UPSC Prelims 2016 Q59: Science & Technology – Health & Diseases
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.
- (a) 1 and 2 only
- (b) 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Explanation
What can viruses infect?
Viruses are obligate parasites.
They multiply only inside living cells, and they infect every kind of organism.
| Host | Can viruses infect it? | Name or example |
|---|---|---|
| 1. Bacteria | Yes | Bacteriophages, such as T4 phage |
| 2. Fungi | Yes | Mycoviruses |
| 3. Plants | Yes | Tobacco mosaic virus, the first virus discovered |
| Animals and humans | Yes | Influenza, HIV, rabies |
Key facts about viruses:
| Feature | Detail |
|---|---|
| Structure | DNA or RNA inside a protein coat (capsid) |
| Outside a cell | Inert, like a crystal |
| Antibiotics | Do not work against viruses |
Answer: (d) 1, 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Viruses also infect plants, as tobacco mosaic virus shows.
- (b) Incorrect. Viruses also infect bacteria and fungi.
- (c) Incorrect. Fungi are also infected, by mycoviruses.
- (d) CORRECT. Viruses can infect bacteria, fungi and plants.
Key point
Viruses infect all life forms: bacteria (bacteriophages), fungi (mycoviruses), plants (tobacco mosaic virus) and animals.
Remember
Viruses infect bacteria, fungi, plants and animals.
Common mistakes
- Thinking viruses infect only animals and humans.
- Not knowing the term mycovirus for viruses of fungi.
- Believing antibiotics kill viruses.
Exam tip
Any living cell can be a virus host. In such lists, mark all.
Sources
- NCERT Class XI — Biology, Ch 2 (Biological Classification: Viruses, Viroids and Lichens)
- NCERT Class XII — Biology (Microbes in Human Welfare)