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 sugarcane, the first stable product of CO2 fixation is a 4-carbon compound. Reason (R): Phosphoenol pyruvate (a 3-carbon compound) acts as the primary CO2 acceptor in the mesophyll 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
Sugarcane is a C4 plant. In the mesophyll cells of C4 plants, the primary CO2 acceptor is Phosphoenol pyruvate (PEP), which is a 3-carbon compound. The enzyme PEP carboxylase (PEPcase) catalyzes the addition of CO2 to PEP, forming the 4-carbon compound Oxaloacetic acid (OAA) as the first stable product. The 3-carbon acceptor combining with 1 carbon from CO2 mathematically explains why the first stable product is a 4-carbon compound. Thus, both Assertion and Reason are correct, and the Reason correctly explains the