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

Answer: (C)

open during the night and close during the day

Answer 2

In CAM plants-dark acidification occurs i.e., during night malic acid in formed. They have scotoactive stomata which open during night and close during day. At night $CO_2$ combines with OAA to form malic acid. During day $CO_2$ is released from malic acid and is used in $C_3$ cycle.