Question

Which one of the following statements is true with respect to energy requirements of photosynthesis in C3 and C4 biochemical cycles?

• A. C3>C4
• B. C4>C3
• C. C3 = C4
• D. Energy requirement is unrelated to C3 or C4 cycle

Hint:

C4 photosynthesis requires more ATP than C3 due to the additional steps involved in fixing carbon dioxide.

Answer 1

The Correct Option is B

Step 1: Understand C3 and C4 photosynthesis.
C3 plants perform the Calvin cycle directly, whereas C4 plants first fix carbon dioxide into a four-carbon compound and then use the Calvin cycle. C4 photosynthesis is more energy-efficient under high light and temperature conditions, but it requires more energy compared to C3 photosynthesis.

Step 2: Evaluate options.
Option (A): Incorrect, as C4 plants require more energy than C3 plants.
Option (B): Correct, C4 plants have higher energy requirements compared to C3 plants due to the extra steps in carbon fixation.
Option (C): Incorrect, as C4 plants have higher energy requirements.
Option (D): Incorrect, energy requirements are related to whether the plant uses C3 or C4 photosynthesis.
Hence, the correct answer is (B).