat of the primitive earth
B. Cosmic rays
C. Lightning
D. All of these
Answer:
D. All of these

Question 18.
In primitive ocean, proteinoids were formed by polymerisation of-…………………….
A. Sugar molecules
B. Fatty acids
C. Nucleic acids
D. Protein molecules
Answer:
D. Protein molecules

Question 19.
The basic physical component of life is-…………………….
A. Nucleic acid
B. Glycerol
C. Glucose
D. Nucleoside
Answer:
A. Nucleic acid

Question 20.
Protobionts are-…………………….
A. A cluster of microsphere molecules, surrounded by a membrane
B. A cluster of protein molecules, surrounded by a lipid layer
C. A cluster of proteinoids, covered with a limiting membrane
D. Nothing but protocells
Answer:
D. Nothing but protocells

Question 21.
The first phase of chemical reactions during chemosynthesis of organic matters started in-…………………….
A. Atmosphere
B. Primitive ocean
C. Earth’s surface
D. Beneath earth’s crust
Answer:
A. Atmosphere

Question 22.
During origin of life, the atmosphere of earth was-…………………….
A. Oxidising
B. Reducing
C. Partially oxidised and partially reduced
D. None of these
Answer:
B. Reducing

Question 23.
The ‘Cyanogen hypothesis’ was given by-…………………….
A. Pfluger
B. Daniken
C. Miller
D. Arrhenius
Answer:
A. Pfluger

Question 24.
Origin of life on the earth was manifested by the formation of-…………………….
A. Microspheres
B. Proteinoids
C. Nucleic acids
D. Protobionts
Answer:
D. Protobionts

Question 25.
Life on the earth originated about-…………………….
A. 2.5 billion years back
B. 4.4 billion years back
C. 3.7 million years back
D. 4.5 million years back
Answer:
B. 4.4 billion years back

Question 26.
The main role played by the organisms in transforming the de-oxidised atmosphere of the primitive earth into an oxidising one, are-…………………….
A. Green plants
B. Photosynthetic bacteria
C. Algae
D. Cyanobacteria
Answer:
D. Cyanobacteria

Question 27.
According to Sidney Fox, prior to the origin of life, numerous thin membrane-bound proteinoid-clusters were termed as-…………………….
A. Coacervates
B. Microspheres
C. Protocells
D. Protobionts
Answer:
B. Microspheres

Question 28.
The relentless effort of a living organism to adjust itself with the changing environment, is called-…………………….
A. Adaptation
B. Migration
C. Evolution
D. Natural selection
Answer:
A. Adaptation

Question 29.
Mutation in organisms occurs-…………………….
A. Slow and steadily
B. With the change in nature
C. Suddenly and temporarily
D. Suddenly and permanently
Answer:
D. Suddenly and permanently

Question 30.
The assumed temperature of the earth during its origin was about-…………………….
A. 2000°-3000°C
B. 3000°-4000°C
C. 400°-500°C
D. 5000°-6000°C
Answer:
D. 5000°-6000°C

Question 31.
The ‘Ancient Astronauts’ hypothesis of origin of life was proposed by scientist-…………………….
A. Pfluger
B. Pasteur
C. Urey
D. Daniken
Answer:
D. Daniken

Question 32.
The physical basis of life is-…………………….
A. Cell
B. Endoplasm
C. Protoplasm
D. Cytoplasm
Answer:
C. Protoplasm

Question 33.
‘Naked gene’ is not covered by-…………………….
A. Plasma membrane
B. Lipid membrane
C. Peptidoglycan membrane
D. Nuclear membrane
Answer:
D. Nuclear membrane

Fill in the blanks:

1. The first nucleic acid which originated on earth was …………….
Answer: RNA

2. The country with the richest biodiversity on earth, is …………….
Answer: Brazil

3. Eye colour is an example of ……………. variation.
Answer: Discontinuous

4. The earliest photosynthetic living organism on this earth was …………….
Answer: Cyanobacteria

5. The concept of spontaneous generation of life was rejected by …………….
Answer: Pasteur

6. ……………. and nucleic acid combined together to form life on primitive earth.
Answer: Protein

7. ……………. is responsible for discontinuous variation.
Answer: Mutation

8. Proteinoid molecules conjugate to form …………….
Answer: Microspheres

State True or False

1. Adaptability is the ability of a living organism to adjust with the changing environment. — True
2. Biogenesis is a synonym of biopoiesis. — False
3. Scientist Haldane coined the term ‘primordial soup’. — False
4. Hydrogen was the predominant gas in the primitive atmosphere. — True
5. Mimosa pudica respond to stimulus. — True
6. Alpha diversity is called turnover diversity. — False

Match the columns

Left column	Right column
1. Biochemical theory of life	A. Aristotle
2. Microsphere	B. Oparin
3. Spontaneous generation	C. Haldane
4. Hot dilute soup	D. Stanley Miller
	E. Sidney fox

Answer:
1-B; 2-E; 3-A; 4-C

Left column	Right column
1. Human weight	A. Beta diversity
2. Species richness in an area	B. Discontinuous variation
3. Turnover diversity	C. Gamma diversity
4. Human eye colour	D. Alpha diversity
	E. Continuous variation

Answer:
1-E; 2-D; 3-A; 4-B

 

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.2A Respiration: Organ-Level Respiration offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.2A Question Answer – Respiration: Organ-Level Respiration

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

Question 1.
Which physiological process provides energy to perform life activities?
Answer:
Respiration provides energy to perform life activities.

Question 2.
Which typical respiratory organ is seen in halophytic plants?
Answer:
Pneumatophore or breathing root is the typical respiratory organ of the halophytic plants.

Question 3.
Name two organisms, which exchange respiratory gases through body surface.
Answer:
Amoeba and Hydra exchange respiratory gases through body surface.

Question 4.
Name two invertebrates, which perform organ-level respiration by skin.
Answer:
Earthworms and leeches are two invertebrates which perform organ-level respiration by skin.

Question 5.
Name two invertebrates, which perform organ-level respiration by gills.
Answer:
Crabs and prawns perform organ-level respiration by gills.

Question 6.
Name a vertebrate, which is capable of performing organ-level respiration by skin.
Answer:
Frogs are capable of performing organ-level respiration through skin.

Question 7.
Which parts of gills act as the site of gaseous exchange?
Answer:
Gill lamellae act as the site of gaseous exchange.

Question 8.
Which part of lungs act as the site of gaseous exchange?
Answer:
Alveoli of lungs act as the site of gaseous exchange.

Question 9.
Mention a common feature of gill lamellae and alveoli of lungs.
Answer:
Both gill lamellae and alveoli of lungs are well vascularised.

Question 10.
Name two parts of the human respiratory system, which do not take part in gaseous exchange?
Answer:
Trachea and bronchioles do not take part in gaseous exchange.

Question 11.
Through which opening, air enters into the trachea from pharynx?
Answer:
Air enters into the trachea from pharynx through an opening, called glottis.

Question 12.
Where is larynx located?
Answer:
Larynx is located at the upper end of the trachea.

Question 13.
Where is bronchus located?
Answer:
Bronchus is located at the lower end of the trachea.

Question 14.
Which bony structure holds the gill lamellae in fishes?
Answer:
In fishes, the gill lamellae are held by bony gill arch.

Question 15.
Which bony plate covers the gill chamber of bony fishes?
Answer:
Operculum covers the gill chamber of bony fishes.

Question 16.
Which fine tubular structures supply air directly to the cells in the body of insects?
Answer:
Tracheoles supply air directly to the cells in the body of insects.

Question 17.
How much air does a healthy adult human inhale or exhale during normal breathing?
Answer:
A healthy adult human inhales or exhales 500 ml of air during normal breathing.

Question 18.
What is the maximum volume of air, which a healthy adult human can hold in the lungs?
Answer:
A healthy adult human can hold a maximum of 4500-5000 \mathrm{ml} of air in the lungs.

Question 19.
How can a person increase the vital capacity of the lungs?
Answer:
A person can increase the vital capacity of the lungs by performing breathing exercises or ‘pranayam’.

Question 20.
Mention two very common diseases caused due to smoking.
Answer:
Smoking causes emphysema and COPD (Chronic Obstructive Pulmonary Disease).

