CBSE Class 10 · Biology 
What happens when both ventricles contract simultaneously?
CBSE Class 10 Biology Life Processes Previous Year Questions
Help your child master CBSE Class 10 Biology Life Processes with this carefully curated collection of previous year board questions spanning 2014–2024. Every question includes detailed, step-by-step answers covering nutrition, respiration, transportation, and excretion — the topics that consistently carry marks in CBSE board exams.
CBSE Class 10 Biology Life Processes — Questions with Solutions
How is the wall of the small intestine adapted for performing the function of absorption of food?
Answer
The inner lining of the small intestine has numerous finger-like projections called villi, which increases the surface area for absorption.
What is the role of saliva in the digestion of food?
Answer
Saliva moistens the ingested food with mucus, sterilises it using lysozyme, and starts the digestion of starch into simple sugars with the help of salivary amylase (ptyalin).
Patients whose gall bladder is removed are recommended to eat less oily food. Why?
Answer
The gall bladder stores bile, which aids in the emulsification of fats. Without stored bile, fat digestion slows down as emulsification is affected, leading to necessary diet restrictions.
Two green plants are kept separately in oxygen free containers, one in the dark and the other in sunlight. It was observed that plant kept in the dark could not survive longer. Give a reason for this observation.
Answer
Plants release oxygen during photosynthesis, which can be utilised by the plant for respiration.
The plant kept in the dark was not able to perform photosynthesis to generate some oxygen for respiration.
The carbon dioxide released by the plant after respiration was utilised by the plants in sunlight to photosynthesise food, hence, that plant was able to survive.
The plant kept in the dark was not able to perform photosynthesis to generate some oxygen for respiration.
The carbon dioxide released by the plant after respiration was utilised by the plants in sunlight to photosynthesise food, hence, that plant was able to survive.
Explain the activity with diagram to show that Carbon dioxide is essential for photosynthesis.
Answer
🌿 Activity: To Show that Carbon Dioxide is Essential for Photosynthesis
Procedure:
1. Take two healthy potted plants which are nearly the same size.
2. Keep both plants in a dark room for 3 days to destarch them.
3. Place each plant on separate glass plates.
4. In Setup (a), place a watch glass containing potassium hydroxide (KOH) beside one plant. KOH absorbs carbon dioxide (CO₂) from the air inside the jar.
5. In Setup (b), do not place any potassium hydroxide.
6. Cover both plants with bell jars and seal them to make the setup airtight.
7. Keep both setups in sunlight for a few hours.
8. Test the leaves of both plants for starch using iodine solution.
Observation:
— Leaves in bell jar (a) with KOH: no starch detected.
— Leaves in bell jar (b) without KOH: positive starch test (turned blue-black).
Conclusion:
The plant in Setup (b) performed photosynthesis as CO₂ was available. The plant in Setup (a) could not, because KOH absorbed the CO₂. This proves that carbon dioxide is essential for photosynthesis.
Procedure:
1. Take two healthy potted plants which are nearly the same size.
2. Keep both plants in a dark room for 3 days to destarch them.
3. Place each plant on separate glass plates.
4. In Setup (a), place a watch glass containing potassium hydroxide (KOH) beside one plant. KOH absorbs carbon dioxide (CO₂) from the air inside the jar.
5. In Setup (b), do not place any potassium hydroxide.
6. Cover both plants with bell jars and seal them to make the setup airtight.
7. Keep both setups in sunlight for a few hours.
8. Test the leaves of both plants for starch using iodine solution.
Observation:
— Leaves in bell jar (a) with KOH: no starch detected.
— Leaves in bell jar (b) without KOH: positive starch test (turned blue-black).
Conclusion:
The plant in Setup (b) performed photosynthesis as CO₂ was available. The plant in Setup (a) could not, because KOH absorbed the CO₂. This proves that carbon dioxide is essential for photosynthesis.
Arthropods and molluscs have a copper-containing respiratory pigment called hemocyanin, while human beings have iron-containing hemoglobin.
(a) How do respiratory pigments help in the process of respiration?
(b) Why do multicellular animals need respiratory pigments?
(a) How do respiratory pigments help in the process of respiration?
(b) Why do multicellular animals need respiratory pigments?
