Which one is not a function of cell coat?

Options

A. osmosis across the membrane
B. cellular recognition
C. rejection of transplanted organ
D. build immunity against the foreign cells

Answer

To determine which option is not a function of the cell coat (glycocalyx), we can analyze each option based on the known functions of the cell coat.

### Step-by-Step Solution:

1. **Understanding the Cell Coat (Glycocalyx)**:
- The cell coat, also known as glycocalyx, is an external layer found on the surface of animal cells. It is primarily composed of glycoproteins and carbohydrates.

2. **Identifying Functions of the Cell Coat**:
- The glycocalyx has several important functions:
- **Cellular Recognition**: It plays a crucial role in recognizing other cells and molecules, which is essential for immune responses and tissue formation.
- **Rejection of Transplanted Organs**: The glycocalyx helps in identifying self from non-self cells, which is vital in organ transplantation.
- **Building Immunity Against Foreign Cells**: It aids in the immune response by interacting with antibodies and antigens.

3. **Analyzing the Options**:
- **Option 1: Osmosis Across the Membrane**: Osmosis is the movement of water across a selectively permeable membrane and is primarily a function of the cell membrane (plasma membrane), not the cell coat.
- **Option 2: Cellular Recognition**: This is a known function of the glycocalyx.
- **Option 3: Rejection of Transplanted Organ**: This is also a known function of the glycocalyx.
- **Option 4: Build Immunity Against Foreign Cells**: This is another recognized function of the glycocalyx.

4. **Conclusion**:
- Among the options provided, **Option 1 (osmosis across the membrane)** is not a function of the cell coat. It is a function of the plasma membrane.

### Final Answer:
The correct answer is **Option 1: Osmosis Across the Membrane**.

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