Stomata of CAM plants
- are always open
- open during the day and close at night
- open during the night and close during the day
- never open.
Answer
(3) open during the night and close during the day
Solution
CAM (Crassulacean Acid Metabolism) plants such as pineapple and Opuntia grow in dry habitats.
To reduce water loss, their stomata open at night, when CO2 is taken in and fixed by PEP carboxylase into malic acid stored in vacuoles.
During the day the stomata remain closed, and the malic acid releases CO2 for the Calvin cycle.
∴ Stomata open during the night and close during the day (scotoactive stomata).
Answer: (3)