Answer
(a) Role of Respiratory Pigments in Respiration:
Haemoglobin (iron-based) and hemocyanin (copper-based) aid in transporting oxygen in the bloodstream. They bind and release oxygen as needed, facilitate efficient gas exchange between lungs or gills and body tissues, and ensure oxygen reaches all cells to support cellular respiration.
(b) Importance of Respiratory Pigments in Multicellular Animals:
Multicellular organisms need efficient oxygen transport due to their complex structures and higher number of cells. Respiratory pigments increase the oxygen-carrying capacity of blood, help meet the high metabolic demands of larger organisms, and ensure oxygen reaches deep tissues that diffusion alone cannot serve.
Haemoglobin (iron-based) and hemocyanin (copper-based) aid in transporting oxygen in the bloodstream. They bind and release oxygen as needed, facilitate efficient gas exchange between lungs or gills and body tissues, and ensure oxygen reaches all cells to support cellular respiration.
(b) Importance of Respiratory Pigments in Multicellular Animals:
Multicellular organisms need efficient oxygen transport due to their complex structures and higher number of cells. Respiratory pigments increase the oxygen-carrying capacity of blood, help meet the high metabolic demands of larger organisms, and ensure oxygen reaches deep tissues that diffusion alone cannot serve.
What is the other name of ’tissue fluid’? Write its two functions.
Answer
Tissue fluid is also known as lymph.
Functions of Tissue Fluid:
(i) Tissue fluid acts as a middle man between blood and tissue cells. It delivers food materials and oxygen from the blood to the tissue cells, and collects carbon dioxide (CO₂), nitrogenous wastes, hormones, and other substances from the tissue cells and returns them to the bloodstream.
(ii) Tissue fluid helps to keep the tissue cells moist, ensuring proper cellular function and chemical exchange.
Functions of Tissue Fluid:
(i) Tissue fluid acts as a middle man between blood and tissue cells. It delivers food materials and oxygen from the blood to the tissue cells, and collects carbon dioxide (CO₂), nitrogenous wastes, hormones, and other substances from the tissue cells and returns them to the bloodstream.
(ii) Tissue fluid helps to keep the tissue cells moist, ensuring proper cellular function and chemical exchange.
Name the substances other than water that are reabsorbed during urine formation.
What are the two parameters that decide the amount of water that is reabsorbed in the kidney?
What are the two parameters that decide the amount of water that is reabsorbed in the kidney?
Answer
Substances other than water reabsorbed during urine formation include:
— Glucose
— Amino acids
— Salts (ions) such as sodium, potassium, and chloride
— Vitamins
The two parameters that determine the amount of water reabsorbed are:
1. The amount of excess water present in the body.
2. The amount of dissolved waste (especially urea and salts) in the body.
— Glucose
— Amino acids
— Salts (ions) such as sodium, potassium, and chloride
— Vitamins
The two parameters that determine the amount of water reabsorbed are:
1. The amount of excess water present in the body.
2. The amount of dissolved waste (especially urea and salts) in the body.
Human beings exhibit double circulation, in which blood passes twice through the heart during one complete cycle — once through the lungs (pulmonary circulation) and once through the body (systemic circulation).
(a) State the route of the first and the second circulation through the chambers of the heart and explain the usefulness of such circulation in humans.
(b) Name the blood vessels that:
(i) carry oxygenated blood from the lungs to the heart
(ii) carry deoxygenated blood from the heart to the lungs
(c) How does it help birds and mammals?
(a) State the route of the first and the second circulation through the chambers of the heart and explain the usefulness of such circulation in humans.
(b) Name the blood vessels that:
(i) carry oxygenated blood from the lungs to the heart
(ii) carry deoxygenated blood from the heart to the lungs
(c) How does it help birds and mammals?
Answer
(a) Double Circulation:
Double circulation is the process in which blood passes twice through the heart during one complete cycle. It includes systemic circulation (blood to body tissues) and pulmonary circulation (blood to lungs for oxygenation). The right side and left side of the heart are completely separated, preventing mixing of oxygenated and deoxygenated blood and ensuring a more efficient supply of oxygen to all body cells.
(b) Blood Vessels:
(i) Pulmonary vein — carries oxygenated blood from the lungs to the heart.
