Fluidity/flexibiliy of a cell membrane is due to are

Options

A. lipids
B. proteins
C. water
D. oligosaccharides

Answer

### Step-by-Step Solution

1. **Understanding Cell Membrane Composition**: The cell membrane, also known as the plasma membrane, is primarily composed of a phospholipid bilayer, which includes lipids and proteins.

2. **Role of Lipids in Fluidity**: The fluidity and flexibility of the cell membrane are largely due to the presence of lipids, particularly phospholipids. These lipids can move laterally within the bilayer, allowing the membrane to be flexible.

3. **Cholesterol's Contribution**: Cholesterol, a type of lipid, is interspersed within the phospholipid bilayer. It helps to stabilize the membrane and maintain its fluidity, especially at varying temperatures.

4. **Other Components**: While proteins, water, and oligosaccharides are present in the membrane, they do not primarily contribute to the fluidity. Proteins assist in transport and signaling, water is a solvent, and oligosaccharides serve as recognition sites.

5. **Conclusion**: Therefore, the fluidity and flexibility of the cell membrane are primarily due to lipids, specifically the phospholipids and cholesterol present in the membrane.

### Final Answer
The fluidity/flexibility of a cell membrane is due to **lipids**.

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