Question 21.
Name the flattened sheet of respiratory muscle, which separates the thoracic cavity from the abdominal cavity.
Answer:
The flattened sheet of respiratory muscle which separates the thoracic cavity from abdominal cavity, is called diaphragm.

Question 22.
Which typical structure prevents the entry of food particles into the larynx?
Answer:
A cartilaginous valve, called epiglottis, prevents entry of food particles into the larynx.

Question 23.
Which structures prevent flattening of trachea during exhalation?
Answer:
There are 16 to 20 half ring-like cartilaginous structures, fitted anteriorly to the trachea, which prevent its flattening during exhalation.

Question 24.
What is the accessory respiratory organ of Koi fish called?
Answer:
The accessory respiratory organ of Koi fish is called labyrinth organ.

Question 25.
Name two muscles of human body, which help in breathing.
Answer:
Intercostal muscles and muscular diaphragm of human body help in breathing.

Question 26.
Name the two parts of pleura.
Answer:
The outer part of pleura is called parietal pleura, and the inner part of pleura is called visceral pleura.

Question 27.
Name a respiratory pigment of vertebrates.
Answer:
A respiratory pigment of vertebrates is haemoglobin.

Question 28.
Name a respiratory pigment of invertebrates.
Answer:
A respiratory pigment of invertebrates is haemocyanin.

Question 29.
When do frogs respire through their skin?
Answer:
Frogs respire through their skin during hibernation (i.e. winter sleep).

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

Question 1.
What is meant by organ-level respiration?
Answer:
The physical process involving the intake of oxygen in the body and release of carbon dioxide from the body, with the help of typical respiratory organs, is known as organ-level respiration.

Question 2.
How do unicellular organisms perform organlevel respiration?
Answer:
Unicellular organisms do not possess organs, therefore they do not perform organ-level respiration, but perform gaseous exchange of O₂ and CO₂ by diffusion through cell membrane.

Question 3.
How do sponges and jellyfishes perform organ-level respiration without respiratory organ?
Sponges and jellyfishes do not have any respiratory organ. Their body cells perform gaseous exchange by diffusion through respective cell membranes. This is how they perform organlevel respiration.

Question 4.
How does the skin of earthworm act as a respiratory organ?
Answer:
The skin of earthworm always remain moist. Atmospheric oxygen is dissolved in the film of fluid over the skin surface. By diffusion, this gas gets mixed in the blood of the capillaries below the skin. Blood plasma of earthworm contains haemoglobin, which receives oxygen and carries it to different parts of the body. This is how the skin of earthworm acts as a respiratory organ.

Question 5.
Mention the role of spiracles and trachea in the respiration of cockroaches.
Answer:
In cockroaches, 10 pairs of spiracles are present at the two lateral sides of the body. Through these pores air enters into the trachea. Trachea forms an intricate network inside the body of cockroach, which ramifies into several branches that help in gaseous exchange.

Question 6.
When and how toads and frogs perform organ-level respiration by skin?
Answer:
Frogs and toads perform organ-level respiration by skin during hibernation. They have moist, naked glandular skin. This is well permeable to gases. The cutaneous capillaries below the skin can absorb oxygen from atmosphere by diffusion, which may fulfill their need of oxygen during hibernation.

Question 7.
How does smoking affect lungs?
Answer:
Smoke of cigarettes and bidis contains different harmful compounds. This smoke enters the human lungs and forms a sticky tar which accumulates in the walls of the alveoli. Due to continuous smoking gradually the lungs lose the ability of gaseous exchange. The harmful compounds cause several diseases like emphysema, COPD and even lung cancer.

Question 8.
How many types intercostal muscles are there? Name them.
Answer:
There are two types of intercostal musclesexternal intercostal muscles and internal intercostal muscles. These muscles are present in between 12 pairs of rib bones.

Question 9.
Distinguish between trachea of cockroach and trachea of human.
Answer:

Features	Trachea of cockroach	Trachea of human
1. Number and shape	Many, which form a network	Single and straight
2. Larynx	Absent	Present
3. Opening	Opens through many paired spiracles	Opens through glottis
4. Termination	Terminates as fine blind tubules within tissues	Terminates into numerous tiny balloon-shaped alveoli

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

Question 1.
What is inhalation and exhalation? Briefly describe the salient features of the respiratory organs of animals. 2 + 3
Answer:
Inhalation
The mechanical process, by which organisms take in air from the environment, is called inhalation.

Exhalation
The mechanical process, by which living organisms give out carbon dioxide-rich air from their respiratory organs, into the environment, is called exhalation.

Salient features of the respiratory organs of animals
Respiratory organs of animals have three main distinctive features, which are mentioned below.
1. Moistness: A typical respiratory organ should be moist, which helps it to trap oxygen before diffusion. Moist cell membrane of unicellular organisms and moist skin of earthworms, leeches, frogs and toads trap atmospheric oxygen very efficiently.

2. Surface area: A respiratory organ should have a large surface area because more surface area improves its efficiency by transporting or exchanging enough oxygen. The thin and numerous lamellae of gills and densely packed alveoli of lungs make these two organs best suited for aquatic & aerial respiration respectively.

3. Vascularity: A respiratory organ should be well vascularised. This helps in better exchange of the respiratory gases. Rich distribution of blood capillaries in gills and lungs make these respiratory organs highly efficient for gaseous exchange.

Question 2.
Explain the role of different parts of plant body in gaseous exchange.
Answer:
Role of different parts of plant body in gaseous exchange
Plants do not have typical respiratory organs like animals. Few sites on a plant body help in exchange of O₂ and CO₂. These are stomata, lenticels, pneumatophores etc. Their role in gaseous exchange is mentioned below.

1. Stomata: Stomata are the tiny pores, present on the surface of leaves, tender stems and other parts of the plant body that help in the exchange of gases. These are the special intracellular spaces bordered by two specialised bean-shaped parenchyma cells, called guard cells, which open and close. Thus, allowing exchange of gases.

2. Lenticels: Lenticels are lens-shaped spaces, formed in the cracks on the bark of trees. These function as pores, providing the pathway for direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases.

3. Pneumatophores: Halophytes (mainly mangrove trees) grow on saline muddy soil in the delta region of rivers. This soil has poor oxygen content. To counter it, some roots of these plants grow vertically upward against gravity and come above the soil. These roots are highly porous. These are called pneumatophores or breathing roots, which help in the exchange of gases directly from the air.

Question 3.
How do insects perform organ-level respiration with the help of trachea?
Answer:
Tracheal respiration in insects
In insects (such as cockroach), a network of a very thin-walled tubes are spread in the body. These tubes are known as trachea. Air enters into the tracheal system through tiny paired pores present on pleurites along the two sides of the body. These pores are called spiracles.

Trachea ramifies or form branches inside the body cavity, longitudinally and transversely to form a tracheal network. The finest ends of tracheal branches are called tracheoles. Each tracheole ends in a large tracheal end cell, which gives off some fine cytoplasmic processes. These processes enter into intercellular tissue fluid. Gaseous exchange occurs between the tracheal end cells and tissue fluid and finally from tissue fluid to the cells by the process of diffusion.

Question 4.
Briefly describe the main respiratory organ of fishes. How do fishes perform aquatic respiration? 3 + 2
Answer:
Structure of respiratory organ of fishes
Gills perform the respiratory function in fishes. In case of cartilaginous fishes, these are present in gill clefts and in bony fishes, these are held in gill chambers at two sides of the head, covered with a bony plate, called the operculum. A gill has a curved bony skeletal structure, called gill arch. Two rows of thin and flat gill filaments are densely arranged in a parallel manner along the gill arch like teeth of a comb. Numerous, very thin membranous folds emerge from either side of a gill filament, called gill lamellae. Gill filaments and lamellae are supplied with dense network of blood capillaries.

Mechanism of aquatic respiration in fishes
Fishes continuously open and close their mouth. When they open their mouth, fresh water flows into the buccal cavity. They open the opercula to allow water to pass through gills to flood the gill filaments before leaving the two gill chambers. As the water passes through the gills, O₂ diffuses into the blood capillaries and CO₂ diffuses out in the water. This is how, fishes perform aquatic respiration.