(ii) Pulmonary artery — carries deoxygenated blood from the heart to the lungs.
(c) Importance in Birds and Mammals:
Birds and mammals are warm-blooded animals (endotherms). They require more energy to maintain a constant body temperature. Double circulation ensures a continuous and rich supply of oxygen for respiration, efficient energy production, and better adaptation to changing environmental temperatures.
Double circulation is the process in which blood passes twice through the heart during one complete cycle. It includes systemic circulation (blood to body tissues) and pulmonary circulation (blood to lungs for oxygenation). The right side and left side of the heart are completely separated, preventing mixing of oxygenated and deoxygenated blood and ensuring a more efficient supply of oxygen to all body cells.
(b) Blood Vessels:
(i) Pulmonary vein — carries oxygenated blood from the lungs to the heart.
(ii) Pulmonary artery — carries deoxygenated blood from the heart to the lungs.
(c) Importance in Birds and Mammals:
Birds and mammals are warm-blooded animals (endotherms). They require more energy to maintain a constant body temperature. Double circulation ensures a continuous and rich supply of oxygen for respiration, efficient energy production, and better adaptation to changing environmental temperatures.
The rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Give reason.
Answer
A terrestrial organism can obtain oxygen directly from the air, which contains a higher concentration of oxygen. Therefore, they have a slower breathing rate.
Aquatic organisms obtain oxygen that is dissolved in water. The amount of oxygen dissolved in water is fairly low compared to the oxygen in air. As a result, aquatic organisms need to breathe faster to extract enough oxygen for respiration.
Aquatic organisms obtain oxygen that is dissolved in water. The amount of oxygen dissolved in water is fairly low compared to the oxygen in air. As a result, aquatic organisms need to breathe faster to extract enough oxygen for respiration.
Name the energy currency in the living organisms. When and where is it produced?
Answer
The energy currency in living organisms is called ATP (Adenosine Triphosphate).
When is ATP produced? ATP is produced during the process of respiration.
Where is ATP produced? ATP is mainly produced in the mitochondria of the cell, also known as the “powerhouse of the cell”.
When is ATP produced? ATP is produced during the process of respiration.
Where is ATP produced? ATP is mainly produced in the mitochondria of the cell, also known as the “powerhouse of the cell”.
What is photosynthesis? Explain its mechanism.
Answer
Photosynthesis is a process in which green plants take carbon dioxide and water and convert it into carbohydrates/food in the presence of sunlight and chlorophyll.
Mechanism:
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy.
(iii) Splitting of water molecules into hydrogen and oxygen.
(iv) Reduction of carbon dioxide to carbohydrate.
Mechanism:
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy.
(iii) Splitting of water molecules into hydrogen and oxygen.
(iv) Reduction of carbon dioxide to carbohydrate.
Name a common nutrient that is:
— Absorbed in the small intestine, and
— Re-absorbed by the kidney tubules.
— Absorbed in the small intestine, and
— Re-absorbed by the kidney tubules.
Answer
Glucose / Amino acid
State the events occurring during the process of photosynthesis. Is it essential that these steps take place one after the other immediately?
Answer
Events in Photosynthesis:
1. Absorption of Light Energy — Chlorophyll absorbs light energy from the sun.
2. Conversion of Light Energy to Chemical Energy — The absorbed light energy is converted into chemical energy. Water molecules are split into hydrogen and oxygen during this process.
3. Reduction of Carbon Dioxide to Carbohydrates — CO₂ is reduced using hydrogen (obtained from water) to form glucose.
Overall Chemical Equation:
$$6CO_2 + 6H_2O \xrightarrow{Light \; \& \; Chlorophyll} C_6H_{12}O_6 + 6O_2$$
No, it is not essential that these steps take place one after the other immediately. For example, the dark reaction (reduction of CO₂) can occur independently of the light reaction.
1. Absorption of Light Energy — Chlorophyll absorbs light energy from the sun.
2. Conversion of Light Energy to Chemical Energy — The absorbed light energy is converted into chemical energy. Water molecules are split into hydrogen and oxygen during this process.
