---
title: "Life Processes: CBSE Class 10 Science previous year questions"
url: https://www.swavid.com/cbse/class-10/science/pyq/life-processes
---

# Life Processes: CBSE Class 10 Science previous year questions

24 questions from CBSE Class 10 board papers, newest first, each with full working.

## CBSE Class 10 Science Question Paper 2026 (Set 31/1/1) with Solutions

### Question 1

*1 mark · MCQ*

Which structure in a leaf is mainly responsible for gaseous exchange ?

- Xylem
- Stomata
- Phloem
- Cuticle

**Solution**

1. Stomata are tiny pores present on the surface of leaves that facilitate massive amounts of gaseous exchange for photosynthesis and respiration.
2. Xylem and phloem are transport tissues, while the cuticle is a protective waxy layer.

**Answer:** (b) Stomata

> Common mistake: Confusing stomata with cuticle or vascular tissues.

### Question 5

*1 mark · MCQ*

Pancreas secretes pancreatic juice which contain certain enzyme that helps in digestion of food. Choose the correct option from the following :

- Trypsin digests emulsified fats and lipase digests proteins.
- Trypsin digests proteins and lipase digests emulsified fats.
- Trypsin and lipase both digests fats.
- Trypsin digests proteins and lipase digests carbohydrates.

**Solution**

1. Pancreatic juice contains trypsin for digesting proteins and lipase for breaking down emulsified fats.
2. Therefore, the correct matching is trypsin digests proteins and lipase digests emulsified fats.

**Answer:** (b) Trypsin digests proteins and lipase digests emulsified fats.

> Common mistake: Mixing up the substrates for trypsin and lipase.

### Question 9

*1 mark · Assertion and reason*

Assertion (A) : In human beings, the respiratory pigment is haemoglobin present in red blood cells.
Reason (R) : Haemoglobin has a very high affinity for carbon dioxide.

- Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.

**Solution**

1. Haemoglobin is the respiratory pigment present in red blood cells that carries oxygen.
2. Haemoglobin has a very high affinity for oxygen, not carbon dioxide, although carbon dioxide is transported dissolved in blood or by haemoglobin to some extent.

**Answer:** Assertion (A) is true, but Reason (R) is false.

> Common mistake: Assuming haemoglobin has a high affinity for carbon dioxide because it carries it as well.

### Question 10

*2 marks · Short answer*

What is the function of diaphragm in human respiratory system ? Where is it present in human body ?

**Solution**

1. Function: The diaphragm flattens and contracts during inhalation to increase the thoracic cavity volume, and relaxes during exhalation to decrease the volume.
2. Location: It is a muscular partition present at the floor of the chest cavity (thorax), separating the thoracic cavity from the abdominal cavity.

**Answer:** The diaphragm helps in expanding and contracting the chest cavity during breathing and is located at the floor of the chest cavity.

> Common mistake: Forgetting to mention its exact location between the thoracic and abdominal cavities.

### Question 11

*2 marks · Short answer*

State two differences between the act of chewing food and salivation on sight of food.

**Solution**

1. Chewing food is a voluntary action controlled by the somatic nervous system, whereas salivation on sight of food is an involuntary reflex action.
2. Chewing involves skeletal muscles of the jaw, while salivation is mediated by the autonomic nervous system and salivary glands.

**Answer:** Chewing is a voluntary action controlled consciously, while salivation on seeing food is an involuntary reflex action.

> Common mistake: Confusing voluntary and involuntary actions in digestive processes.

### Question 14

*3 marks · Short answer*

Give differences between the following :
(a) Nephron and neuron
(b) Sensory nerve and motor nerve
(c) Consumers and decomposers

**Part (a)**

1. Nephron is the structural and functional unit of the kidney involved in filtration.
2. Neuron is the structural and functional unit of the nervous system involved in signal transmission.

Answer (a): Nephron is for excretion; Neuron is for nerve impulse conduction.

**Part (b)**

1. Sensory nerves carry impulses from receptors to the central nervous system.
2. Motor nerves carry impulses from the central nervous system to effectors like muscles or glands.

Answer (b): Sensory nerves carry signals to the CNS; Motor nerves carry signals from the CNS.

