Question

In a CAM-plant, the concentration of organic acid

• A. Increases during the day
• B. Decreases or increases during the day
• C. Increases during night
• D. Decreases during any time

Answer 1

The correct option is C Increases during night

In CAM-plants, during the night, when stomata are open, carbon dioxide enters the leaf and is fixed into oxaloacetic acid, which is then converted to malic acid. This malic acid is stored in cells during night. So, in CAM-plants, organic acids accumulate (or their concentration increases) in the dark (i.e. at night ) in vacuoles.
During the day, when the stomata are closed, carbon dioxide stored in the form of malic acid inside the cell is used to perform photosynthesis and thus, the concentration of acid, during the day decreases in the cell.