Final answer:
C4 plants like corn rapidly transfer malic acid from mesophyll to bundle sheath cells for efficient water use and carbon fixation under dry conditions. CAM plants such as cacti and succulents fix CO2 at night to minimize water loss, storing it as malic acid which is used during the day.
Step-by-step explanation:
Comparing C4 and CAM Plants
The strategies employed by C4 plants and CAM plants are adaptations for photosynthesis in challenging environments. In C4 plants, like corn, malic acid is rapidly transferred from mesophyll to adjacent bundle sheath cells, where CO2 is released and then fixed by Rubisco in the Calvin cycle. This allows the C4 plants to efficiently use water and fix carbon faster under high-temperature, dry conditions unlike the C3 pathway. On the other hand, CAM plants, including cacti and succulents like the jade plant, open their stomata only at night to fix CO2, thus reducing water loss during the hot daylight hours. The fixed CO2 is stored as malic acid in vacuoles and then used in the Calvin cycle during the day when the stomata are closed.
Both methods add steps prior to the traditional C3 carbon fixation pathway to minimize water loss and adapt to their specific environments. The C4 metabolism is characterized by the separation of initial CO2 fixation and the Calvin cycle in different cell types, while CAM metabolism separates these processes temporally, occurring at different times of the day.