**Part (c)**

1. Consumers are organisms that depend on other organisms for food.
2. Decomposers are organisms that break down dead and decaying organic matter.

Answer (c): Consumers are heterotrophs; Decomposers are saprotrophs.

**Answer:** Differences between biological structures and functions.

> Common mistake: Confusing the direction of nerve impulses in sensory and motor nerves.

## CBSE Class 10 Science Question Paper 2025 (Set 31/1/1) with Solutions

### Question 8

*1 mark · MCQ*

Secretion of less saliva in mouth will effect the conversion of :

- proteins into amino acids
- fats into fatty acids and glycerol
- starch into simple sugars
- sugars into alcohol

**Solution**

1. Saliva contains the enzyme salivary amylase that breaks down starch into simple sugars.
2. Less saliva secretion will therefore affect the conversion of starch into simple sugars.

**Answer:** (c) starch into simple sugars

> Common mistake: Thinking saliva digests proteins or fats.

### Question 12

*1 mark · MCQ*

The breakdown of glucose has taken the following pathway :
Glucose -(a)-> Pyruvate + Energy -(b)-> Lactic acid + Energy
The sites 'a' and 'b' respectively are :

- Mitochondria and Oxygen deficient muscle cells
- Cytoplasm and Oxygen rich muscle cells
- Cytoplasm and Yeast cells
- Cytoplasm and Oxygen deficient muscle cells

**Solution**

1. The first step of glucose breakdown (glycolysis) takes place in the cytoplasm where glucose is converted into pyruvate.
2. The breakdown of pyruvate into lactic acid takes place in muscle cells during oxygen deficiency (lack of oxygen).

**Answer:** (d) Cytoplasm and Oxygen deficient muscle cells

> Common mistake: Confusing cytoplasm with mitochondria as the site for the first step of glucose breakdown.

### Question 23

*2 marks · Very short answer*

(a) Besides minimising the loss of blood, why is it essential to plug any leak in a blood vessel ? Name the component of blood which helps in this process and state how this component perform this function.

**Solution**

1. Plugging leaks is essential to maintain the pressure of the circulatory system which would otherwise result in loss of efficiency and internal bleeding.
2. Blood platelets circulate around the body and plug these leaks by clotting the blood at the site of injury.

**Answer:** To maintain blood pressure and circulatory efficiency; platelets perform this function by blood clotting.

> Common mistake: Forgetting to mention the role of blood pressure or platelets.

### Question 23 (OR)

*2 marks · Very short answer*

(b) (i) The transport system in plants is relatively slower than in animals. Give reasons.
(ii) State the role of phloem in the transport of materials in plants.

**Part (i)**

1. Plants do not move and have many dead cells in their plant body, so their energy needs are low.
2. Hence, the plant transport systems can be slower compared to animals.

Answer (i): Plants have lower energy needs due to stationary habit and dead cells.

**Part (ii)**

1. Phloem transports soluble products of photosynthesis from leaves to other parts of the plant.

Answer (ii): Phloem transports food and other substances from leaves to storage organs and growing regions.

**Answer:** Plants are stationary and have a high proportion of dead cells in many tissues, requiring less energy and slower transport systems.

> Common mistake: Confusing xylem function with phloem function.

### Question 38

*4 marks · Case-based*

The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even when we are just sitting in a class or even asleep, this maintenance job has to go on. These maintenance processes require energy to prevent damage and break-down of cells and tissues, which is obtained by the individual organism from the food prepared by the autotrophs, called producers.
(a) Name and define the process by which green plants prepare food.
(b) Write chemical equation involved in the above process.
(c) (i) State in proper sequence the events that occur in synthesis of food by desert plants.

**Part (a)**

1. The process by which green plants prepare their food is called photosynthesis.
2. Photosynthesis is the process by which autotrophs take in substances from outside and convert them into stored forms of energy in the presence of sunlight and chlorophyll.

Answer (a): Photosynthesis; it is the conversion of carbon dioxide and water into carbohydrates using sunlight.

**Part (b)**

1. Write the reactants: carbon dioxide and water in the presence of sunlight and chlorophyll.
2. Write the balanced chemical equation: $6\text{CO}_2 + 12\text{H}_2\text{O} \xrightarrow{\text{Sunlight}_{\text{Chlorophyll}}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 + 6\text{H}_2\text{O}$.

