Which sequence correctly represents the path of air during inhalation in humans?

Nasal cavity → pharynx → larynx → trachea → bronchi → lungs

Nostrils → larynx → pharynx → trachea → lungs

Nasal cavity → pharynx → larynx → trachea → bronchi → lungs

Pharynx → nasal cavity → larynx → bronchi → trachea

Larynx → pharynx → trachea → bronchi → nasal cavity

What is the primary function of xylem in plants?

Transport of water and minerals

On a hot, windy day, a plant's rate of transpiration exceeds its rate of water absorption. What is most likely to occur?

Stomata will close and the plant may wilt

Roots will immediately increase water uptake

Leaf temperature will rise significantly

Stomata will close and the plant may wilt

Photosynthesis will be enhanced

Assertion (A): The opening and closing of stomata is controlled by changes in the turgor pressure of guard cells. Reason (R): Guard cells contain chloroplasts that perform photosynthesis, which directly causes stomatal opening.

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.

The small intestine is highly efficient in absorbing digested food. Describe any two structural adaptations that make this possible.

The inner wall of the small intestine is folded into numerous finger‑like projections called villi, which vastly increase the surface area for absorption. Each villus is richly supplied with blood capillaries and a central lacteal (lymph vessel) to transport absorbed nutrients quickly away from the intestine.

Veins contain valves, whereas arteries do not. Explain this difference based on the direction of blood flow and the pressure within each type of vessel.

Veins carry blood back towards the heart, often against gravity (especially in limbs), and the blood pressure inside veins is low. Valves prevent the back‑flow of blood. Arteries carry blood away from the heart under high pressure, so unidirectional flow is maintained without valves.

During vigorous exercise, athletes sometimes suffer from muscle cramps. Explain the metabolic pathway that causes this, and suggest why massage and rest help in relief.

During intense exercise, muscles switch to anaerobic respiration because oxygen supply is insufficient. Pyruvate is converted to lactic acid, which accumulates and causes cramps. Massage improves blood flow, increasing oxygen delivery to muscles, which converts lactic acid back to pyruvate for aerobic breakdown. Rest reduces energy demand, allowing the accumulated acid to be cleared gradually.

A student set up an experiment with two identical potted plants. Plant A was kept in sunlight and Plant B in a dark cupboard for 48 hours. After that, a leaf from each was tested for starch. Leaves of Plant A turned blue-black with iodine, while leaves of Plant B remained brown. Explain these results and state the conclusion drawn.

Plant A in sunlight performed photosynthesis, producing starch which gave a blue-black colour with iodine. Plant B in darkness could not photosynthesise, so no starch was present and iodine remained brown. The experiment demonstrates that light is essential for photosynthesis.

A person is suffering from chronic kidney failure. Explain the underlying principle of hemodialysis. Why must the dialyzing fluid contain electrolytes in the correct proportion?

Hemodialysis removes metabolic wastes like urea from blood using an artificial kidney. Principle: diffusion across a semipermeable membrane. Blood from artery passes through dialysis machine with cellophane membrane bathed in dialyzing fluid. Urea, creatinine diffuse out down concentration gradient into fluid. Proteins and blood cells remain. Electrolytes (Na+, K+, Cl-, HCO3-) in fluid are at normal plasma levels so that only excess is removed; if absent, vital electrolytes would be lost, causing imbalance. Correct proportion maintains homeostasis.

Prove that the energy released during respiration is not directly used for cellular activities. Justify with a schematic representation of ATP formation and utilization.

Respiration breaks down glucose, releasing energy which is stored in ATP molecules, not used directly. ATP is the energy currency. Schematic: Glucose → Glycolysis → Krebs cycle → ETS → ATP synthesis (from ADP + Pi). This energy is then used for: muscle contraction (myosin ATPase), active transport (Na+-K+ pump), biosynthesis. Direct use of energy would be uncontrolled and inefficient. ATP acts as intermediate. Proof: isolated mitochondria produce ATP, not direct work; uncouplers dissipate energy as heat, no ATP, no work. Thus, energy is transduced into ATP.

Seema placed a potted plant in a dark cupboard for 72 hours. Then she took a leaf, covered the upper surface of a part with aluminium foil, and exposed the plant to sunlight for 5 hours. Later she tested the leaf for starch using iodine solution. (1) Why was the plant kept in darkness for 72 hours? (2) What is the purpose of covering a part of the leaf? (3) What result would you expect and what does it prove?

The plant was destarched; the covered part serves as control. The result shows starch only in the exposed part, proving light is required for photosynthesis.

Class 10 Science Chapter 5: Life Processes — Important Questions & Sample Paper

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Yes — this page has 44+ original Class 10 Science Chapter 5 (“Life Processes”) important questions with answers (Multiple Choice (MCQ), Assertion–Reason, Short Answer, Short Answer, Long Answer, Case Study). Practise them free, or generate a full CBSE board-pattern sample paper (80 marks) and export it to PDF or Word — in English & Hindi, for 2026-27.

