Human body, health & diseases

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.

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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.

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Answer: (a) Nitric oxide

Nitric oxide (NO) is made by the cells lining our blood vessels (the endothelium). It diffuses into the surrounding smooth muscle and makes it relax, which widens the vessels and lets more blood flow; its discovery as a signalling molecule won the 1998 Nobel Prize in Physiology or Medicine.

• ✓ (a) Furchgott, Ignarro and Murad showed that the 'endothelium-derived relaxing factor' that dilates blood vessels is nitric oxide; heart drugs such as nitroglycerin work by releasing NO.
• ✗ (b) Nitrous oxide (N2O) is 'laughing gas', used as an anaesthetic and a greenhouse gas; the body does not make it to control blood vessels.
• ✗ (c) Nitrogen dioxide (NO2) is a brown, toxic air pollutant from vehicle exhausts and combustion that irritates the lungs; it is not a body signal.

Remember · Nitric oxide (NO) = body's own vasodilator, made by the endothelium; 1998 Nobel (Furchgott, Ignarro, Murad). Nitroglycerin relieves angina by releasing NO. N2O = laughing gas.

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Answer: (b) 2 only

Only statement 2 is correct: PMSMA encourages private doctors to volunteer at government health facilities. Statement 1 goes wrong because PMSMA is an antenatal (before-birth) care programme run at designated government facilities; it has no six-month post-delivery package.

• ✗ 1. PMSMA guarantees a minimum antenatal package for women in the 2nd/3rd trimesters at designated government facilities, on the 9th of every month. Post-delivery care for six months is not part of it, and it is not offered at any government facility.
• ✓ 2. The programme has a systematic approach to engage the private sector, motivating private practitioners to volunteer for the campaign at government health facilities.

Remember · PMSMA (2016): free antenatal check-up on the 9th of every month for 2nd/3rd-trimester women at designated government facilities; private doctors volunteer.

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Answer: (d) All four

Mushrooms are the fruiting bodies of a very diverse group of fungi, and each property in the list is shown by at least some species: medicine (reishi, turkey tail), mind-altering chemicals (psilocybin), insect-deterring proteins and compounds, and a natural glow.

• ✓ 1. NCERT notes that wild edible mushrooms have high nutritional and medicinal values. Medicinal mushrooms such as reishi and turkey tail have been used against infections for centuries in Asia, and for over 30 years have been approved as an add-on to standard cancer treatment in Japan and China.
• ✓ 2. Psilocybin, a hallucinogen found in certain mushrooms ("magic mushrooms"), alters perception, mood and thought.
• ✓ 3. Some mushrooms are rarely attacked by insects; studies of their fruit bodies have found insecticidal proteins and antifeedant compounds that are being explored for pest control.
• ✓ 4. Several gilled mushrooms glow in the dark through a luciferin–luciferase reaction.

Remember · Fungi, including mushrooms, give medicines (reishi), psychoactive psilocybin, insecticidal proteins and bioluminescence (luciferin–luciferase light).

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Answer: (c) All three

Microbes live in places no other life can: hot vents, snow and ice, and strongly acidic sites. Such extremophiles (thermophiles, psychrophiles, acidophiles) make all three statements true.

• ✓ 1. Hyperthermophiles thrive in hydrothermal vents. Under high pressure, the methanogen Methanopyrus kandleri strain 116 has multiplied at 122 °C in the laboratory, above water's normal boiling point of 100 °C.
• ✓ 2. Cold-loving microbes (psychrophiles) live in permafrost, sea ice and under thick snow, where they stay active below 0 °C in films of salty, unfrozen water.
• ✓ 3. Acidophiles grow in highly acidic places such as acid mine drainage and acidic hot springs; some archaea grow best at a pH below 1.

Remember · Extremophiles: thermophiles (up to 122 °C under pressure), psychrophiles (below 0 °C), acidophiles (pH < 3), halophiles (salt).

