Zinc is essential for :

Options

A. Biosynthesis of chlorophylls
B. Biosynthesis of 3-IAA
C. Stomatal closing
D. Oxidation of carbohydrates

Answer

To solve the question "Zinc is essential for:", we will analyze each option provided and determine the role of zinc in relation to each function.

### Step-by-Step Solution:

1. **Understanding the Role of Zinc**:
- Zinc is an essential micronutrient that plays a crucial role in various biological processes, particularly in plants.

2. **Analyzing Each Option**:
- **Option A: Biosynthesis of Chlorophylls**:
- Chlorophyll synthesis primarily requires magnesium, not zinc. Therefore, this option is incorrect.

- **Option B: Biosynthesis of 3 IAA (Indole Acetic Acid)**:
- Indole Acetic Acid (IAA) is a type of auxin, which is a plant hormone. The synthesis of IAA involves several enzymes, and zinc acts as a cofactor for these enzymes. Thus, this option is correct.

- **Option C: Stomatal Closing**:
- The process of stomatal closing is mainly regulated by potassium ions. Zinc does not play a significant role in this process, making this option incorrect.

- **Option D: Oxidation of Carbohydrates**:
- The oxidation of carbohydrates is generally associated with magnesium. Zinc is not primarily involved in this process, so this option is also incorrect.

3. **Conclusion**:
- After analyzing all the options, the correct answer is that zinc is essential for the **biosynthesis of 3 IAA (Indole Acetic Acid)**.

### Final Answer:
Zinc is essential for the biosynthesis of 3 IAA (Indole Acetic Acid).

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