Which of the following is present in Calvin Cycle.

Options

A. Oxidative carboxylation
B. Dark phosphorylation
C. Dark respiration
D. Reductive carboxylation

Answer

To determine which of the following options is present in the Calvin Cycle, we need to analyze each option in relation to the processes that occur during the Calvin Cycle.

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**: The Calvin Cycle, also known as the C3 cycle or Benson-Calvin cycle, is a series of biochemical reactions that take place in the chloroplasts of photosynthetic organisms. It is crucial for the conversion of carbon dioxide into glucose.

2. **Identifying the Steps of the Calvin Cycle**: The Calvin Cycle consists of three main stages:
- **Carbon Fixation**: The enzyme RuBisCO catalyzes the reaction of carbon dioxide with ribulose bisphosphate (RuBP) to form 3-phosphoglycerate (3-PGA).
- **Reduction Phase**: ATP and NADPH produced in the light-dependent reactions are used to convert 3-PGA into glyceraldehyde-3-phosphate (G3P).
- **Regeneration of RuBP**: Some G3P molecules are used to regenerate RuBP, allowing the cycle to continue.

3. **Analyzing the Options**:
- **Oxidative Carboxylation**: This process is not part of the Calvin Cycle. It typically refers to the conversion of a compound into a carboxylic acid with the involvement of oxidation.
- **Dark Phosphorylation**: This term is not commonly used in the context of the Calvin Cycle. The Calvin Cycle does not directly involve phosphorylation in the dark; rather, it uses ATP generated during the light-dependent reactions.
- **Dark Respiration**: This refers to the process of cellular respiration that occurs in the absence of light and is not a part of the Calvin Cycle.
- **Reductive Carboxylation**: This is a key process in the Calvin Cycle, where carbon dioxide is fixed and reduced to form carbohydrates.

4. **Conclusion**: Based on the analysis, the correct answer is **D) Reductive Carboxylation**, as it is a fundamental part of the Calvin Cycle.