The alternative pathways of photosynthesis using the C₄ or CAM systems are said to be compromises. Why?
A) Each one minimizes both water loss and rate of photosynthesis.
B) C₄ compromises on water loss and CAM compromises on photorespiration.
C) Both minimize photorespiration but expend more ATP during carbon fixation.
D) CAM plants allow more water loss, while C₄ plants allow less CO₂ into the plant.
E) C₄ plants allow less water loss but CAM plants allow more water loss.

Question

Quizplus · Accepted Answer

Both C₄ and CAM photosynthesis pathways are adaptations to arid environments, designed to minimize water loss while still allowing photosynthesis to occur. However, these adaptations come at a cost of requiring more ATP to fix carbon compared to the C₃ pathway. C₄ plants achieve this by physically separating the initial CO₂ fixation and the Calvin cycle in different cell types, while CAM plants separate these processes temporally, fixing CO₂ at night and performing the Calvin cycle during the day. Both strategies reduce photorespiration but increase the energy cost of carbon fixation.

The Alternative Pathways of Photosynthesis Using the C₄ or CAM