Exercise — Life Processes

1. 11 markNCERT Cl-10 Science, Exercise Q1

   The kidneys in human beings are a part of the system for (a) nutrition. (b) respiration. (c) excretion. (d) transportation.

   Hint. What is the main waste product the kidneys remove from the blood?

   Step 1 — Recall what kidneys do. Kidneys filter nitrogenous waste out of the blood and form urine.

   Step 2 — Match to the correct system. Since removing waste products from the body is the definition of excretion, that's the system the kidneys belong to.

   ✦ Answer: (c) excretion.

   Where students slip. Picking transportation because 'blood flows through the kidneys' — the kidneys' defining role is removing waste from that blood, which is an excretory function, not a transport one.

2. 21 markNCERT Cl-10 Science, Exercise Q2

   The xylem in plants are responsible for (a) transport of water. (b) transport of food. (c) transport of amino acids. (d) transport of oxygen.

   Hint. Phloem is the other plant tissue you're being asked to distinguish this from.

   Step 1 — Recall the division of labour between xylem and phloem. Xylem transports water and minerals; phloem transports food and other organic substances like amino acids.

   Step 2 — Match to the option. Since transport of water is specifically xylem's job, that's the correct choice here.

   ✦ Answer: (a) transport of water.

   Where students slip. Picking transport of amino acids — that's phloem's job, not xylem's; xylem is specifically about water and dissolved minerals from the soil.

3. 31 markNCERT Cl-10 Science, Exercise Q3

   The autotrophic mode of nutrition requires (a) carbon dioxide and water. (b) chlorophyll. (c) sunlight. (d) all of the above.

   Hint. Photosynthesis needs every one of the first three things listed — none of them alone is sufficient.

   Step 1 — List what photosynthesis actually needs. Carbon dioxide and water are the raw materials, chlorophyll is what absorbs light energy, and sunlight is the energy source — all three are required together.

   Step 2 — Match to the option. Since all three are necessary, not just one, the complete answer is 'all of the above.'

   ✦ Answer: (d) all of the above.

   Where students slip. Picking just (a) or just (c) — each one alone is necessary but not sufficient; photosynthesis fails without any one of the three.

4. 41 markNCERT Cl-10 Science, Exercise Q4

   The breakdown of pyruvate to give carbon dioxide, water and energy takes place in (a) cytoplasm. (b) mitochondria. (c) chloroplast. (d) nucleus.

   Hint. Glucose breaks down to pyruvate in one location — but this question is asking about what happens to pyruvate next.

   Step 1 — Separate the two stages of respiration. Glucose breaks down into pyruvate in the cytoplasm, since that's always the first step; pyruvate is then further broken down using oxygen inside the mitochondria.

   Step 2 — Match to the question. The question asks specifically about pyruvate's breakdown into CO₂, water and energy — the oxygen-using, mitochondrial stage.

   ✦ Answer: (b) mitochondria.

   Where students slip. Picking cytoplasm — that's where glucose becomes pyruvate; the further breakdown of pyruvate itself (into CO₂ and water, with oxygen) happens in the mitochondria.

5. 52 marksNCERT Cl-10 Science, Exercise Q5

   How are fats digested in our bodies? Where does this process take place?

   Hint. Fats need to be broken into smaller globules before an enzyme can act on them efficiently — think about what does that job.

   Step 1 — Name the location. Fat digestion takes place in the small intestine.

   Step 2 — Describe the emulsification step. Fats enter as large globules, which bile juice from the liver breaks down into smaller globules (emulsification), increasing the surface area available for enzyme action.

   Step 3 — Describe the enzymatic breakdown. The pancreas secretes lipase, since this is the enzyme that breaks down the emulsified fats into fatty acids and glycerol.

   ✦ Answer: In the small intestine — bile from the liver first emulsifies fats into smaller globules, and then pancreatic lipase breaks them down into fatty acids and glycerol.

   Where students slip. Saying bile 'digests' fat — bile only emulsifies (physically breaks up) fat into smaller globules; the actual chemical digestion into fatty acids and glycerol is done by the enzyme lipase.

6. 62 marksNCERT Cl-10 Science, Exercise Q6

   What is the role of saliva in the digestion of food?

   Hint. Saliva has both a physical role and a chemical (enzymatic) role.

   Step 1 — Physical role. Saliva moistens and softens the food, making it easier to chew and swallow.

   Step 2 — Chemical role. It contains the enzyme salivary amylase, since this is what begins breaking down starch into a simpler sugar.