Chapter 5 'Life Processes' in Class 10 Science explores the essential maintenance functions that sustain living organisms. The chapter is structured around four core processes: nutrition, respiration, transportation, and excretion. Nutrition covers autotrophic (photosynthesis) and heterotrophic modes (holozoic, saprophytic, parasitic), including the overall equation for photosynthesis and the role of chlorophyll. Respiration distinguishes between aerobic and anaerobic pathways, with ATP production and the respiratory substrates. Transportation addresses the movement of water and minerals in plants via xylem (transpiration pull) and food via phloem, while in humans it details the double circulatory system, heart chambers, and blood vessel types (arteries, veins, capillaries). Excretion covers nitrogenous waste removal in humans through the nephron’s filtration mechanism and in plants through stomata and storage. Key skills tested include diagram interpretation (e.g., cross-section of leaf, nephron, heart), experimental reasoning (starch test for photosynthesis), and comparative analysis (aerobic vs. anaerobic, arteries vs. veins). Exam questions range from direct definitions and equations to application-based scenarios on transpiration, blood pressure, and dialysis, making this chapter a high-scoring section when conceptual clarity is achieved.

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Science — Life Processes

Class 10Time: 3 hrsMax Marks: 80

SECTION A

1.
Which sequence correctly represents the path of air during inhalation in humans?
(a) Nostrils → larynx → pharynx → trachea → lungs(b) Nasal cavity → pharynx → larynx → trachea → bronchi → lungs(c) Pharynx → nasal cavity → larynx → bronchi → trachea(d) Larynx → pharynx → trachea → bronchi → nasal cavity
1
2.
Chronic high blood pressure (hypertension) often leads to structural changes in blood vessel walls. In which type of vessel is thickening of the muscular wall most pronounced?
(a) Capillaries(b) Veins(c) Arteries(d) Lymph vessels
1
3.
What is the primary function of xylem in plants?
(a) Transport of food(b) Transport of water and minerals(c) Protection from herbivores(d) Exchange of gases
1

+ 41 more questions in the full paper

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Marks distribution & blueprint

In a CBSE exam, this chapter typically contributes questions across the following types. The last column shows how many original questions of each type we have ready in our bank for this chapter:

Question type	Marks each	In our bank
Multiple Choice (MCQ)	1 mark	13
Assertion–Reason	1 mark	6
Short Answer	2 marks	8
Short Answer	3 marks	6
Long Answer	5 marks	5
Case Study	4 marks	6

44 original, exam-style questions in our bank for this chapter — with answers.

Important & sample questions (with answers)

