Class X · Science · Chapter 5
Life Processes
Term Examination — Question Paper
General Instructions
- This paper contains three sections: Section A (MCQs, 1 mark each), Section B (Short Answer, 3 marks each), and Section C (Long Answer, 5 marks each).
- All questions are compulsory. There is no internal choice unless stated.
- Write neatly. Diagrams, wherever required, should be well-labelled.
- The answer key is printed after the question paper for reference.
Section A
1.
Which of the following is not considered a life process?
[1]
2.
The autotrophic mode of nutrition requires which of the following?
[1]
3.
The green dots visible inside leaf cells under a microscope are:
[1]
4.
Opening and closing of stomatal pores is controlled by:
[1]
5.
Which enzyme in saliva begins the digestion of starch?
[1]
6.
The rhythmic contractions of the canal wall that push food forward are called:
[1]
7.
Breakdown of pyruvate to give CO₂, water and energy takes place in the:
[1]
8.
The build-up of lactic acid in muscle cells during sudden activity causes:
[1]
9.
The respiratory pigment in human beings that has a high affinity for oxygen is:
[1]
10.
In a fish heart, blood passes through the heart:
[1]
11.
Which blood vessels carry blood away from the heart?
[1]
12.
Normal systolic / diastolic blood pressure in humans is:
[1]
13.
The loss of water in the form of vapour from the aerial parts of a plant is called:
[1]
14.
Phloem in plants is responsible for:
[1]
15.
The basic filtration units of the kidneys are called:
[1]
16.
Organisms that derive nutrition from plants or animals without killing them are called:
[1]
17.
The finger-like projections in the small intestine that increase surface area for absorption are:
[1]
18.
The energy currency used for most cellular processes is:
[1]
19.
The kidneys in human beings are part of which body system?
[1]
20.
In anaerobic respiration in yeast, glucose is broken down to produce:
[1]
Section B
21.
What are life processes? Name the four essential life processes required to maintain life in an organism.
[3]
22.
Distinguish between autotrophic and heterotrophic nutrition. Give one example of each.
[3]
23.
What is the role of hydrochloric acid and mucus in the stomach?
[3]
24.
Write the events that occur during photosynthesis. Write the chemical equation for the process.
[3]
25.
Why do aquatic organisms breathe faster than terrestrial organisms? Explain briefly.
[3]
26.
Describe the role of bile juice in digestion. Where is it produced and stored?
[3]
27.
What is transpiration? State two functions it performs in a plant.
[3]
28.
How do platelets help in the maintenance of the blood circulatory system?
[3]
29.
How do plants excrete their waste products? Mention any three methods.
[3]
30.
What is lymph? How is it different from blood? State one function of lymph.
[3]
Section C
31.
Describe the process of digestion of food in the small intestine in human beings. Include the roles of the liver, pancreas, and intestinal walls in your answer.
[5]
32.
With the help of a labelled diagram, explain the structure of the human respiratory system. How is gas exchange carried out in the alveoli?
[5]
33.
(a) Draw a neat, labelled diagram of the human heart and describe how blood circulates through it. (3 marks)
(b) Why is double circulation important for mammals and birds? (2 marks)
(b) Why is double circulation important for mammals and birds? (2 marks)
[5]
34.
Compare aerobic and anaerobic respiration under the following heads: (i) definition, (ii) site of reaction, (iii) end products, (iv) energy released, (v) organisms that use it.
[5]
35.
Describe the structure and functioning of a nephron. How does an artificial kidney (hemodialysis) mimic the natural kidney's function? How does it differ?
[5]
36.
