Select out the odd one with respect to discovery of plant growth regulators ?

Options

A. Coleoptile of oat – Auxin
B. Bakane disease – GA
C. Yeast extract – cytokinin
D. Ripened Grapes – Ethylene

Answer

To solve the question of selecting the odd one out with respect to the discovery of plant growth regulators, we will analyze each option provided.

### Step-by-Step Solution:

1. **Option 1: Choleoptile of Oat leads to the discovery of Auxin.**
- The choleoptile, which is the protective sheath covering the emerging shoot of a seedling, has been studied extensively. It was found that when light is shone on one side, the plant bends towards the light due to the elongation of cells on the shaded side, a phenomenon attributed to the plant growth regulator Auxin.
- **Conclusion:** This is a correct match.

2. **Option 2: Bacillus cereus leads to the discovery of Gibberellins.**
- Gibberellins were discovered through research on the Bakanae disease of rice, which is caused by the fungus Gibberella fujikuroi. The fungus produces gibberellins that affect the growth of rice seedlings.
- **Conclusion:** This is also a correct match.

3. **Option 3: Yeast extract leads to the discovery of Cytokinins.**
- Cytokinins were discovered from the study of yeast extracts, which showed that they promote cell division and growth in plants. This discovery was significant in understanding plant growth regulators.
- **Conclusion:** This is a correct match.

4. **Option 4: Ripened grapes lead to the discovery of Ethylene.**
- Ethylene is a plant hormone that is produced by ripening fruits, including grapes. However, the statement implies that ripened grapes directly led to the discovery of ethylene, which is misleading. Ethylene was identified as a plant hormone due to various studies, not solely from ripened grapes.
- **Conclusion:** This is the odd one out.

### Final Answer:
The odd one with respect to the discovery of plant growth regulators is **Option 4: Ripened grapes lead to the discovery of Ethylene.**

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