Biology, health and biotechnology: previous-year questions
68 real UPSC Prelims questions (2011–2026) with the official answer and a clear explanation. 12 of them came in the last five papers.
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What is the importance of using Pneumococcal Conjugate Vaccines in India ?
- 1. These vaccines are effective against pneumonia as well as meningitis and sepsis.
- 2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.
- 3. These vaccines have no side effects and cause no allergic reactions.
Select the correct answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Pneumococcal Conjugate Vaccine (PCV) protects against Streptococcus pneumoniae, a bacterium that causes pneumonia, meningitis and sepsis (1). Pneumonia is a leading killer of young children in India. Statement 2 is right because fewer infections mean less antibiotic use, which slows the spread of drug-resistant bacteria. Statement 3 is wrong because, like every vaccine, PCV can cause side effects such as fever or swelling, and rare allergic reactions.
PCV was added to the Universal Immunisation Programme in 2017 and expanded across India in 2021. Notice India's own PCV, Pneumosil, made by the Serum Institute and approved in 2020. The U-WIN portal (2024) now records every vaccination digitally.
Answer as per the official UPSC answer key.
Which of the following statements are correct regarding the general difference between plant and animal cells?
- 1. Plant cells have cellulose cell walls whilst animal cells do not.
- 2. Plant cells do not have plasma membrane unlike animal cells which do.
- 3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles.
Select the correct answer using the code given below :
Answer (c) & explanation
Statements 1 and 3 are correct (c). Statement 1 is right because plant cells have a rigid cell wall made of cellulose, outside the cell membrane, which gives them shape and support. Animal cells have no cell wall. Statement 3 is right because a mature plant cell usually has one large central vacuole, filled with cell sap, which keeps the cell firm (turgid). Animal cells have only small, temporary vacuoles, or none. Statement 2 is wrong because both plant and animal cells have a plasma membrane. In plants it lies just inside the cell wall and controls what enters and leaves.
Other differences: plant cells have chloroplasts for photosynthesis, while animal cells have centrioles. Notice that fungi have walls of chitin, not cellulose.
Answer as per the official UPSC answer key.
‘RNA interference (RNAi)’ technology has gained popularity in the last few years. Why?
- 1. It is used in developing gene silencing therapies.
- 2. It can be used in developing therapies for the treatment of cancer.
- 3. It can be used to develop hormone replacement therapies.
- 4. It can be used to produce crop plants that are resistant to viral pathogens.
Select the correct answer using the code given below.
Answer (a) & explanation
Statements 1, 2 and 4 are correct (a). RNA interference (RNAi) uses small RNA molecules to silence specific genes by destroying their messenger RNA. It is the basis of gene-silencing drugs such as patisiran (1), approved in 2018. It is being tested in cancer therapies to switch off genes that help tumours grow (2). It is used to make virus-resistant crops, such as papaya resistant to ringspot virus (4). Statement 3 is wrong because hormone replacement adds a missing hormone, rather than switching a gene off, so RNAi plays no role.
Fire and Mello won the 2006 Medicine Nobel for discovering RNAi. Notice the related microRNA discovery, which won Ambros and Ruvkun the 2024 Medicine Nobel.
Answer as per the official UPSC answer key.
Which of the following are the reasons for the occurrence of multi-drug resistance in microbial pathogens in India?
- 1. Genetic predisposition of some people
- 2. Taking incorrect doses of antibiotics to cure diseases
- 3. Using antibiotics in livestock farming
- 4. Multiple chronic diseases in some people
Select the correct answer using the code given below.
Answer (b) & explanation
Statements 2 and 3 are correct (b). Antimicrobial resistance develops in the microbes themselves, when antibiotics kill weak germs and leave the resistant ones to multiply. In India, causes include wrong or incomplete doses of antibiotics (2), easy over-the-counter sales, and heavy antibiotic use in poultry and livestock to boost growth (3). Statements 1 and 4 are wrong because a person's genes or chronic diseases can make infections worse, but they do not make microbes resistant.
Notice India's response: the National Action Plan on AMR (2017, version 2.0 in 2025), the Chennai Declaration, the Red Line campaign on medicine packs, and the ban on colistin as a growth promoter in animals (2019). Kerala was the first state with its own AMR plan.
Answer as per the official UPSC answer key.
What is Cas9 protein that is often mentioned in news?
