Plant Physiology MCQ:

1. Water potential is equal to___________

a) Ts + O.P

b) = T.P.

c) xl’p + Y

d) Zero

Answer: d) Zero

2. Transpiration is least in_____

a) good soil moisture

b) high wind velocity

c) dry environment

d) high atmospheric humidity.

Answer: d) high atmospheric humidity.

3. Phenyl mercuric acetate (PMA) results in_________

a) reduced photosynthesis

b) reduced transpiration

c) reduced respiration

d) killing of plants.

Answer: b) reduced transpiration 

4. Stomata open and close due to_______

a) circadian rhythm

b) genetic clock

c) pressure of gases inside the leaves

d) turgor pressure of guard cells.

Answer: d) turgor pressure of guard cells.

6. Phytochrome is involved in________

a) phototropism

b) photorespiration

c) photoperiodism

d) geotropism

Answer: c) photoperiodism 

7. Which of the following is responsible for the opening and closing of stomata in plants?

a) Chlorophyll

b) Gibberellin

c) Abscisic acid

d) Auxin

Answer: c) Abscisic acid

8. What is the primary function of auxins in plants?

a) Stimulating stem elongation

b) Promoting root growth

c) Inducing flowering

d) Enhancing photosynthesis

Answer: a) Stimulating stem elongation

9. Which of the following pigments is responsible for the red coloration of leaves in autumn?

a) Chlorophyll

b) Carotenoids

c) Anthocyanins

d) Xanthophylls

Answer: c) Anthocyanins

10. Phytohormones are________

a) chemical regulation of flowering

b) chemical regulation secondary growth

c) hormones regulating growth from seed to adulthood

d) regulators synthesized by plants and influencing physiological processes.

Answer: d) regulators synthesized by plants and influencing physiological processes.

11. Highest auxin concentration occurs__________

a) in growing tips

b) in leaves

c) at the base of plant organs

d) in the xylem and phloem.

Answer: a) in growing tips 

12. Kranz’s anatomy is typical of__________

a) C4 plants

b) C3 plants

c) C2 plants

d) CAM plants

Answer: a) C4 plants 

13. Which of the following processes involves the conversion of light energy into chemical energy in plants?

a) Transpiration

b) Respiration

c) Photosynthesis

d) Translocation

Answer: c) Photosynthesis

14. Which of the following is not a factor that affects the rate of photosynthesis in plants?

a) Temperature

b) Light intensity

c) Carbon dioxide concentration

d) Soil pH

Answer: d) Soil pH

15. Which of the following plant hormones is responsible for initiating the formation of roots in cuttings?

a) Cytokinins

b) Ethylene

c) Abscisic acid

d) Auxins

Answer: d) Auxins

16. What is the primary function of gibberellins in plants?

a) Inhibiting stem elongation

b) Promoting leaf growth

c) Promoting seed germination

d) Regulating stomatal closure

Answer: c) Promoting seed germination

17. Which of the following is a key component of the electron transport chain during photosynthesis?

a) NADP+

b) ATP

c) CO2

d) H2O

Answer: a) NADP+

18. Which of the following is responsible for transporting water and nutrients from the roots to the leaves in plants?

a) Xylem

b) Phloem

c) Stomata

d) Epidermis

Answer: a) Xylem

19. Which of the following is a plant hormone that is involved in promoting cell division and differentiation?

a) Gibberellin

b) Ethylene

c) Cytokinin

d) Abscisic acid

Answer: c) Cytokinin

20. Which of the following is the process by which plants release water vapor through stomata?

a) Osmosis

b) Transpiration

c) Respiration

d) Photosynthesis

Answer: b) Transpiration

21. Which of the following pigments is responsible for the green color of plants?

a) Chlorophyll

b) Carotenoids

c) Anthocyanins

d) Xanthophylls

Answer: a) Chlorophyll

22. Which of the following is the process by which green plants convert light energy into chemical energy?

a) Respiration

b) Photosynthesis

c) Transpiration

d) Translocation

Answer: b) Photosynthesis

23. Which of the following is the primary site of photosynthesis in a plant cell?

a) Mitochondria

b) Chloroplasts

c) Nucleus

d) Endoplasmic reticulum

Answer: b) Chloroplasts

24. Which of the following is a plant hormone that stimulates cell elongation and regulates phototropism and gravitropism?

a) Auxin

b) Gibberellin

c) Cytokinin

d) Abscisic acid

Answer: a) Auxin

25. Which of the following is the process by which plants take in carbon dioxide from the atmosphere and release oxygen?

a) Respiration

b) Photosynthesis

c) Transpiration

d) Translocation

Answer: b) Photosynthesis

26. Which plant pigments are responsible for the red, purple, and blue colors of flowers and fruits?

a) Chlorophyll

b) Carotenoids

c) Anthocyanins

d) Xanthophylls

Answer: c) Anthocyanins

27. Which of the following is a plant hormone that inhibits cell growth and promotes seed dormancy?

a) Auxin

b) Gibberellin

c) Cytokinin

d) Abscisic acid

Answer: d) Abscisic acid

28. Which of the following is the process by which plants convert glucose into energy in the presence of oxygen?

a) Respiration

b) Photosynthesis

c) Transpiration

d) Translocation

Answer: a) Respiration

29. In C3 and C4 plants, primary carboxylation takes place with the help of_________

a) PEP carboxylase and pyruvate carboxylase

b) RuBP carboxylase and PEP carboxylase

c) PEP carboxylase and RuBP carboxylase

d) RuBP carboxylase and pyruvate carboxylase

Answer: b) RuBP carboxylase and PEP carboxylase

30. The fundamental feature of Kranz Anatomy of C4 plants is_____________

a) Presence of agranal chloroplasts in bundle sheath cells and granal chloroplasts in mesophyll cells

b) Presence of granal chloroplasts in bundle sheath cells and agranal chloroplasts in mesophyll cells

c) Presence of chloroplasts in epidermal and mesophyll cells

d) Presence of agranal chloroplasts in both mesophyll and bundle sheath cells

Answer: a) Presence of agranal chloroplasts in bundle sheath cells and granal chloroplasts in mesophyll cells