Why are C4 plants able to photosynthesise with no apparent photorespiration?
A) They do not participate in the Calvin cycle.
B) They use PEP carboxylase to initially fix CO₂.
C) They conserve water more efficiently.
D) They exclude oxygen from their tissues.

Question

Quizplus · Accepted Answer

C4 plants use PEP carboxylase to initially fix CO2, which results in the formation of a four-carbon compound. This compound is then transported to specialized cells in which it is decarboxylated, releasing CO2 for use in the Calvin cycle. The CO2 is thus concentrated in the vicinity of the Calvin cycle enzymes, which reduces the likelihood of oxygen inhibiting this cycle and causing photorespiration.

Why Are C4 Plants Able to Photosynthesise with No Apparent