Which is essential for selective permeability of cell membrane.

Options

A. Zn
B. Ca
C. Mo
D. S

Answer

**Step-by-Step Solution:**

1. **Understanding Selective Permeability**: Selective permeability refers to the ability of a cell membrane to allow certain substances to pass through while blocking others. This is crucial for maintaining the internal environment of the cell.

2. **Identifying the Role of Calcium**: Among the options provided (Zinc, Calcium, Molybdenum, Sulphur), we need to identify which element plays a significant role in the structure and function of the cell membrane.

3. **Calcium's Function in Cell Membranes**: Calcium ions (Ca²⁺) are known to bind with phospholipids in the cell membrane. This binding is essential for stabilizing the lipid bilayer, which is the fundamental structure of the cell membrane.

4. **Stabilization of the Lipid Bilayer**: The stabilization provided by calcium ions contributes to the structural integrity of the cell membrane. A stable membrane is crucial for its selective permeability, as it determines how easily substances can enter or exit the cell.

5. **Conclusion**: Given that calcium plays a vital role in maintaining the structural integrity and controlling the permeability of the cell membrane, we conclude that calcium is essential for selective permeability.

6. **Final Answer**: The correct option is **B) Calcium**.

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