Question 5.
Describe the structure of human lung.
Answer:
Structure of human lung

Lungs are paired, sac-like structures located in the thoracic cavity of human body, well protected by the rib cage. Lungs remain separated from the abdominal cavity by a muscular sheet or membrane, called the diaphragm. Each lung is covered with a double layered covering called pleura. The outer layer is called parietal and the inner one is called visceral pleura. A fluid-filled space is present in between these two layers. The left lung is slightly smaller with two lobes to accommodate the heart and the right one is larger with three lobes.

A long, thin walled, tubular wind-pipe or trachea goes down vertically along the medial chest line and divides into two bronchi (singular-bronchus) before entering the lungs. Each bronchus then ramifies several times, from finer to finest air tubules, called bronchioles. Finally, each of the bronchioles ends into a tiny balloon shaped alveolus (plural-alveoli). Thus, countless alveoli form a lung. Two human lungs are composed of 30 to 50 crore of alveoli. Wall of each alveolus is rich in blood capillaries. That is why healthy lungs appear reddish pink.

Question 6.
Describe the breathing mechanism of man.
Answer:
Mechanism of human breathing
The organ-level respiration or breathing in man involves two phases-
1. Inspiration
2. Expiration. The mechanism of breathing is discussed below.

1. Inspiration: The events which occur during inspiration are as follows-

As we breathe in, diaphragm muscles contract and move down towards the abdominal cavity.
Intercostal (present in between ribs) muscles contract to pull the ribs upward to some extent.
By these two actions, the space inside the ribcage increases. This reduces the pressure inside the chest cavity and in the pleural fluid.

In this situation, thoracic pressure reaches below the atmospheric pressure. As a result, oxygen-rich air from the atmosphere rushes into the body through nostrils, nasal passage, glottis, larynx, trachea, bronchus and bronchioles to reach the alveoli. Gaseous exchange occurs in between alveolar air and capillary blood. After this exchange, the air inside lungs become rich in carbon-dioxide (CO₂). After this, the brain sends signal for expiration.

2. Expiration: The events which occur during expiration are as follows-

• The diaphragm expands and moves towards the chest cavity.
• Intercostal muscles relax and the ribs go downward to their normal position.
• Due to the above two actions, the internal volume of the chest cavity reduces. As a result, pressure increases in the pleural fluid, as well as in the lungs.
• The lungs contract and the CO₂-rich air, inside the lung, is pushed out along the reverse path.

Question 7.
How do the lungs get weak and diseased? How can the lungs be kept fit? 3 + 2
Answer:
Reason of weak and diseased lungs
Lungs are very important organs in our body, which are involved in respiration. If lungs do not perform their function perfectly, we will fall sick. Lungs lose its efficienc due to aging, obesity, infections and in most cases due to smoking. A dark coloured tar is deposited in the lungs of smokers, that contains several potential carcinogens (cancer inducing substances), leading to lung cancer.

Smokers develop a chronic lung disease, called emphysema. In this case, gaseous exchange reduces and the efficiency of lungs decline permanently. Passive smokers (who unconsciously inhale the smoke released by active smokers) are the worst victims of this bad habit and also suffer from the same diseases. Due to allergic effect, a person may suffer from asthma and COPD (Chronic Obstructive Pulmonary Disease). Infection with Mycobacterium tuberculosis may lead to a serious lung disease, called tuberculosis, whose symptoms are coughing (sometimes with sputum with blood), chest pain, weakness, weight loss, fever etc.

Methods of keeping the lungs fit
Breathing exercise or ‘pranayam’ keeps our lungs healthy. The basis of this exercise is steady, forceful & rhythmic inspiration & expiration. It increases the extensibility of the lungs and thus, increases the oxygen intake capacity of the body. But, pranayam should be practiced under the proper guidance of a competent yoga teacher. Moreover, swimming, cycling, jogging and even walking keeps our lungs healthy.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.1D Movement of Water, Minerals, Food and Gases offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.1D Question Answer – Movement of Water, Minerals, Food and Gases

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

Question 1.
By which process water molecules enter through the cell membrane of root hair cells?
Answer:
Water molecules enter through the cell membrane of root hair cells by endosmosis.

Question 2.
How do cells of aquatic plants absorb dissolved CO₂ from water?
Answer:
Aquatic plants absorb dissolved CO₂ from the water by diffusion.

Question 3.
How is facilitated diffusion different from active transport?
Answer:
In active transport, chemical energy is needed in the form of ATP but facilitated diffusion does not need energy.

Question 4.
In which type of active transport, two different diffusible molecules or ions move against each other at the same time?
Answer:
In antiport, two different diffusible molecules or ions move against each other at the same time.

Question 5.
In which type of active transport, a single type of ion or molecule moves through the cell membrane?
Answer:
In uniport, a single type of ion or molecule moves through the cell membrane.

Question 6.
In which type of active transport, two different ions or molecules move together in the same direction through a cell membrane?
Answer:
In symport, two different ions or molecules move together in the same direction through a cell membrane.

Question 7.
Name two biomolecules, which pass through the cell membrane by active transport.
Answer:
Glucose and amino acids pass through the cell membrane by active transport.

Question 8.
Mention two matters, which are taken into a cell by passive transport.
Answer:
Oxygen and water are two matters, which are taken into a cell by passive transport.

Question 9.
Diffusion pressure deficit increases in leaves during daytime due to which phenomenon?
Answer:
Diffusion pressure deficit increases in leaves during the daytime due to transpiration.

Question 10.
How does sap pass through the cells of cortex of root?
Answer:
Sap passes through the cells of cortex of root by cell to cell osmosis.

Question 11.
Which pressure is created within the xylem vessels by the inflow of sap from the root?
Answer:
Root pressure is created within the xylem vessels by the inflow of sap from the root.

Question 12.
Which force pulls the sap up from roots to the leaves of tall plants?
Answer:
Transpiration pull helps the sap to reach the top leaves of tall plants.

Question 13.
How much pulling force may transpiration pull create in a xylem vessel?
Answer:
About 20 atmospheric pressure is created in the xylem vessels of taller plants by transpiration pull.

Question 14.
How does the size of diffusible molecules affect the rate of diffusion?
Answer:
Larger size of diffusible molecules reduces the rate of diffusion and vice versa.

Question 15.
How does the density of diffusible molecules affect the rate of diffusion?
Answer:
Higher density of diffusible molecules increases the rate of diffusion.

Question 16.
Due to which pressure young meristematic cells grow in size?
Answer:
Young meristematic cells grow in size due to turgor pressure.

Question 17.
Name the scientist who proposed the ‘Root Pressure Theory’.
Answer:
British scientist Stephen Hales proposed the ‘Root Pressure Theory’.

Question 18.
Who proposed the ‘Transpiration pull and Cohesion Tension Theory’ to explain the ascent of sap?
Answer:
Scientists Dixon and Joly proposed the ‘Transpiration pull and Cohesion tension theory’ to explain the ascent of sap.

Question 19.
Give an example of an impermeable membrane.
Answer:
An example of an impermeable membrane is plastic sheet.

Question 20.
Give an example of a permeable membrane.
Answer:
Cell wall is an example of a permeable membrane.

Question 21.
Give an example of a semi-permeable membrane.
Answer:
An example of a semi-permeable membrane is parchment paper.

Question 22.
By which type of active transport, two different diffusible molecules are carried by a single carrier protein?
Answer:
In coupled transport, two different diffusible molecules are carried by a single carrier protein.

Question 23.
Name the components of xylem, which play a major role in the transport of water.
Answer:
The components of xylem, which play a major role in the transport of water are tracheid and trachea.

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

Question 1.
What is meant by transport?
Answer:
The process by which food materials, mineral salts, hormones and various gases reach the cells of living organisms and different harmful metabolic waste matters are sent from tissues to respective excretory organs through liquid medium, is called transport.

Question 2.
How is facilitated diffusion different from simple diffusion
Answer:
In facilitated diffusion, a carrier molecule or a channel protein in the membrane helps the entry of the diffusible molecules through it, but in simple diffusion, carrier protein is not required.