(a) Explain how water and minerals are transported from roots to leaves in plants (xylem transport). Include the role of transpiration pull and root pressure. (3 marks)
(b) How is food transported from leaves to other parts in plants (phloem transport)? (2 marks)
(b) How is food transported from leaves to other parts in plants (phloem transport)? (2 marks)
[5]
Section A — MCQ Answers
Q1
c
Q2
d
Q3
b
Q4
b
Q5
c
Q6
b
Q7
d
Q8
b
Q9
b
Q10
c
Q11
c
Q12
b
Q13
a
Q14
c
Q15
c
Q16
b
Q17
c
Q18
b
Q19
c
Q20
c
Section B — Short Answer Key (3 marks each)
Q21 — Life Processes
Life processes are the maintenance functions that living organisms must perform continuously to stay alive and prevent breakdown of their ordered structures.
The four essential life processes are: (i) Nutrition — obtaining energy/raw material from food; (ii) Respiration — breaking down food to release energy (ATP); (iii) Transportation — moving materials to all parts of the body; (iv) Excretion — removing harmful metabolic waste products from the body.
The four essential life processes are: (i) Nutrition — obtaining energy/raw material from food; (ii) Respiration — breaking down food to release energy (ATP); (iii) Transportation — moving materials to all parts of the body; (iv) Excretion — removing harmful metabolic waste products from the body.
Q22 — Autotrophic vs Heterotrophic Nutrition
Autotrophic nutrition: The organism synthesises its own food from simple inorganic substances (CO₂ and water) using an external energy source (sunlight). Requires chlorophyll. Example: Green plants.
Heterotrophic nutrition: The organism cannot make its own food; it obtains complex organic molecules from other organisms and breaks them down using enzymes. Example: Animals/Fungi.
Heterotrophic nutrition: The organism cannot make its own food; it obtains complex organic molecules from other organisms and breaks them down using enzymes. Example: Animals/Fungi.
Q23 — Role of HCl and Mucus in the Stomach
Hydrochloric acid (HCl): Creates an acidic medium (low pH) which (i) activates the enzyme pepsin to digest proteins, and (ii) kills harmful bacteria ingested with food.
Mucus: Secreted by gastric glands, it coats the inner lining of the stomach and protects it from the corrosive action of the acid under normal conditions, preventing self-digestion.
Mucus: Secreted by gastric glands, it coats the inner lining of the stomach and protects it from the corrosive action of the acid under normal conditions, preventing self-digestion.
Q24 — Events of Photosynthesis
Three events:
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
(iii) Reduction of carbon dioxide to carbohydrates (glucose).
Chemical equation:
6CO₂ + 12H₂O Chlorophyll/Sunlight→ C₆H₁₂O₆ + 6O₂ + 6H₂O
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
(iii) Reduction of carbon dioxide to carbohydrates (glucose).
Chemical equation:
6CO₂ + 12H₂O Chlorophyll/Sunlight→ C₆H₁₂O₆ + 6O₂ + 6H₂O
Q25 — Faster Breathing in Aquatic Organisms
Aquatic organisms breathe faster because the amount of dissolved oxygen in water is much lower compared to the concentration of oxygen in air. To obtain sufficient oxygen for their metabolic needs, aquatic organisms such as fish have to pass a much larger volume of water over their gills per unit time, resulting in a significantly higher breathing rate than in terrestrial organisms who breathe oxygen-rich air.
Q26 — Role of Bile Juice
Role of bile juice: (i) It makes the acidic food arriving from the stomach alkaline so that pancreatic enzymes can act. (ii) Bile salts emulsify fats — they break large fat globules into smaller droplets, greatly increasing the surface area for enzyme (lipase) action. This is similar to the emulsifying action of soaps.
Bile is produced by the liver and stored in the gall bladder, from where it is released via the bile duct into the small intestine.
Bile is produced by the liver and stored in the gall bladder, from where it is released via the bile duct into the small intestine.
Q27 — Transpiration
Transpiration is the loss of water in the form of water vapour from the aerial parts of a plant, mainly through stomata.
Two functions:
(i) Helps in absorption and upward movement of water and dissolved minerals from roots to leaves (transpiration pull creates suction).
