The ability to transform normal cells into cancerous cells is found in

Options

A. Ti plasmid
B. Retrovirus
C. All plasmids
D. Both (1) & (2)

Answer

To answer the question about which entities have the ability to transform normal cells into cancerous cells, we can analyze the options provided:

1. **TI Plasmid**:
- The TI plasmid (Tumor Inducing plasmid) is found in the bacterium *Agrobacterium tumefaciens*. This plasmid is known for its ability to induce tumors in plants. It carries genes that can be transferred into the plant's genome, leading to uncontrolled cell division, which is characteristic of cancer. Therefore, the TI plasmid can transform normal plant cells into cancerous cells.

2. **Retrovirus**:
- Retroviruses are a type of virus that contain RNA as their genetic material. They can integrate their genetic material into the host cell's DNA through a process called reverse transcription. Some retroviruses are known to cause cancer in animal cells by inserting their oncogenes into the host genome, leading to uncontrolled cell growth. Thus, retroviruses can also transform normal cells into cancerous cells.

3. **All Plasmids**:
- Not all plasmids have the ability to cause cancer. Plasmids are extrachromosomal DNA molecules that can replicate independently of chromosomal DNA, but their functions vary widely. Only specific plasmids, like the TI plasmid, have been shown to induce cancer.

4. **Both 1 and 2**:
- Since both the TI plasmid and retroviruses have the ability to transform normal cells into cancerous cells, this option is correct.

### Conclusion:
The correct answer is **Both 1 and 2** (TI plasmid and retrovirus) as both have the ability to transform normal cells into cancerous cells.