Question 3.
What is meant by passive transport?
Answer:
Passive transport is a process by which any molecule or ion of a substance passes through cell membrane along concentration gradient without consuming any metabolic energy. ExampleDiffusion and osmosis.

Question 4.
What is meant by active transport?
Answer:
Active transport is a process by which any molecule or ion needs some metabolic energy to pass through a cell membrane by the help of carrier protein, against concentration gradient. Example-Intake of glucose molecules by a cell.

Question 5.
What is diffusion?
Answer:
The physical process by which molecules or ions of any substance, moves from a region of higher concentration to a region of lower concentration, with the help of their own kinetic energy, is called diffusion. Example-Aroma of incense stick spreads to all corners of the room by diffusion.

Question 6.
What is meant by osmosis?
Answer:
If two solutions of different concentration, prepared from the same liquid solvent, are separated by a semi-permeable membrane, the solvent molecules move from the region of higher solvent concentration towards the region of lower solvent concentration, until equilibrium is attained. This physical phenomenon is known as osmosis. Example-Raisins swell in water due to osmosis.

Question 7.
What is meant by facilitated diffusion?
Answer:
Facilitated diffusion is a type of diffusion, where diffusible molecules pass through a cell membrane with the help of some channel proteins present in it. In this process, no metabolic energy is needed.

Question 8
What is meant by root pressure? Mention the importance of root pressure.
Answer:

• Root pressure: The cumulative turgor pressure created in the cells, surrounding the xylem vessels of the root, due to absorption of sap is known as root pressure.
• Importance: Root pressure pushes the sap into the xylem vessels through their thick cell wall and drives the sap upward.

Question 9.
What is cohesive force? What is meant by adhesive force.
Answer:

• Cohesive force: The force of attraction between two particles or molecules of a same substance, is called cohesion force. Inside the xylem vessels water droplets remain attached to each other by cohesive force.
• Adhesive force: The force of attraction between the particles of different substances, is called the adhesive force. The water droplets remain attached to the wall of xylem vessel by adhesive force.

Question 10.
What is transpiration pull?
Answer:
In xylem vessels, uninterrupted water column is formed by cohesive-adhesive force. These columns extend from the roots to the stomata of the leaves. During transpiration, when a molecule of water leaves the stomatal opening, it applies an upward pulling force on the receding water column, which is known as transpiration pull.

Question 11.
What is meant by ascent of sap?
Answer:
The transport of water and minerals, known as sap, from root to the leaves through xylem vessels against the force of gravity, is known as the ascent of sap.

Question 12.
The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time. Which phenomenon is responsible for this?
Answer:
The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time due to a phenomenon called diffusion.

Question 13.
Name the forces which control the ascent of sap in plants.
Answer:
The forces which control the ascent of sap in plants are-

• root pressure
• transpiration pull
• adhesive force and
• cohesive force.

Question 14.
Give two examples of liquid-liquid diffusion.
Answer:
Two examples of liquid-liquid diffusion are-

• Diffusion between water and ink and
• Diffusion between water and sugar syrup.

Question 15.
Give two examples of liquid-solid diffusion.
Answer:
Two examples of liquid-solid diffusion are-

• Diffusion between water and sugar crystal and
• Diffusion between water and copper sulphate (CuSO₄)crystals.

Question 16.
Give two examples of solid-gas diffusion.
Answer:
Two examples of solid-gas diffusion are-

• Diffusion between asafoetida and air and
• Diffusion between camphor and air.

Question 17.
Give two examples of gas-gas diffusion.
Answer:
Two examples of gas-gas diffusion are-

• Diffusion between air and ammonia gas and
• Diffusion between air and smoke of inscence stick.

Question 18.
Mention two examples of carrier proteins which help in active transport.
Answer:
Two examples of carrier proteins which help in active transport are-

• Sodium-Potassium pump (Na⁺/K⁺-ATPase pump) and
• Proton pump (H- ATPase pump).

Question 19.
Define hypertonic solution.
Answer:
A solution that has a higher concentration of solutes on the outer side of a cell in comparison to the inner side of it, is known as a hypertonic solution.

Question 20.
What is an isotonic solution?
Answer:
A solution that has identical concentration of solutes on both outer and inner side of a cell, is known as isotonic solution.

Question 21.
Define a hypotonic solution.
Answer:
A solution that has lower concentration of solutes on the outer side of a cell in comparison to the inner side of it, is known as hypotonic solution.

Question 22.
What is absorption in plants?
Answer:
The physical process by which water and mineral salts enter the plant body through root hair by the process of endosmosis, is called absorption.

Question 23
Why the water potential of any solution is always negative?
Answer:
The water potential of pure water is zero. Thus, solute mixed any solution always has negative water potential.

Question 24.
What are the major components of pholem sap?
Answer:
The major components of pholem sap arecarbohydrate, amino acid, minerals and organic acid and water.

Question 25.
Mention the differences between active transport and passive transport.
Answer:

Feature	Active transport	Passive transport
1. Metabolic Energy	Cellular metabolic energy is requried	Cellular metabolic energy is not required
2. Enzymes	Play important role	Play no role
3. Transpiration pull	Plays no role	Plays major role
4. Effect of O2	Transport is hampered in the absence of free O2	Transport is not effected by the absence of free O2

Question 26.
Mention the differences between diffusion and osmosis.
Answer:

Feature	Diffusion	Osmosis
1. Semi-permeable membrane	Not necessary for diffusion	Essential for osmosis
2. Medium	Occurs between different media (solid, liquid, gas)	Occurs between two liquids
3. Transportability	Both solute and solvent are transported	Only solvents are transported

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

Question 1.
Mention the role of different factors in controlling diffusion.
Answer:
Role of different factors in controlling diffusion

Various factors play important role in controlling the rate of diffusion. These are mentioned below.

1. Temperature: With the increase in temperature of the medium, movement of diffusible molecules increase. Therefore, increase in temperature enhances the rate of diffusion.

2. Size of diffusible molecules: Larger size of the diffusible molecules restricts their movement. Therefore, larger molecules show slower diffusion rate.

3. Extent of concentration gradient: Rate of diffusion also depends upon the concentration gradient of molecules of both media. The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of both molecules gets to equilibrium, the slower the rate of diffusion becomes.

4. Solubility: A molecule with higher rate of solubility, diffuses quickly in a given medium.

5. Viscosity of the medium: The rate of diffusion is inversely proportional to the viscosity of the medium. That is, if the viscosity of the medium is high, then the rate of diffusion will be lower and vice versa.

Question 2.
Mention the salient features of diffusion. Give two examples of diffusion in plants.
Answer:
The salient features of diffusion:

The salient features of diffusion are as follows—

• Diffusible molecules of solid, liquid or gaseous substances can diffuse within either liquid or in gaseous medium.
• Diffusible molecules move from a region of higher concentration to a region of lower concentration.
• Diffusion of molecules continues until homogeneity’ is attained, i.e. the concentration of molecules in both directions becomes same.
• It is a passive process, i.e. does not require any metabolic energy.

Example of diffusion in plants
Two examples of diffusion in plants are —

• passive absorption of ions and
• absorption of O and CO₂ in cells.

Question 3.
What is meant by plasmolysis and deplasmotysis? What happens when a living cell is placed in a solution with concentration identical to its protoplasm?
Answer:
Plasmolysis:
If a cell with intact cell membrane is placed in a hypertonic solution, i.e. a solution with concentration higher than the concentration of the protoplasm of the cell, water from the protoplasm will gradually move out from the ceil through its cell membrane by exosmosis. In this case the protoplasm of the cell will shrink and the cell will appear wrrinkied. This phenomenon is called plasmolysis.

Deplasmolysis
If a plasmolysed cell is placed in a hypotonic solution, i.e. a solution with concentration lower than the concentration of the protoplasm of the cell, water from the outer medium will enter into the protoplasm through the cell membrane by endosmosis. In this case, the protoplasm will get more water and the cell will be distended. This phenomenon is called deplasmolysis.

Fate of living cell in isotonic solution
If a living cell is placed in a solution with concentration identical to its protoplasm, i.e., isotonic solution, water from outer medium and from the protoplasm will move through the cell membrane at same rate against each other. Therefore, no change will appear in the cell.

