Which of the following is not a criterion for an essential nutrient?

Options

A. It is required for growth and reproduction
B. Form large molecules in plants
C. No other element can replace it
D. it is required for a specific structure or metabolic function

Answer

To determine which of the following is not a criterion for an essential nutrient, let's analyze each option step by step:

1. **Option 1: It is required for growth and reproduction.**
- Essential nutrients are indeed required for the growth and reproduction of plants. This is a valid criterion for an essential nutrient.

2. **Option 2: Form large molecules in plants.**
- This statement is incorrect. While some essential nutrients may be part of large molecules, it is not a requirement for all essential nutrients. For instance, manganese is an essential nutrient that plays a critical role in photosynthesis but does not form large molecules. Therefore, this option does not qualify as a criterion for an essential nutrient.

3. **Option 3: No other element can replace it.**
- This is a correct criterion. Essential nutrients cannot be substituted by other elements. Each essential nutrient has a specific role that cannot be fulfilled by any other element.

4. **Option 4: It is required for a specific structure or metabolic function.**
- This is also a valid criterion. Essential nutrients often have specific roles in metabolic processes or structural functions within the plant. For example, manganese is specifically required for splitting water during photosynthesis.

**Conclusion:**
Based on the analysis, the option that is not a criterion for an essential nutrient is **Option 2: Form large molecules in plants.**

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