Answer (b): $6\text{CO}_2 + 12\text{H}_2\text{O} \xrightarrow{\text{Sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 + 6\text{H}_2\text{O}$

**Part (c)**

1. Desert plants take up carbon dioxide at night and prepare an intermediate compound.
2. This intermediate compound is acted upon by the energy absorbed by chlorophyll during the day to form food.

Answer (c): Desert plants take up carbon dioxide at night to form an intermediate compound which is absorbed by energy from sunlight during the day.

**Answer:** Refer to sub-parts for the detailed answers.

> Common mistake: Forgetting to write water as a product in the photosynthesis equation or missing the specific nocturnal absorption of CO2 in desert plants.

### Question 38 (OR)

*2 marks · Case-based*

(c) (ii) Explain giving reasons what happens to the rate at which the green plants will prepare food
(I) during cloudy weather, and
(II) when stomata get blocked due to dust.

**Part (i)**

1. 1. Explain that during cloudy weather, sunlight intensity decreases, which reduces the rate of photosynthesis.
2. 2. Explain that when stomata get blocked by dust, the intake of carbon dioxide is prevented, which also decreases the rate of photosynthesis.

Answer (i): (I) Rate decreases due to less sunlight. (II) Rate decreases due to restricted $\text{CO}_2$ intake.

**Answer:** Rate of photosynthesis decreases during cloudy weather and when stomata are blocked due to dust.

> Common mistake: Not relating stomatal block to $\text{CO}_2$ uptake.

## CBSE Class 10 Science Question Paper 2024 (Set 31/1/1) with Solutions

### Question 11

*1 mark · MCQ*

A stomata closes when :
(i) it needs carbon dioxide for photosynthesis.
(ii) it does not need carbon dioxide for photosynthesis.
(iii) water flows out of the guard cells.
(iv) water flows into the guard cells.
The correct reason(s) in this process is/are :

- (i) only
- (i) and (iii)
- (ii) and (iii)
- (ii) and (iv)

**Solution**

1. Stomata close when water flows out of the guard cells, causing them to shrink.
2. When the plant does not need carbon dioxide for photosynthesis, stomata remain closed.

**Answer:** (c) (ii) and (iii)

> Common mistake: Reversing the movement of water into and out of guard cells during stomatal closing.

### Question 19

*1 mark · MCQ*

Assertion (A) : The rate of breathing in aquatic organisms is much faster than in terrestrial organisms.
Reason (R) : The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.

- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.

**Solution**

1. Aquatic organisms take up oxygen dissolved in water. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that in terrestrial organisms.
2. Therefore, Assertion (A) is true, but Reason (R) is false because the amount of dissolved oxygen is very low, not high.

**Answer:** (c) Assertion (A) is true, but Reason (R) is false.

> Common mistake: Assuming oxygen dissolved in water is high because water contains oxygen ($H_2O$).

### Question 22

*2 marks · Very short answer*

State one role of each of the following in human digestive system :
(i) Hydrochloric acid
(ii) Villi
(iii) Anal Sphincter
(iv) Lipase

**Part (i)**

1. Hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.

Answer (i): Creates an acidic medium for pepsin.

**Part (ii)**

1. Villi increase the surface area for the absorption of digested food.

Answer (ii): Increase surface area for absorption.

**Part (iii)**

1. Anal sphincter regulates the exit of waste material from the body.

Answer (iii): Regulates the exit of waste material.

**Part (iv)**

1. Lipase breaks down emulsified fats into fatty acids and glycerol.

Answer (iv): Emulsifies and breaks down fats.

**Answer:** Roles of the components in the human digestive system.

> Common mistake: Confusing the function of lipase with pepsin or amylase.

### Question 29

*3 marks · Short answer*

(i) Why is respiratory pigment needed in multicellular organisms with large body size ?
(ii) Give reasons for the following :
(a) Rings of cartilage are present in the throat.
(b) Lungs always contain a residual volume of air.
(c) The diaphragm flattens and ribs are lifted up when we breathe in.
(d) Walls of alveoli contain an extensive network of blood vessels.

**Part (i)**

1. In large multicellular organisms, the body size is large and diffusion pressure alone cannot take oxygen to all parts of the body efficiently.
2. Respiratory pigments like haemoglobin have high affinity for oxygen and transport it from the lungs to all body tissues.

