Question

While C-4 plants have carbon dioxide fixation and carbon dioxide uptake separated by location within the plant, CAM plants

A. have these processes separated by time.
B. fix much greater amounts of carbon dioxide than C-4 plants.
C. are found in tropical regions where nutrients are abundant.
D. All of the choices are correct.

Answer 1

CAM plants separate carbon dioxide fixation and uptake by time, conserving water by opening their stomata at night, as opposed to C-4 plants which separate these processes spatially and are more efficient in hot, dry climates.

Step-by-step explanation:

While C-4 plants have carbon dioxide fixation and uptake separated by location within the plant, CAM plants have these processes separated by time (A). This adaptation allows CAM plants to open their stomata at night to collect CO2, fix it as organic acids, and then close the stomata during the day to minimize water loss. During the daytime, the stored acids are broken down to release CO2 for the Calvin cycle and carbohydrate production. This makes CAM plants particularly well-suited to arid environments where water conservation is critical.

C-4 plants, on the other hand, are able to maintain some degree of stomatal opening for CO2 capture during the day because they have a mechanism to concentrate CO2 in specialized bundle sheath cells, making their water use and carbon fixation more efficient in hot, dry conditions compared to C3 photosynthesis.