Crassulacean acid metabolism (CAM) refers to which type of photosynthesis?

• A. A form of photosynthesis adapted to wet environments.
• B. A form of photosynthesis adapted to dry environments.
• C. A type of cellular respiration.
• D. The production of chlorophyll.

Answer: (B)

CAM is a photosynthetic strategy that helps plants survive in dry environments by saving water. In CAM, the plant opens its stomata at night when it's cooler and more humid, taking in carbon dioxide and fixing it into organic acids that are stored in vacuoles. Then, during the day, the stomata stay closed to limit water loss, and the CO2 is released from those stored acids to fuel the Calvin cycle for photosynthesis. This separation of gas exchange from the daytime, and the storage of carbon in acids, makes CAM well-suited for arid conditions. It’s not about cellular respiration or producing chlorophyll.