Question

CAM plants do not show photorespiration as they

• A. Keep stomata closed during day time
• B. Use PEP carboxylase
• C. Fix $C{O}_2$ into organic acid during the night and release $C{O}_2$ during the day
• D. Perform Calvin cycle at night

Answer 1

Answer: (B)

Use PEP carboxylase

A) CAM plants have scotoactive stomata that fix carbon dioxide at night and form sugars during the day. They are closed during the day and are open at night, but this does not play a role in photorespiration.
B) Photorespiration does not occur in CAM plants because they use PEP Carboxylase instead of RUBISCO for the absorption of carbon dioxide.

C) CAM plants fix carbon dioxide during the dark and synthesis of organic acids from it. But this does not prevent photorespiration.

D) CAM plants perform Calvin cycle at night but this does not prevent photorespiration.
So the correct answer is 'Use PEP carboxylase'.