Which of the following is indispensable in all culture

Options

A. Gibberellin `(GA_3)`
B. Kinetin
C. Ethylene
D. ABA

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which substance is indispensable in all cultures. This refers to plant tissue cultures, which are methods used to grow plants in a controlled environment.

2. **Identifying the Options**: The options provided are:
- A) Gibberellin
- B) Kinetin
- C) Ethylene
- D) ABA (Abscisic Acid)

3. **Analyzing Each Option**:
- **Gibberellin**: This hormone is involved in promoting stem elongation, seed germination, and flowering, but it is not essential for all types of plant cultures.
- **Kinetin**: This is a type of cytokinin, a plant hormone that promotes cell division and is crucial in tissue culture for stimulating cell multiplication. It is particularly important in callus culture, where it helps in the formation of new plant tissues.
- **Ethylene**: This hormone is primarily involved in fruit ripening and is not necessary for all cultures.
- **ABA (Abscisic Acid)**: This hormone plays a role in stress responses and inhibiting growth, but it is not a requirement for all cultures.

4. **Conclusion**: Based on the analysis, Kinetin is the hormone that is indispensable in all cultures, especially in promoting cell division in tissue cultures.

5. **Final Answer**: The correct option is **B) Kinetin**.

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