(ii) Helps in temperature regulation of the plant — evaporation of water has a cooling effect.
Two functions:
(i) Helps in absorption and upward movement of water and dissolved minerals from roots to leaves (transpiration pull creates suction).
(ii) Helps in temperature regulation of the plant — evaporation of water has a cooling effect.
Q28 — Role of Platelets
Platelets are small cell fragments that circulate in the blood. When a blood vessel is damaged or cut, platelets rush to the site and help plug leaks by initiating blood clotting. They aggregate at the point of injury and release chemicals that trigger a clotting cascade, forming a clot (fibrin plug) that seals the wound. This prevents excessive blood loss and maintains pressure in the circulatory system.
Q29 — Excretion in Plants (3 methods)
(i) Storage in cellular vacuoles — waste products are deposited in vacuoles within cells.
(ii) Shedding of leaves — waste products accumulated in leaves are removed when the plant sheds them.
(iii) Storage as resins and gums — particularly in old xylem tissue, waste is stored in this form.
Bonus: Plants also excrete some waste substances into the surrounding soil.
(ii) Shedding of leaves — waste products accumulated in leaves are removed when the plant sheds them.
(iii) Storage as resins and gums — particularly in old xylem tissue, waste is stored in this form.
Bonus: Plants also excrete some waste substances into the surrounding soil.
Q30 — Lymph
Lymph (tissue fluid): A fluid that leaks out through the pores of capillary walls into the intercellular spaces of tissues.
Difference from blood: Lymph is colourless (no RBCs), contains less protein than blood plasma, and is not under arterial pressure.
Function: Lymph carries digested and absorbed fats from the intestine and drains excess fluid from extracellular spaces back into the bloodstream.
Difference from blood: Lymph is colourless (no RBCs), contains less protein than blood plasma, and is not under arterial pressure.
Function: Lymph carries digested and absorbed fats from the intestine and drains excess fluid from extracellular spaces back into the bloodstream.
Section C — Long Answer Key (5 marks each)
Q31 — Digestion in the Small Intestine
The small intestine is the site of complete digestion of carbohydrates, proteins, and fats. Acidic food from the stomach must first be made alkaline here for pancreatic enzymes to function.
Role of Liver: Produces bile juice, stored in the gall bladder, which (i) neutralises acidity and (ii) emulsifies large fat globules into smaller droplets via bile salts, increasing efficiency of lipase.
Role of Pancreas: Secretes pancreatic juice containing: trypsin (digests proteins) and lipase (breaks down emulsified fats).
Intestinal glands: The walls of the small intestine contain glands secreting intestinal juice whose enzymes convert proteins → amino acids, complex carbohydrates → glucose, and fats → fatty acids + glycerol.
Absorption: The inner lining bears numerous villi (finger-like projections) which increase surface area. Villi are richly supplied with blood vessels that carry absorbed food to all body cells for energy, growth, and tissue repair. Unabsorbed material passes to the large intestine.
Role of Liver: Produces bile juice, stored in the gall bladder, which (i) neutralises acidity and (ii) emulsifies large fat globules into smaller droplets via bile salts, increasing efficiency of lipase.
Role of Pancreas: Secretes pancreatic juice containing: trypsin (digests proteins) and lipase (breaks down emulsified fats).
Intestinal glands: The walls of the small intestine contain glands secreting intestinal juice whose enzymes convert proteins → amino acids, complex carbohydrates → glucose, and fats → fatty acids + glycerol.
Absorption: The inner lining bears numerous villi (finger-like projections) which increase surface area. Villi are richly supplied with blood vessels that carry absorbed food to all body cells for energy, growth, and tissue repair. Unabsorbed material passes to the large intestine.
Q32 — Human Respiratory System & Gas Exchange
Structure: Air enters through the nostrils (filtered by fine hairs and mucus) → throat/pharynx/larynx (rings of cartilage prevent collapse) → trachea → bronchi → bronchioles → millions of tiny alveoli (balloon-like sacs).
Alveoli: Provide an enormous surface area (~80 m² if spread out). Their thin walls contain an extensive network of blood capillaries.
Gas exchange mechanism:
• Breathing in: ribs lift, diaphragm flattens → chest cavity expands → air drawn in → fills alveoli.
• Deoxygenated blood arriving at alveolar capillaries releases CO₂ (diffuses into alveolar air) and picks up O₂ (diffuses into blood).
• O₂ is carried by haemoglobin in RBCs to all body cells. CO₂ (more soluble in water) is transported in dissolved form in plasma.
• A residual volume of air remains in lungs during breathing cycle to allow continuous gas exchange.
[Diagram: label nasal passage, trachea, bronchi, bronchioles, alveoli, diaphragm, ribs]
Alveoli: Provide an enormous surface area (~80 m² if spread out). Their thin walls contain an extensive network of blood capillaries.
Gas exchange mechanism:
• Breathing in: ribs lift, diaphragm flattens → chest cavity expands → air drawn in → fills alveoli.
• Deoxygenated blood arriving at alveolar capillaries releases CO₂ (diffuses into alveolar air) and picks up O₂ (diffuses into blood).
• O₂ is carried by haemoglobin in RBCs to all body cells. CO₂ (more soluble in water) is transported in dissolved form in plasma.
• A residual volume of air remains in lungs during breathing cycle to allow continuous gas exchange.
[Diagram: label nasal passage, trachea, bronchi, bronchioles, alveoli, diaphragm, ribs]
Q33 — The Human Heart & Double Circulation
(a) Heart structure & blood flow (3 marks):
The heart is a muscular, fist-sized organ with 4 chambers: Right atrium (RA), Right ventricle (RV), Left atrium (LA), Left ventricle (LV). Valves prevent backflow.
Blood flow: Deoxygenated blood from body → RA → RV → lungs (oxygenation). Oxygenated blood from lungs → LA → LV → body.
Ventricles have thicker walls than atria as they pump blood over longer distances.
[Diagram: label RA, RV, LA, LV, aorta, pulmonary artery, pulmonary vein, vena cava, septum]
(b) Importance of double circulation (2 marks):
Blood passes through the heart twice per cycle — once to lungs (pulmonary) and once to the body (systemic). This keeps oxygenated and deoxygenated blood completely separate, allowing a highly efficient supply of oxygen. This is essential for birds and mammals which are warm-blooded and need sustained high-energy output to maintain constant body temperature.
The heart is a muscular, fist-sized organ with 4 chambers: Right atrium (RA), Right ventricle (RV), Left atrium (LA), Left ventricle (LV). Valves prevent backflow.
Blood flow: Deoxygenated blood from body → RA → RV → lungs (oxygenation). Oxygenated blood from lungs → LA → LV → body.
Ventricles have thicker walls than atria as they pump blood over longer distances.
[Diagram: label RA, RV, LA, LV, aorta, pulmonary artery, pulmonary vein, vena cava, septum]
(b) Importance of double circulation (2 marks):
Blood passes through the heart twice per cycle — once to lungs (pulmonary) and once to the body (systemic). This keeps oxygenated and deoxygenated blood completely separate, allowing a highly efficient supply of oxygen. This is essential for birds and mammals which are warm-blooded and need sustained high-energy output to maintain constant body temperature.
Q34 — Aerobic vs Anaerobic Respiration
| Feature | Aerobic | Anaerobic |
|---|---|---|
| (i) Definition | Breakdown of glucose in presence of O₂ | Breakdown of glucose in absence of O₂ |
| (ii) Site | Cytoplasm + Mitochondria | Cytoplasm only |
| (iii) End products | CO₂ + H₂O + Energy (ATP) | Ethanol + CO₂ (yeast) or Lactic acid (muscles) + Energy |
| (iv) Energy | Large amount released | Small amount released |
| (v) Organisms | Most plants and animals | Yeast, some bacteria; human muscle cells (temporarily) |
Q35 — Nephron Structure, Function & Hemodialysis
Nephron structure: Each nephron consists of (i) a glomerulus — a cluster of thin-walled blood capillaries — enclosed in a cup-shaped Bowman's capsule. This leads to (ii) a long coiled tubule that ends in a collecting duct.