   ✦ Answer: Saliva moistens food for easier swallowing, and its enzyme salivary amylase starts breaking down starch into simple sugar.

   Where students slip. Saying saliva digests protein or fat — salivary amylase acts specifically on starch (a carbohydrate); protein and fat digestion happen later, in the stomach and small intestine respectively.

7. 72 marksNCERT Cl-10 Science, Exercise Q7

   What are the necessary conditions for autotrophic nutrition and what are its by-products?

   Hint. Conditions are the inputs; by-products are what comes out besides the main food product.

   Step 1 — Necessary conditions. Sunlight, chlorophyll, carbon dioxide and water are all required for autotrophic nutrition (photosynthesis).

   Step 2 — By-products. Oxygen is released as a by-product, since it comes from the splitting of water molecules; carbohydrates are the main product, some of which are stored (as starch in plants).

   ✦ Answer: Conditions needed: sunlight, chlorophyll, carbon dioxide and water. By-product: oxygen (with carbohydrate as the main product, stored as starch).

   Where students slip. Calling carbohydrate a 'by-product' — carbohydrate is the main intended product of photosynthesis; oxygen is the by-product released alongside it.

8. 83 marksNCERT Cl-10 Science, Exercise Q8

   What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

   Hint. Compare where each happens, what it needs, what it produces, and how much energy it releases.

   Step 1 — Requirement and location. Aerobic respiration needs oxygen and occurs in the mitochondria; anaerobic respiration occurs without oxygen, in the cytoplasm.

   Step 2 — Products. Aerobic respiration completely breaks glucose down into carbon dioxide and water. Anaerobic respiration only partially breaks it down — into ethanol and CO₂ (in yeast) or lactic acid (in our muscles).

   Step 3 — Energy released. Aerobic respiration releases much more energy than anaerobic respiration, since the breakdown is complete.

   Step 4 — Examples of anaerobic organisms. Yeast (during fermentation) and certain bacteria carry out anaerobic respiration; our own muscle cells also switch to it temporarily during sudden vigorous activity.

   ✦ Answer: Aerobic respiration uses oxygen (in mitochondria) to fully break down glucose into CO₂ and water, releasing lots of energy. Anaerobic respiration happens without oxygen (in the cytoplasm), only partially breaking glucose down into ethanol+CO₂ (yeast) or lactic acid (muscles), releasing much less energy. Examples: yeast, certain bacteria, and human muscle cells under oxygen-deficient conditions.

   Where students slip. Naming only one anaerobic example — the question specifically says 'some organisms' (plural), so yeast alone isn't a complete answer; bacteria and oxygen-starved muscle cells are equally valid examples.

9. 92 marksNCERT Cl-10 Science, Exercise Q9

   How are the alveoli designed to maximise the exchange of gases?

   Hint. Think in terms of number, wall thickness, and blood supply.

   Step 1 — Number and total area. There are enormous numbers of alveoli in the lungs, giving a very large total surface area for gas exchange.

   Step 2 — Wall thickness. Their walls are extremely thin (one cell thick), allowing gases to diffuse across easily.

   Step 3 — Blood supply. Each alveolus is surrounded by an extensive network of blood capillaries, since this is what ensures efficient and rapid exchange between air and blood.

   ✦ Answer: Alveoli are present in huge numbers (giving a large total surface area), have very thin walls for easy diffusion, and are richly supplied with blood capillaries — all of which maximise the efficiency of gas exchange.

   Where students slip. Mentioning only 'large surface area' without explaining what produces it — it's specifically the enormous number of tiny alveoli (not one big sac) that creates such a large total area.

10. 102 marksNCERT Cl-10 Science, Exercise Q10

    What would be the consequences of a deficiency of haemoglobin in our bodies?

    Hint. Haemoglobin's whole job is carrying one particular gas — think about what happens to cells when less of it gets delivered.

    Step 1 — Recall haemoglobin's role. Haemoglobin, present in red blood corpuscles, carries oxygen from the lungs to all body tissues.

    Step 2 — Work out the consequence of a deficiency. With less haemoglobin, the blood's oxygen-carrying capacity drops, so body cells receive less oxygen than they need.

    Step 3 — State the resulting symptoms. This leads to fatigue, weakness and breathlessness, since cells can't release energy efficiently through respiration without enough oxygen — a condition known as anaemia.

    ✦ Answer: A haemoglobin deficiency reduces the blood's oxygen-carrying capacity, starving body tissues of oxygen and causing fatigue, weakness and breathlessness (anaemia).

