A mineral deficiency is likely to affect older leaves more than younger leaves if:

Options

A. mineral is a micronutrient
B. mineral is very mobile within the plant
C. deficiency persists for a long period of time
D. mineral is required for chlorophyll synthesis

Answer

To solve the question "A mineral deficiency is likely to affect older leaves more than younger leaves if:", we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the Question**:
- The question is asking under what condition a mineral deficiency would impact older leaves more than younger leaves.

2. **Analyzing the Options**:
- **Option 1: Mineral is a micronutrient**:
- Micronutrients are essential but are typically required in smaller amounts. Young leaves often act as sinks for these nutrients, meaning they absorb more of them. Therefore, this option does not support the idea that older leaves are more affected.

- **Option 2: Mineral is very mobile within the plant**:
- If a mineral is mobile, it can be transported from older leaves to younger leaves when there is a deficiency. Thus, older leaves would not be as severely affected because the plant reallocates the mineral to support new growth. This option suggests that older leaves would be less affected, making it a strong candidate for the correct answer.

- **Option 3: Deficiency persists for a long period of time**:
- A prolonged deficiency would impact the overall health of the plant, but it does not specifically indicate that older leaves would be affected more than younger leaves. Both could be affected equally, so this option is not correct.

- **Option 4: Mineral is required for chlorophyll synthesis**:
- Minerals like magnesium are essential for chlorophyll production. If such a mineral is deficient, it would affect both older and younger leaves, as chlorophyll is crucial for photosynthesis in all parts of the plant. Therefore, this option does not support the idea that older leaves are more affected.

3. **Conclusion**:
- After analyzing all the options, the correct answer is **Option 2: Mineral is very mobile within the plant**. This is because mobile minerals can be redistributed to younger leaves, thus sparing them from the effects of deficiency, while older leaves suffer more.

### Final Answer:
A mineral deficiency is likely to affect older leaves more than younger leaves if the mineral is very mobile within the plant.