The plasma membrane of plant and animal cells

Options

A. may not be seen by any microscope
B. contains two layers of lipid between layers of protein
C. is not selectively permeable
D. can only be visualized with the aid of the electron microscope

Explanation

To answer the question regarding the plasma membrane of plant and animal cells, we will evaluate each of the four statements provided and determine which one is correct.

### Step-by-Step Solution:

1. **Evaluate the First Statement**:
- The first statement claims that the plasma membrane of plant and animal cells may not be seen by any microscope.
- **Analysis**: This statement is incorrect because the plasma membrane can indeed be observed under an electron microscope, which provides the necessary resolution to visualize its structure.
- **Conclusion**: This statement is **wrong**.

2. **Evaluate the Second Statement**:
- The second statement asserts that the plasma membrane contains two layers of lipid between layers of proteins.
- **Analysis**: This statement is also incorrect. The plasma membrane is composed of a lipid bilayer, where the lipids form two layers, and proteins are embedded within this bilayer, not between the layers of lipids.
- **Conclusion**: This statement is **wrong**.

3. **Evaluate the Third Statement**:
- The third statement claims that the plasma membrane is not selectively permeable.
- **Analysis**: This statement is incorrect. The plasma membrane is selectively permeable (or semi-permeable), meaning it allows certain molecules to pass through while restricting others.
- **Conclusion**: This statement is **wrong**.

4. **Evaluate the Fourth Statement**:
- The fourth statement states that the plasma membrane can only be visualized with the aid of an electron microscope.
- **Analysis**: This statement is correct. The plasma membrane's structure can be clearly visualized using an electron microscope, which provides a detailed view of the lipid bilayer and embedded proteins.
- **Conclusion**: This statement is **correct**.

### Final Answer:
The correct statement regarding the plasma membrane of plant and animal cells is the fourth statement: **"It can only be visualized with the aid of an electron microscope."**

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