AP BIOLOGY

Detailed explanation-1: -In aquatic plants, the CAM pathway occurs due to scarcity of CO2. Carbon dioxide supply is limited due to slower diffusion in water. Aquatic CAM plants absorb CO2 at night when there is less competition from other photosynthetic plants.

Detailed explanation-2: -CAM plants are known for their capacity to fix carbon dioxide at night, using PEP carboxylase as the primary carboxylating enzyme and the accumulation of malate (which is made by the enzyme malate dehydrogenase) in the large vacuoles of their cells.

Detailed explanation-3: -CAM plants have a different leaf anatomy from C3 plants, and fix the CO2 at night, when their stomata are open. CAM plants store the CO2 mostly in the form of malic acid via carboxylation of phosphoenolpyruvate to oxaloacetate, which is then reduced to malate.

Detailed explanation-4: -In CAM plants, carbon dioxide is only gathered at night, when the stomata open. Click for more detail. During the day, the malic acid is converted back to carbon dioxide. With the sun shining, the light reactions can create energy for the Calvin cycle and the carbon dioxide can be converted into sugars.

Detailed explanation-5: -The majority of CAM plants are found in hot, dry, very arid regions with little water. CAM plants undergo photosynthesis. Therefore, the stomata of such plants only open at night and remain closed throughout the day in order to prevent excessive water loss through transpiration.