50 Short Answer Type Questions & Answers

Answers are concise (2–4 sentences) and follow NCERT terminology — suitable for 2–3 mark questions.

1. Q1: What are life processes? A: Life processes are the essential activities that organisms carry out to stay alive, including nutrition, respiration, circulation, excretion, movement and response. These help with energy production, growth and maintaining internal balance.
2. Q2: Explain heterotrophic nutrition with an example.A: Heterotrophic nutrition is when organisms obtain food from other organisms because they cannot make it themselves. For example, humans and animals eat plants or other animals to obtain nutrients and energy.
3. Q3: Describe the main steps of human digestion.A: Digestion begins in the mouth with chewing and salivary enzymes, continues in the stomach with acids and enzymes, and is completed in the small intestine where digestion and absorption occur. The large intestine absorbs water and forms feces for egestion.
4. Q4: How does Amoeba digest food?A: Amoeba engulfs food by extending pseudopodia to form a food vacuole where enzymes break down the food; digestion is intracellular. Undigested remains are removed by egestion through the cell membrane.
5. Q5: What is peristalsis?A: Peristalsis is the wave-like muscular movement in the walls of the alimentary canal that pushes food along, for example from the esophagus to the stomach.
6. Q6: Why are villi important in the small intestine?A: Villi increase the surface area of the small intestine to enhance absorption of digested nutrients into the bloodstream. Each villus has a rich blood supply to quickly transport absorbed substances.
7. Q7: Differentiate between ingestion and egestion.A: Ingestion is taking food into the body (e.g., eating), while egestion is the removal of undigested waste from the body (e.g., defecation).
8. Q8: What is respiration and why is it important?A: Respiration is the process of releasing energy from food molecules; it is important because the energy released is used for growth, movement, and other life activities.
9. Q9: Explain the difference between aerobic and anaerobic respiration.A: Aerobic respiration uses oxygen to completely break down glucose into carbon dioxide and water, releasing more energy. Anaerobic respiration occurs without oxygen, producing less energy and often resulting in lactic acid or alcohol and CO₂.
10. Q10: How do fish perform gaseous exchange?A: Fish use gills, where thin filaments and lamellae provide a large surface area for oxygen to diffuse from water into blood and carbon dioxide to diffuse out.
11. Q11: Describe the tracheal system in insects.A: The tracheal system is a network of air-filled tubes (tracheae) that open to the outside through small holes called spiracles; air reaches tissues directly without blood transport.
12. Q12: Explain how human lungs are adapted for gas exchange.A: Human lungs contain millions of alveoli, providing a huge surface area and thin walls for efficient diffusion of oxygen into blood and carbon dioxide out; rich blood supply and ventilation aid this process.
13. Q13: What is circulation? Give its primary function.A: Circulation is the movement of blood or haemolymph in an organism to transport oxygen, nutrients, hormones and wastes. Its primary function is to maintain internal homeostasis by distributing substances to and from cells.
14. Q14: Contrast open and closed circulatory systems.A: In an open system (e.g., insects), blood-like fluid bathes organs directly in body cavities. In a closed system (e.g., mammals), blood flows inside vessels, allowing more efficient transport and higher pressure.
15. Q15: What are the main components of human blood?A: Blood consists of plasma, red blood cells (carry oxygen via haemoglobin), white blood cells (defense), and platelets (help in clotting).
16. Q16: Describe the role of the heart in circulation.A: The heart pumps blood, creating pressure to circulate it through arteries, capillaries and veins; it ensures oxygenated blood reaches tissues and deoxygenated blood is carried to lungs for oxygenation.
17. Q17: What is excretion and name excretory organs in animals.A: Excretion removes metabolic waste products from the body to maintain internal balance. Excretory organs include kidneys in mammals, nephridia in earthworms, and malpighian tubules in insects.
18. Q18: Briefly explain how kidneys form urine.A: Kidneys filter blood to remove waste and excess substances; useful molecules are reabsorbed while remaining fluid becomes urine which passes to the bladder and is expelled.
19. Q19: What are malpighian tubules and their function?A: Malpighian tubules are excretory structures in insects that collect wastes from body fluids and pass them to the gut to be eliminated with feces.
20. Q20: How do earthworms respire?A: Earthworms respire through their moist skin where gases diffuse directly between the blood and the surrounding air; moisture is essential for respiration.
21. Q21: Explain the concept of homeostasis simply.A: Homeostasis is the maintenance of a stable internal environment (e.g., temperature, water balance) despite external changes, essential for proper functioning of cells and organs.
22. Q22: How does the human body respond to high body temperature?A: To cool down, blood vessels near the skin dilate and sweat glands produce sweat; evaporation of sweat removes heat, helping reduce body temperature.
23. Q23: What is a reflex action and give an example.A: A reflex action is a rapid, involuntary response to a stimulus that protects the body; for example, withdrawing a hand on touching a hot surface.
24. Q24: Describe the flow from stimulus to response in animals.A: A stimulus is detected by receptors, the signal is transmitted to the nervous system for coordination, and effectors (muscles or glands) produce the response.