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Answer: (c) Only three

Statements 2, 3 and 4 are correct; statement 1 is wrong. Anaemia Mukt Bharat supplies prophylactic iron and folic acid, not calcium, and adds deworming, a behaviour-change campaign that includes delayed cord clamping, and action on non-nutritional causes such as malaria, haemoglobinopathies and fluorosis.

• ✗ 1. The first of the six interventions is prophylactic Iron Folic Acid supplementation (for example, 60 mg iron plus 500 mcg folic acid tablets for pregnant women). Calcium supplementation is not part of it.
• ✓ 2. The year-round Behaviour Change Communication campaign includes promoting the practice of delayed cord clamping.
• ✓ 3. Periodic deworming runs through National Deworming Day, with mass deworming of children and adolescents aged 1 to 19 years twice a year, on 10 February and 10 August.
• ✓ 4. The strategy includes awareness, screening and treatment of non-nutritional causes of anaemia in endemic pockets, with special focus on malaria, haemoglobinopathies and fluorosis.

Remember · Anaemia Mukt Bharat's six interventions: iron-folic acid, deworming, behaviour-change (incl. delayed cord clamping), testing and treatment, fortified foods, non-nutritional causes. No calcium.

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Answer: (a) Controlling the viral diseases spread by mosquitoes

The Wolbachia method is used to control viral diseases spread by mosquitoes, mainly dengue. Wolbachia is a bacterium that lives naturally in many insects; when it is introduced into Aedes aegypti mosquitoes, they transmit dengue virus much less.

• ✓ (a) Wolbachia has been transferred into Aedes aegypti mosquitoes and reduces their transmission of dengue virus. WHO's Vector Control Advisory Group has assessed the approach and confirmed its public health value for dengue control.
• ✗ (b) Turning crop residue into packing material is a materials process and has nothing to do with a bacterium living inside insects.
• ✗ (d) Biochar comes from heating biomass in a thermochemical process such as pyrolysis. It is not a mosquito-control method.

Remember · Wolbachia is an insect-dwelling bacterium. Released in Aedes aegypti mosquitoes, it cuts dengue transmission, so it is a mosquito-borne disease control method.

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Answer: (a) Studying the evolutionary relationships among various species of fauna

Microsatellite DNA is used to study genetic variation between individuals and populations, which is why it helps in tracing evolutionary relationships among species. Microsatellites are short DNA stretches repeated many times, and the number of repeats varies from one organism to another.

• ✓ (a) Because repeat numbers in microsatellites differ so much between individuals and populations, they work as genetic markers. Comparing them shows how closely related organisms or populations are.
• ✗ (b) Turning stem cells into different tissues is done with growth signals and culture conditions. It does not use microsatellite DNA.
• ✗ (d) Drug trials in a population test how well a medicine works. Microsatellites do not assess drug efficacy.

Remember · Microsatellites are short repeated DNA stretches whose repeat number varies between individuals. They serve as genetic markers, for DNA fingerprinting and for studying relationships and diversity.

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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.

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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.

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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.

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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.

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Answer: (b) 1, 2 and 4 only

Pollution-derived magnetite nanoparticles form when iron-bearing material is burnt or heated by friction, so they come from vehicle engine exhaust, brake wear and combustion at power stations. A 2016 study found such particles in human brain tissue and linked them to oxidative damage of the kind seen in Alzheimer's disease. Microwave ovens and telephone lines are not among the sources it names.

• ✓ 1. Frictional heating of brake pads produces high-temperature magnetite nanoparticles at the roadside.
• ✓ 2. Magnetite nanoparticles have been captured from the exhaust plume of diesel engines; combustion is the main source.
• ✗ 3. The study names open fires and poorly sealed cooking or heating stoves as indoor sources of magnetite nanoparticles; microwave ovens are not among them.
• ✓ 4. The study shows spherical, fused magnetite particles collected at a power station, an example of industrial combustion.
• ✗ 5. Telephone lines are not among the sources the study names; they carry electrical signals, not iron-oxide particles from combustion or friction.