3. Reduction of Carbon Dioxide to Carbohydrates — CO₂ is reduced using hydrogen (obtained from water) to form glucose.
Overall Chemical Equation:
$$6CO_2 + 6H_2O \xrightarrow{Light \; \& \; Chlorophyll} C_6H_{12}O_6 + 6O_2$$
No, it is not essential that these steps take place one after the other immediately. For example, the dark reaction (reduction of CO₂) can occur independently of the light reaction.
Why do arteries have thick and elastic walls whereas veins have valves?
Answer
The blood emerges from the heart under high pressure and flows through the arteries. To withstand this pressure, arteries have thick and elastic walls. This helps them to expand and recoil as blood is pumped through them.
Veins, on the other hand, carry blood back to the heart under low pressure. Veins have valves to ensure that the blood flows in one direction only, preventing backflow.
Veins, on the other hand, carry blood back to the heart under low pressure. Veins have valves to ensure that the blood flows in one direction only, preventing backflow.
A gas is released during photosynthesis. Name the gas and state the way by which the gas is evolved. What are stomata? What governs the opening and closing of stomata?
Answer
(a) Gas Released:
The gas released during photosynthesis is oxygen (O₂), which originates from water (H₂O). Solar energy trapped by chlorophyll causes the photolysis of water, releasing oxygen as a by-product.
(b) What are Stomata?
Stomata are tiny pores present on the surface of leaves, primarily on the underside. They play a crucial role in gaseous exchange and transpiration in plants.
(c) Opening and Closing Mechanism:
The opening and closing of stomata are controlled by the turgidity of guard cells.
Stomatal Opening: When guard cells absorb water, they swell and become turgid, causing the pore to enlarge.
Stomatal Closing: When water is released, guard cells become flaccid and shrink, causing the pore to close.
The gas released during photosynthesis is oxygen (O₂), which originates from water (H₂O). Solar energy trapped by chlorophyll causes the photolysis of water, releasing oxygen as a by-product.
(b) What are Stomata?
Stomata are tiny pores present on the surface of leaves, primarily on the underside. They play a crucial role in gaseous exchange and transpiration in plants.
(c) Opening and Closing Mechanism:
The opening and closing of stomata are controlled by the turgidity of guard cells.
Stomatal Opening: When guard cells absorb water, they swell and become turgid, causing the pore to enlarge.
Stomatal Closing: When water is released, guard cells become flaccid and shrink, causing the pore to close.
(a) Draw diagram of Human Alimentary Canal
(b) Why Absorption Occurs Mainly in the Small Intestine
(b) Why Absorption Occurs Mainly in the Small Intestine
Answer
(a) Human Alimentary Canal:
(b) Why absorption occurs mainly in the small intestine:
1. The inner lining of the small intestine has millions of villi, which increase the surface area for maximum absorption of nutrients.
2. The walls of the small intestine are richly supplied with blood vessels, which help in the quick transport of absorbed nutrients into the bloodstream.
(b) Why absorption occurs mainly in the small intestine:
1. The inner lining of the small intestine has millions of villi, which increase the surface area for maximum absorption of nutrients.
2. The walls of the small intestine are richly supplied with blood vessels, which help in the quick transport of absorbed nutrients into the bloodstream.
(a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain.
(b) Draw a diagram of human respiratory system and label — pharynx, trachea, lungs, diaphragm and alveolar sac on it.
(b) Draw a diagram of human respiratory system and label — pharynx, trachea, lungs, diaphragm and alveolar sac on it.
Answer
(a) Rate of breathing is faster in aquatic organisms because the amount of dissolved oxygen in water is lower as compared to the amount of oxygen in air. Aquatic organisms must therefore breathe more rapidly to obtain sufficient oxygen for respiration.
(b) Human Respiratory System:
(b) Human Respiratory System:
(a) Name the organs that form the excretory system in human beings
(b) How is urine produced in the human body?
(b) How is urine produced in the human body?
Answer
(a) Organs of the Human Excretory System:
— A pair of kidneys
— A pair of ureters
— A urinary bladder
— A urethra
(b) Urine Production:
Each kidney contains a large number of filtration units called nephrons. Each nephron has a cup-shaped Bowman’s capsule containing a bunch of capillaries known as the glomerulus. Blood gets filtered in the glomerulus, and the filtrate is collected in the Bowman’s capsule. As the filtrate passes through the nephron tubule, useful substances such as glucose, amino acids, salts, and water are selectively reabsorbed back into the blood. The remaining fluid forms urine, which flows through collecting ducts and is stored in the urinary bladder before being expelled through the urethra.
— A pair of kidneys
— A pair of ureters
— A urinary bladder
— A urethra
(b) Urine Production:
Each kidney contains a large number of filtration units called nephrons. Each nephron has a cup-shaped Bowman’s capsule containing a bunch of capillaries known as the glomerulus. Blood gets filtered in the glomerulus, and the filtrate is collected in the Bowman’s capsule. As the filtrate passes through the nephron tubule, useful substances such as glucose, amino acids, salts, and water are selectively reabsorbed back into the blood. The remaining fluid forms urine, which flows through collecting ducts and is stored in the urinary bladder before being expelled through the urethra.
(a) How do leaves of plants help in excretion?
(b) Describe the Structure and Function of a Nephron
(b) Describe the Structure and Function of a Nephron
Answer
(a) How leaves help in excretion:
— Oxygen and carbon dioxide produced during photosynthesis and respiration are given out through stomata in the leaves.
— Excess water is released by the process of transpiration.
— When leaves become old, they fall off, carrying waste materials stored in their vacuoles, thus helping in excretion.
(b) Structure of Nephron:
A nephron is the basic filtration unit of the kidney. It is made up of fine tubules, one end of which forms a cup-shaped structure called the Bowman’s capsule, and the other end opens into a collecting duct. Inside the Bowman’s capsule lies a network of capillaries called the glomerulus.
Function of Nephron:
Blood carrying nitrogenous wastes (like urea) is filtered through the glomerulus, and the filtrate is collected in the Bowman’s capsule. As the filtrate passes along the tubule, useful substances such as glucose, salts, and water are selectively reabsorbed back into the blood. The remaining fluid forms urine, which flows into the collecting duct.
— Oxygen and carbon dioxide produced during photosynthesis and respiration are given out through stomata in the leaves.
— Excess water is released by the process of transpiration.
— When leaves become old, they fall off, carrying waste materials stored in their vacuoles, thus helping in excretion.
(b) Structure of Nephron:
A nephron is the basic filtration unit of the kidney. It is made up of fine tubules, one end of which forms a cup-shaped structure called the Bowman’s capsule, and the other end opens into a collecting duct. Inside the Bowman’s capsule lies a network of capillaries called the glomerulus.
Function of Nephron:
Blood carrying nitrogenous wastes (like urea) is filtered through the glomerulus, and the filtrate is collected in the Bowman’s capsule. As the filtrate passes along the tubule, useful substances such as glucose, salts, and water are selectively reabsorbed back into the blood. The remaining fluid forms urine, which flows into the collecting duct.
Assertion and Reason Question
Directions: Mark the correct choice as:
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is true.
Assertion (A): Nitrogen is an essential element for plant growth and is taken up by plants in the form of inorganic nitrates or nitrites.
Reason (R): The soil is the nearest and richest source of raw materials like Nitrogen, Phosphorus, and other minerals for the plants.
Directions: Mark the correct choice as:
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is true.
Assertion (A): Nitrogen is an essential element for plant growth and is taken up by plants in the form of inorganic nitrates or nitrites.
Reason (R): The soil is the nearest and richest source of raw materials like Nitrogen, Phosphorus, and other minerals for the plants.
Answer
Correct Option: (B) — Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Nitrogen is indeed an essential element for plant growth, but plants cannot absorb atmospheric nitrogen directly. Instead, they take it up in the form of inorganic nitrates (NO₃⁻), nitrites (NO₂⁻), or ammonia after it is fixed by bacteria or through industrial processes.
The Reason is also true: soil is a rich source of minerals including nitrogen, phosphorus, and potassium. However, the reason does not directly explain how nitrogen is absorbed in specific forms, so it is not the correct explanation of the assertion.
Explanation:
Nitrogen is indeed an essential element for plant growth, but plants cannot absorb atmospheric nitrogen directly. Instead, they take it up in the form of inorganic nitrates (NO₃⁻), nitrites (NO₂⁻), or ammonia after it is fixed by bacteria or through industrial processes.
