NEETBotanyPhotosynthesis in Higher Plants
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In C₄ plants, photorespiration does not occur. Reason (R): The breakdown of C₄ acids in the mesophyll cells releases CO₂ , increasing its intracellular concentration at the enzyme site. In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
Assertion (A) is correct. In C₄ plants, photorespiration does not occur because they possess a mechanism that increases the concentration of CO₂ at the enzyme site. Reason (R) is incorrect. The increase in CO₂ concentration takes place when the C₄ acid (such as malic acid or aspartic acid) from the mesophyll is broken down in the bundle sheath cells, not in the mesophyll cells. This release of CO₂ in the bundle sheath cells ensures that RuBisCO functions primarily as a carboxylase, thereby minimizing its oxygenase