Multiple Choice
Which of the following best describes what occurs during the regeneration stage of the Calvin cycle?
7
views
9. Photosynthesis
Calvin Cycle
Struggling with General Biology?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
In the Calvin cycle, how many ATP molecules are required to regenerate ribulose-1,5-bisphosphate (RuBP) from five molecules of glyceraldehyde-3-phosphate (G3P)?
A
9 ATP molecules
B
6 ATP molecules
C
3 ATP molecules
D
5 ATP molecules
Verified step by step guidance1
Understand the context: The Calvin cycle is a series of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. It uses ATP and NADPH to convert carbon dioxide into glucose. One key step in the cycle is the regeneration of ribulose-1,5-bisphosphate (RuBP), which is essential for the cycle to continue.
Recall the relationship between glyceraldehyde-3-phosphate (G3P) and RuBP: For every three CO₂ molecules fixed, the Calvin cycle produces six molecules of G3P. Five of these G3P molecules are used to regenerate three molecules of RuBP, while the sixth G3P molecule can be used to form glucose or other carbohydrates.
Focus on the regeneration step: The regeneration of RuBP from G3P requires energy in the form of ATP. Specifically, the conversion of five molecules of G3P into three molecules of RuBP involves phosphorylation reactions that consume ATP.
Determine the ATP requirement: Each molecule of RuBP requires one ATP molecule for its regeneration. Since three molecules of RuBP are regenerated from five molecules of G3P, a total of 3 ATP molecules are required for this step.
Summarize the process: To regenerate RuBP from five molecules of G3P, the Calvin cycle consumes 3 ATP molecules. This step is crucial for maintaining the cycle and ensuring the continuous fixation of carbon dioxide.
Related Videos
Related Practice
