Chargaff rule is not applicable to

Options

A. Rice dwarf virus
B. `phixx-174` bacteriophage
C. Wound tumour virus
D. Reo viurs

Answer

To determine where Chargaff's rule is not applicable, we need to understand what Chargaff's rule states and the types of genetic materials involved in the options provided.

### Step-by-Step Solution:

1. **Understanding Chargaff's Rule**:
Chargaff's rule states that in double-stranded DNA, the amount of adenine (A) is equal to thymine (T), and the amount of guanine (G) is equal to cytosine (C). This means that the total number of purines (A + G) is equal to the total number of pyrimidines (T + C). This rule is applicable to double-stranded nucleic acids.

2. **Identifying the Options**:
- **Rice Dwarf Virus**: This virus has double-stranded RNA.
- **5174 Bacteriophage**: This phage has single-stranded RNA.
- **Wound Tumor Virus**: This virus has double-stranded RNA.
- **Reo Virus**: This virus also has double-stranded RNA.

3. **Analyzing Each Option**:
- **Rice Dwarf Virus**: Since it has double-stranded RNA, Chargaff's rule applies.
- **5174 Bacteriophage**: This is single-stranded RNA, so Chargaff's rule does not apply.
- **Wound Tumor Virus**: This has double-stranded RNA, so Chargaff's rule applies.
- **Reo Virus**: This also has double-stranded RNA, so Chargaff's rule applies.

4. **Conclusion**:
The only option where Chargaff's rule is not applicable is the **5174 Bacteriophage** because it contains single-stranded RNA.

### Final Answer:
**The Chargaff rule is not applicable to the 5174 bacteriophage.**