Teichoic acid is present in cell wall of

Options

A. Bacteriophage
B. Mycoplasma
C. Nostoc
D. Pneumococcus.

Answer

To determine where teichoic acid is present in the cell wall, we can analyze the options provided in the question: bacteriophage, mycoplasma, nostoc, and pneumococcus.

### Step-by-Step Solution:

1. **Understand Teichoic Acid**:
- Teichoic acids are polymers found in the cell wall of certain bacteria, particularly Gram-positive bacteria. They play a role in maintaining cell wall structure and regulating cell growth.

2. **Analyze Each Option**:
- **Bacteriophage**: This is a type of virus that infects bacteria. Viruses do not have a cell wall, so teichoic acid cannot be present here.
- **Mycoplasma**: These are a group of bacteria that lack a cell wall entirely. Therefore, teichoic acid is not present in mycoplasma.
- **Nostoc**: This is a genus of cyanobacteria, which typically have a different type of cell wall structure and do not contain teichoic acid.
- **Pneumococcus**: This refers to Streptococcus pneumoniae, which is a Gram-positive bacterium. Gram-positive bacteria have thick peptidoglycan layers in their cell walls, which contain teichoic acids.

3. **Conclusion**:
- Based on the analysis, teichoic acid is present in the cell wall of **pneumococcus** (Streptococcus pneumoniae).

### Final Answer:
Teichoic acid is present in the cell wall of **pneumococcus**.

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