Which is true for viruses

Options

A. they are living organisms
B. they are larger than bacteria
C. they have DNA or RNA
D. they replicate in animal cells only

Answer

To determine which statement is true for viruses, let's analyze each option step by step:

### Step 1: Analyze the first option - "They are living organisms."
- **Explanation**: Viruses are considered to be on the borderline between living and non-living. They cannot carry out metabolic processes on their own and only exhibit characteristics of life when inside a host cell.
- **Conclusion**: This statement is **incorrect**.

### Step 2: Analyze the second option - "They are larger than bacteria."
- **Explanation**: Viruses are significantly smaller than bacteria. For example, a typical virus can be about 20-300 nanometers in size, while bacteria usually range from 1,000 to 10,000 nanometers.
- **Conclusion**: This statement is **incorrect**.

### Step 3: Analyze the third option - "They have DNA or RNA."
- **Explanation**: Viruses can have either DNA or RNA as their genetic material. Those with DNA are referred to as deoxyviruses, while those with RNA are called riboviruses.
- **Conclusion**: This statement is **correct**.

### Step 4: Analyze the fourth option - "They replicate in animal cells only."
- **Explanation**: Viruses can replicate in a variety of hosts, including animals, plants, and even bacteria (the latter being known as bacteriophages).
- **Conclusion**: This statement is **incorrect**.

### Final Answer:
The only true statement about viruses is that **they have DNA or RNA** as their genetic material.

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