Answer (i): Diffusion is insufficient to deliver oxygen to all cells in large bodies, so respiratory pigments are needed for efficient transport.

**Part (ii)**

1. (a) Rings of cartilage are present in the throat to ensure that the air-passage does not collapse.
2. (b) Lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for carbon dioxide to be released.
3. (c) During inhalation, the diaphragm flattens and ribs are lifted up to increase the chest cavity volume and reduce air pressure, drawing air into the lungs.
4. (d) The walls of alveoli contain an extensive network of blood vessels to provide a large surface area for gaseous exchange.

Answer (ii): (a) Prevent collapse of trachea (b) Provide sufficient time for gas exchange (c) Increase chest cavity volume (d) Provide large surface area for gas exchange.

**Answer:** Multicellular organisms need respiratory pigments like haemoglobin because diffusion alone is too slow to transport oxygen to all body cells.

> Common mistake: Missing out on mentioning the increase in surface area or pressure changes during breathing.

## CBSE Class 10 Science Question Paper 2023 (Set 31/1/1) with Solutions

### Question 8

*1 mark · MCQ*

An organism which breaks down the food material outside the body and then absorbs it is

- a plant parasite, Cuscuta
- an animal parasite, Tapeworm
- a bacteria, Rhizobium
- a fungi, Rhizopus

**Solution**

1. Organisms like fungi break down food material outside the body and then absorb it.
2. Rhizopus (bread mould) is an example of a saprophytic fungus that exhibits this mode of nutrition.

**Answer:** (d) a fungi, Rhizopus

> Common mistake: Confusing saprophytic nutrition in fungi with parasitic nutrition.

### Question 9

*1 mark · MCQ*

Consider the following statements about small intestine and select the one which is NOT correct :

- The length of the small intestine in animals differs as it depends on the type of food they eat.
- The small intestine is the site of complete digestion of food.
- The small intestine receives secretions from liver and pancreas.
- The villi of the small intestine absorb water from the unabsorbed food before it gets removed from the body via the anus.

**Solution**

1. Water absorption from unabsorbed food mainly takes place in the large intestine, not by the villi in the small intestine.
2. Therefore, the statement regarding villi absorbing water before removal via anus is incorrect.

**Answer:** (d) The villi of the small intestine absorb water from the unabsorbed food before it gets removed from the body via the anus.

> Common mistake: Confusing the functions of the small and large intestines regarding water absorption.

### Question 19

*1 mark · Assertion and reason*

Assertion (A) : Blood clotting prevents excessive loss of blood.
Reason (R) : Blood clotting is due to blood plasma and white blood cells present in the blood.

- Both (A) and (R) are true and (R) is the correct explanation of (A).
- Both (A) and (R) are true, but (R) is not the correct explanation of (A).
- (A) is true, but (R) is false.
- (A) is false, but (R) is true.

**Solution**

1. Blood clotting prevents excessive loss of blood from the body during an injury, making Assertion (A) true.
2. Blood clotting is actually due to platelets and fibrinogen present in the blood plasma, not white blood cells, making Reason (R) false.

**Answer:** (A) is true, but (R) is false.

> Common mistake: Confusing the function of white blood cells with platelets in blood clotting.

### Question 23

*2 marks · Very short answer*

(a) Name the type of blood (oxygenated / deoxygenated) transported by each of the following mentioning the path (i.e. from one organ (which place) to another (which place)).
(i) Vena cava
(ii) Pulmonary artery

**Part (i)**

1. Vena cava transports deoxygenated blood.
2. It carries blood from various body organs to the right atrium of the heart.

Answer (i): Deoxygenated blood from body organs to the right atrium.

**Part (ii)**

1. Pulmonary artery transports deoxygenated blood.
2. It carries blood from the right ventricle of the heart to the lungs for oxygenation.

Answer (ii): Deoxygenated blood from the right ventricle to the lungs.

**Answer:** (i) Vena cava transports deoxygenated blood from body organs to the right atrium. (ii) Pulmonary artery transports deoxygenated blood from the right ventricle to the lungs.

> Common mistake: Confusing pulmonary artery with pulmonary vein regarding the type of blood carried.

