Which of the following is not a macromolecule but present in a acid-insoluble fraction?

Options

A. Nucleic acid
B. Polysaccharide
C. Lipids
D. Proteins

Answer

To solve the question "Which of the following is not a macromolecule but present in an acid-insoluble fraction?", we need to analyze the options provided and understand the characteristics of macromolecules and the acid-insoluble fraction.

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Macromolecules**: These are large molecules typically with a molecular weight greater than 800 Daltons. Examples include proteins, nucleic acids, and polysaccharides.
- **Acid-insoluble fraction**: This fraction consists of high molecular weight molecules that do not dissolve in acid.

2. **Analyze the Options**:
- **Nucleic Acids**: These are macromolecules (e.g., DNA, RNA) and have a high molecular weight. They are part of the acid-insoluble fraction.
- **Polysaccharides**: These are also macromolecules (e.g., starch, cellulose) and are included in the acid-insoluble fraction.
- **Lipids**: Lipids are unique in that they can be classified as not being true macromolecules (as their molecular weight can be less than 800 Daltons) but they are still found in the acid-insoluble fraction.
- **Proteins**: Proteins are macromolecules and are also found in the acid-insoluble fraction.

3. **Identify the Correct Answer**:
- Among the options, lipids are the only ones that are not classified as macromolecules but are present in the acid-insoluble fraction. Therefore, the correct answer is **Lipids**.

### Conclusion:
The answer to the question is **Lipids**, as they are not macromolecules but are present in the acid-insoluble fraction.