Which of the following statements is incorrect?

Options

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

Answer

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

### Step-by-Step Solution:

1. **Analyze Statement A**:
- **Statement**: "Viroids have a protein coat."
- **Explanation**: Viroids are known to be infectious agents that consist solely of a short strand of RNA and do not have a protein coat. Therefore, this statement is correct in saying that viroids do not have a protein coat.

2. **Analyze Statement B**:
- **Statement**: "Viruses are obligate parasites."
- **Explanation**: This statement is true. Viruses can only reproduce inside a host cell, making them obligate parasites. They require a host to complete their life cycle.

3. **Analyze Statement C**:
- **Statement**: "The infective constituent in viruses is the protein coat."
- **Explanation**: This statement is incorrect. The infective part of a virus is its genetic material (either DNA or RNA), not the protein coat. The protein coat serves to protect the genetic material and aid in the infection process, but it is not the component that causes infection.

4. **Analyze Statement D**:
- **Statement**: "Prions consist of abnormally folded proteins."
- **Explanation**: This statement is correct. Prions are indeed infectious agents composed of misfolded proteins and do not contain any nucleic acids.

### Conclusion:
The incorrect statement among the options provided is **Statement C**: "The infective constituent in viruses is the protein coat."