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

Options

A. `CO_(2)`
B. Water
C. Sugar
D. Pyruvic acid

Answer

**Step-by-Step Solution:**

1. **Understanding the Calvin Cycle**: The Calvin Cycle, also known as the light-independent reactions or dark reactions of photosynthesis, is a crucial part of the photosynthetic process in plants. It uses the products of the light-dependent reactions (ATP and NADPH) to convert carbon dioxide into glucose.

2. **Identifying the Discoverer**: The Calvin Cycle was discovered by Melvin Calvin, who was awarded the Nobel Prize in Chemistry for his work on the pathways of photosynthesis.

3. **Experimental Setup**: In his experiments, Melvin Calvin introduced carbon dioxide along with trace amounts of radioactive carbon-14 into an illuminated suspension of a single-celled green algae known as Chlorella pyrenoidosa.

4. **Use of Radioactive Tracer**: The use of carbon-14 as a radioactive tracer was essential in tracking the incorporation of carbon dioxide into organic compounds during the photosynthesis process.

5. **Stopping Growth and Analyzing Compounds**: Calvin stopped the growth of the algae at various stages and employed paper chromatography to isolate and identify the small quantities of radioactive compounds formed during the reactions.

6. **Conclusion**: Through these experiments, Calvin was able to elucidate the chemical reactions involved in the conversion of carbon dioxide into carbohydrates, confirming that carbon dioxide was a key component in the discovery of the Calvin Cycle.

7. **Final Answer**: From the options provided (carbon dioxide, water, sugar, pyruvic acid), the correct answer is **carbon dioxide**.

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