Remember · Airborne magnetite nanoparticles come from combustion and friction: vehicle exhaust, brake wear, power plants, open fires. They have been found in human brain tissue.

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Answer: (c) Both 1 and 2

Both statements are correct: a recombinant vector vaccine is built by genetic engineering, and the carrier (vector) that delivers the disease-causing agent's gene into our cells is a harmless virus or bacterium.

• ✓ 1. Recombinant DNA technology lets scientists make a pathogen's antigen in bacteria or yeast, as with the hepatitis B vaccine from yeast. Recombinant vector vaccines rest on the same gene-splicing methods.
• ✓ 2. NIAID, part of the US National Institutes of Health, describes recombinant vector vaccines as those that use a harmless virus or bacterium as a vector, or carrier, to introduce genetic material into cells. Covishield is a vectored vaccine that uses a virus as the carrier.

Remember · Recombinant vector vaccine = genetic engineering plus a harmless virus or bacterium as the carrier that delivers the pathogen's gene into our cells.

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Answer: (c) Both 1 and 2

Both statements are correct: mitochondrial DNA comes only from the mother's egg, and mitochondrial replacement therapy swaps the faulty mitochondria either before fertilisation (spindle transfer) or after it (pronuclear transfer).

• ✓ 1. Two techniques are used: in maternal spindle transfer the mother's nuclear genetic material is moved into a donor egg before fertilisation, and in pronuclear transfer the fertilised embryo's nuclear material is moved into a donor embryo after fertilisation. Either way the child gets healthy donor mitochondria.
• ✓ 2. Only egg cells contribute mitochondria to the embryo, so only females pass on mitochondrial DNA variants; a father's sperm does not pass them on.

Remember · Mitochondrial DNA is inherited only from the mother. Mitochondrial replacement therapy: spindle transfer (before fertilisation) or pronuclear transfer (after fertilisation).

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Answer: (a) 1 and 2 only

Bacteria and fungi are living cells that can feed and multiply on a lab-made nutrient medium, so they can be cultured in it. A virus has no cell machinery of its own and multiplies only inside a living host cell, so it cannot grow in a cell-free artificial medium.

• ✓ 1. Bacteria grow as visible colonies on nutrient-rich gel or broth in a petri dish.
• ✓ 2. Fungi also grow as colonies in a petri dish on a suitable nutrient medium.
• ✗ 3. Viruses are acellular and multiply only after entering a living cell. To grow them, labs use living cells (cell culture, or fertilised eggs), not a synthetic medium.

Remember · Bacteria and fungi grow on artificial nutrient media; viruses need living host cells, so they cannot be cultured on a synthetic medium alone.

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Answer: (b) 2 only

Statement 2 is correct: adenoviruses can cause cold-like illness, and AIDS is caused by HIV, which is a retrovirus. Statement 1 is wrong on both counts, because adenoviruses have double-stranded DNA genomes, while retroviruses carry an RNA genome.

• ✗ 1. Adenoviruses are non-enveloped viruses with double-stranded DNA, not single-stranded DNA. Retroviruses, such as HIV, have an RNA genome (later copied into DNA inside the host cell), not a double-stranded DNA genome.
• ✓ 2. Adenoviruses cause respiratory infections, including mild cold-like illness. AIDS is caused by the Human Immunodeficiency Virus (HIV), a retrovirus.

Remember · Adenovirus: double-stranded DNA, respiratory infections. Retrovirus (HIV, cause of AIDS): RNA genome.

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Answer: (d) spread of viral diseases

ACE2, short for angiotensin-converting enzyme 2, sits on the outer surface of human cells, and the spike of SARS-CoV-2 (the virus behind COVID-19) latches onto it to get inside. So it was discussed in the context of how a viral disease spreads.

