Question

In which of the following plants is there phosphoenol pyruvate receptor of CO2?

• A. C-3
• B. C-4
• C. C-6
• D. All of these

Hint:

C-4 plants use phosphoenol pyruvate as a CO2 receptor, making them more efficient in hot and dry environments.

Answer 1

The Correct Option is B

Step 1: Understand CO2 fixation pathways.
Plants fix CO2 in two main ways: C-3 and C-4 pathways. In C-4 plants, CO2 is first fixed into a 4-carbon compound, using phosphoenol pyruvate (PEP) as a receptor.
Step 2: Review the options.
- C-3 plants fix CO2 directly into a 3-carbon compound via the Calvin cycle, and they do not have phosphoenol pyruvate as a CO2 receptor.
- C-4 plants, like maize and sugarcane, have phosphoenol pyruvate as a CO2 receptor during the initial steps of photosynthesis.
- C-6 plants are not a recognized category for CO2 fixation.
- Option (D) is incorrect because only C-4 plants use PEP for CO2 fixation.
Step 3: Conclude.
C-4 plants are the ones that use phosphoenol pyruvate as a CO2 receptor, making option (B) the correct answer.
Final Answer: \[ \boxed{\text{C-4}} \]