GRE Subject Test: Biology : Understanding Photosynthesis

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

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Example Question #11 : Understanding Photosynthesis

CAM (crassulacean acid metabolism) plants undergo __________ photosynthesis and keep their stomata __________ during the day.

Possible Answers:

C4 . . . open

reverse . . . closed

C3 . . . closed

C3 . . . open

C4 . . . closed

Correct answer:

C4 . . . closed


CAM plants utilize C4 photosynthesis and keep their stomata closed during the day. By using the enzyme PEP carboxylase, CAM plants are able to store up enough fixed carbon during the night in order to keep their stomata closed during the day. The closure of the stomata prevents the loss of water from the plant. This is especially important in hot, dry climates.

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