Viroids are different from viruses w.r.t :

Options

A. Size and cell type
B. Size and structural components
C. Structural organisation and non-infectious nature
D. Multiplication and cellular organisation

Answer

To solve the question regarding how viroids differ from viruses, we can follow these steps:

### Step 1: Understand the Definition of Viroids and Viruses
- **Viroids** are small infectious agents that consist solely of a short strand of circular RNA without a protein coat.
- **Viruses** are larger infectious agents that consist of genetic material (either DNA or RNA) surrounded by a protein coat.

### Step 2: Compare Size
- Viroids are significantly smaller than viruses. This is a crucial distinction as size plays a role in their classification.

### Step 3: Analyze Genetic Material
- The genetic material of viroids is exclusively RNA, whereas viruses can have either DNA or RNA as their genetic material.

### Step 4: Examine Structural Components
- Viruses have a protein coat (capsid) that protects their genetic material, while viroids lack this protein coat entirely.

### Step 5: Consider Infectious Nature
- Both viroids and viruses are infectious agents. Therefore, they are similar in this aspect, which means this option is not a distinguishing factor.

### Step 6: Evaluate Multiplication and Cellular Organization
- Viroids replicate within the host cell using the host's cellular machinery, similar to viruses, but they do not have a cellular organization as they are not made of cells.

### Conclusion
Based on the comparisons, the primary differences between viroids and viruses are their size and structural components. Therefore, the correct answer to the question is that viroids differ from viruses with respect to **size and structural components**.