Question

Which of the following statements about C4 carbon fixation is not true?
a. C4 carbon fixation is an adaptation for plants exposed to high light intensity.
b. C4 carbon fixation occurs in more plants than C3 carbon fixation.
c. C4 carbon fixation is more common in areas of high temperatures than C3 carbon fixation.
d. C4 carbon fixation occurs in the inner cells of a leaf rather than the entire leaf.

Answer 1

Since C4 plants have a competitive advantage over plants possessing the more common C3 carbon fixation pathway under conditions of drought, high temperatures, and nitrogen or CO2 limitation and C3's photosynthetic efficiency  suffers during hot dry season because of photorespiration, the answer is more likely letter a. C4 carbon fixation is an adaptation for plants exposed to high light intensity.

Answer 2

The correct answer should be a. C4 carbon fixation is an adaptation for plants exposed to high light intensity.

It is not true because it is not an adaptation. C3 are the ones who need adapting during high light intensity and drought, C4 don't.