Question

Stomata of CAM plants

• A. Are always open
• B. Open during the day and close at night
• C. Open during the night and close during the day
• D. Never open

Answer 1

The correct option is C Open during the night and close during the day

CAM plants are generally xerophytes, growing in deserts. They open their stomata during night and fix atmospheric carbon into organic acids, like oxaloacetic acid and malic acid. These organic acids are generally four carbon atom containing compounds.

During daytime the organic acids are decarboxylated to release carbon dioxide, which is fixed through RuBisCo and usual Calvin cycle. The opening of stomata during night time is a physiological adaptation to prevent loss of water through transpiration.