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Q1. Which sequence correctly represents the path of air during inhalation in humans?
1 mark
Multiple Choice (MCQ)
(A) Nostrils → larynx → pharynx → trachea → lungs(B) Nasal cavity → pharynx → larynx → trachea → bronchi → lungs(C) Pharynx → nasal cavity → larynx → bronchi → trachea(D) Larynx → pharynx → trachea → bronchi → nasal cavity
▸ Answer▾ Answer
Nasal cavity → pharynx → larynx → trachea → bronchi → lungs
Q2. Chronic high blood pressure (hypertension) often leads to structural changes in blood vessel walls. In which type of vessel is thickening of the muscular wall most pronounced?
1 mark
Multiple Choice (MCQ)
(A) Capillaries(B) Veins(C) Arteries(D) Lymph vessels
▸ Answer▾ Answer
Arteries
Q3. What is the primary function of xylem in plants?
1 mark
Multiple Choice (MCQ)
(A) Transport of food(B) Transport of water and minerals(C) Protection from herbivores(D) Exchange of gases
▸ Answer▾ Answer
Transport of water and minerals
Q4. On a hot, windy day, a plant's rate of transpiration exceeds its rate of water absorption. What is most likely to occur?
1 mark
Multiple Choice (MCQ)
(A) Roots will immediately increase water uptake(B) Leaf temperature will rise significantly(C) Stomata will close and the plant may wilt(D) Photosynthesis will be enhanced
▸ Answer▾ Answer
Stomata will close and the plant may wilt
Q5. Assertion (A): The opening and closing of stomata is controlled by changes in the turgor pressure of guard cells. Reason (R): Guard cells contain chloroplasts that perform photosynthesis, which directly causes stomatal opening.
1 mark
Assertion–Reason
(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 but R is true.
▸ Answer▾ Answer
A is true but R is false.
Q6. The small intestine is highly efficient in absorbing digested food. Describe any two structural adaptations that make this possible.
2 marks
Short Answer
▸ Answer▾ Answer
The inner wall of the small intestine is folded into numerous finger‑like projections called villi, which vastly increase the surface area for absorption. Each villus is richly supplied with blood capillaries and a central lacteal (lymph vessel) to transport absorbed nutrients quickly away from the intestine.
Q7. Veins contain valves, whereas arteries do not. Explain this difference based on the direction of blood flow and the pressure within each type of vessel.
2 marks
Short Answer
▸ Answer▾ Answer
Veins carry blood back towards the heart, often against gravity (especially in limbs), and the blood pressure inside veins is low. Valves prevent the back‑flow of blood. Arteries carry blood away from the heart under high pressure, so unidirectional flow is maintained without valves.
Q8. During vigorous exercise, athletes sometimes suffer from muscle cramps. Explain the metabolic pathway that causes this, and suggest why massage and rest help in relief.
3 marks
Short Answer
▸ Answer▾ Answer
During intense exercise, muscles switch to anaerobic respiration because oxygen supply is insufficient. Pyruvate is converted to lactic acid, which accumulates and causes cramps. Massage improves blood flow, increasing oxygen delivery to muscles, which converts lactic acid back to pyruvate for aerobic breakdown. Rest reduces energy demand, allowing the accumulated acid to be cleared gradually.
Q9. A student set up an experiment with two identical potted plants. Plant A was kept in sunlight and Plant B in a dark cupboard for 48 hours. After that, a leaf from each was tested for starch. Leaves of Plant A turned blue-black with iodine, while leaves of Plant B remained brown. Explain these results and state the conclusion drawn.
3 marks
Short Answer
▸ Answer▾ Answer
Plant A in sunlight performed photosynthesis, producing starch which gave a blue-black colour with iodine. Plant B in darkness could not photosynthesise, so no starch was present and iodine remained brown. The experiment demonstrates that light is essential for photosynthesis.
Q10. A person is suffering from chronic kidney failure. Explain the underlying principle of hemodialysis. Why must the dialyzing fluid contain electrolytes in the correct proportion?
5 marks
Long Answer
▸ Answer▾ Answer
Hemodialysis removes metabolic wastes like urea from blood using an artificial kidney. Principle: diffusion across a semipermeable membrane. Blood from artery passes through dialysis machine with cellophane membrane bathed in dialyzing fluid. Urea, creatinine diffuse out down concentration gradient into fluid. Proteins and blood cells remain. Electrolytes (Na+, K+, Cl-, HCO3-) in fluid are at normal plasma levels so that only excess is removed; if absent, vital electrolytes would be lost, causing imbalance. Correct proportion maintains homeostasis.
Q11. Prove that the energy released during respiration is not directly used for cellular activities. Justify with a schematic representation of ATP formation and utilization.
5 marks
Long Answer
▸ Answer▾ Answer
Respiration breaks down glucose, releasing energy which is stored in ATP molecules, not used directly. ATP is the energy currency. Schematic: Glucose → Glycolysis → Krebs cycle → ETS → ATP synthesis (from ADP + Pi). This energy is then used for: muscle contraction (myosin ATPase), active transport (Na+-K+ pump), biosynthesis. Direct use of energy would be uncontrolled and inefficient. ATP acts as intermediate. Proof: isolated mitochondria produce ATP, not direct work; uncouplers dissipate energy as heat, no ATP, no work. Thus, energy is transduced into ATP.
Q12. Seema placed a potted plant in a dark cupboard for 72 hours. Then she took a leaf, covered the upper surface of a part with aluminium foil, and exposed the plant to sunlight for 5 hours. Later she tested the leaf for starch using iodine solution.
4 marks
Case Study
1. (i) Why was the plant kept in darkness for 72 hours?1 mark
2. (ii) What is the purpose of covering a part of the leaf?1 mark
3. (iii) What result would you expect and what does it prove?2 marks
▸ Answer▾ Answer
The plant was destarched; the covered part serves as control. The result shows starch only in the exposed part, proving light is required for photosynthesis.

Frequently asked questions

What is the significance of double circulation in humans?

Double circulation ensures complete separation of oxygenated and deoxygenated blood, allowing efficient oxygen delivery to body tissues and maintaining high metabolic rates.

How can I set up a simple experiment to show that light is essential for photosynthesis?

Destarch a potted plant by keeping it in the dark for 48 hours, then expose half a leaf to sunlight while covering the other half. Test for starch with iodine; only the illuminated part turns blue-black.

Which life processes are linked in the functioning of the nephron?

The nephron integrates filtration (glomerulus), selective reabsorption (tubule), and secretion (tubule) to form urine, maintaining fluid and electrolyte balance and removing metabolic wastes.

What are the main differences between transport in xylem and phloem?

Xylem transports water and minerals unidirectionally from roots to leaves using physical forces (transpiration pull), while phloem transports sugars bidirectionally using energy (active transport) from source to sink.

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