• ✓ (d) The spike protein of SARS-CoV-2 binds to ACE2 on host cells, which lets the virus enter them. The earlier SARS coronavirus used the same receptor.
• ✗ (a) ACE2 is a human protein, not a gene introduced into genetically modified plants.
• ✗ (b) India's own satellite navigation system is NavIC; ACE2 has nothing to do with navigation or radio collars.

Remember · ACE2 is the human cell-surface receptor that SARS-CoV-2 (and SARS-CoV) binds to for entry into cells.

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Answer: (d) Toiletries

Triclosan is an antibacterial chemical added to personal-care products such as some soaps, skin cleansers, deodorants and toothpastes, which are toiletries. It is a suspected endocrine (hormone-system) disruptor, so long exposure to high levels is a worry.

• ✓ (d) The US FDA says triclosan is added to some antibacterial soaps and body washes, toothpastes and cosmetics, all toiletries. Some short-term animal studies link high doses to lower levels of some thyroid hormones, which is why long exposure is a concern.
• ✗ (a) Food preservatives keep food from spoiling; triclosan is not a permitted food preservative. It is an antibacterial for personal-care products.
• ✗ (b) Fruit-ripening substances are chemicals that release ethylene, the ripening hormone of plants. Triclosan is not a ripening agent.
• ✗ (c) Triclosan is mainly an antibacterial added to personal-care products. The usual worry about reused plastic containers is a different one: chemicals such as BPA leaching out of the plastic.

Remember · Triclosan is an antibacterial agent in toiletries (soaps, toothpaste, deodorants) and a suspected endocrine disruptor.

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Answer: (d) prevention of mitochondrial diseases in offspring

Pronuclear transfer is a form of mitochondrial donation, used to stop a mother from passing a serious mitochondrial disease to her child. The nuclear DNA of her fertilised egg is moved into a donor egg that has healthy mitochondria, so the baby gets the parents' genes but the donor's healthy mitochondria.

• ✗ (a) Fertilising an egg in the lab with donor sperm is ordinary IVF. Pronuclear transfer is an extra step done on embryos, not a way of fertilising an egg.
• ✗ (b) The technique does not modify sperm-producing cells or edit genes; it swaps whole nuclear material between embryos.
• ✗ (c) It does not turn stem cells into embryos. It moves the nuclear genetic material of one embryo into another embryo whose own nucleus has been removed.
• ✓ (d) Mitochondrial donation treatment lets people with severe mitochondrial disease avoid passing it to their children. Pronuclear transfer is one of the two approved techniques, the other being maternal spindle transfer.

Remember · Pronuclear transfer = swap the nuclear DNA of an embryo into a donor embryo with healthy mitochondria, to prevent mitochondrial disease.

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Answer: (b) 1 and 2 only

Pneumococcal conjugate vaccines (PCVs) protect against the diseases caused by the pneumococcus bacterium, chiefly pneumonia, meningitis and blood infection (sepsis), and fewer infections mean less reliance on antibiotics against resistant strains. No vaccine is free of side effects, so the claim in statement 3 is too absolute.

• ✓ 1. The Health Ministry says PCV protects children against severe pneumococcal disease such as pneumonia and meningitis. Pneumococcus (Streptococcus pneumoniae) also causes blood infection (sepsis), and the vaccine greatly reduced this burden where it was introduced.
• ✓ 2. After PCVs were introduced across the world, the share of pneumococci resistant to first-line antibiotics for pneumonia fell. Fewer infections and less resistance mean less dependence on failing antibiotics.
• ✗ 3. WHO's vaccine safety notes list mild reactions, such as swelling, redness, tenderness and fever, and say severe allergic reactions are very rare, not absent.

Remember · PCV prevents pneumonia, meningitis and sepsis and helps check antibiotic resistance, but every vaccine can have mild side effects and, rarely, allergy.