Answer (a) & explanation
Cas9 is a molecular scissors for gene editing (a). Cas9 is an enzyme found in bacteria, which use it to defend against viruses. A guide RNA leads Cas9 to a matching DNA sequence, where it cuts both strands. Scientists can then remove, fix or add genes. This is the CRISPR-Cas9 system, which won Charpentier and Doudna the 2020 Chemistry Nobel. It is not a biosensor (b), though related Cas proteins are used in tests. It is not a pest-resistance gene (c) like Bt, nor a herbicide (d).
Notice India's uses: the FELUDA COVID test used a related Cas protein, and India released two genome-edited rice varieties in 2025. The USA approved Casgevy, the first CRISPR therapy for sickle cell disease, in 2023.
Answer as per the official UPSC answer key.
Which one of the following statements is not correct?
Answer (b) & explanation
Option (b) is not correct, so it is the answer. Hepatitis B has had a safe, effective vaccine since the 1980s, and India gives it at birth under the Universal Immunisation Programme. Hepatitis C has no vaccine, but it can now be cured with antiviral drugs. Option (a) is correct because Hepatitis B spreads through blood, sex and from mother to child, much like HIV. Option (c) is correct because about 300 million people live with hepatitis B or C, far more than the roughly 40 million with HIV. Option (d) is correct because both can stay silent for years before causing cirrhosis or liver cancer.
Notice India's National Viral Hepatitis Control Programme (2018) and the WHO goal of eliminating hepatitis by 2030.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. According to the Indian Patents Act, a biological process to create a seed can be patented in India.
- 2. In India, there is no Intellectual Property Appellate Board.
- 3. Plant varieties are not eligible to be patented in India.
Which of the statements given above is/are correct?
Answer (c) & explanation
Only statement 3 is correct (c). Statement 1 is wrong because Section 3(j) of the Patents Act, 1970 excludes plants, animals, seeds, varieties, and essentially biological processes for producing them. Statement 2 was wrong in 2019, because the Intellectual Property Appellate Board (IPAB) existed, set up in 2003. It was abolished only in 2021 by the Tribunals Reforms Act, and its work went to the High Courts. Statement 3 is right because plant varieties cannot be patented. They are protected under the Protection of Plant Varieties and Farmers' Rights (PPV&FR) Act, 2001, a sui generis law allowed by TRIPS.
Notice the PepsiCo case: in 2024, the Delhi High Court upheld the cancellation of its registration for the FL-2027 potato variety, used for Lay's chips.
When an institution has since been abolished, answer from the year the question was set.
Answer as per the official UPSC answer key.
The word ‘Denisovan’ is sometimes mentioned in media in reference to
Answer (b) & explanation
Denisovans are an early human species (b). They are an archaic human species, closely related to the Neanderthals. They were first identified in 2010 from DNA in a finger bone found in Denisova Cave, in Siberia's Altai Mountains. They interbred with modern humans. Traces of their DNA survive in people of Melanesia, Papua New Guinea and parts of Asia. A Denisovan gene, EPAS1, helps Tibetans live at high altitude. They are not dinosaurs (a), a North-East Indian cave (c), or a geological period (d).
Notice the newer finds: a Denisovan jaw from Tibet's Baishiya Cave, and the Harbin skull from China, confirmed as Denisovan in 2025. Svante Pääbo won the 2022 Medicine Nobel for this work.
Answer as per the official UPSC answer key.
With reference to the recent developments in science, which one of the following statements is not correct?
Answer (a) & explanation
Option (a) is the statement that is not correct. Option (b) is correct because scientists can synthesise DNA in the lab, and Craig Venter's team made a bacterium with a fully synthetic genome (2010). Option (c) is correct because the polymerase chain reaction (PCR) copies DNA outside a living cell. Option (d) is correct because plant and animal cells can be grown and made to divide in tissue culture in petri dishes. Recombinant DNA does join genes from different species, but UPSC's key treats building a working chromosome by splicing segments from different species as not possible.
Notice the related news: genome-edited rice varieties released by India in 2025, and synthetic biology research on yeast with synthetic chromosomes (Sc2.0).
Answer as per the official UPSC answer key.
Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss ?
- 1. Hard and waxy leaves
- 2. Tiny leaves
- 3. Thorns instead of leaves
Select the correct answer using the code given below :
Answer (d) & explanation
All three are desert adaptations (d). Desert plants, called xerophytes, cut water loss in several ways. They have hard, waxy leaves with a thick cuticle that reduces evaporation (1), as in Calotropis (aak). They have tiny leaves with fewer, often sunken, stomata (2), as in Acacia and Prosopis (khejri). In some plants, leaves turn into spines or thorns (3), as in cacti and Opuntia, where the green, fleshy stem takes over photosynthesis.
