MCQ Detailed View

Viruses are tiny infectious agents that cannot reproduce on their own. They need a host cell to multiply. Every virus has a simple structure made up of two main parts: genetic material and a protective outer layer. The protective layer that surrounds the genetic material is called the capsid.

The capsid is made of proteins and acts like a shield for the viral DNA or RNA. It protects the virus’s genetic material from damage and helps the virus attach to and enter host cells. The structure of a capsid can vary between viruses. Some are shaped like spheres, rods, or more complex shapes. The capsid is built from repeating units of proteins called capsomeres.

It is important to not confuse the capsid with other biological terms:

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  Plasmid: A small circular piece of DNA found in bacteria, not viruses.

  
  


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  Capsule: A sticky layer found outside the cell wall of some bacteria, not part of viruses.

  
  


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  Plastid: A structure found in plant cells, such as chloroplasts, and has no role in viruses.

  
  

The capsid is essential for a virus’s ability to infect host cells. In many viruses, the capsid also plays a role in recognizing the correct host cells and helping the virus attach to them. Some viruses have an extra layer outside the capsid called the envelope, but the capsid is the core protein structure that all viruses have.

In conclusion, the correct answer is “Capsid,” which is the protein shell that encloses and protects a virus’s genetic material.

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