RER is well developed in cells engaged in the synthesis of
(a) Nucleotides
(b) Proteins
(c) Lipids
(d) Secretory products

Options

A. Nucleotides
B. Proteins
C. Lipids
D. Secretory products

Answer

To solve the question regarding the rough endoplasmic reticulum (RER) and its development in cells engaged in synthesis, follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure**: Recognize that RER stands for Rough Endoplasmic Reticulum. It is called "rough" because its surface is studded with ribosomes, which are the sites of protein synthesis.

2. **Identify the Function of RER**: The primary function of the RER is to synthesize proteins. The ribosomes attached to the RER translate mRNA into polypeptide chains, which then fold into functional proteins.

3. **Analyze the Options**:
- (a) Nucleotides: These are the building blocks of nucleic acids and are not primarily synthesized by the RER.
- (b) Proteins: This is the main function of the RER, as it is directly involved in protein synthesis.
- (c) Lipids: Lipids are primarily synthesized in the smooth endoplasmic reticulum (SER), not RER.
- (d) Secretory products: While secretory products can include proteins, the term is broader and does not specifically indicate protein synthesis.

4. **Select the Correct Answer**: Based on the analysis, the RER is well developed in cells engaged in the synthesis of proteins. Therefore, the correct answer is (b) Proteins.

### Final Answer:
(b) Proteins

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