Difference between virus and viroid is

Options

A. absence of protein coat in viroid but present in virus
B. presence of low molelcular weight RNA in virus but absent in viroid
C. both (a) and (b)
D. none of the above

Explanation

To understand the differences between viruses and viroids, we can break down the information into clear, step-by-step points.

### Step-by-Step Solution:

1. **Definition of Virus and Viroid**:
- **Virus**: A virus is an infectious agent that can contain either DNA or RNA as its genetic material, and it is surrounded by a protein coat called a capsid.
- **Viroid**: A viroid is a simpler infectious agent that consists solely of a short strand of circular RNA and lacks a protein coat.

2. **Genetic Material**:
- **Virus**: The genetic material can be either DNA or RNA. If it is DNA, it is usually double-stranded, while RNA can be either single-stranded or double-stranded.
- **Viroid**: The genetic material is exclusively single-stranded RNA of low molecular weight.

3. **Presence of Protein Coat**:
- **Virus**: Viruses have a protein coat (capsid) that protects their genetic material.
- **Viroid**: Viroids do not have a protein coat.

4. **Protein Coding**:
- **Virus**: Viruses can manufacture proteins by using the host cell's machinery after they invade the host.
- **Viroid**: Viroids do not code for any proteins.

5. **Host Range**:
- **Virus**: Viruses can infect a wide range of hosts, including bacteria, plants, and animals.
- **Viroid**: Viroids primarily infect plants.

### Conclusion:
Based on the differences outlined, we can summarize that:
- Viruses have a protein coat, while viroids do not.
- Viruses can contain either DNA or RNA, while viroids only contain RNA.
- Viruses can code for proteins, while viroids cannot.
- Viruses can infect various organisms, while viroids are limited to plants.

### Correct Option:
From the options given in the question, the correct answer is:
- **Option A**: Absence of protein coat in viroid but present in virus.