Smooth E.R. of animal cell does not synthesize :–

Options

A. Cholesterol
B. Phospholipid
C. Saturated fatty acid
D. Unsaturated fatty acid

Answer

To answer the question "Smooth E.R. of animal cell does not synthesize:", we will analyze the options provided and determine which substance is not synthesized by the smooth endoplasmic reticulum (E.R.) in animal cells.

### Step-by-Step Solution:

1. **Understand the Function of Smooth E.R.:**
- The smooth endoplasmic reticulum is primarily involved in the synthesis of lipids, including phospholipids and steroids. It also plays a role in carbohydrate metabolism and detoxification processes.

2. **Evaluate the Options:**
- **Option 1: Cholesterol**
- The smooth E.R. synthesizes cholesterol, so this option is incorrect.
- **Option 2: Phospholipid**
- The smooth E.R. is responsible for synthesizing phospholipids, making this option also incorrect.
- **Option 3: Saturated Fatty Acid**
- The smooth E.R. can synthesize saturated fatty acids, so this option is incorrect as well.
- **Option 4: Unsaturated Fatty Acid**
- The smooth E.R. does not synthesize unsaturated fatty acids. Therefore, this option is correct.

3. **Conclusion:**
- The smooth endoplasmic reticulum of the animal cell does not synthesize unsaturated fatty acids.

### Final Answer:
The smooth E.R. of animal cell does not synthesize: **Unsaturated Fatty Acid (Option 4)**.

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