NUMS — Medical & Dental Entry Test
Take the NUMS Biology — Biodiversity: Viruses, Bacteria and Kingdoms (Set 1): 30 multiple-choice questions (40 minutes) with instant scoring and a full…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. Viruses are often described as being at the borderline of living and non-living because they:
Answer: A. Can reproduce only inside living host cells and are inert outside them
Explanation: Viruses lack metabolism and cell structure; they crystallise outside cells but replicate using host machinery inside cells.
Q2. HIV is classified as a retrovirus because it:
Answer: B. Uses reverse transcriptase to make DNA from its RNA genome
Explanation: Retroviruses carry RNA and reverse transcriptase, converting RNA → DNA, which integrates into the host genome as a provirus.
Q3. HIV causes immunodeficiency mainly because it destroys:
Answer: D. Helper T (CD4⁺) lymphocytes
Explanation: HIV's gp120 binds CD4 on helper T cells; their loss cripples both humoral and cell-mediated immunity.
Q4. In the lysogenic cycle of a bacteriophage:
Answer: B. The viral DNA integrates into the bacterial chromosome as a prophage and is replicated with it
Explanation: In lysogeny phage DNA integrates as a prophage and is passed to daughter cells until induced to enter the lytic cycle.
Q5. A bacteriophage injects which part into the host bacterium during infection?
Answer: C. Its nucleic acid only
Explanation: The tail sheath contracts and the DNA is injected; the protein coat remains outside (as shown by Hershey–Chase).
Take the timed test (free, no sign-up) to see your score and the answer and explanation for every question.
Q6. Which statement about viral capsids is correct?
Q7. A bacterium stains purple in the Gram stain. This indicates it has:
Q8. Penicillin is effective against many bacteria because it:
Q9. Why is penicillin generally more effective against Gram-positive than Gram-negative bacteria?
Q10. Bacterial endospores allow survival in harsh conditions because they:
Q11. Transfer of genetic material between two bacteria through a pilus is called:
Q12. Griffith found that heat-killed virulent pneumococci mixed with live harmless bacteria killed mice. The harmless bacteria had undergone:
Q13. Spherical bacteria arranged in grape-like clusters are called:
Q14. Cyanobacteria are placed in Kingdom Prokaryotae (Monera) although they photosynthesise, because they:
Q15. Heterocysts in cyanobacteria such as Nostoc are specialised for:
Q16. In the five-kingdom system, organisms that are eukaryotic, mostly unicellular and include algae and protozoa belong to:
Q17. Fungi are not classified as plants mainly because they:
Q18. A fungus that obtains nutrients from dead organic matter by secreting digestive enzymes outside its body is a:
Q19. The association between fungal hyphae and plant roots that improves mineral uptake is called:
Q20. A lichen is a mutualistic association between:
Q21. Two organisms belong to the same order but different families. Which statement must be true?
Q22. Which sequence of taxonomic ranks is in the correct descending order?
Q23. Which disease is caused by a virus rather than a bacterium?
Q24. Hepatitis B is most commonly transmitted through:
Q25. Antibiotics are ineffective against the common cold because:
Q26. Prions differ from viruses in that prions:
Q27. Bacteria which can grow with or without oxygen are termed:
Q28. Under ideal conditions a bacterium divides every 20 minutes. Starting from one cell, how many cells are present after 2 hours?
Q29. A virus that has an envelope derived from the host cell membrane typically acquires it when:
Q30. The structure in some bacteria that helps them resist phagocytosis by white blood cells is the: