What is true of viruses ?

Options

A. They are obligate intracellular parsites
B. They are bigger than bacteria
C. They are non-specific for their hosts
D. They can raproduce in non-living medium.

Answer

**Step-by-step Solution:**

1. **Understanding the Question:**
The question asks which statement is true regarding viruses among the provided options.

2. **Analyzing the Options:**
- **Option 1:** "They are obligate intracellular parasites."
- **Option 2:** "They are bigger than bacteria."
- **Option 3:** "They are not specific for their host."
- **Option 4:** "They can reproduce in non-living medium."

3. **Evaluating Option 1:**
- Viruses are indeed obligate intracellular parasites. This means they cannot survive or reproduce outside of a host cell. They require a living cell to carry out their life processes. Therefore, this statement is **true**.

4. **Evaluating Option 2:**
- This statement claims that viruses are bigger than bacteria. However, this is incorrect. Bacteria are generally larger and more complex than viruses. Therefore, this statement is **false**.

5. **Evaluating Option 3:**
- This option suggests that viruses are not specific for their host. This is also incorrect. Viruses are known to be host-specific, meaning they can only infect certain types of cells in specific organisms. Therefore, this statement is **false**.

6. **Evaluating Option 4:**
- The statement claims that viruses can reproduce in a non-living medium. This is incorrect as well. Viruses cannot reproduce outside of a living host cell; they cannot be grown or reproduced in an artificial medium. Therefore, this statement is **false**.

7. **Conclusion:**
After evaluating all the options, the only true statement regarding viruses is **Option 1: They are obligate intracellular parasites**.

**Final Answer:**
The correct statement about viruses is that they are obligate intracellular parasites.

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