Question 4.
Mention the salient features of osmosis. Mention three roles of osmosis in plant body.
Answer:
The salient features of osmosis:

The salient features of osmosis have been mentioned below.

• Osmosis occurs only in liquid medium.
• This process involves the presence of semi-permeable membrane.
• Solvent molecules move from a region of its higher concentration to a region of lower concentration across the semi-permeable membrane. Movement of solutes does not occur in osmosis.
• Movement of solvent molecules continues until homogeneity is attained. In osmosis, rate of movement of solvent molecules on either side of the semi-permeable membrane becomes the same.
• It is a passive process, i.e. does not require any metabolic energy.

Role of osmosis in plant body
In plants, osmosis helps in-

• absorption of water,
• opening and closing of the stomata and
• maintaining turgidity of cell.

Question 5
Briefly describe the characteristic features of active transport. Mention the importance of cell to cell transport.
Answer:
The characteristic features of active transport:

The characteristic features of active transport has been briefly described below.

• In this process, the movement of substances occur from a region of lower concentration to a region of higher concentration.
• The cell membrane has different carrier proteins that remain suspended in its lipid bi-layer. The substances to be transported, first bind to a specific carrier protein and then passes from one side of the membrane to another.
• The movement of substances against the concentration gradient requires the involvement of energy, which is supplied by ATP. In plants, active transport occurs during absorption of mineral ions by plant roots, loading of sugar into the phloem etc.
• Active transport requires a semi-permeable membrane.

Importance of cell to cell transport:

The importance of cell to cell transport are as follows

• Diffusible materials like O₂ ,CO₂ etc. move from one cell to the next, by cell to cell diffusion.
• Water passes from one cell to another, by cell to cell osmosis.
• Sugar is loaded into the phloem cells from the leaf cells by means of cell to cell active transport.

Question 6.
How does ascent of sap occur in a plant?
Answer:
Ascent of sap:

Transpiration is the process that acts as a driving force for the ascent of sap, from roots to the top of a tree, via xylem vessels. The sequence of events during ascent of sap occurs in the following order:

• Release of water through stomata by transpiration.
• Lowering of turgor pressure of leaf cells due to loss of water.
• Uptake of water by leaf cells from the xylem elements causing a vacuum in the xylem vessels.
• Generation of a vertically upward suction force on the water column in the xylem vessel, called transpiration pull.
• Cohesive and adhesive forces of water molecules maintain the uninterrupted water column within the xylem vessels.
• Roots absorb water and minerals from the soil by imbibition and endosmosis, that moves through the endodermis and increases turgor pressure in the cells surrounding the xylem vessels.
• The mounting root pressure pushes sap into xylem vessels and starts to drive it against gravity towards the leaves upwards.

Question 7.
How is food transported in different parts of the plant body?
Answer:
Transportation of food in plant body:

Transportation of food in plants occurs through sieve tubes of phloem. The cells of selve tube are arranged one after the other forming a continuous structure. Regarding the mechanism of this process, ‘pressure flow hypothesis’ by Ernst Munch, is the most accepted one. According to this hypothesis, following events occur during food transport in plants.

1. Transfer of food from mesophyll tissue to sieve tube: In mesophyll tissues, glucose produced by photosynthesis is soon converted into a larger sugar (sucrose). The sucrose solution is then transferred to the sieve tube via bundle sheath cells, phloem parenchyma and companion cells by cell to cell transport.

2. Creation of pressure within sieve tube: With the entry of sucrose, the cytoplasm of sieve tube becomes denser. As a result, a concentration gradient develops between the sieve tube & neighbouring xylem vessels. Due to this, water moves into the sieve tube from xylem vessels by osmosis, thereby, creating additional pressure within the sieve tubes.

3. Flow of food: This mounting pressure produced within the sieve tube, pushes the food solution to different parts of the plant body. Finally, the sucrose solution enters into the tissue cells from the sieve tube.

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.2B Cellular Level Respiration offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.2B Question Answer – Cellular Level Respiration

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

Question 1.
Which type of respiratory process generates energy inside the living cell?
Answer:
Internal or cellular respiration generates energy inside the living cell.

Question 2.
What is meant by respiratory substrate?
Answer:
The compounds, which are oxidised during cellular respiration to release energy, are known as respiratory substrates.

Question 3.
In which form does respiratory substrate liberate energy during cellular respiration?
Answer:
During cellular respiration, energy is liberated from respiratory substrate in the form of ATP.

Question 4.
Where do reactions of glycolysis take place during cellular respiration?
Answer:
Reactions of glycolysis take place in the cytoplasm during cellular respiration.

Question 5.
What is meant by glycolysis?
Answer:
The breakdown of glucose by enzymes, releasing energy and pyruvic acid, is called glycolysis.

Question 6.
How many pyruvic acid molecules are formed at the end of glycolysis?
Answer:
Two pyruvic acid molecules are formed at the end of glycolysis.

Question 7.
Where do the reactions of Krebs cycle take place?
Answer:
Reactions of Krebs cycle occur in the mitochondria.

Question 8.
Mention the by-products of Krebs cycle.
Answer:
The by-products of Krebs cycle are CO₂, reduced NAD and FAD (i.e. NADH + H⁺ and FADH₂ respectively).

Question 9.
Which reactions of respiration occur in the inner membrane of mitochondria?
Answer:
The reactions of electron transport system or terminal respiration occur in the inner membrane of mitochondria.

Question 10.
In which phase of aerobic respiration is ATP produced?
Answer:
ATP is produced by ETS (electron transport system) of aerobic respiration.

Question 11.
Mention two organic end-products of anaerobic respiration.
Answer:
Lactic acid and ethyl alcohol are two organic end-products of anaerobic respiration.

Question 12.
Name a type of animal tissue, where anaerobic respiration takes place.
Answer:
Anaerobic respiration occurs in the voluntary muscles of animals.

Question 13.
Which organic compound is formed in muscle cells due to anaerobic respiration?
Answer:
Lactic acid is formed in muscle cells due to anaerobic respiration.

Question 14.
Which organic compound is produced in plant cells due to anaerobic respiration?
Answer:
Ethyl alcohol is produced in plant cells by anaerobic respiration.

Question 15.
Which organic compound is produced by fermentation of milk?
Answer:
Lactic acid is produced by fermentation of milk.

Question 16.
Which organic compound is produced by fermentation of glucose or sucrose in oxygen free condition?
Answer:
Ethyl alcohol is produced by fermentation of glucose or sucrose in oxygen free condition.

Question 17.
Name an enzyme present in yeast, wihch helps in aicoholic fermentation of sugar solution.
Answer:
Enzyme zymase is present in yeast, which helps in alcoholic fermentation of sugar solution.

Question 18.
Which enzyme, present in Lactobacillus, helps in fermentation of milk-sugar?
Answer:
Lactate dehydrogenase is the enzyme, present in Lactobacillus, which helps in fermentation of milk-sugar.

Question 19.
Where does aerobic respiration take place?
Answer:
Aerobic respiration takes place in all organisms living in air, water and soil in contact with free molecular oxygen.

Question 20.
How many high energy bonds are present in ATP?
Answer:
Two high energy bonds are present in ATP.

Question 21.
How much energy is released during hydrolysis of 1 molecule of ATP?
Answer:
During hydrolysis of 1 molecule of ATP, 7.3 kcal energy is released.

Question 22.
Which cell organelies are called ‘energy transducers’?
Answer:
Those cell organelles which convert one form of energy into another, are called ‘energy transducers’.

Question 23.
Name two organelles which act as energy transducers.
Answer:
Two organelles which act as energy transducers are chloroplast and mitochondrion.

Question 24.
Name the scientist who first observed the difference between respiration and combustion.
Answer:
Antoine Lavoisier first observed the difference between respiration and combustion.

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

Question 1.
What is respiration?
Answer:
Respiration is a catabolic process, which involves the intake of oxygen within cells and liberation of kinetic energy by oxidation of food or respiratory substrates, for performing different life activities.

