Large number of RER are found in the cells actively involved in

Options

A. Lipid synthesis
B. Steroidogenesis
C. Protein synthesis
D. Starch synthesis

Answer

**Step-by-Step Solution:**

1. **Understanding RER**: The Rough Endoplasmic Reticulum (RER) is a type of endoplasmic reticulum that is studded with ribosomes on its cytoplasmic surface, giving it a "rough" appearance.

2. **Function of RER**: The primary function of the RER is to synthesize proteins. The ribosomes attached to the RER are the sites of protein synthesis, where amino acids are assembled into polypeptide chains.

3. **Analyzing the Options**:
- **Lipid Synthesis**: This is primarily the function of the Smooth Endoplasmic Reticulum (SER), not RER. Therefore, this option is incorrect.
- **Steroidogenesis**: This process also occurs in the Smooth Endoplasmic Reticulum, which is responsible for the synthesis of steroid hormones. Hence, this option is also incorrect.
- **Protein Synthesis**: This is the main function of the Rough Endoplasmic Reticulum due to the presence of ribosomes. This option is correct.
- **Starch Synthesis**: This process is not associated with RER. Starch synthesis occurs in plastids, specifically in amyloplasts in plants. Thus, this option is incorrect.

4. **Conclusion**: After evaluating all the options, the correct answer is that a large number of RER are found in cells actively involved in **protein synthesis**.

**Final Answer**: Protein synthesis (Option C).

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