Question

Source of $C{O}_2$ for photosynthesis during day, in CAM plant is

• A. 3-PGA
• B. Malic acid
• C. Oxalo-acetic acid
• D. Pyruvate

Answer 1

The correct option is B Malic acid

Crassulacean acid metabolism is a carbon fixation pathway, that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide. The $C{O}_2$ is stored as the four-carbon acid malate, and then used during photosynthesis during the day. The pre-collected $C{O}_2$ is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency.