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) : Photorespiration does not occur in C ₄ plants. Reason (R) : C ₄ plants have a mechanism that increases the concentration of CO ₂ at the enzyme site in the bundle sheath cells. 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
A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
Step-by-step solution
Assertion (A) is correct because C ₄ plants lack photorespiration. Reason (R) is correct and explains the assertion. In C ₄ plants, the C ₄ acid from the mesophyll is broken down in the bundle sheath cells to release CO ₂ . This increases the intracellular concentration of CO ₂ at the enzyme site, ensuring that RuBisCO functions primarily as a carboxylase, thereby minimising its oxygenase activity and preventing photorespiration. Therefore, both (A) and (R) are correct and (R) is the correct explanation of (A). Ans