Choose the incorrect statement regarding the bacteria-`

Options

A. Bacteria as a group show the most extensive metabolic diversity.
B. Many bacteria have small circular DNA inside the genomic DNA
C. mesosome are infolding of cell membrane
D. Bacteria have thin filamentous extensions from their cell wall.

Explanation

To solve the question regarding which statement about bacteria is incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze Statement 1**: "Bacteria as a group show the most extensive metabolic diversity."
- **Evaluation**: This statement is true. Bacteria are known for their vast metabolic capabilities, allowing them to thrive in various environments and utilize a wide range of substrates.

**Hint**: Consider the various environments where bacteria can be found and the different metabolic processes they can perform.

2. **Analyze Statement 2**: "Bacteria have small circular DNA inside the genomic DNA."
- **Evaluation**: This statement is incorrect. Bacteria typically have a single circular chromosome, and they also possess plasmids, which are small circular DNA molecules that exist independently of the chromosomal DNA in the cytoplasm. Plasmids are not contained within the genomic DNA.

**Hint**: Recall the structure of bacterial DNA and the role of plasmids in genetic diversity.

3. **Analyze Statement 3**: "Mesosomes are the infoldings of the cell membrane."
- **Evaluation**: This statement is true. Mesosomes are indeed infoldings of the bacterial cell membrane, which increase the surface area for enzymatic reactions and help in DNA replication during cell division.

**Hint**: Think about the functions of mesosomes in bacterial cells.

4. **Analyze Statement 4**: "Bacteria have thin filamentous extensions from the cell wall."
- **Evaluation**: This statement is true. Bacteria can have structures such as pili or fimbriae, which are thin filamentous extensions that help in attachment and conjugation.

**Hint**: Consider the various appendages that bacteria might have and their functions.

### Conclusion:
After evaluating all statements, we find that **Statement 2** is the incorrect statement regarding bacteria.

### Final Answer:
**The incorrect statement regarding bacteria is: "Bacteria have small circular DNA inside the genomic DNA."**