Question

Assertion: The efficiency of C₄ plant is more than those of C₃ plant.
Reason: C₄ plants are more efficient in picking CO₂.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (A)

The efficiency of C₄ plants is more than those of C₃ plants because (i) C₄ plants are more efficient in picking up CO₂ even when it is found in low concentration because of the high affinity of PEP, (ii) concentric arrangement of mesophyll cells produces a smaller area in relation to volume for better utilization of available water and reduce the intensity of solar radiations, (iii) they can tolerate excess salts because of the presence of organic acids, (iv) normal oxygen concentration is not inhibitory for the growth in contrast to C₃ plants, (v) they are adapted to high temperature and intense radiation of tropics.