Select the correct statement regarding mechanism of absorption of mineral elements :

Options

A. Initial phase involves slow uptake of ions
B. Metabolic phase involves rapid uptake of ions
C. Initial phase involves active absorption with expenditure of ATP
D. Metabolic phase may involve passive or active absorption

Answer

### Step-by-Step Solution:

1. **Understanding the Mechanism of Absorption**: The absorption of mineral elements in plants occurs in two main phases. The first phase is characterized by the uptake of ions into the outer space of the cells, while the second phase involves the uptake into the inner space.

2. **Identifying the First Phase**: In the first phase, known as the apoplast pathway, there is a rapid uptake of ions. This process occurs in the intercellular spaces and does not require energy, making it a passive process.

3. **Identifying the Second Phase**: The second phase involves the uptake of ions into the inner space of the cells. This process requires the ions to pass through ion channels and transmembrane proteins, which act as selective pores. Since this phase requires energy (ATP), it is classified as an active process.

4. **Evaluating the Given Statements**: Now, we need to evaluate the statements provided in the question:
- **Statement 1**: "Initial phase involves slow uptake of ions." - This is incorrect; the initial phase involves rapid uptake.
- **Statement 2**: "Metabolic phase involves the rapid uptake of ions." - This is also incorrect; the metabolic phase involves slow uptake.
- **Statement 3**: "Initial phase involves active absorption with expenditure of ATP." - This is incorrect; the initial phase is passive and does not require ATP.
- **Statement 4**: "Metabolic phase may involve passive or active absorption." - This statement is correct as it acknowledges that some minerals may be absorbed passively while others actively during the metabolic phase.

5. **Conclusion**: After evaluating all the statements, the correct answer is that the metabolic phase may involve passive or active absorption.

### Final Answer:
The correct statement regarding the mechanism of absorption of mineral elements is: **"Metabolic phase may involve passive or active absorption."**

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