Periplast of Euglena lies

Options

A. External to plasma membrane
B. Internal to plasma membrane
C. As a thickening of plasma membrane
D. On one side of the organism.

Answer

To answer the question about the location of the periplast in Euglena, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Euglena**: Euglena is a unicellular organism that has a unique structure, including a plasma membrane and a periplast.

2. **Define Periplast**: The periplast is a proteinaceous covering that provides support and shape to the Euglena. It is not a rigid cell wall but rather a flexible layer.

3. **Identify the Location of Periplast**: The periplast is located beneath the plasma membrane of Euglena. This means it is not on the outside but rather internal to the plasma membrane.

4. **Evaluate the Options**:
- Option A: External to plasma membrane - This is incorrect.
- Option B: Internal to plasma membrane - This is correct.
- Option C: As a thickening of plasma membrane - This is incorrect.
- Option D: On one side of organism - This is incorrect.

5. **Conclusion**: Based on the evaluation, the correct answer is that the periplast of Euglena lies internal to the plasma membrane.

### Final Answer:
The periplast of Euglena lies **internal to the plasma membrane** (Option B).

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