The organism/s used in discovering Calvin's cycle was/were

Options

A. Chlorella
B. chlorella and volvox
C. chlorella and chlamydomonas
D. Chlorella and Scenedesmus

Answer

To answer the question regarding the organisms used in discovering Calvin's cycle, let's break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Calvin's Cycle**: The Calvin cycle, also known as the dark reaction of photosynthesis, was discovered by Melvin Calvin and his colleague Andrew Benson. This cycle is crucial for the process of photosynthesis, where carbon dioxide is fixed into sugars.

2. **Identifying the Organisms**: The question asks for the specific organisms used in the discovery of the Calvin cycle. Melvin Calvin conducted his experiments primarily using certain types of green algae.

3. **Key Organisms Used**: The two main organisms that were used by Melvin Calvin in his research were:
- **Chlorella**: A type of green algae that is unicellular and widely studied for its photosynthetic capabilities.
- **Scenedesmus**: Another type of green algae that is also used in studies related to photosynthesis.

4. **Role of Radioactive Carbon**: To trace the process of carbon fixation in the Calvin cycle, Calvin and Benson used radioactive carbon (specifically carbon-14). This helped them understand how carbon dioxide is converted into organic compounds during photosynthesis.

5. **Conclusion**: Therefore, the organisms used in discovering the Calvin cycle were **Chlorella and Scenedesmus**.

### Final Answer:
The organisms used in discovering Calvin's cycle were **Chlorella and Scenedesmus**.

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