What is the number of ATP utilized during regeneration of 3 molecules of RUBP from 5 molecules of G-3P?

Options

A. six
B. tweleve
C. three
D. five

Answer

To solve the question regarding the number of ATP molecules utilized during the regeneration of 3 molecules of RuBP from 5 molecules of G3P, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**: The process of regeneration of RuBP (Ribulose bisphosphate) occurs in the Calvin cycle, which is also known as the C3 cycle. This cycle involves several steps, including carboxylation, reduction, and regeneration.

2. **Identifying the Inputs**: In the Calvin cycle, 5 molecules of G3P (glyceraldehyde-3-phosphate) are produced for every 3 molecules of RuBP that are regenerated.

3. **ATP Utilization in Regeneration**: During the regeneration phase of the Calvin cycle, ATP is utilized to convert G3P back into RuBP. Specifically, for every molecule of G3P that is converted back into RuBP, 1 ATP molecule is consumed.

4. **Calculating ATP for 3 RuBP**: Since we need to regenerate 3 molecules of RuBP, we need to determine how many G3P molecules are required. From the stoichiometry of the Calvin cycle, we know that to regenerate 3 RuBP, 5 G3P molecules are needed.

5. **Total ATP Calculation**: Each G3P requires 1 ATP for regeneration. Therefore, for 5 G3P molecules, the total ATP utilized will be:
\[ \text{Total ATP} = 5 \text{ G3P} \times 1 \text{ ATP/G3P} = 5 \text{ ATP} \]

6. **Final Answer**: The number of ATP utilized during the regeneration of 3 molecules of RuBP from 5 molecules of G3P is **5 ATP**.