The Reason is also true: soil is a rich source of minerals including nitrogen, phosphorus, and potassium. However, the reason does not directly explain how nitrogen is absorbed in specific forms, so it is not the correct explanation of the assertion.
Assertion and Reason Question
Directions: Mark the correct choice as:
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is true.
Assertion (A): Hydrochloric acid helps in the digestion of food in the stomach.
Reason (R): Hydrochloric acid creates an acidic medium to activate protein-digesting enzymes.
Directions: Mark the correct choice as:
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is true.
Assertion (A): Hydrochloric acid helps in the digestion of food in the stomach.
Reason (R): Hydrochloric acid creates an acidic medium to activate protein-digesting enzymes.
Answer
Correct Option: (A) — Both A and R are true and R is the correct explanation of A.
Explanation:
The gastric glands present in the walls of the stomach secrete hydrochloric acid (HCl), pepsinogen, and mucus. HCl creates an acidic medium that helps in the activation of pepsinogen (an inactive enzyme) into pepsin (an active enzyme). Pepsin then helps in the digestion of proteins in the stomach. Thus, HCl plays an essential role in protein digestion by maintaining the acidic environment required for enzyme activity.
Explanation:
The gastric glands present in the walls of the stomach secrete hydrochloric acid (HCl), pepsinogen, and mucus. HCl creates an acidic medium that helps in the activation of pepsinogen (an inactive enzyme) into pepsin (an active enzyme). Pepsin then helps in the digestion of proteins in the stomach. Thus, HCl plays an essential role in protein digestion by maintaining the acidic environment required for enzyme activity.
Experimental Setup – Gas Absorption in Respiration
Name the chemical indicated as ‘X’ that can absorb the gas which is evolved as a by-product of respiration.
Hint: The gas evolved during aerobic respiration is carbon dioxide (CO₂). Chemical ‘X’ should be one that absorbs CO₂.
Name the chemical indicated as ‘X’ that can absorb the gas which is evolved as a by-product of respiration.
Hint: The gas evolved during aerobic respiration is carbon dioxide (CO₂). Chemical ‘X’ should be one that absorbs CO₂.
Solution
Answer: Option (B) is correct.
Potassium hydroxide (KOH) absorbs all the available carbon dioxide (CO₂) present inside the bell jar. It is commonly used in experiments to remove CO₂ so as to study its role in specific biological processes.
Potassium hydroxide (KOH) absorbs all the available carbon dioxide (CO₂) present inside the bell jar. It is commonly used in experiments to remove CO₂ so as to study its role in specific biological processes.
In the given transverse section of the leaf, identify the layer of cells where maximum photosynthesis occurs.
Solution
Answer: Option (B) is correct.
The palisade mesophyll layer is made up of closely-packed, elongated cells located just below the upper epidermis. They contain chloroplasts and carry out most of the photosynthesis.
The palisade mesophyll layer is made up of closely-packed, elongated cells located just below the upper epidermis. They contain chloroplasts and carry out most of the photosynthesis.
Respiratory structures of two different animals, a fish and a human being are as shown.
Observe (a) and (b) and select one characteristic that holds true for both of them.
Observe (a) and (b) and select one characteristic that holds true for both of them.
Solution
Answer: Option (B) is correct.
Both gills (in fish) and alveoli (in humans) have thin and moist surfaces that help in the easy diffusion of respiratory gases like oxygen and carbon dioxide. Both structures are also richly supplied with blood vessels to facilitate efficient gas exchange. Note that gills are located externally in fish whereas alveoli are located internally in human lungs.
Both gills (in fish) and alveoli (in humans) have thin and moist surfaces that help in the easy diffusion of respiratory gases like oxygen and carbon dioxide. Both structures are also richly supplied with blood vessels to facilitate efficient gas exchange. Note that gills are located externally in fish whereas alveoli are located internally in human lungs.
What happens when both ventricles contract simultaneously?
Solution
Answer: Option (B) is correct.
Ventricular contraction results in pumping out of blood. In the left ventricle, the oxygenated blood is pumped to other parts of the body, while in the right ventricle, deoxygenated blood is pumped to the lungs for purification — both happening simultaneously.
Ventricular contraction results in pumping out of blood. In the left ventricle, the oxygenated blood is pumped to other parts of the body, while in the right ventricle, deoxygenated blood is pumped to the lungs for purification — both happening simultaneously.
