Which of the following is used during the discovery of Calvin ?

Options

A. Spirogyra
B. Volvox
C. Chlamydomonas
D. Chlorella

Answer

To answer the question regarding which organism was used during the discovery of the Calvin cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Calvin Cycle**: The Calvin cycle, also known as the Calvin-Benson cycle, is a crucial part of photosynthesis where carbon dioxide is converted into glucose. It was discovered by researchers including Melvin Calvin, Andrew Benson, and James Bassham.

2. **Identify the Organisms**: The question provides four options: Spirogyra, Birnbach's, Climatoma, and Chlorella. We need to determine which of these was used in the discovery of the Calvin cycle.

3. **Research the Discovery**: The researchers used a specific unicellular alga in their experiments. The key organism they used was Chlorella, which is known for its role in photosynthesis and was suitable for the experiments conducted.

4. **Use of C-14 Labeled CO2**: During their experiments, they utilized C-14 labeled carbon dioxide to trace the incorporation of carbon into organic molecules, which helped in understanding the steps of the Calvin cycle.

5. **Conclusion**: Based on the information gathered, the organism used during the discovery of the Calvin cycle is Chlorella.

### Final Answer:
The correct answer is **Chlorella**.

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