Single stranded DNA occurs as a genetic material in virus

Options

A. `T_(2)`
B. `T_(4)`
C. `phixx174`
D. Lambda.

Answer

To answer the question regarding which viruses have single-stranded DNA (ssDNA) as their genetic material, we will analyze the options provided and identify the correct virus.

### Step-by-Step Solution:

1. **Understanding the Types of DNA in Viruses**:
- Viruses can have either single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) as their genetic material. It's essential to differentiate between these two types.

2. **Analyzing the Options**:
- **Option 1: T2 Virus**: This virus is known to have double-stranded DNA (dsDNA). Therefore, this option is incorrect.
- **Option 2: T4 Virus**: Similar to T2, T4 also contains double-stranded DNA (dsDNA). Thus, this option is also incorrect.
- **Option 3: 5, 5, 5, 7, 7, 4 Virus**: This virus is mentioned to have single-stranded DNA (ssDNA). However, the name seems unusual and may not be widely recognized. Further verification is needed.
- **Option 4: Another Virus**: This option also states that it has double-stranded DNA (dsDNA), making it incorrect.

3. **Identifying the Correct Virus**:
- The only option that mentions single-stranded DNA is option 3 (5, 5, 5, 7, 7, 4). However, the more commonly recognized virus with ssDNA is the **Phi X 174 virus**.
- Phi X 174 is a well-known bacteriophage that infects E. coli and has a circular single-stranded DNA genome.

4. **Conclusion**:
- The virus that has single-stranded DNA as its genetic material is **Phi X 174**. Therefore, the correct answer is that ssDNA occurs in the Phi X 174 virus.

### Final Answer:
Single-stranded DNA occurs as the genetic material in the **Phi X 174 virus**.