S-type strain of Streptococcus pneumoniae is!

Options

A. capsulated,virulent smooth
B. non capsulated avirulent rough
C. capsulated avirulent rough
D. non capsulated virulent smooth

Answer

**Step-by-Step Text Solution:**

1. **Understanding the S-type Strain**: The S-type strain of Streptococcus pneumoniae is characterized by its smooth appearance. This smoothness is due to the presence of a polysaccharide capsule surrounding the bacterial cell.

2. **Capsulation**: The capsule is a protective layer that helps the bacteria evade the host's immune system. This means that the S-type strain is capsulated, which is a key feature of its virulence.

3. **Virulence**: The S-type strain is considered virulent, meaning it has the ability to cause disease. This is primarily due to the protective capsule that allows it to survive in the host and resist phagocytosis by immune cells.

4. **Comparison with R-type Strain**: In contrast, the R-type strain (rough strain) of Streptococcus pneumoniae lacks this capsule, giving it a rough appearance. The R-type strain is non-virulent, meaning it does not cause disease.

5. **Conclusion**: Therefore, the S-type strain of Streptococcus pneumoniae is capsulated, virulent, and smooth in appearance.

**Final Answer**: The S-type strain of Streptococcus pneumoniae is capsulated, virulent, and smooth.

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