The carbon dioxide acceptor in Calvin cycle/ `C_(3)`- plants is

Options

A. Phosphoenol Pyruvate (PEP)
B. Ribulose 1,5-Diphosphate (RuDP)
C. Phosphoglyceric acid (PGA)
D. Ribulose monophosphate (RMP)

Explanation

To determine the carbon dioxide acceptor in the Calvin cycle (C3 plants), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Calvin Cycle**: The Calvin cycle is a series of biochemical reactions that take place in the chloroplasts of photosynthetic organisms. It is responsible for fixing carbon dioxide into organic molecules.

2. **Identify the Role of Rubisco**: The enzyme Ribulose-1,5-bisphosphate carboxylase/oxygenase (commonly known as Rubisco) plays a crucial role in the Calvin cycle. It catalyzes the reaction where carbon dioxide is added to a 5-carbon sugar.

3. **Identify the Carbon Dioxide Acceptor**: In the Calvin cycle, the first molecule that carbon dioxide combines with is Ribulose-1,5-bisphosphate (RUBP). This molecule is the carbon dioxide acceptor.

4. **Formation of the First Stable Product**: After the reaction between carbon dioxide and RUBP, the product formed is a 3-carbon compound known as phosphoglyceric acid (PGA). However, PGA is not the carbon dioxide acceptor; it is the product of the reaction.

5. **Evaluate the Options**:
- A. Phosphoenolpyruvate (PEP) - Not involved in the Calvin cycle.
- B. Ribulose 1,5-diphosphate (RUBP) - Correct, as it is the carbon dioxide acceptor.
- C. Phosphoglyceric acid (PGA) - This is the first stable product, not the acceptor.
- D. Ribulose monophosphate (RMP) - Not involved in the Calvin cycle.

6. **Conclusion**: The correct answer is option B, Ribulose 1,5-diphosphate (RUBP), as it is the carbon dioxide acceptor in the Calvin cycle of C3 plants.

### Final Answer:
The carbon dioxide acceptor in the Calvin cycle/C3 plants is Ribulose 1,5-diphosphate (RUBP).

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