Which one of the following statements is correct about effects of antibiotics on viruses?

The correct answer is 3.

Key Points

• A virus is an acellular structure which is a non-living particle outside of the body of its host.
• Thus, it lacks protoplasm which is the site of most of the metabolic activities, antibiotics which are effective against bacteria (living prokaryotic cell), are ineffective on viruses.
• Viruses don't have cell walls that can be attacked by antibiotics instead, they are surrounded by a protective protein coat, Unlike bacteria, which attack your body's cells from the outside, viruses actually move into the body cell and make copies of themselves in your body's cells.

Important Points

• Viruses are non-cellular, microscopic infectious agents that can only replicate inside a host cell. 
• From a biological perspective, viruses cannot be classified either as living organisms or non-living.
• They act as living organisms when they are present in a host organism (cell), otherwise, they are nonliving organisms.
• Viruses are classified on the basis of genetic material - ds DNA (polio), dsRNA, ssDNA, ssRNA (orthomyxoviruses).
• Viruses cause diseases among animals and plants.
  • Potato mosaic and tobacco mosaic are common viral diseases among plants.
  • Chickenpox, AIDS, and Ebola are common viral animal diseases.  
• Viroids and prions are the infecting proteins and RNA, they lack cell covers like a virus or any other eukaryotes.
  • They were discovered by T Dienner in 1971 and these are also responsible for diseases among animals, E.g. mad cow disease.