Compared to C₃ plants, C₄ plants
A) can continue to fix CO₂ even at relatively low CO₂ concentrations and high oxygen concentrations.
B) have higher rates of photorespiration.
C) do not use rubisco for carbon fixation.
D) grow better under cool, moist conditions.
E) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.

Question

Quizplus · Accepted Answer

C₄ plants can continue to fix CO₂ efficiently even when CO₂ concentrations are low and oxygen concentrations are high, due to their specialized anatomy and the enzyme PEP carboxylase, which has a higher affinity for CO₂ and does not bind oxygen. This adaptation reduces photorespiration, allowing C₄ plants to photosynthesize more efficiently under these conditions compared to C₃ plants.

Compared to C₃ Plants, C₄ Plants