Which is not a criterion for the essentiality of a mineral?

Options

A. Direct role in metabolism
B. Requirement is specific
C. Deficiency causes hunger signs
D. Dispensable for growth

Answer

To determine which option is not a criterion for the essentiality of a mineral, we need to analyze the provided options based on the established criteria for essential minerals in plants.

### Step-by-Step Solution:

1. **Understanding Essential Minerals**: Essential minerals are those that are required by plants for their growth and development. There are specific criteria that define whether a mineral is considered essential.

2. **Criteria for Essentiality**:
- **Direct Role in Metabolism**: An essential mineral must play a direct role in the plant's metabolic processes. If a mineral is involved in crucial biochemical reactions, it is considered essential.
- **Specific Requirement**: The plant must have a specific requirement for that mineral. This means that the absence of the mineral will hinder the plant's growth or development.
- **Deficiency Symptoms**: If the deficiency of a mineral leads to specific symptoms (like chlorosis or necrosis), it indicates that the mineral is essential. These symptoms are signs of hunger in plants due to the lack of that mineral.

3. **Evaluating the Options**:
- **Option 1**: Direct role in metabolism - This is a criterion for essentiality.
- **Option 2**: Requirement is specific - This is also a criterion for essentiality.
- **Option 3**: Deficiency causes hunger signs (like chlorosis, necrosis) - This is a criterion for essentiality as well.
- **Option 4**: Dispensable growth - This implies that the mineral is not crucial for growth, which means it does not meet the criteria for essentiality.

4. **Conclusion**: The option that is not a criterion for the essentiality of a mineral is **Option 4: Dispensable growth**.

### Final Answer:
The criterion that is not essential for the essentiality of a mineral is **Dispensable growth**.

---