Nutrition — Very Short Questions (1–10)

1. 1. What is photosynthesis?
   Process by which green plants make glucose and oxygen from CO₂ and H₂O using sunlight.
2. 2. Where does photosynthesis mainly occur?
   In chloroplasts of leaf mesophyll cells, especially palisade parenchyma.
3. 3. Write the overall chemical equation of photosynthesis.
   6CO₂ + 6H₂O —(light, chlorophyll)→ C₆H₁₂O₆ + 6O₂.
4. 4. Name the two main stages of photosynthesis.
   Light reactions and the Calvin cycle (dark reactions).
5. 5. What is autotrophic nutrition?
   Mode where organisms synthesise their own food (e.g., green plants via photosynthesis).
6. 6. Define heterotrophic nutrition.
   Obtaining food by consuming other organisms (animals, fungi) or their products.
7. 7. What is holozoic nutrition?
   A form of heterotrophic nutrition involving ingestion, digestion, absorption — as in animals.
8. 8. Give an example of saprophytic nutrition.
   Fungi secreting enzymes to digest dead organic matter externally (mushrooms on wood).
9. 9. What are stomata?
   Small pores on leaf surfaces for gas exchange and transpiration controlled by guard cells.
10. 10. Name two factors that affect photosynthesis.
    Light intensity, CO₂ concentration, temperature, and chlorophyll availability (any two).

Respiration — Very Short Questions (11–20)

1. 11. What is respiration (biological)?
   Oxidation of food to release energy for cellular activities.
2. 12. Distinguish breathing from cellular respiration in one line.
   Breathing is mechanical exchange of air; cellular respiration is biochemical oxidation of glucose in cells.
3. 13. Give the equation for aerobic respiration.
   C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP).
4. 14. Where does aerobic respiration occur in cells?
   Mitochondria (Krebs cycle and electron transport), glycolysis occurs in cytosol.
5. 15. What is anaerobic respiration in yeast?
   Fermentation: Glucose → ethanol + CO₂ + small amount of ATP.
6. 16. What is lactic acid fermentation?
   In muscles under low O₂: Glucose → lactic acid + small ATP.
7. 17. Name the first step of glucose breakdown.
   Glycolysis (occurs in cytoplasm producing pyruvate and ATP).
8. 18. What is ATP?
   Adenosine triphosphate — the cell’s energy currency produced during respiration.
9. 19. Which gas is used and produced in photosynthesis and respiration respectively?
   Photosynthesis uses CO₂ and produces O₂; respiration uses O₂ and produces CO₂.
10. 20. Why does breathing rate increase during exercise?
    To meet increased O₂ demand and remove excess CO₂ from tissues.

Transport — Very Short Questions (21–30)

1. 21. What is transpiration?
   Loss of water vapour from plant surfaces, mainly through stomata.
2. 22. Name the tissue that transports water in plants.
   Xylem transports water and minerals from roots to shoots.
3. 23. Which tissue transports food in plants?
   Phloem transports organic food (sugars) from leaves to other parts.
4. 24. Define translocation.
   Movement of soluble food materials (e.g., sucrose) through phloem from source to sink.
5. 25. What is root pressure?
   Upward push generated by osmotic pressure in roots contributing to xylem sap movement.
6. 26. What is double circulation?
   Separate pulmonary and systemic circuits in higher vertebrates where blood passes through heart twice per cycle.
7. 27. Name the oxygen-carrying component of blood.
   Haemoglobin in red blood cells carries oxygen.
8. 28. What is plasma?
   Liquid component of blood carrying nutrients, hormones, and waste products.
9. 29. State the function of platelets.
   Platelets help in blood clotting to prevent excessive bleeding.
10. 30. What is lymph?
    A pale fluid carrying tissue fluid, WBCs and fats; returns excess tissue fluid to blood circulation.

Excretion — Very Short Questions (31–40)

1. 31. What is excretion?
   Removal of metabolic waste products from the body to maintain homeostasis.
2. 32. What is the functional unit of the kidney?
   The nephron is the functional and structural unit of the kidney.
3. 33. Name the process by which blood is filtered in the kidney.
   Glomerular filtration at the glomerulus/Bowman’s capsule.
4. 34. Where does reabsorption of useful substances occur?
   In the renal tubules — proximal tubule, loop of Henle, distal tubule and collecting duct.
5. 35. What major nitrogenous waste do humans excrete?
   Urea is the primary nitrogenous waste excreted in urine.
6. 36. What is ultrafiltrate?
   Fluid filtered from blood in glomerulus containing water, ions, glucose and urea (no proteins/cells).
7. 37. Name two organs other than kidney involved in excretion.
   Lungs (CO₂) and skin (sweat — water and salts).
8. 38. Why is selective reabsorption important?
   It ensures useful substances (glucose, ions) are returned to blood while wastes are excreted.
9. 39. What role does ADH play in kidney function?
   Antidiuretic hormone (ADH) increases water reabsorption in collecting ducts, concentrating urine.
10. 40. Where is urine stored before excretion?
    Urine is stored in the urinary bladder before being expelled via the urethra.

Breathing & Exchange of Gases — Very Short Questions (41–45)

1. 41. What is the basic mechanism of inhalation?
   Diaphragm contracts and moves downward; rib muscles raise rib cage increasing thoracic volume and drawing air in.
2. 42. Where does gas exchange occur in human lungs?
   At the alveoli — tiny sacs with thin walls and capillary networks for diffusion.
3. 43. Why is alveolar surface suited for gas exchange?
   Large surface area, thin walls, moist lining and rich blood supply enable efficient diffusion.
4. 44. How is oxygen transported in blood?
   Mostly bound to haemoglobin in RBCs as oxyhaemoglobin; small amount dissolved in plasma.
5. 45. What causes breathing rate to change?
   Changes in blood CO₂ levels, physical activity, and metabolic demand affect breathing rate.

Application & Miscellaneous — Very Short Questions (46–50)

1. 46. Define homeostasis in one line.
   Maintenance of a stable internal environment despite external changes.
2. 47. What is the role of enzymes in digestion?
   Enzymes catalyse breakdown of complex food molecules into absorbable units (e.g., amylase, protease, lipase).
3. 48. Name a multicellular organism that shows both autotrophic and heterotrophic features.
   Some plants like insectivorous plants (e.g., Venus flytrap) photosynthesise and also trap insects.
4. 49. What is transpiration pull?
   Tension created by transpiration in leaves that helps draw water upward through xylem.
5. 50. Give one reason why exercise improves circulation.
   Exercise increases heart rate and stroke volume, enhancing blood flow and oxygen delivery to tissues.

Tip: Use these very short questions for quick daily drills — practice recalling answers aloud to boost retention before exams.