Plants use completely different processes for excretion as compared to animals. Which one of the following processes is NOT followed by plants for excretion?
Solution
Answer: Option (B) is correct.
Plants cannot selectively filter toxic substances through their leaves. This process does not occur in plants.
Plants cannot selectively filter toxic substances through their leaves. This process does not occur in plants.
In a person, the tubule part of the nephron is not functioning at all. What will its effect be on urine formation?
Solution
Answer: Option (D) is correct.
The function of the tubule is re-absorption of useful substances such as glucose, amino acids, salts, and a major amount of water into the blood capillaries. If the tubule part is not functioning, the urine is more diluted since it contains both useful and waste substances.
The function of the tubule is re-absorption of useful substances such as glucose, amino acids, salts, and a major amount of water into the blood capillaries. If the tubule part is not functioning, the urine is more diluted since it contains both useful and waste substances.
Generally food is broken and absorbed within the body of organisms. In which of the following organisms is it done outside the body?
Solution
Answer: Option (B) is correct.
Mushroom is a fungus. Fungi are organisms that break down food into simpler chemicals outside the body before absorbing it — a process called extracellular digestion.
Mushroom is a fungus. Fungi are organisms that break down food into simpler chemicals outside the body before absorbing it — a process called extracellular digestion.
Small hair-like structures line the upper part of the human respiratory tract. These structures trap the dust particles, germs and chemicals entering the human body during breathing. Smoking is likely to cause infections in the respiratory tract. Which statement best explains the fact?
Solution
Answer: Option (A) is correct.
Cilia are tiny hair-like projections that protect the airways by sweeping away mucus and dust particles and keeping the lungs clear. Smoking damages and eventually destroys these cilia, leaving the respiratory tract exposed to infections.
Cilia are tiny hair-like projections that protect the airways by sweeping away mucus and dust particles and keeping the lungs clear. Smoking damages and eventually destroys these cilia, leaving the respiratory tract exposed to infections.
Enzymes and Their Actions
Given below are two columns — Column I shows enzymes secreted by the glands in the alimentary canal of human beings, and Column II indicates the components of food on which these enzymes act.
.png)
Select the correct enzyme–substrate matching from the given options.
Given below are two columns — Column I shows enzymes secreted by the glands in the alimentary canal of human beings, and Column II indicates the components of food on which these enzymes act.
Select the correct enzyme–substrate matching from the given options.
Solution
Answer: Option (B) is correct.
— Trypsin: Breaks down proteins into smaller peptides in the duodenum.
— Pepsin: A stomach enzyme that digests proteins in ingested food.
— Lipase: Breaks down fats (lipids) so they can be absorbed in the intestines.
— Amylase: Helps break down starch into simpler sugars.
.png)
— Trypsin: Breaks down proteins into smaller peptides in the duodenum.
— Pepsin: A stomach enzyme that digests proteins in ingested food.
— Lipase: Breaks down fats (lipids) so they can be absorbed in the intestines.
— Amylase: Helps break down starch into simpler sugars.
The diagram below shows a leaf that was covered by a piece of black paper for a period of three days. After three days, the paper was removed. On testing, it was found that the area under the black paper tested negative for starch, while the rest of the leaf tested positive for starch.
What was the experiment trying to test?
What was the experiment trying to test?
Solution
Answer: Option (B) is correct.
The part of the leaf exposed to sunlight gives a positive iodine test, proving that sunlight is necessary for photosynthesis. The area covered by the black paper received no light and hence could not produce starch.
The part of the leaf exposed to sunlight gives a positive iodine test, proving that sunlight is necessary for photosynthesis. The area covered by the black paper received no light and hence could not produce starch.
Consider the following statements in connection with the functions of the blood vessels marked A and B in the diagram of a human heart as shown.
(i) Blood vessel A – It carries carbon dioxide-rich blood to the lungs.
(ii) Blood vessel B – It carries oxygen-rich blood from the lungs.
(iii) Blood vessel B – The left atrium relaxes as it receives blood from this vessel.
(iv) Blood vessel A – The right atrium has a thick muscular wall as it has to pump blood to this vessel.
(i) Blood vessel A – It carries carbon dioxide-rich blood to the lungs.
