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.

Asked in 8 of 11 years · most in 2022 (4)

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Prelims 2022 · Q37

Easy

Consider the following statements:

1.Biofilms can form on medical implants within human tissues.
2.Biofilms can form on food and food processing surfaces.
3.Biofilms can exhibit antibiotic resistance.

Which of the statements given above are correct?

Answer & explanation

Answer: (d) 1, 2 and 3

All three statements are true. A biofilm is a community of microbes attached to a surface and wrapped in a protective matrix; it can grow on implants inside the body and on food and food-processing equipment, and the microbes in it survive antibiotics far better than free-floating ones.

✓ 1. Biofilms form on medical implants and other devices in the body and cause serious chronic infections that are hard to clear.
✓ 2. Food and food-processing surfaces give biofilms nutrients to grow on, which makes them a food-safety problem.
✓ 3. The biofilm lifestyle makes bacteria more resistant to antibiotics and to the body's immune defences.

Remember · Biofilm = microbes stuck to a surface in a protective matrix. Found on implants and food surfaces; tolerates antibiotics, so infections turn chronic.

Sources

NIH National Library of Medicine (PMC), The Role of Bacterial Biofilm in Antibiotic Resistance and Food Contamination ↗ “Biofilm is a critical problem in the medical sector since it is formed on medical implants within human tissue and involved in a multitude of serious chronic infections. … Food and food processing surface become an ideal environment for biofilm formation where there are sufficient nutrients for microbial growth and attachment. … the biofilm phenotype that these bacteria adapt during device-associated infection facilitates increased resistance to antibiotics and host immune defenses”

Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2022 · Q38

Medium

Consider the following statements in respect of probiotics:

1.Probiotics are made of both bacteria and yeast.
2.The organisms in probiotics are found in foods we ingest but they do not naturally occur in our gut.
3.Probiotics help in the digestion of milk sugars.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (c) 1 and 3

Statements 1 and 3 are correct. Probiotics are live microbes, mostly bacteria but also some yeasts, and certain probiotic bacteria help digest lactose, the sugar in milk. Statement 2 is wrong because many probiotic organisms are the same as or similar to microbes that already live naturally in our body.

✓ 1. Most probiotics are bacteria (Lactobacillus and Bifidobacterium are the commonest), but some are yeasts such as Saccharomyces boulardii.
✗ 2. Many probiotic microbes are the same as or similar to those that naturally live in our bodies. NCERT too notes that lactic acid bacteria in our stomach help check disease-causing microbes.
✓ 3. Probiotic bacteria that carry the enzyme beta-galactosidase help break down lactose. Yogurt cultures such as L. bulgaricus and S. thermophilus give a similar benefit to people who cannot digest milk sugar well.

Remember · Probiotics: live microbes, mostly bacteria (Lactobacillus, Bifidobacterium) plus some yeasts; they resemble our natural gut flora and can ease lactose digestion.

📘 Read it in NCERT: Class 12 Biology, Ch 8 (practise this chapter)

Sources

NIH National Center for Complementary and Integrative Health, Probiotics: Usefulness and Safety (Internet Archive copy) ↗ “The most common are bacteria that belong to groups called Lactobacillus and Bifidobacterium . Other bacteria may also be used as probiotics, and so may yeasts such as Saccharomyces boulardii . … Many of the microorganisms in probiotic products are the same as or similar to microorganisms that naturally live in our bodies.”
FAO/WHO, Probiotics in food: health and nutritional properties and guidelines for evaluation ↗ “Probiotic bacteria containing β-galactosidase can be added to food to improve lactose maldigestion”
NCERT Class 12 · Biology, Chapter 8 “In our stomach too, the LAB play very beneficial role in checking disease- causing microbes.”

Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2022 · Q39

Medium

In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements:

1.The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform.
2.Sputnik V vaccine is manufactured using vector based platform.
3.COVAXIN is an inactivated pathogen based vaccine.

Which of the statements given above are correct?

Answer & explanation

Answer: (b) 2 and 3 only

Statements 2 and 3 are correct. Sputnik V is a vector vaccine and COVAXIN is a whole-virus inactivated vaccine. Statement 1 is wrong because Covishield, made by the Serum Institute of India, is a viral-vector vaccine (adenovirus carrier), not an mRNA vaccine.

✗ 1. Covishield is the Oxford-AstraZeneca vaccine produced in India by the Serum Institute. It uses a weakened chimpanzee adenovirus as a carrier, so it is a viral-vector vaccine. No mRNA is involved.
✓ 2. Sputnik V (Gam-COVID-Vac) from Russia's Gamaleya Institute is a combined vector vaccine given in two components.
✓ 3. COVAXIN by Bharat Biotech, developed with ICMR-NIV, uses a whole-virion inactivated Vero-cell platform: dead virus that cannot infect but still trains the immune system.

Remember · Covishield and Sputnik V: viral-vector vaccines. COVAXIN: inactivated whole virus. ZyCoV-D: DNA. mRNA is the Pfizer and Moderna type.

Sources

PIB, Marking the first year of COVID-19 Vaccination (Internet Archive copy) ↗ “The COVISHIELD vaccine contains a weakened strain of a common cold virus (adenovirus) from chimpanzees. … COVAXIN uses an inactivated virus platform, Zycov-D is a DNA vaccine, Covishield a viral vector vaccine”
PIB, National Regulator grants permission for restricted use in emergency situations to Sputnik-V vaccine (Internet Archive copy) ↗ “import and market Gam-COVID-Vac combined vector vaccine, popularly called Sputnik-V, developed by M/s Gamaleya Institute, Russia”

Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2022 · Q97

Easy

Which one of the following statements best describes the role of B cells and T cells in the human body?

Answer & explanation

Answer: (d) They protect the body from the diseases caused by pathogens.

B cells and T cells are the two lymphocytes that run the body's specific immune response, so they protect us from diseases caused by pathogens (disease-causing microbes). B cells make antibodies; T cells help B cells make them.

✓ (d) NCERT: immune responses are carried out by B-lymphocytes and T-lymphocytes. B cells produce antibodies against pathogens, and T cells help B cells produce them.
✗ (a) An allergy is an exaggerated immune response to harmless substances in the environment such as pollen or mites. That reaction is the problem, not the protection.
✗ (c) Immunosuppressants are drugs that damp down the immune system. B and T cells are what carry out the immune response.

Remember · B cells make antibodies against pathogens; T cells help B cells do so. Together they carry out the body's immune response, with memory of the first encounter.

📘 Read it in NCERT: Class 12 Biology, Ch 7 (practise this chapter) · Class 12 Biology, Ch 7 (practise this chapter) · Class 12 Biology, Ch 7 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 7 “The primary and secondary immune responses are carried out with the help of two special types of lymphocytes present in our blood, i.e., B-lymphocytes and T-lymphocytes.”
NCERT Class 12 · Biology, Chapter 7 “The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them.”
NCERT Class 12 · Biology, Chapter 7 “The exaggerated response of the immune system to certain antigens present in the environment is called allergy.”

Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

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Science & technology in everyday lifeGS 3 syllabus

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Class 12 Biology, Chapter 7cited in 3 explanations
Class 12 Biology, Chapter 8cited in 1 explanation

Human body, health & diseases

Prelims 2022 · Q37

Prelims 2022 · Q38

Prelims 2022 · Q39

Prelims 2022 · Q97

The same topic in Mains

Read it in NCERT

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