AP BIOLOGY

Detailed explanation-1: -Carbon dioxide enters the cycle and is fixed by Rubisco to a 5-carbon sugar called ribulose biphosphate (RuBP), which is immediately broken down to form two 3-carbon molecules of phosphoglycerate (PGA).

Detailed explanation-2: -The fixation of CO2 by Rubisco to the acceptor molecule RuBP initiates the cycle with the production of two molecules of PGA. The subsequent, enzyme catalysed, generation of cycle intermediates are cycled to either regenerate RuBP or produce triose phosphates which are precursors for carbohydrate synthesis.

Detailed explanation-3: -In the first stage of the Calvin cycle, the light-independent reactions are initiated and carbon dioxide is fixed. In the second stage of the C3 cycle, ATP and NADPH reduce 3PGA to G3P. ATP and NADPH are then converted into ATP and NADP+. In the last stage, RuBP is regenerated.

Detailed explanation-4: -Complete answer: The compound Erythrose-4-phosphate is the four-carbon molecule which is formed in the Calvin cycle.

Detailed explanation-5: -In the Calvin-Benson cycle, RuBP is a product of the phosphorylation of ribulose-5-phosphate (produced by glyceraldehyde 3-phosphate) by ATP.