### Question 23 (OR)

*2 marks · Very short answer*

(b) With the help of a schematic flow chart, show the breakdown of glucose in a cell to provide energy -
(i) in the presence of oxygen
(ii) in lack of oxygen

**Part (i)**

1. Glucose (6-carbon) breaks down into pyruvate (3-carbon) in the cytoplasm.
2. In the presence of oxygen (mitochondria), pyruvate breaks down to give carbon dioxide, water and energy.

Answer (i): Glucose $\rightarrow$ Pyruvate (in cytoplasm) $\rightarrow$ $\text{CO}_2 + \text{H}_2\text{O} + \text{Energy}$ (in mitochondria).

**Part (ii)**

1. In the lack of oxygen (such as in muscle cells during vigorous exercise), pyruvate is converted into lactic acid and energy.

Answer (ii): Glucose $\rightarrow$ Pyruvate $\rightarrow$ Lactic acid (3-carbon molecule) + Energy.

**Answer:** Glucose breakdown: (i) Presence of oxygen yields $\text{CO}_2$, $\text{H}_2\text{O}$ and energy in mitochondria. (ii) Lack of oxygen (in muscle cells) yields lactic acid and energy.

> Common mistake: Confusing lack of oxygen in muscles (produces lactic acid) with absence of oxygen in yeast (produces ethanol and $\text{CO}_2$).

### Question 24

*2 marks · Very short answer*

Name the part of the human excretory system where nephrons are found. Write the structure and function of nephrons.

**Solution**

1. Nephrons are found in the kidneys, which are the basic filtering units of the human excretory system.
2. A nephron consists of a cup-shaped end called Bowman's capsule containing a cluster of capillaries called glomerulus, connected to a tubular part.
3. Its main function is to filter nitrogenous wastes from the blood and form urine.

**Answer:** Nephrons are found in the kidneys. Each consists of a glomerulus, Bowman's capsule and a renal tubule, functioning to filter blood and form urine.

> Common mistake: Stating nephrons are found in the urinary bladder instead of the kidneys.

### Question 29

*3 marks · Short answer*

(a) (i) State the role of ATP in cellular respiration.
(ii) What ensures sufficient exchange of gases in plants?
(iii) State the conditions on which the direction of diffusion of gases in plant depend upon.

**Part (i)**

1. ATP acts as the energy currency for cellular processes, releasing energy when broken down to drive endergonic reactions in the cell.

Answer (i): ATP provides energy for various cellular activities.

**Part (ii)**

1. Large intercellular spaces ensure that all cells are in contact with air, and stomata facilitate the exchange of gases with the atmosphere.

Answer (ii): Stomata and large intercellular spaces ensure sufficient exchange of gases.

**Part (iii)**

1. The direction of diffusion depends upon the environmental conditions and the requirement of the plant at the time.

Answer (iii): Environmental conditions and the physiological requirements of the plant.

**Answer:** (a)(i) ATP provides energy, (ii) stomata and intercellular spaces ensure exchange, (iii) environmental conditions and plant requirements determine diffusion direction.

> Common mistake: Writing incomplete roles of ATP.

### Question 29 (OR)

*3 marks · Short answer*

(b) (i) What is the internal energy reserve in plants and animals?
(ii) How do desert plants perform photosynthesis if their stomata remain closed during the day?

**Part (i)**

1. The internal energy reserve in plants is starch, and in animals, it is glycogen.

Answer (i): Starch in plants and glycogen in animals.

**Part (ii)**

1. Desert plants take up carbon dioxide at night and prepare an intermediate compound.
2. This intermediate is acted upon by the energy absorbed by chlorophyll during the day when their stomata are open or using the stored $\text{CO}_2$.

Answer (ii): They take up $\text{CO}_2$ at night to form an intermediate which is used for photosynthesis during the day.

**Answer:** (a)(i) Starch and glycogen, (ii) desert plants take up $\text{CO}_2$ at night and form an intermediate.

> Common mistake: Confusing plant and animal energy reserves.

## Related pages

- [Life Processes: NCERT solutions](https://www.swavid.com/science/class/10/chapter/life-processes/ncert-solutions)
- [All CBSE Class 10 Science papers](https://www.swavid.com/cbse/class-10/science/previous-year-papers)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student