Question 2.
What is meant by cellular respiration?
Answer:
The bio-chemical process by which food or respiratory substrates are oxidised within the cells to liberate kinetic energy in the form of ATP, is known as cellular respiration.

Question 3.
What is meant by aerobic respiration?
Answer:
Aerobic respiration is a type of cellular respiration, where respiratory substrate is oxidised completely in the presence of free oxygen to discharge carbon dioxide and water as by-products and to liberate the total energy from the substrate.

Question 4.
Write down the chemical equation of aerobic respiration.
Answer:
The chemical equation of aerobic respiration is mentioned below.

Question 5.
What is meant by anaerobic respiration?
Answer:
Anaerobic respiration is a type of cellular respiration, where respiratory substrate is incompletely oxidised in absence of free molecular oxygen but by the help of the oxygen of inorganic compounds like \(\mathrm{NO}_3^{-}\) \(\mathrm{SO}_4^{2-}\), \(\mathrm{CO}_3^{2-}\), etc. to release carbon dioxide as by-products and to a little amount of energy from the substrate, along with organic compounds.

Question 6.
In which organisms anaerobic respiration occurs?
Answer:
Anaerobic respiration occurs in some bacteria such as Paracoccus denitrificans, Methanobacterium autotrophicum, Bacillus licheniformis etc., few fungi such as yeast, protozoa, all endoparasitic worms (Taenia, Ascaris, Echinococcus etc.). It also occurs in the seeds and few other cells of plants and voluntary muscle cells of animals.

Question 7.
What is meant by fermentation?
Answer:
Fermentation is a typical anaerobic, enzymedependent process of incomplete oxidation of sugar, which produces different organic compounds (ethyl alcohol, lactic acid, butyric acid etc.) with partial liberation of energy from the respiratory substrate.

Question 8.
Write down the chemical equation of ethyi alcohol fermentation.
Answer:
The chemical equation of ethyl alcohol fermentation is mentioned below.

Question 9.
Write down the chemical equation of lactic acid fermentation.
Answer:
The chemical equation of lactic acid fermentation is as follows-

Question 10.
What is meant by alcoholic fermentation?
Answer:
Alcoholic fermentation is a special type of fermentation, where yeast (Saccharomyces) ferments sugar (glucose, fructose, sucrose etc.) solutions to produce ethyl alcohol with the help of a typical enzyme, zymase. In this process, CO₂ and a little energy are also released.

Question 11.
What is meant by lactic acid fermentation?
Answer:
The fermentation process, where certain bacteria (Lactobacillus) ferment milk-sugar (lactose), to produce lactic acid in absence of O₂, liberating a little amount of energy ( 36 kcal ), called lactic acid fermentation.

Question 12.
What is glycolysis?
Answer:
Glycolysis is an oxygen-independent reaction, where glucose, within the cytoplasm of living cells, is broken into pyruvic acid molecules through a series of enzyme-mediated reactions and in this process produce NADH+H⁺, H₂ O and ATP as by-products.

Question 13.
Why is glycolysis called EMP path?
Answer:
Scientists Embden, Meyerhof and Parnas discovered the reaction pathway of glycolysis. Therefore, after the first letter of the names of these three scientists, glycolysis is known as EMP path.

Question 14.
What is Krebs cycle?
Answer:
Krebs cycle is a cyclic reaction pathway, through which, acetyl Co-A, the decarboxylated end product of pyruvate (produced in glycolysis), is oxidised in steps to produce CO₂ and H₂ O and in this process, NAD and FAD are reduced to NADH+H⁺and FADH₂ respectively. It is named after scientist Hans Krebs.

Question 15.
Why is Krebs cycle known as TCA cycle and citric acid cycle?
Answer:
Citric acid is produced in the first step of Krebs cycle, therefore it is called Citric acid cycle. Citric acid contains three carboxylic groups, therefore, this cycle is also known as tricarboxylic acid cycle or TCA cycle.

Question 16.
What is meant by terminal respiration?
Answer:
Terminal respiration is the last step of aerobic respiration, where NADH+H⁺and FADH₂, produced in giycolysis and Krebs cycle, are oxidised by electron carriers, situated in the inner membrane of mitochondria, and hydrogen is oxidised by the atmospheric oxygen to form water and piroduce ATP.

Question 17.
Mention the four phases involved in aerobic respiration.
Answer:
The four phases involved in aerobic respiration are-

• glycolysis
• oxidation of pyruvate
• kerbs cycle
• terminal respiration.

Question 18.
What is ATP synthases?
Answer:
ATP synthase is a enzyme, present on the inner membrane of mitochondria and helps in the synthesis of ATP.

Question 19.
How does organ-level respiration differs from cellular respiration?
Answer:

Features	Organ level respination	Cellatar respiration
1. Nature of reaction	It is a physical process	It is bio-chemical process
2. Site of respiration	Different respiratory organs are involved	All living cells are involved
3. Occurence of chemical reaction	No chemical reaction occurs	Various chemical reactions occur
4. Steps involved	Inspiration, gaseous exchange and expiration	Glycolysis, Krebs cycle and terminal respiration

Question 20.
Distinguish between glycolysis and Krebs cycle.
Answer:

Features	Glycolysis	Krebs cycle
1. Occurrence	Cytoplasm	Mitochondria
2. Entry-level substrate	Glucose	Acetyl Co-A
3. Reaction path	Straight	Circular
4. End product	Pyruvate, ATP, NADH + H+	CO2, NADH + H+, FADH2 and GTP

Question 21.
Distinguish between combustion and respiration.
Answer:

Features	Combustion	Respiration
1. Nature of reaction	Physico-chemical process	Bio-chemical process
2. Enzymes	No role	Plays essential role
3. Free oxygen	Essential	May occur in absence of oxygen
4. Regulation of oxidation	Very fast and not controlled	Slow and controlled
5. Energy generated	Heat and light energy	Only heat energy

Question 22.
Distinguish between alcoholic fermentation and lactic acid fermentation.
Answer:

Features	Alcoholic fermentation	Lactic acid fermentation
1. Occurence	Occurs in yeast cell	Occurs in voluntary muscles and certain bacterial cells
2. CO2 production	Occurs	Does not occur
3. End-products	Ethyl alcohol	Lactic acid

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

Question 1.
Briefly describe the process of glycolysis with the help of a schematic diagram.
Answer:
Glycolysis
Glycolysis is the primary step of cellular respiration occurring in cytoplasm of all living cells. By this process, glucose is enzymatically broken into two pyruvic acids (3C) through a straight chain reaction path. Each step requires a specific enzyme which acts as biocatalyst.
In this metabolic process, glucose is first converted into glucose 6-phosphate and then to fructose 1, 6-bisphosphate. In this phase, two ATP molecules are consumed. In the next step, this fructose

1, 6-bisphosphate is broken into two 3C compounds-glycerabldehyde 3-phosphate and dihydroxyacetone phosphate. Enzymatically, this dihydroxyacetone phosphate is transformed into glyceraldehyde 3 phosphate. At the final phase, two molecules of glyceraldehyde 3phosphate transforms step-by-step to form two molecules of pyruvic acid. By glycolytic breakdown of one molecule of glucose, four ATP molecules are produced and two are consumed, therefore, two ATP molecules are net gained. In this reaction, two molecules of NADH + H⁺ are also produced.

Question 2.
Briefly describe the reaction process of Krebs cycle with the help of schematic diagram.
Answer:
Krebs cycle

Krebs cycle is the second major phase of aerobic respiration. This reaction occurs in the mitochondria in a cyclic reaction path, where a 6 carbon substrate, citric acid is converted step-by-step into 5 C and 4 C substrates. The entry-level substrate of Krebs cycle is acetyl Co-A, which is produced from pyruvic acid, the end product of glycolysis. In Krebs cycle, acetyl Co-A and oxaloacetic acid combine to form citric acid. This is the initial product of this cycle.

In this process CO₂, is released in steps. The other products are NADH+H⁺, FADH₂ and GTP. This GTP is transformed into ATP directly. The other two products NADH+H⁺ and FADH₂ are oxidised by dissociation of hydrogen through electron transport system.