Many desert plants also use CAM photosynthesis, opening their stomata only at night, and they have very deep roots. Notice the opposite case: hydrophytes such as lotus and water hyacinth have stomata on the upper leaf surface and air spaces for floating.
Answer as per the official UPSC answer key.
With reference to the Genetically Modified mustard (GM mustard) developed in India, consider the following statements :
- 1. GM mustard has the genes of a soil bacterium that give the plant the property of pest-resistance to a wide variety of pests.
- 2. GM mustard has the genes that allow the plant cross-pollination and hybridization.
- 3. GM mustard has been developed jointly by the IARI and Punjab Agricultural University.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Only statement 2 is correct (b). GM mustard DMH-11 carries the barnase–barstar genes from a soil bacterium, Bacillus amyloliquefaciens. Barnase makes one parent line male-sterile, and barstar restores fertility in the cross, allowing hybrid seed production (2). A third gene, bar, gives herbicide tolerance. Statement 1 is wrong because it does not give pest resistance; that is Bt technology, as in Bt cotton. Statement 3 is wrong because it was developed by Delhi University's Centre for Genetic Manipulation of Crop Plants under Deepak Pental, not IARI and PAU.
The GEAC approved its environmental release in October 2022. Notice the Supreme Court's split verdict (July 2024), which asked the Centre to frame a national GM crops policy.
The genes do come from a soil bacterium, but they are for hybridisation, not pest resistance.
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Answer as per the official UPSC answer key.
Consider the following statements :
- 1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
- 2. Sexual transmission of Zika virus disease is possible.
Which of the statements given above is/are correct ?
Answer (c) & explanation
Both statements are correct (c). Zika, a flavivirus, is spread mainly by Aedes aegypti (1). This is the same day-biting mosquito that carries dengue, chikungunya and yellow fever, and it breeds in clean, standing water. Zika can also spread sexually (2), through blood transfusion, and from mother to foetus, where it can cause microcephaly (an abnormally small head). The 2015–16 outbreak in Brazil led the WHO to declare a public health emergency of international concern.
India has seen outbreaks in Gujarat (2017), Rajasthan, Kerala and Maharashtra. Notice the control methods, such as source reduction and Wolbachia-infected mosquitoes that cut virus spread. Also remember the different carrier for malaria: the Anopheles mosquito.
Answer as per the official UPSC answer key.
With reference to agriculture in India, how can the technique of ‘genome sequencing’ often seen in the news, be used in the immediate future ?
- 1. Genome sequencing can be used to identify genetic markers for disease resistance and drought tolerance in various crop plants.
- 2. This technique helps in reducing the time required to develop new varieties of crop plants.
- 3. It can be used to decipher the host-pathogen relationships in crops.
Select the correct answer using the code given below :
Answer (d) & explanation
All three are correct (d). Genome sequencing reads an organism's full DNA. In crops, it helps scientists find genetic markers for traits such as disease resistance and drought tolerance (1). These markers drive marker-assisted selection, which can cut years off breeding new varieties (2). Sequencing both the crop and its pathogen shows how infection works, revealing host–pathogen relationships (3) and helping to design resistance.
India helped sequence rice, wheat, tomato and chickpea. Notice the new tools: in 2025, ICAR released the world's first genome-edited rice varieties (DRR Dhan 100 Kamala and Pusa DST Rice 1) using SDN-1/2 editing, which India exempts from GM rules. Pusa Basmati 1509 with blast resistance came from marker-assisted breeding.
Answer as per the official UPSC answer key.
What is the application of Somatic Cell Nuclear Transfer Technology ?
Answer (c) & explanation
SCNT is used for reproductive cloning of animals (c). In Somatic Cell Nuclear Transfer, the nucleus of a body (somatic) cell is placed into an egg whose own nucleus has been removed. The egg is then made to divide and grows into a genetic copy of the donor. Dolly the sheep (1996, Roslin Institute) was the first mammal cloned this way. In India, NDRI Karnal cloned the buffalo Garima (2010), and India later cloned a Gir calf and cloned camels in Dubai. SCNT has nothing to do with biolarvicides (a), bioplastics (b), or disease-free organisms (d).
It is also used for therapeutic cloning, to make patient-matched stem cells. Notice the ethics: India bans human reproductive cloning under ICMR guidelines.
Answer as per the official UPSC answer key.
In the context of the developments in Bioinformatics, the term ‘transcriptome’, sometimes seen in the news, refers to
Answer (b) & explanation
The transcriptome is the full set of RNA transcripts, mainly mRNA, that an organism or cell expresses at a given time (b). Option (a) is wrong: genome-editing enzymes such as CRISPR-Cas9 are tools, not a transcriptome. Option (c) is wrong because the transcriptome is a set of molecules, not a description of how genes are expressed. Option (d) is wrong because mutations change DNA itself.
Think of the "-omes" in a row: the genome is all the DNA, the transcriptome all the RNA, and the proteome all the proteins. Notice how comparing transcriptomes of healthy and diseased cells reveals which genes are switched on, helping cancer research and crop science.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct?
Viruses can infect
- 1. bacteria
- 2. fungi
- 3. plants
Select the correct answer using the code given below.
Answer (d) & explanation
All three are correct (d). Viruses can infect every kind of cellular life. Bacteriophages infect bacteria (1). The T4 phage is the classic example, and phages are now being tested as phage therapy against antibiotic-resistant germs. Mycoviruses infect fungi (2), and some are being explored as biocontrol agents. Plant viruses infect plants (3). Tobacco mosaic virus, the first virus ever discovered (Ivanovsky, 1892), is one example, along with banana bunchy top and cotton leaf curl.
Viruses also infect archaea, and even giant viruses can be attacked by virophages. Notice why viruses sit outside the five-kingdom classification: they have no cell machinery of their own. They are inert outside a host and come alive only inside a living cell.
Answer as per the official UPSC answer key.
H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases?
Answer (d) & explanation
H1N1 is the influenza A strain behind the 2009 swine flu pandemic (d), and it has returned in seasonal waves in India. H and N stand for the surface proteins haemagglutinin and neuraminidase. AIDS (a) is caused by HIV, dengue (c) by the dengue virus spread by the Aedes mosquito, and bird flu (b) is usually caused by H5N1.
The 2009 virus mixed genes from pig, bird and human flu viruses, which is why it was called swine flu. Notice how the One Health approach links human, animal and environmental health to prevent such outbreaks.
Answer as per the official UPSC answer key.
With reference to the use of nano-technology in health sector, which of the following statements is/are correct?
- 1. Targeted drug delivery is made possible by nanotechnology.
- 2. Nanotechnology can largely contribute to gene therapy.
Select the correct answer using the code given below.
Answer (c) & explanation
Both are correct (c). Nanoparticles such as liposomes, dendrimers and gold particles can carry drugs straight to diseased cells like tumours, sparing healthy tissue (1). They also act as non-viral carriers of genes in gene therapy (2).
The lipid nanoparticles used in mRNA COVID-19 vaccines apply the same idea, wrapping fragile genetic material to carry it into cells. Nano-based diagnostics can also detect diseases earlier. Notice how a physics idea, the special behaviour of matter at the nanoscale, is reshaping medicine, though safety and toxicity questions remain.
Answer as per the official UPSC answer key.
The Genetic Engineering Appraisal Committee is constituted under the
Answer (c) & explanation
The Genetic Engineering Appraisal Committee works under the Rules, 1989 framed under the Environment (Protection) Act, 1986 (c). It sits in the Environment Ministry and approves the environmental release of GM organisms. The Food Safety Act (a), the GI Act (b) and the Wildlife Act (d) do not create it.
GEAC approved Bt cotton in 2002, India's only commercial GM crop so far, and conditionally approved GM mustard (DMH-11) for environmental release in 2022. It also cleared then put on hold Bt brinjal in 2009–10. Notice how biotech regulation balances innovation with biosafety.
Answer as per the official UPSC answer key.
Consider the following diseases :
- 1. Diphtheria
- 2. Chickenpox
- 3. Smallpox
Which of the above diseases has/have been eradicated in India?
Answer (b) & explanation
Only smallpox has been eradicated (b). India's last case was in 1975, and WHO certified global eradication in 1980, the first disease ever wiped out. Diphtheria still breaks out where vaccine coverage is low, and chickenpox remains common, so options with 1 or 2 fail.
India was declared polio-free in 2014; that is regional elimination, since wild polio still exists in a few countries. Among animal diseases, rinderpest was eradicated in 2011. Notice the language: eradication is worldwide and permanent, elimination is national or regional. The DPT vaccine in the Universal Immunisation Programme protects against diphtheria.
Answer as per the official UPSC answer key.