Final answer:
The assertion that malate is used in the Calvin Cycle instead of PGA is false; in reality, the main molecule used is PGA, which eventually converts into G3P and regenerates RuBP within the cycle.
Step-by-step explanation:
The statement that malate is used in the Calvin Cycle instead of PGA is FALSE. In the Calvin Cycle, the molecule that is primarily used and regenerated is 3-phosphoglycerate (PGA), not malate. The Calvin Cycle begins with carbon fixation, where CO₂ is attached to a five-carbon sugar called ribulose bisphosphate (RuBP), resulting in a six-carbon compound that quickly splits into two molecules of 3-PGA. These PGA molecules are then reduced to glyceraldehyde-3-phosphate (G3P) using ATP and NADPH produced during the light-dependent reactions of photosynthesis. One of the G3P molecules exits the cycle and can contribute to the formation of glucose, while the remaining G3P molecules are used to regenerate RuBP, thus allowing the cycle to continue processing new molecules of CO₂.