(ii) Blood vessel B – It carries oxygen-rich blood from the lungs.
(iii) Blood vessel B – The left atrium relaxes as it receives blood from this vessel.
(iv) Blood vessel A – The right atrium has a thick muscular wall as it has to pump blood to this vessel.
Solution
Answer: Option (D) is correct.
Blood vessel A is the pulmonary artery and Blood vessel B is the pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs to the left atrium, which relaxes to receive it. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. Statement (iv) is incorrect — it is the right ventricle, not the atrium, that has thick muscular walls to pump blood to the lungs.
Blood vessel A is the pulmonary artery and Blood vessel B is the pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs to the left atrium, which relaxes to receive it. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. Statement (iv) is incorrect — it is the right ventricle, not the atrium, that has thick muscular walls to pump blood to the lungs.
(a) Write the correct sequence of steps followed during the journey of oxygen-rich blood from the lungs to various organs of the human body.
(b) What happens when the system of blood vessels develops a leak?
(b) What happens when the system of blood vessels develops a leak?
Answer
(a) Journey of oxygen-rich blood from lungs to body organs:
(b) There will be a loss of pressure in the blood, which would reduce the circulatory efficiency and may damage the surrounding tissues.
(b) There will be a loss of pressure in the blood, which would reduce the circulatory efficiency and may damage the surrounding tissues.
(a) Draw a diagram of the human excretory system and label the following parts on it:
(i) Right Renal Artery (ii) Vena Cava (iii) Urinary Bladder (iv) Left Kidney
(b) List two vital functions of the kidney.
(i) Right Renal Artery (ii) Vena Cava (iii) Urinary Bladder (iv) Left Kidney
(b) List two vital functions of the kidney.
Answer
(a) Human Excretory System:
.png)
(b) Vital Functions of the Kidney:
(i) To regulate the right amount of water in the body.
(ii) To help in filtering out nitrogenous wastes like urea from the blood.
(b) Vital Functions of the Kidney:
(i) To regulate the right amount of water in the body.
(ii) To help in filtering out nitrogenous wastes like urea from the blood.
Explore More CBSE Class 10 Biology Chapters
Frequently Asked Questions
What does the Life Processes chapter cover in CBSE Class 10 Biology? ⌄
The Life Processes chapter in CBSE Class 10 Biology covers four major topics: Nutrition (autotrophic and heterotrophic, including photosynthesis and human digestion), Respiration (aerobic, anaerobic, and the human respiratory system), Transportation (human circulatory system, double circulation, and transport in plants), and Excretion (human excretory system, nephron, and excretion in plants). These topics are tested across all question types in the board exam.
How many marks does Life Processes carry in the CBSE Class 10 board exam? ⌄
Life Processes is part of the Biology section under Unit 2: World of Living, which carries approximately 13 marks in the CBSE Class 10 Science board paper. Questions appear as 1-mark MCQs, 2-mark short answers, 3-mark and 5-mark long answers, as well as case-study questions — making it one of the highest-weightage chapters in Science.
What are the most important topics to focus on in Life Processes? ⌄
The most frequently tested topics are: the process and conditions for photosynthesis, structure and function of the nephron, double circulation and why it is necessary in humans, the role of enzymes in digestion, adaptations of the small intestine for absorption, and the difference in breathing rate between aquatic and terrestrial organisms. Diagram-based questions on the excretory and respiratory systems are also very common.
What are common mistakes students make in Life Processes questions? ⌄
A very common error is confusing the pulmonary artery (carries deoxygenated blood to the lungs) with the pulmonary vein — students often expect arteries to always carry oxygenated blood. Another frequent mistake is incomplete diagram labelling during board exams. Students also lose marks by not mentioning both functions when a question asks for “two functions”. Practising previous year questions helps your child avoid these specific errors under exam pressure.
How does Angle Belearn help students score well in Life Processes? ⌄
Angle Belearn’s CBSE specialists curate chapter-wise question banks drawn from real board papers, each paired with clear, step-by-step solutions that mirror the marking scheme. Students practising on Angle Belearn develop the habit of writing structured answers — including labelled diagrams, point-wise explanations, and relevant scientific terms — which is exactly what earns full marks in the board exam. Regular practice builds both accuracy and exam confidence.