Functioning: Blood enters the glomerulus under pressure → filtration of small molecules (water, glucose, amino acids, salts, urea) into Bowman's capsule. As filtrate flows along the tubule, useful substances (glucose, amino acids, most water, salts) are selectively re-absorbed back into the blood. The remaining concentrated waste (urine) flows into the ureter → urinary bladder → urethra.
Hemodialysis (artificial kidney): Blood is passed through semi-permeable tubes suspended in dialysing fluid (same osmotic pressure as blood but lacking nitrogenous waste). Urea and other wastes diffuse out into the dialysing fluid; purified blood is returned to the patient.
Key difference: In artificial kidneys there is no selective reabsorption — all small molecules diffuse out and must be maintained in dialysing fluid. Normal kidneys filter ~180 L/day but excrete only 1–2 L as urine due to reabsorption.
Functioning: Blood enters the glomerulus under pressure → filtration of small molecules (water, glucose, amino acids, salts, urea) into Bowman's capsule. As filtrate flows along the tubule, useful substances (glucose, amino acids, most water, salts) are selectively re-absorbed back into the blood. The remaining concentrated waste (urine) flows into the ureter → urinary bladder → urethra.
Hemodialysis (artificial kidney): Blood is passed through semi-permeable tubes suspended in dialysing fluid (same osmotic pressure as blood but lacking nitrogenous waste). Urea and other wastes diffuse out into the dialysing fluid; purified blood is returned to the patient.
Key difference: In artificial kidneys there is no selective reabsorption — all small molecules diffuse out and must be maintained in dialysing fluid. Normal kidneys filter ~180 L/day but excrete only 1–2 L as urine due to reabsorption.
Q36 — Transport in Plants (Xylem & Phloem)
(a) Xylem Transport — Water & Minerals (3 marks):
Xylem vessels and tracheids in roots, stems, and leaves form a continuous water-conducting network. Root pressure: Root cells actively absorb ions from soil, creating a concentration difference; water moves into root xylem by osmosis, pushing a column of water upward. Transpiration pull (major daytime force): Water evaporating from leaf cells through stomata creates suction that pulls water upward through the xylem all the way from roots. At night, root pressure is the primary driving force.
(b) Phloem Transport — Food (2 marks):
The movement of soluble photosynthesis products (sucrose) from leaves to other parts is called translocation. Sucrose is loaded into phloem sieve tubes using ATP energy (active transport). This raises the osmotic pressure, drawing water in and building pressure that moves the contents toward tissues with lower pressure (growing regions, storage organs). Translocation occurs in both upward and downward directions with the help of adjacent companion cells.
Xylem vessels and tracheids in roots, stems, and leaves form a continuous water-conducting network. Root pressure: Root cells actively absorb ions from soil, creating a concentration difference; water moves into root xylem by osmosis, pushing a column of water upward. Transpiration pull (major daytime force): Water evaporating from leaf cells through stomata creates suction that pulls water upward through the xylem all the way from roots. At night, root pressure is the primary driving force.
(b) Phloem Transport — Food (2 marks):
The movement of soluble photosynthesis products (sucrose) from leaves to other parts is called translocation. Sucrose is loaded into phloem sieve tubes using ATP energy (active transport). This raises the osmotic pressure, drawing water in and building pressure that moves the contents toward tissues with lower pressure (growing regions, storage organs). Translocation occurs in both upward and downward directions with the help of adjacent companion cells.