Question 3.
Mame the enzyme present in the oxysomes of mitochondria. How does terminal respiration occur in a cell of any aerobic organism? 1 + 4
Answer:
Enzyme in oxysome
ATP synthetase enzyme is present in the oxysomes of mitochondria.

Terminal respiration
Terminal respiration is the final phase of aerobic reaction, which involves the production of ATP and H₂ O. This is the energy generating, i.e., ATP producing final phase of cellular respiration. NADH + H⁺ and FADH₂, (reduced hydrogen carriers) which are produced during glycolysis, decarboxylation of pyruvic acid & Krebs cycle, are oxidised in this reaction path. At first, hydrogen atoms are released from NADH + H⁺ and FADH₂. Then each hydrogen atom releases one electron, which is then transported by iron containing electron carriers cytochrome. This process generates huge chemical energy, which finally produces energy-rich ATP molecules. So, this reaction pathway is also known as electron transport system or ETS. The hydrogen atoms, released from NADH+ H⁺ and FADH₂ finally react with O₂ present in the atmosphere to produce H₂ O.

Question 4.
Mention the significance of respiration.
Answer:
Significance of respiration
The significance of respiration are mentioned below.
1. Conversion of energy and ATP production: The potential energy stored in food, is converted into kinetic energy by respiration. This energy is dissipated as heat and some portion of it is stored in ATP within the cells, as chemical energy for future use.

2. Maintenance of O₂-CO₂ balance: During respiration, atmospheric oxygen is consumed and carbon dioxide is released. Whereas, photosynthesis does the opposite. Thus, photosynthesis and respiration jointly maintain the balance of oxygen and carbon dioxide in the environment.

3. Economic importance: Fermentation of flour (starch) by yeast makes cakes and breads puffy. Ethyl alcohol is a fermentation product, which has great economic importance for medicinal purpose and to prepare alcoholic beverages. Cheese, butter, curds are prepared by fermentation of milk. Some vitamins like vit B₁, vit B₁₂, vit C etc. are also produced in the body by bacterial fermentation.

4. Excretion: Various excretory products like ammonia, ketone body, alcohol, water vapour, volatile fatty acids, etc., are given out of the body through respiration.

5. Maintenance of Acid-Base balance: Since CO₂ is liberated during respiration, it helps to maintain acid-base balance in the body.

6. Regulation of temperature: When animals exhale, certain amount of heat is liberated from their bodies, thus regulating the temperature of the body.

7. Light generation: Certain deep-sea animals, like Ctenophorans and insects, like fireflies can generate light. This phenomenon is called bioluminescence. This light is generated from the chemical energy, gained by respiration.

8. Electrical power generation: Some fishes like Torpedo and electric eel can generate huge electrical power within their electric organs to kill preys. Respiration produces this power from chemical energy.

Question 5.
Compare among aerobic respiration, anaerobic respiration and fermentation.
Answer:
Comparison among aerobic respiration, anaerobic respiration and fermentation

Question 6.
Distinguish between photosynthesis and respiration.
Answer:
Differences between photosynthesis and respiration

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

WBBSE Class 9 Science Chapter 3.1C Question Answer – Transpiration

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

Question 1.
Which tiny pores, present on the leaf surface help in gaseous exchange and liberation of excess water as vapour?
Answer:
Stomata are the tiny pores, present on the leaf surface, helping in gaseous exchange and liberation of excess water as vapour.

Question 2.
Which cells control the opening and closing of stomata?
Answer:
Guard cells control the opening and closing of stomata.

Question 3.
Name the small lens-shaped pores present on the stems of plants, which serve as site of transpiration.
Answer:
The small lens-shaped pores present on the stems of plants, which serve as site of transpiration, are called lenticels.

Question 4.
Which layer on the leaf surface prevents transpiration in desert plants?
Answer:
Cuticle layer on the leaf surface prevents transpiration in desert plants.

Question 5.
At which time of a day does transpiration occurs at the maximum rate?
Answer:
During mid-day, transpiration occurs at the maximum rate.

Question 6.
Why does transpiration occur mainly during the daytime?
Answer:
Light helps in opening of the stomata, therefore, transpiration occurs mainly during the daytime.

Question 7.
In which type of plants do stomata open at night?
Answer:
In some desert plants stomata open at night.

Question 8.
Why do stomata of some desert plants open at night?
Answer:
To prevent excess water loss during daytime, stomata of some desert plants open at night.

Question 9.
In lotus, on which surface of the leaf are stomata present?
Answer:
In lotus, stomata are present on the dorsal surface of the leaf.

Question 10.
In which season of the year does transpiration in terrestrial plants reaches the peak?
Answer:
In dry summer season, transpiration in terrestrial plants reaches the peak.

Question 11.
Why are the leaves of many desert plants modified into spines?
Answer:
The leaves of many desert plants are modified into spines in order to prevent water loss by transpiration.

Question 12.
Why do many desert plants possess dense hairs on the body surface?
Answer:
Dense hairs prevent direct air contact on leaf surface and thus, reduce the rate of transpiration, therefore, many desert plants possess dense hairs on the body surface.

Question 13.
How does air flow affect the rate of transpiration?
Answer:
Rate of transpiration increases with the increase in air flow.

Question 14.
Why is the rate of transpiration low in pine leaves?
Answer:
Needle-shaped pine leaves possess lesser number of stomata, which are slightly sunken in nature, so rate of transpiration is low in pine leaves.

Question 15.
Which instrument is used to measure the rate of transpiration?
Answer:
Ganong’s potometer is used to measure the rate of transpiration.

Question 16.
Why is rate of transpiration higher on the ventral surface of the leaves of dicotyledonous plants?
Answer:
Leaves of dicotyledonous plants possess more stomata on the ventral surface, therefore, the rate of transpiration is higher on that side.

Question 17.
Mention the phenomenon through which plants give out excess water in the form of droplets?
Answer:
The phenomenon through which plants give out excess water in the form of droplets, is known as guttation.

Question 18.
In which side of an isobilateral leaf, do we find more number of stomata?
Answer:
In an isobilateral leaf, stomata are distributed equally on both sides of the leaf.

Question 19.
How is the rate of transpiration affected on a rainy day?
Answer:
Since the percentage of water vapour is high in the atmosphere on a rainy day, the rate of transpiration decreases.

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

Question 1.
How do guard cells control the opening and closing of stomata?
Answer:
In the presence of light, hygroscopic pressure increases inside the guard cells. Due to unequal elasticity of cell walls of the two opposite sides of each guard cell, the cells bend like beans. As a result, the space between two guard cells widens to open the stomata. In the absence of light, hygroscopic pressure decreases inside the guard cells and the stomata close.

Question 2.
Why is the stomata of lotus plant present on the dersal surface of the leaves?
Answer:
The lotus leaves float on the water surface and the stomata are present on the dorsal surface to keep direct contact with air. This typical placement of stomata helps lotus leaves to maintain gaseous exchange with atmosphere and thus, perform transpiration.

Therefore, a plant with wider leaves shows higher rate of transpiration than a plant with narrow leaves. Also, in some plants (e.g. cactus) leaves are modified into spines to reduce transpiration. Thus, shape of leaves influence the rate of transpiration.

Question 3.
Why do plants with wider leaves wilt in summer but a pine tree remains unaffected?
Answer:
Plants with wider leaves have more number of stomata, through which they lose excess water in form of vapours due to transpiration on summer days. This loss of water makes the cells turgid and the protoplasm shrinks. This results into wilting of these plants. Whereas, a pine tree possesses needle-like leaves with very little number of sunken stomata. Therefore, pine trees lose much less water by transpiration and remain unaffected even on a summer day.

Question 4.
Why is transpiration called a necessary evil?
Answer:
Transpiration helps plants in the ascent of sap, removal of excess water, cooling the plant body, maintaining the water balance. On the other hand, excessive transpiration causes decrease in protoplasmic water content and thus, resulting into shrinkage of cells followed by wilting of leaves and tender branches. This is why, transpiration is called a necessary evil.

