Classification of essential element is:

Options

A. A quantitative feature
B. Based on the size of minerals
C. A qualitative feature
D. Based on the size of the plant

Answer

### Step-by-Step Solution:

1. **Understanding Essential Elements**: Essential elements are nutrients that plants require for their growth and development. They are classified based on two main criteria: quantitative requirement and functional role.

2. **Classification Based on Quantitative Requirement**:
- **Macronutrients**: These are elements that plants need in large quantities. Examples include:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- Potassium (K)
- Calcium (Ca)
- Magnesium (Mg)
- **Micronutrients**: These are elements that are required in smaller amounts. Examples include:
- Iron (Fe)
- Manganese (Mn)
- Copper (Cu)
- Zinc (Zn)

3. **Classification Based on Function**:
- **Structural Elements**: These elements are integral to the structure of plant cells. Examples include:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- **Components of Energy-Related Compounds**: These elements are involved in energy transfer and storage. For example, Magnesium (Mg) is crucial for chlorophyll.
- **Enzyme Activators or Inhibitors**: Certain minerals act as activators or inhibitors for enzymes. Examples include:
- Magnesium (Mg²⁺) as an activator of Ribulose bisphosphate carboxylase/oxygenase (Rubisco)
- Zinc (Zn²⁺) as an activator of alcohol dehydrogenase
- **Maintaining Osmotic Potential**: Elements like Chlorine (Cl), Potassium (K), and Sulfate (SO₄²⁻) help maintain osmotic balance in plants.

4. **Conclusion**: The classification of essential elements is primarily based on quantitative requirement (macronutrients and micronutrients) and functional roles (structural elements, energy-related compounds, enzyme activators, and osmotic potential).