Free Viruses MCQs with Answers
42 Viruses MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
42 questions · page 5 of 5
41. Which statement about HIV is correct?
- A. It can be cured with a course of antibiotics
- B. It survives for weeks on dry surfaces
- C. It is commonly spread by mosquito bites
- D. It destroys helper T cells and progressively weakens immunity
Explanation: HIV replicates inside helper T lymphocytes and destroys them, so immunity collapses and opportunistic infections follow. Antibiotics cannot touch a virus, the virus dies quickly outside the body, and mosquitoes do not transmit it.
Correct answer: It destroys helper T cells and progressively weakens immunity42. Why are retroviruses placed in a separate class of RNA viruses?
- A. They always infect animal cells only
- B. Their RNA acts directly as mRNA
- C. They lack protein coats
- D. They use reverse transcriptase to make DNA from RNA
Explanation: A retrovirus reverses the usual flow of information by copying its RNA genome into DNA, which integrase then inserts into the host chromosome as a provirus, and that integration is why HIV infection is lifelong. In other RNA viruses the genome often does act directly as messenger RNA, which is the contrast the second option draws. Retroviruses have perfectly ordinary capsids and envelopes.
Correct answer: They use reverse transcriptase to make DNA from RNA