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Answer: (c) 1 and 3 only

A plant cell has a cellulose cell wall and, when mature, usually one large central vacuole, while an animal cell has no cell wall and only small vacuoles, if any. Statement 2 is wrong because every cell, plant or animal, is enclosed by a plasma membrane.

• ✓ 1. The plant cell wall is made mainly of cellulose. Animal cells lack a rigid cell wall, which lets them change shape easily.
• ✗ 2. The plasma membrane (cell membrane) is the universal boundary of a cell. Plant cells have it too, just inside the cell wall.
• ✓ 3. A mature plant cell usually has one large central vacuole filled with cell sap. Animal cells may have vacuoles, but they are not as large.

Remember · Cell wall (cellulose) and one big central vacuole belong to plant cells. The plasma membrane is present in all cells.

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Answer: (a) 1, 2 and 3 only

Benzene is a volatile chemical released when fuels and other organic material burn, so vehicle exhaust, tobacco smoke and wood burning are all recognised sources of exposure. Varnished wooden furniture and polyurethane products are not named in the official lists of benzene sources.

• ✓ 1. Benzene is present in motor vehicle exhaust and in petrol (gasoline) vapour.
• ✓ 2. Tobacco smoke contains benzene, and WHO calls active and passive smoke exposure a significant source of exposure.
• ✓ 3. Wood-burning fires are named among the common sources of benzene in air.
• ✗ 4. UPSC's key does not count this as a benzene source. EPA's summary names glues, paints and furniture wax among household sources, but not varnished wooden furniture itself.
• ✗ 5. Polyurethane products are not named among the recognised benzene sources in the EPA and WHO summaries, and UPSC's key does not count them.

Remember · Benzene comes from burning and fuels: vehicle exhaust, tobacco smoke, wood-burning fires, petrol vapour, and some glues and paints.

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Answer: (d) 1, 2 and 3

All three tasks are done by wearable devices. Wrist-worn trackers and watches with GPS locate the wearer, their motion sensors estimate sleep patterns, and worn hearing aids help people with hearing loss.

• ✓ 1. WHO describes global positioning system locators that track the location of the wearer, used for example to find people with dementia who wander. Some fitness wearables also carry a built-in GPS receiver that records position, speed and altitude.
• ✓ 2. WHO notes that wrist- or hip-worn accelerometers give continuous data on physical activity and potentially sleep; accelerometer-based fitness wearables can estimate sleep patterns, along with steps and energy use.
• ✓ 3. Hearing aids are among the assistive products WHO prioritises to mitigate hearing loss, and they are worn on or in the ear, so wearable devices can assist the hearing impaired.

Remember · Wearables include GPS trackers (location), fitness bands and watches (sleep, activity) and hearing aids: all three tasks are covered.

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Answer: (b) 2 and 3 only

Multi-drug resistance builds up when disease-causing microbes are repeatedly exposed to antibiotics they can survive, so wrong use of antibiotics in people and in farm animals is the cause. A patient's genes or other illnesses do not make a microbe resistant.

• ✗ 1. Resistance is a trait of the microbe, not of the patient. It spreads when misused antibiotics let the hardiest microbes survive and multiply; a person's genetic make-up plays no part in that.
• ✓ 2. Wrong doses, or stopping a course early, leave part of the bacterial population alive to multiply. WHO names the misuse and overuse of antimicrobials as the driver of drug-resistant pathogens.
• ✓ 3. Antibiotics given to food-producing animals expose bacteria on farms to the same drugs. India's animal husbandry department has advised all States and Union Territories to stop the use of antibiotics in animal feed for this reason.
• ✗ 4. Long-term illnesses may mean more infections and more medicines, but it is the misuse of antibiotics, not the patient's other disease, that produces resistant microbes.

Remember · Antimicrobial resistance is created by misuse and overuse of antibiotics, in humans and in animals. It is a property of the microbe, not of the patient.

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Answer: (b) Hepatitis B, unlike Hepatitis C, does not have a vaccine.

