Q. Membrane thickness of E.R. is

Options

A. a) `75 Ã…`
B. b) `90 Ã…`
C. c) `50-60 Ã…`
D. d) `30-40 Ã…`

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of Endoplasmic Reticulum (E.R.):**
- The endoplasmic reticulum is a complex network of flattened membrane-enclosed sacs or tube-like structures found throughout the cytoplasm of a cell.

2. **Membrane Characteristics:**
- The endoplasmic reticulum is characterized by its unit membrane, which is a single membrane that encloses the sacs (cisternae), vesicles, and tubules.

3. **Determining Membrane Thickness:**
- The thickness of the membrane of the endoplasmic reticulum is a specific measurement that can be found in biological literature.
- It is known that the membrane thickness of the endoplasmic reticulum typically ranges between 50 to 60 Ångströms (Å).

4. **Identifying the Correct Option:**
- Given the options:
- A) 75 Å
- B) 90 Å
- C) 50 to 60 Å
- D) 30 to 40 Å
- The correct answer based on the known thickness of the endoplasmic reticulum membrane is option C: 50 to 60 Å.

5. **Final Conclusion:**
- Therefore, the membrane thickness of the endoplasmic reticulum is 50 to 60 Ångströms.