Select the incorrect statement regarding the plasma membrane.

Options

A. Ratio of proteins and lipids varies considerably in different cell types.
B. 52 % proteins and 40 % lipids constitute the membrane of human RBC.
C. Arrangement of proteins (P) and Lipids (L) is L-P-P-L.
D. Head of lipid is hydrophilic.

Explanation

To solve the question regarding the incorrect statement about the plasma membrane, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Plasma Membrane**:
- The plasma membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipids. Each phospholipid has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.

2. **Identify the Components**:
- In the phospholipid bilayer, the hydrophilic heads face outward towards the aqueous environment, while the hydrophobic tails face inward, away from water. Proteins are interspersed within this bilayer.

3. **Analyze Each Statement**:
- The question provides several statements about the plasma membrane. We need to evaluate each one to determine which is incorrect.

4. **Evaluate the Statements**:
- **Statement 1**: "The ratio of proteins and lipids vary considerably in different cell types."
- This statement is correct. Different cell types have varying compositions of proteins and lipids.
- **Statement 2**: "The arrangement of proteins is such that they are on the inner side of the membrane."
- This statement is incorrect. Proteins are found on both the inner and outer sides of the membrane, but they are not exclusively on the inner side.
- **Statement 3**: "The head of the lipid is hydrophilic."
- This statement is correct. The heads of phospholipids are indeed hydrophilic.
- **Statement 4**: "The tails of the lipid are hydrophobic."
- This statement is also correct. The tails are hydrophobic.

5. **Conclusion**:
- Based on the evaluation, the incorrect statement is the one regarding the arrangement of proteins, which is Statement 2. Therefore, the answer to the question is that Statement 2 is incorrect.

### Final Answer:
The incorrect statement regarding the plasma membrane is: "The arrangement of proteins is such that they are on the inner side of the membrane."

---