Prelims · Science & technology · 32 questions

Human body, health & diseases

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

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Prelims 2025 · Q48

Easy

With reference to monoclonal antibodies, often mentioned in news, consider the following statements:

I.They are man-made proteins.
II.They stimulate immunological function due to their ability to bind to specific antigens.
III.They are used in treating viral infections like that of Nipah virus.

Which of the statements given above are correct?

Answer & explanation

Answer: (d) I, II and III

All three statements are correct. Monoclonal antibodies are identical antibody proteins made in a laboratory, each locking on to one specific antigen, and one of them (m102.4) was kept ready in India to treat Nipah virus patients.

✓ I They are antibodies, which are proteins, produced in the laboratory (for example from hybridoma cells), not by the patient's own body.
✓ II Each one is designed to bind a single antigen with high precision, and that binding helps the immune system attack the target.
✓ III The monoclonal antibody m102.4 was procured by ICMR for Nipah cases, and a facility to administer it was set up in Kerala during the 2019 outbreak.
• Since then WHO's fact sheet says there is no licensed specific treatment or vaccine for Nipah yet, so such antibodies are used on an emergency or experimental basis.

Remember · Monoclonal antibodies are lab-made, single-target antibody proteins; m102.4 is the one kept ready by ICMR against Nipah virus.

Sources

A Comprehensive Review of Monoclonal Antibodies in Modern Medicine (NIH/PMC) ↗ “Monoclonal antibodies (mAbs) are laboratory-produced molecules engineered to mimic the immune system's ability to fight off harmful pathogens and diseased cells”
Experiential learnings from the Nipah virus outbreaks in Kerala (ICMR authors, Indian J Med Res, via PMC) ↗ “monoclonal antibodies (m102.4) preparations and administrations in Nipah cases, if necessary.”
WHO fact sheet: Nipah virus ↗ “There is currently no treatment or vaccine available for Nipah virus, however several candidate products are under development.”

Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2025 · Q49

Easy

Consider the following statements:

I.No virus can survive in ocean waters.
II.No virus can infect bacteria.
III.No virus can change the cellular transcriptional activity in host cells.

How many of the statements given above are correct?

Answer & explanation

Answer: (d) None

None of the statements is correct, because each one is an absolute claim ("no virus can...") and a single counter-example disproves it. Viruses are abundant in seawater, bacteriophages infect bacteria, and many viruses take over the host cell's gene activity.

✗ I Viruses are the most abundant biological entities in the oceans, reaching up to about 10 crore (10^8) particles in every millilitre of seawater.
✗ II Bacteriophages are viruses that infect bacteria. NCERT describes how a phage attaches to a bacterium and its genetic material enters the bacterial cell.
✗ III An infected cell treats the viral genetic material as its own and makes more virus particles, so its gene activity is redirected. Many viruses actively shut off the host's own gene expression to help themselves multiply.

Remember · Viruses live in seawater, bacteriophages infect bacteria, and viruses reprogram host-cell gene activity, so 'no virus can...' statements are false.

📘 Read it in NCERT: Class 12 Biology, Ch 5 (practise this chapter) · Class 12 Biology, Ch 5 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 5 “They worked with viruses that infect bacteria called bacteriophages. The bacteriophage attaches to the bacteria and its genetic material then enters the bacterial cell.”
NCERT Class 12 · Biology, Chapter 5 “The bacterial cell treats the viral genetic material as if it was its own and subsequently manufactures more virus particles.”
Marine Viruses: Key Players in Marine Ecosystems (Viruses, via NIH/PMC) ↗ “The discovery that viruses were the most abundant biological entities in oceanic marine environments”
Shutoff of Host Gene Expression in Influenza A Virus and Herpesviruses (Viruses, via NIH/PMC) ↗ “The ability to shut off host gene expression is a shared feature of many viral infections, and it is thought to promote viral replication by freeing host cell machinery and blocking immune responses.”

Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

The same topic in Mains

Science & technology in everyday lifeGS 3 syllabus

Read it in NCERT

Class 12 Biology, Chapter 5cited in 2 explanations