Question 5.
How does shape of leaves influence the rate of transpiration?
Answer:
Number of stomata is directly proportional to the rate of transpiration. A wider leaf has more stomata than a leaf with narrow leaf lamina. Therefore, a plant with wider leaves shows higher rate of transpiration than a plant with narrow leaves. Also, in some plants (e.g. cactus) leaves are modified into spines to reduce transpiration. Thus, shape of leaves influence the rate of transpiration.

Question 6.
If all the leaves of a plant are applied with a layer of vaseline, what will happen to it?
Answer:
If all the leaves of a plant are applied with a layer of vaseline, the stomatal openings will be sealed completely. In this situation, the plants will not be able to carry out gaseous exchange for photosynthesis and respiration. The excess water in the plant body will not be expelled out. This will affect many necessary physiological activities of the cells and the cells will die and eventually the whole plant.

Question 7.
What is wilting?
Answer:
In case of excess transpiration during daytime in summer, the plants lose large amount of water. As a result, protoplasm of cells lose turgidity and shrink. Hence, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.

Question 8.
How does transpiration control environmental condition?
Answer:
By transpiration, water vapour is released in the atmosphere. This increases the relative humidity, which in turn helps in the formation of clouds. Therefore, transpiration initiates rainfall in an area and thus, regulates atmospheric temperature and soil water content of that environment.

Question 9.
What are hydathodes? What is the function of hydathodes?
Answer:

• Hydathodes: Several plants, specially herbs, possess small pores on the apices and edges of their leaves. These small pores are known as hydathodes.
• Function: Hydathodes help the plants to dispose excess water from the body in the form of droplets, by a process called guttation but they do not take part in transpiration.

Question 10.
State the relationship between transpiration and root-shoot ratio.
Answer:
The rate of transpiration is reduced if the rootshoot ratio is less i.e root system is less branched and less deep or shoot is larger in size.

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

Question 1.
What is transpiration? Mention the differences between transpiration and evaporation.
Answer:
Transpiration
Transpiration is a life process, by which terrestrial plants eliminate excess water from the aerial parts of the body in form of water vapour, into the atmosphere.

Differences between transpiration and evaporation

Features	Transpiration	Evaporation
1. Nature	It is a physiological process	It is a physical process
2. Occurrence	Occurs in plants through stomata, lenticels and cuticle	Occurs in any free surface
3. Factors	Vapour pressure, diffusion pressure and osmotic pressure are the main controlling factors of this process	Relative humidity and air current are the main controlling factors of this process
4. Rate	It is a slow and controlled process	It is a quick process

Question  2.
How do plants eliminate excess water from their body? Give the difference between transpiration and guttation.
Answer:
Elimination of excess water from plant body Plants release maximum amount of the excess water from their body in the form of water vapour by the process of transpiration. This occurs through the stomata, cuticular pores and lenticels. Some herbs dispose excess water as droplets through small pores, present at the edges of their leaves, called hydathodes. This process of disposal of water by plants is known as guttation.

Differences between transpiration and guttation

Features	Transpiration	Guttation
1. Disposition of mineral salts	Excess water is given out in the form of vapour	Excess water is given out in the form of small droplets
2. Site of occurrence	Stomata, lenticels, cuticle	Small pores on the edges of leaves, called hydathodes
3. Factors	Mineral salts are not disposed in this process	Mineral salts are disposed along with water in this process

Question 3.
Mention one difference between stomata and hydathodes. Give a brief account of different structures involved in transpiration of plants.
Answer:
Difference between stomata and hydathodes:
One difference between stomata and hydathodes is that, stomata usually, open during the day and remain closed during the night (and in some desert plants, like Aloe vera, remain closed during the day, and open during the night). Whereas, hydathodes remain open all the time.

Different structures involved in transpiration:
Transpiration occurs through three different parts of plant body-stomata, lenticels and cuticle. Based on this, the process is divided into the following types.

1. Stomatal transpiration: Stomata are small pores, present mainly on leaves and a few other parts of tender shoot. Each of these pores is surrounded by two guard cells, that help to open the stomatal pores during the day and close at night. Maximum amount of excess water (about 90-97% ) is eliminated through the stomata.

2. Cuticular transpiration: Cuticle is a layer of waxy coating present on the epidermis of leaves. Very little amount of water (about 3-10% ) is eliminated through the minute pores of the cuticle.

3. Cuticular transpiration: Cuticle is a layer of waxy coating present on the epidermis of leaves. Very little amout of water (about 3-10%) is eliminated through the minute pores of the cuticle.

3 Lenticular transpiration: Lenticels are permanent, minute lens-shaped pores, found on the cracked bark of the trees. Negligible amount of water (about 0.1% ) is eliminated through these pores.

Question 4.
Mention the roles of different external factors regulating the rate of transpiration.
Answer:
External factors regulating transpiration
Various external factors control the rate of transpiration. These are discussed below.

1. Intensity of light: The most important external factor which regulates the rate of transpiration is the intensity of light. Stomata open during daylight in the presence of light and close at night. Thus, light controls transpiration by regulating the opening and closing of stomata. Increase in the intensity of light, increases the rate of transpiration. But decrease in light intensity decreases the rate of transpiration.

2. Temperature: Rate of transpiration increases with the rise in temperature. But when temperature rises above 35°C, the stomata start closing, in order to prevent excess water loss.

3. Humidity: Increase in relative humidity decreases the rate of transpiration and decrease in relative humidity increases transpiration rate. Therefore, transpiration is inversely proportional to the rate of humidity.

4. Wind flow: In airy environment, transpiration occurs at a faster rate. Therefore, wind flow is directly proportional to the rate of transpiration.

5. Density of carbon dioxide: Rate of transpiration also depends on the density of CO₂ in the atmosphere. When density of CO₂ increases and more CO₂ accumulates in leaves, stomatal pores close, and rate of transpiration decreases and when density of CO₂ is less, rate of transpiration increases. Thus, density of CO₂ in the atmosphere is inversely proportional to the rate of transpiration.

Question 5.
Mention the roles of different internal factors regulating the rate of transpiration.
Answer:
Internal factors regulating transpiration
Various internal factors control the process of transpiration. These are discussed below.

1. Surface area and number of stomata in the leaves: Leaves with larger surface area possess more number of stomata. Therefore, transpiration rate is higher in plants with broader and larger leaves.

2. Size of stomata: Size of stomata is directly proportional to the rate of transpiration of a plant.

3. Position of stomata: Stomata, present on the surface of leaves, facilitate transpiration, but in some plants, stomata is slightly sunken below the surface of leaves. This type of stomata helps to reduce the rate of transpiration.

4. Cuticle: A plant with thick and waxy cuticle reduces cuticular transpiration. On the other hand, a thin and porous cuticle enhances transpiration rate.

5. Age of leaves: In older leaves, many stomata become clogged. So age of leaves is inversely proportional to the rate of transpiration.

6. Protoplasm: Increased density of cellular protoplasm results in an increase in the rate of transpiration and vice versa. Thus, density of protoplasm in the cell is directly proportional to the rate of transpiration.

7. Presence of hormones: Hormones such as abscisic acid control the rate of transpiration by regulating the opening and closing of stomata.

Question 6.
Explain the beneficial effects of transpiration. Mention its harmful effects.
Answer:
Beneficial effects of transpiration
The beneficial effects of transpiration are as follows-

• Ascent of sap: Transpiration results in transpiration pull by which water and minerals reach the top leaves of the trees.
• Elimination of excess water: By transpiration, excess water from the plant body is removed. It eases the physiological activities within the cells.
• Cooling plant body: By this process, latent heat of evaporation is lost from the plant body, which cools the plant.
• Maintaining water balance: Due to the removal of excess water from plant body, water balance is maintained within it.

Harmful effects of transpiration:

The harmful effects of transpiration are as follows-

• Drying of leaves and twigs: Excess transpiration reduces water content in plant cells. As a result, leaves and softer parts of plants become dry.
• Wilting: In case of excess transpiration, the cells loseturgidity and shrink. Hence, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.
• Wastage of energy: Plant utilises only about 5% of the total absorbed water for various functions of its body. The rest (about 95% ) is given out by transpiration. Thus, there is a wastage of energy.
• Inhibition of gaseous exchange: Due to excess stomatal transpiration, gaseous exchange during photosynthesis and respiration through stomata, is inhibited.

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.