Statement (b) is the false one: hepatitis B has a safe and effective vaccine, usually given soon after birth, whereas it is hepatitis C that has no vaccine.

• ✗ (a) This statement is true, so it is not the answer. Both viruses pass on through blood and other body fluids, for example through unsafe injections, sex with an infected partner and from mother to child.
• ✓ (b) This is the statement that is not correct, so it is the answer. Hepatitis B can be prevented by a vaccine. NCERT Class 12 Biology notes that the hepatitis B vaccine is produced from yeast. Hepatitis C has no vaccine, but antiviral medicines can cure it.
• ✗ (c) This statement is true. WHO puts chronic hepatitis B at 240 million and chronic hepatitis C at 47 million people, against about 41 million people living with HIV.
• ✗ (d) This statement is true. Most people newly infected with hepatitis B have no symptoms, and chronic hepatitis C often stays silent for decades until the liver is damaged.
• • Since then The figures above are the latest WHO estimates (2024-25), not the 2019 numbers; the gap between hepatitis B and C infections and HIV infections is still several-fold.

Remember · Hepatitis B has a vaccine; hepatitis C does not. Both spread through blood and body fluids, and both can stay silent for years.

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (d) 1, 2, 3 and 4

All four spread plant diseases. Most plant pathogens travel as spores or bacteria, and these are carried by wind, blown dust, splashing rain and even by birds.

• ✓ 1. Spores stick to birds' feathers and beaks and are dropped on other plants. Chestnut blight spores, for example, are spread by many bird species, and powdery mildew fruiting bodies are carried on feathers.
• ✓ 2. Dust is lifted soil, and soil is a recognised carrier of fungal spores. Blowing dust moves them from diseased fields to healthy ones.
• ✓ 3. Rain splash and running water carry spores and bacteria from an infected leaf to healthy plant surfaces.
• ✓ 4. Wind brings the first spores from neighbouring fields or far away, and then spreads the secondary infection from plant to plant.

Remember · Plant pathogens are dispersed by wind, water (rain), dust or soil, insects and birds. Every listed agent can spread plant diseases.

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (c) Both 1 and 2

Zika is spread mainly by Aedes mosquitoes (chiefly Aedes aegypti), the same day-biting mosquitoes that carry dengue and chikungunya, and WHO confirms that it can also pass through sexual contact. Both statements are correct.

• ✓ 1. Aedes aegypti and Aedes albopictus carry Zika as well as dengue, chikungunya and urban yellow fever; these mosquitoes are most common in tropical and subtropical regions.
• ✓ 2. Besides mosquito bites, Zika spreads from mother to fetus in pregnancy, through sexual contact, blood transfusion and laboratory exposure.

Remember · Zika: flavivirus spread by Aedes aegypti (also dengue, chikungunya vector); also sexual and mother-to-fetus transmission; infection in pregnancy can cause microcephaly.

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (a) immunization of children and pregnant women

Mission Indradhanush is the Health Ministry's catch-up vaccination drive, launched in December 2014 under the Universal Immunization Programme. It targets districts and pockets where many children are unvaccinated or partly vaccinated, and also vaccinates pregnant women, with the aim of raising full immunisation coverage of children to 90%.

• ✓ (a) In its first three phases the mission reached more than 2.1 crore children and also vaccinated 55.9 lakh pregnant women against tetanus (MoHFW).
• ✗ (b) Urban development of 100 cities is the Smart Cities Mission (2015) of the Ministry of Housing and Urban Affairs.
• ✗ (c) Indradhanush ('rainbow') refers to the several vaccine-preventable diseases the drive targets; it has no link to astronomy or exoplanet searches.

Remember · Mission Indradhanush (December 2014, MoHFW): intensified vaccination of unvaccinated/partly vaccinated children and pregnant women in low-coverage areas; goal of 90% full immunisation.

Question and answer: UPSC's official GS Paper I (2016, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error