Q1. What is the main component of a virus?
a) DNA
b) RNA
c) Protein coat
d) Lipid membrane
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Correct Answer: c) Protein coat
Explanation: Viruses consist of genetic material (either DNA or RNA) surrounded by a protein coat, known as a capsid.
Q2. Which of the following is NOT a characteristic feature of viruses?
a) Cellular structure
b) Ability to reproduce
c) Ability to evolve
d) Parasitic nature
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Correct Answer: a) Cellular structure
Explanation: Viruses lack cellular structure and are obligate intracellular parasites.
Q3. Viroids are infectious agents that primarily infect:
a) Bacteria
b) Plants
c) Animals
d) Fungi
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Correct Answer: b) Plants
Explanation: Viroids are small, single-stranded RNA molecules that infect plants, causing various diseases.
Q4. Lichens are a symbiotic association between:
a) Fungi and bacteria
b) Fungi and algae
c) Algae and bacteria
d) Algae and plants
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Correct Answer: b) Fungi and algae
Explanation: Lichens are a mutualistic symbiosis between a fungus (usually an ascomycete) and an alga or a cyanobacterium.
Q5. Which of the following is a characteristic of viroids?
a) Protein coat
b) Double-stranded RNA
c) Single-stranded RNA
d) Double-stranded DNA
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Correct Answer: c) Single-stranded RNA
Explanation: Viroids are small, single-stranded RNA molecules that lack a protein coat.
Q6. The protein coat of a virus is composed of:
a) Nucleic acids
b) Carbohydrates
c) Lipids
d) Capsid proteins
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Correct Answer: d) Capsid proteins
Explanation: The protein coat of a virus, known as the capsid, is composed of capsid proteins.
Q7. Which of the following is NOT a type of virus transmission?
a) Vector-borne
b) Airborne
c) Vertical
d) Analogous
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Correct Answer: d) Analogous
Explanation: Viruses are transmitted through vectors (e.g., mosquitoes), airborne droplets, or vertically (from parent to offspring).
Q8. Lichens are commonly found growing on:
a) Desert sand
b) Tree bark
c) Volcanic rocks
d) Ocean floors
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Correct Answer: b) Tree bark
Explanation: Lichens are often found growing on tree bark, rocks, and soil surfaces.
Q9. Which of the following is NOT a viral disease in humans?
a) Measles
b) Influenza
c) Tuberculosis
d) AIDS
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Correct Answer: c) Tuberculosis
Explanation: Tuberculosis is caused by bacteria (Mycobacterium tuberculosis), not viruses.
Q10. Viroids cause diseases mainly in:
a) Animals
b) Plants
c) Humans
d) Fungi
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Correct Answer: b) Plants
Explanation: Viroids primarily infect plants, causing diseases such as potato spindle tuber disease and citrus exocortis.