Viruses


 
 
Concept Explanation
 

Viruses

Virus: The name virus come from latin word  which means "slimy liquid or poison". These are small size and simple composition that can multiply only in the living cells of animals, plants or bacteria.

Characteristics of viruses:

  • They are non cellular and very simple in structure, consisting mainly of a nucleic acid surrounded by a protein envelope called capsid.
  • They are considered non living as they are not made up of living cells but as they can grow only inside the living cell therefore they can also be considered as living.
  • They are ultra microscopic  and can only be visualised under electron microscope.
  • They do not increase in size.
  • They can pass through the filters through which bacteria cannot pass.
  • A virus is called as DNA virus or RNA virus depending on whether it contains RNA or DNA as their genetic material.
  • Virus are harmful for all living organsims. They infect the organisms and cause diseases like common cold, influenza, HIV aids, Ebola, COVID -19,Chickenpox, smallpox, tobacco mosaic  disease in plants etc.

                            

    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the statements is false ?

    Right Option : B
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    Explanation
    Question : 2

    Choose the correct definition for "virus" ?

    Right Option : A
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    Explanation
    Question : 3

    Observe the following figure carefully and identify it.

                                  

     

    Right Option : B
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    Explanation
     
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