The special arrangement of the lipids in the cell membrane ensures that the

Options

A. polar tail of saturated hydrocarbons is protected from the aqueous environment.
B. non-polar tail of unsaturated hydrocarbons is protected from the aqueous environment.
C. polar tail of unsaturated hydrocarbons is protected from the aqueous environment.
D. non-polar tail of saturated hydrocarbons is protected from the aqueous environment.

Answer

To solve the question regarding the special arrangement of lipids in the cell membrane, we can break it down step by step.

### Step-by-Step Solution:

1. **Understanding the Cell Membrane Structure**:
- The cell membrane, also known as the plasma membrane, is primarily composed of lipids, proteins, and carbohydrates. The most significant lipids in this structure are phospholipids.

2. **Phospholipid Bilayer**:
- Phospholipids consist of two main parts: a hydrophilic (water-attracting) "head" and two hydrophobic (water-repelling) "tails". In an aqueous environment, these phospholipids arrange themselves into a bilayer.

3. **Orientation of Phospholipids**:
- In the bilayer, the hydrophilic heads face outward towards the aqueous environment (both inside and outside the cell), while the hydrophobic tails are oriented inward, away from the water. This arrangement protects the hydrophobic tails from the aqueous environment.

4. **Identifying the Correct Answer**:
- The question presents four options regarding which part of the lipid is protected from the aqueous environment:
1. Polar tail of saturated hydrocarbon
2. Non-polar tail of unsaturated hydrocarbon
3. Polar tail of unsaturated hydrocarbon
4. Non-polar tail of saturated hydrocarbon
- Given the arrangement of the phospholipid bilayer, the correct statement is that the **non-polar tail of unsaturated hydrocarbon is protected from the aqueous environment**.

5. **Conclusion**:
- Therefore, the special arrangement of lipids in the cell membrane ensures that the non-polar tails (which are hydrophobic) are shielded from water, allowing the cell membrane to maintain its integrity and function.