    Where students slip. Saying haemoglobin deficiency stops respiration completely — it doesn't stop it, but it does reduce the efficiency of oxygen delivery, weakening the body's energy release rather than halting it entirely.

11. 113 marksNCERT Cl-10 Science, Exercise Q11

    Describe double circulation of blood in human beings. Why is it necessary?

    Hint. Trace blood through two separate loops, and think about what mammals need that reptiles don't.

    Step 1 — Pulmonary circulation. Deoxygenated blood from the body enters the heart's right side and is pumped to the lungs, where it picks up oxygen.

    Step 2 — Systemic circulation. This oxygenated blood returns to the heart's left side and is pumped out to the rest of the body; the blood then returns deoxygenated to the right side again, completing the double pass through the heart.

    Step 3 — Why it's necessary. This arrangement, via the four-chambered heart, keeps oxygenated and deoxygenated blood separate, giving a highly efficient oxygen supply — necessary because humans (like other mammals) constantly use energy to maintain body temperature.

    ✦ Answer: Blood passes through the heart twice per cycle — once via pulmonary circulation (heart to lungs and back) and once via systemic circulation (heart to body and back). This keeps oxygenated and deoxygenated blood separate, giving efficient oxygen delivery, which mammals need to sustain their constant energy use for maintaining body temperature.

    Where students slip. Describing only one of the two circuits (usually systemic) — 'double' circulation specifically means blood passes through the heart twice, so both the pulmonary and systemic loops must be described.

12. 123 marksNCERT Cl-10 Science, Exercise Q12

    What are the differences between the transport of materials in xylem and phloem?

    Hint. Compare what's carried, which direction it moves, and whether energy is spent to move it.

    Step 1 — What is transported. Xylem carries water and minerals; phloem carries food (mainly sucrose) and other substances like amino acids.

    Step 2 — Direction of movement. Xylem transport is one-directional, upward from roots to leaves; phloem transport can go both upward and downward, depending on the plant's needs.

    Step 3 — Driving mechanism. Xylem transport is driven by physical forces — root pressure and transpiration pull — and needs no energy expenditure, since these forces act on their own. Phloem transport actively uses ATP energy to build osmotic pressure differences that drive movement.

    ✦ Answer: Xylem moves water/minerals upward only, driven by root pressure and transpiration (no energy used). Phloem moves food/amino acids in either direction, driven by ATP-powered osmotic pressure changes.

    Where students slip. Saying both tissues use the same driving mechanism — xylem transport is passive (physical forces only), while phloem transport specifically requires active, energy-consuming loading of sucrose.

13. 133 marksNCERT Cl-10 Science, Exercise Q13

    Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

    Hint. Both are tiny, numerous units wrapped in capillaries — but one just lets gas pass through, while the other actively filters and reabsorbs.

    Step 1 — Structural similarity. Both alveoli and nephrons are the basic functional units of their organs, present in enormous numbers, and richly supplied with networks of thin-walled blood capillaries for efficient exchange.

    Step 2 — Functional difference — alveoli. Alveoli are concerned only with gas exchange: oxygen diffuses into the blood and carbon dioxide diffuses out, by simple diffusion, with no filtration involved.

    Step 3 — Functional difference — nephrons. Nephrons filter the blood at the glomerulus/Bowman's capsule, then selectively reabsorb useful substances (glucose, amino acids, salts, water) back into the blood as the filtrate flows along the tubule, since this two-step, selective process is what forms urine rather than simple diffusion.

    ✦ Answer: Both are numerous, capillary-rich basic units of their organs. But alveoli only carry out simple two-way gas diffusion, while nephrons carry out a two-step process — filtering blood at the glomerulus, then selectively reabsorbing useful substances back into it as urine forms.

    Where students slip. Describing nephrons as working 'just like alveoli, but for waste' — nephrons don't merely let waste diffuse out; they filter everything first and then selectively take back what's useful, which is a fundamentally different (and more selective) process than the passive diffusion in alveoli.

Solutions written by the tuition.in editorial team and checked against the NCERT Class 10 Science textbook, Reprint 2026-27 (jesc105.pdf) — five in-text question sets (21 questions total) plus one end-of-chapter Exercise (13 questions, not 20 as some older manifests claim). Unchanged by rationalisation; the chapter describes the breathing passage and the nephron's tubule in generic functional terms rather than naming every intermediate structure.. Questions are referenced from the NCERT textbook for identification.