Which of the following statements is incorrect ?

Options

A. Prions consist of abnormally folded protein
B. Viroids lack a protein coat.
C. Viruses are obligate parasites
D. Infective constituent in viruses is the protein coat.

Answer

To determine which statement is incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze the First Statement**:
- **Statement**: "Pyrons consist of abnormally folded proteins."
- **Analysis**: This statement is correct. Pyrons are indeed misfolded proteins that cause neurological diseases, such as Mad Cow Disease.

2. **Analyze the Second Statement**:
- **Statement**: "Viroids lack a protein coat."
- **Analysis**: This statement is also correct. Viroids are infectious agents that consist of small, circular RNA and do not have a protein coat, distinguishing them from viruses.

3. **Analyze the Third Statement**:
- **Statement**: "Viruses are obligate parasites."
- **Analysis**: This statement is correct as well. Viruses cannot replicate on their own and must infect a host cell to reproduce, making them obligate parasites.

4. **Analyze the Fourth Statement**:
- **Statement**: "Infective constituent in viruses is the protein coat."
- **Analysis**: This statement is incorrect. The infective constituent of viruses is their genetic material (either RNA or DNA), while the protein coat serves to protect this genetic material.

### Conclusion:
Based on the analysis, the incorrect statement is the fourth one: "Infective constituent in viruses is the protein coat."

### Final Answer:
The incorrect statement is: **"Infective constituent in viruses is the protein coat."**

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