UPSC Prelims 2016 · Question 84 of 98

UPSC Prelims 2016 question on Viruses Host Range

Which of the following statements is/are correct? Viruses can infect

1. bacteria
2. fungi
3. plants

Select the correct answer using the code given below.

  1. 1 and 2 only
  2. 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer

Answer: D. 1, 2 and 3

Verdict

The answer is 1, 2 and 3. Viruses can infect bacteria, fungi and plants.

Analysis

Viruses cannot multiply on their own and must invade a host cell and take over its machinery, and hosts exist across every domain of life. Bacteriophages infect bacteria and are among the most abundant biological entities on Earth. Mycoviruses infect fungi and mostly carry double stranded RNA genomes. Plant viruses are numerous and economically important, affecting crops and ornamentals alike, with tobacco mosaic virus the classic example. There is therefore no group among the three that viruses cannot infect.

Source

NCERT Class XII Biology.

How to crack it

Reason from the requirement rather than from a host list. A virus needs only a cell with replication machinery to hijack, and bacteria, fungi and plants all have one, so all three are infectible in principle. Any option excluding a cellular group would require a positive reason why that group is immune, and none exists. When a question asks whether a parasite can exploit several host types, ask what the parasite actually needs and check each host against that requirement.

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