Mg and Fe are needed for plants in the

Options

A. energy transfer
B. synthesis of chlorophyll pigment in the leaves
C. stomatal opening
D. translocation of carbohydrates .

Answer

### Step-by-Step Solution:

1. **Identify the Role of Magnesium and Iron in Plants:**
- Magnesium (Mg) and Iron (Fe) are essential nutrients for plants. They play crucial roles in various physiological processes.

2. **Understand the Importance of Chlorophyll:**
- Chlorophyll is the green pigment found in plants that is essential for photosynthesis, the process by which plants convert light energy into chemical energy.

3. **Link Magnesium and Iron to Chlorophyll Synthesis:**
- Magnesium is a key component of the chlorophyll molecule, forming the central part of its structure. Without magnesium, chlorophyll cannot be synthesized effectively.
- Iron is also important for the synthesis of chlorophyll and other pigments. It acts as a cofactor for enzymes involved in the chlorophyll synthesis pathway.

4. **Evaluate Other Options Provided:**
- **Energy Transfer:** This primarily involves ATP, which requires oxygen for its synthesis, not specifically magnesium or iron.
- **Stomatal Opening:** This process is mainly regulated by potassium ions, not magnesium or iron.
- **Translocation of Carbohydrates:** This involves boron, which is crucial for the movement of carbohydrates within the plant.

5. **Conclude with the Correct Answer:**
- Based on the roles of magnesium and iron, the correct answer is that they are needed for the **synthesis of chlorophyll pigment in the leaves**.

### Final Answer:
Magnesium and Iron are needed for plants in the **synthesis of chlorophyll pigment in the leaves**.

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