25. Q25: What adaptations help birds to fly?A: Adaptations include wings, aerodynamic body shape, hollow lightweight bones, strong flight muscles and feathers for lift and control.
26. Q26: Explain how teeth reflect diet in animals.A: Herbivores have flat molars for grinding plant matter; carnivores have sharp canines and incisors for tearing flesh; omnivores have mixed dentition to process varied diets.
27. Q27: What is the role of bile in digestion?A: Bile produced by the liver emulsifies fats, increasing the surface area for digestive enzymes to act, aiding fat digestion but it does not contain digestive enzymes itself.
28. Q28: How is oxygen transported in human blood?A: Oxygen binds to haemoglobin in red blood cells, forming oxyhaemoglobin, and is transported from the lungs to body tissues by the blood.
29. Q29: Why do multicellular organisms need a circulatory system?A: Multicellular organisms have many layers of cells; diffusion alone is insufficient to transport substances quickly, so a circulatory system distributes materials efficiently to all cells.
30. Q30: Compare respiration in earthworms and fish.A: Earthworms respire through moist skin while fish use gills to extract oxygen from water; both require moist surfaces but structures differ according to habitat.
31. Q31: How does the small intestine maximize digestion and absorption?A: The small intestine has enzymes for final digestion; villi and microvilli increase surface area for efficient absorption into blood vessels and lacteals.
32. Q32: What causes indigestion and how can it be prevented?A: Indigestion can be caused by overeating, eating too fast, or fatty/spicy foods; prevention includes balanced diet, eating slowly, and regular exercise.
33. Q33: Explain how insects adapt to terrestrial life in terms of respiration and excretion.A: Insects have a tracheal system for direct air delivery and malpighian tubules to conserve water by removing wastes efficiently, adaptations for life on land.
34. Q34: What is the function of the oesophagus?A: The oesophagus transports food from the mouth to the stomach by peristaltic movements; it does not digest food itself.
35. Q35: Name two animals that show intracellular digestion.A: Amoeba and some protozoans digest food inside food vacuoles (intracellular digestion).
36. Q36: How do protozoans obtain oxygen?A: Protozoans like Amoeba obtain oxygen by simple diffusion across the cell membrane from the surrounding water.
37. Q37: Describe one way fish maintain unidirectional flow of water over gills.A: Many fish open and close their mouths and opercula (gill covers) in a coordinated way to create a steady flow of water over gill filaments for continuous gas exchange.
38. Q38: Why is water important for life processes?A: Water is a solvent for biochemical reactions, helps in transport, digestion, temperature regulation, and is essential for most metabolic processes.
39. Q39: What is the role of enzymes in digestion?A: Enzymes speed up chemical reactions that break down complex food molecules into simpler absorbable forms, e.g., proteases for proteins and amylases for starch.
40. Q40: How do lampreys or leeches differ in their method of nutrition compared to humans?A: Lampreys/leech are parasitic and feed on hosts' blood, whereas humans are omnivores consuming a variety of foods; parasitic feeding involves specialized mouthparts and anticoagulants.
41. Q41: Give a brief reason why birds have a higher metabolism than reptiles.A: Birds maintain high body temperatures for flight and activity, requiring faster metabolic rates supported by efficient respiratory and circulatory systems.
42. Q42: Explain how oxygen and nutrients reach individual cells.A: Oxygen and nutrients are carried by blood to capillaries; substances diffuse from capillaries into tissue fluid and then into cells for use.
43. Q43: What is the function of bile salts specifically?A: Bile salts emulsify fat into tiny droplets, increasing surface area for lipase enzymes to act, aiding fat digestion and absorption.
44. Q44: How is carbon dioxide removed from the body?A: Carbon dioxide produced by cells diffuses into the blood, is transported mainly as bicarbonate ions, and is expelled through the lungs during exhalation.
45. Q45: Describe one adaptation of aquatic animals for movement.A: Fish have streamlined bodies and fins that reduce resistance and generate thrust, allowing efficient swimming in water.
46. Q46: What causes muscle fatigue after vigorous exercise?A: Muscle fatigue can result from accumulation of lactic acid (from anaerobic respiration) and depletion of energy reserves, causing temporary reduced efficiency.
47. Q47: Why is maintaining blood glucose important and how is it controlled briefly?A: Stable blood glucose ensures a steady energy supply; hormones like insulin and glucagon from the pancreas regulate glucose uptake and release.
48. Q48: Give two differences between plant and animal nutrition.A: Plants synthesize food via photosynthesis (autotrophic) using sunlight, CO₂ and water; animals are heterotrophic and ingest ready-made organic compounds.
49. Q49: What practical steps can students take to study this chapter effectively?A: Draw and label diagrams, make comparison tables, use flashcards for terms, and practice short and long answer questions under timed conditions.
50. Q50: Summarize why understanding life processes is important for CBSE exams.A: Understanding life processes builds a foundation for biology, helps answer definition, diagram and explanation-based questions, and links structure to function — key for scoring in CBSE exams.

Note: Questions and answers are strictly NCERT-level for CBSE Class 7 examination standard. Use alongside the revision notes and diagrams for best results.