Question

Place the stages of the Calvin cycle in the correct order of events

a. Carbon fixation
b. Regeneration of RuBP
c. Reduction and Carbohydrate production

Answer 1

The Calvin cycle includes three main stages: carbon fixation where CO2 is attached to RuBP, reduction where G3P is formed and carbohydrates are produced, and regeneration where RuBP is replenished for the cycle to continue.

Step-by-step explanation:

The Calvin cycle is an essential part of photosynthesis, specifically the light-independent reactions, and can be divided into three major stages: carbon fixation, reduction and carbohydrate production, and regeneration of RuBP. The correct order of these stages is as follows:

1. Carbon fixation - The enzyme RuBisCO incorporates CO2 into an organic molecule, 3-phosphoglycerate (3-PGA), using the molecule ribulose bisphosphate (RuBP).
2. Reduction and Carbohydrate production - 3-PGA is reduced to Glyceraldehyde-3-phosphate (G3P) using electrons supplied by NADPH. ATP is also used in this process. Eventually, some of the G3P molecules are used to form carbohydrates like glucose.
3. Regeneration of RuBP - The remaining G3P molecules are used to regenerate RuBP so the cycle can continue.

Completing these stages efficiently allows plants to synthesize glucose from carbon dioxide, using the ATP and NADPH produced in the light reactions of photosynthesis.