Unit 4: Plant Physiology – MCQs (NCERT Based, Hard Level)
1. The main water-transporting elements in angiosperms are:
Vessel elements
2. Root pressure is maximum:
During early morning
3. Which element is essential for opening and closing of stomata?
Potassium
4. The Casparian strip is chemically made up of:
Suberin
5. Guttation is the loss of water in the form of:
Liquid droplets
6. Symplastic movement occurs through:
Plasmodesmata
7. C4 plants are more efficient in photosynthesis because:
They minimize photorespiration
8. Enzyme Rubisco is located in:
Chloroplast
9. First stable product of C3 cycle is:
3-PGA
10. Kranz anatomy is seen in:
C4 plants
11. The term 'photorespiration' is related to:
O2 binding to Rubisco
12. The final hydrogen acceptor in ETS is:
Oxygen
13. Which is the connecting link between glycolysis and Krebs cycle?
Acetyl CoA
14. The number of ATP molecules generated by one NADH during ETS is:
3
15. The site of Glycolysis is:
Cytoplasm
16. The site of Krebs cycle is:
Mitochondrial matrix
17. In C4 plants, CO₂ is first accepted by:
PEP
18. Which hormone is responsible for apical dominance?
Auxin
19. Vernalization is:
Induction of flowering by low temperature
20. Triple response of ethylene includes:
Inhibition of elongation, thickening of stem, and horizontal growth
21. Seed dormancy can be broken by:
Gibberellins
22. Which hormone delays senescence?
Cytokinins
23. Abscisic acid promotes:
Dormancy
24. The first gaseous plant hormone discovered is:
Ethylene
25. Phototropism is caused by:
Auxin
26. Which ion activates RuBisCO?
Mg²⁺
27. First stable compound of Hatch and Slack pathway is:
Oxaloacetic acid
28. ATP synthesis during respiration occurs by:
Chemiosmosis
29. Which hormone induces parthenocarpy?
Auxin
30. Photorespiration occurs in:
Peroxisomes, mitochondria, and chloroplasts
31. The common pathway for aerobic and anaerobic respiration is:
Glycolysis
32. The enzyme nitrogenase functions under:
Anaerobic condition
33. Essential mineral involved in stomatal movement:
Potassium
34. Passive absorption of water occurs due to:
Transpiration pull
35. Water potential of pure water is:
Zero
36. Which layer in roots prevents entry of harmful substances?
Endodermis
37. The most abundant enzyme on Earth:
Rubisco
38. The main product of oxidative phosphorylation:
ATP
39. In which organelle does photorespiration not occur?
Golgi body
40. Phloem loading involves:
Active transport
41. Which gas inhibits photosynthesis?
O₂
42. Transpiration mainly occurs through:
Stomata
43. During senescence, nutrients are:
Translocated to storage organs
44. Which plant hormone induces fruit ripening?
Ethylene
45. Respiratory quotient (RQ) for carbohydrates is:
1
46. Which element is a component of chlorophyll?
Magnesium
47. Conversion of ADP to ATP during photosynthesis is called:
Photophosphorylation
48. Translocation in phloem is:
Bidirectional
49. Gibberellins cause:
Stem elongation
50. The respiratory quotient (RQ) of fats is:
Less than 1