Class 10 Biology - Life Processes - Exercises

Multiple Choice Questions

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

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

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

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

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Short and Long Answer Questions

5. How are fats digested in our bodies? Where does this process take place? Answer: Fats are digested in the small intestine. The process involves:

• Emulsification: Large globules of fats are broken down into smaller globules by bile salts from the liver. This increases the efficiency of enzyme action.
• Enzymatic Action: The enzyme lipase, present in pancreatic juice and intestinal juice, breaks down the emulsified fats into fatty acids and glycerol.

6. What is the role of saliva in the digestion of food? Answer: Saliva plays a crucial role in the initial stages of digestion:

• It contains an enzyme called salivary amylase, which breaks down complex starch molecules into simpler sugars like maltose.
• It moistens the food, making it easier to chew and swallow.

7. What are the necessary conditions for autotrophic nutrition and what are its by-products? Answer:

• Necessary conditions: Presence of chlorophyll, sunlight, carbon dioxide (CO₂), and water (H₂O).
• By-products: Oxygen (O₂) is the major by-product released into the atmosphere. Carbohydrates (glucose) are produced as the primary energy source.

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

• Aerobic Respiration: Takes place in the presence of oxygen, occurs in the mitochondria, releases a large amount of energy, and produces CO₂ and water as end products.
• Anaerobic Respiration: Takes place in the absence of oxygen, occurs in the cytoplasm, releases a relatively small amount of energy, and produces ethanol and CO₂ (in yeast) or lactic acid (in muscle cells).
• Organisms: Yeast and certain bacteria use anaerobic respiration.

9. How are the alveoli designed to maximise the exchange of gases? Answer:

• Alveoli are balloon-like structures that provide a very large surface area for gas exchange.
• Their walls are extremely thin (one-cell thick), allowing for rapid diffusion of gases.
• They are surrounded by an extensive network of blood capillaries, ensuring a constant flow of blood to pick up oxygen and release carbon dioxide.

10. What would be the consequences of a deficiency of haemoglobin in our bodies? Answer: Haemoglobin is responsible for carrying oxygen from the lungs to all body tissues. A deficiency leads to:

• Reduced oxygen-carrying capacity of the blood.
• Fatigue, weakness, and breathlessness (anemia).
• Impaired physical and mental performance as cells do not receive enough oxygen for energy production.

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

• Double Circulation: Blood passes through the heart twice during one complete cycle through the body. It consists of pulmonary circulation (heart to lungs and back) and systemic circulation (heart to body and back).
• Necessity: It prevents the mixing of oxygenated and deoxygenated blood, ensuring a highly efficient supply of oxygen to all body parts. This is essential for maintaining high metabolic rates and constant body temperature in mammals and birds.

12. What are the differences between the transport of materials in xylem and phloem? Answer:

• Xylem: Transports water and minerals upwards from roots to leaves. It uses physical forces like transpiration pull and root pressure. Xylem tissue consists mostly of dead cells.
• Phloem: Transports products of photosynthesis (food), amino acids, and other substances from leaves to storage organs and growing parts. It uses active transport (requires energy from ATP). Phloem tissue consists of living cells (sieve tubes and companion cells).

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

• Alveoli: Thin-walled, balloon-like structures in lungs designed for gas exchange (O₂ intake, CO₂ release). They function through simple diffusion across a large surface area.
• Nephrons: Long, coiled tubes in kidneys designed for filtering blood and removing nitrogenous wastes. They involve complex processes like filtration (in Bowman's capsule), selective reabsorption (of glucose, amino acids, salts, and water), and secretion to form urine.