Consider the following statements: Statement-I. India does not import apples from the United States of America. Statement-II. In India, the law prohibits the import of Genetically Modified food without the approval of the competent authority. Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

(c) Statement-I is correct, but Statement-II is incorrect

Prelims · Science & technology · 30 questions

Biotechnology & genetics

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 10 of 11 years · most in 2021 (3)

UPSC syllabus: “General Science.” See the full syllabus →

Prelims 2026 · Q41

Easy Provisional key

Which of the following statements with regard to genetic medicine is/are correct?

1.Genetic medicines correct/compensate for the faulty genes responsible for disease.
2.Engineered viruses and lipid nanoparticles are used as carriers of the genetic medicine.
3.Genetic medicines alter the entire DNA sequence.

Select the answer using the code given below:

Answer & explanation

Answer: (c) 1 and 2 only

Genetic medicines work at the level of a faulty gene: they supply a working copy, replace the defective gene or give cells instructions. They need a carrier to get into cells, and engineered viruses and lipid bubbles are the usual ones. They do not rewrite the whole DNA sequence.

✓ 1. Gene therapy delivers a normal gene to take over the work of, and compensate for, a non-functional gene. Adding a healthy copy or replacing a defective gene is the standard approach.
✓ 2. Viral vectors are the classic carrier: NCERT's example uses a retroviral vector to put a working gene into a patient's lymphocytes. Lipid or fat bubbles are the other carrier, as in mRNA vaccines, where they surround the mRNA.
✗ 3. Genetic medicines target a gene or its message, not the whole DNA sequence. Gene therapy adds or replaces a defective gene, and a synthetic mRNA cannot alter DNA at all.

Remember · Genetic medicine (gene therapy, mRNA medicines): fixes or compensates for a faulty gene, using carriers such as engineered viruses or lipid nanoparticles. It never rewrites the whole genome.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 12 Biology, Ch 10 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 10 “Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.”
NCERT Class 12 · Biology, Chapter 10 “A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient.”
NHGRI (NIH), Understanding COVID-19 mRNA Vaccines ↗ “mRNA vaccines do not contain viral material. Instead, these vaccines contain lipid or fat bubbles that surround a segment of mRNA, which provide cells with the instructions to make a certain viral protein.”
NHGRI (NIH), Talking Glossary: Gene Therapy ↗ “Often, gene therapy works by adding new copies of a gene that is broken, or by replacing a defective or missing gene in a patient’s cells with a healthy version of that gene.”

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

Prelims 2026 · Q48

Easy Provisional key

Which of the following statements with regard to GenomeIndia Project is/are correct?

1.It is a part of the Human Genome Project.
2.The project is funded by the Department of Biotechnology (DBT), Government of India.
3.Its primary aim is to build a catalogue of genetic diversity of the Indian population.

Select the answer using the code given below:

Answer & explanation

Answer: (b) 2 and 3 only

GenomeIndia is India's own national genomics project, funded by the Department of Biotechnology, and its main goal is a catalogue of genetic variation across the Indian population. It is not a component of the Human Genome Project, which was a separate international effort completed in 2003.

✗ 1. The Human Genome Project was an international effort carried out from 1990 to 2003. GenomeIndia is a separate national initiative of 20 Indian institutions, not a part of it.
✓ 2. GenomeIndia is funded by the Department of Biotechnology, Ministry of Science and Technology.
✓ 3. Its primary objective is a comprehensive catalogue of genetic variations reflecting the diversity of the Indian population; whole-genome sequencing of 10,000 samples has been completed towards it.

Remember · GenomeIndia = DBT-funded national project cataloguing Indian genetic variation; data released January 2025 through the Indian Biological Data Centre. Not part of the 1990–2003 Human Genome Project.

Sources

GenomeIndia (Department of Biotechnology project website): funding ↗ · reference work “GenomeIndia is a pioneering scientific project funded by the Department of Biotechnology, Ministry of Science and Technology, Government of India. … The primary objective of GenomeIndia is to build a comprehensive catalogue of genetic variations that reflect the unique diversity of the Indian population.”
National Human Genome Research Institute (NIH, USA): Human Genome Project Fact Sheet ↗ “The Human Genome Project was a large, well-organized, and highly collaborative international effort that generated the first sequence of the human genome and that of several additional well-studied organisms.”

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

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 ·

Prelims 2024 · Q36

Medium

In which of the following are hydrogels used?

1.Controlled drug delivery in patients
2.Mobile air-conditioning systems
3.Preparation of industrial lubricants

Select the correct answer using the code given below:

Answer & explanation

Answer: (a) 1 only

Hydrogels are water-swollen networks of cross-linked polymers, soft and compatible with body tissue. Their best-established use is medical: a drug trapped in the gel is released over time at a controlled rate, and the gels are also used in wound dressings, contact lenses and tissue engineering. UPSC's key treats statements 2 and 3 as incorrect.

✓ 1. Hydrogels can hold small drugs, proteins or even cells and release them over time and at a chosen site, and several such delivery systems are in clinical use.
✗ 2. UPSC's official key treats this statement as incorrect; we could not confirm the detail from an official source, so we do not explain it here.
✗ 3. UPSC's official key treats this statement as incorrect; we could not confirm the detail from an official source, so we do not explain it here.

Remember · Hydrogel = cross-linked, water-absorbing polymer network; soft, biocompatible. Uses: controlled drug release, wound dressings, soft contact lenses, tissue engineering.

Sources

Li J, Mooney DJ. Designing hydrogels for controlled drug delivery. Nat Rev Mater 2016 (PubMed Central, US NIH) ↗ “Hydrogel delivery systems can leverage therapeutically beneficial outcomes of drug delivery and have found clinical use. Hydrogels can provide spatial and temporal control over the release of various therapeutic agents, including small-molecule drugs, macromolecular drugs and cells.”
Versatility of Hydrogels: From Synthetic Strategies, Classification, and Properties to Biomedical Applications (peer-reviewed review, via PubMed Central) ↗ “they are widely accepted for various biomedical applications such as wound dressing, controlled drug delivery, bone regeneration, tissue engineering, biosensors, and artificial contact lenses”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2024 · Q39

Easy

"Membrane Bioreactors" are often discussed in the context of:

Answer & explanation

Answer: (d) Wastewater treatment technologies

A membrane bioreactor (MBR) is a sewage and industrial-effluent treatment system. It joins the usual biological step, in which microbes break down organic waste, with fine membrane filtration that holds back solids and bacteria, so it produces clean, reusable water from a much smaller plant than conventional settling tanks.

✓ (d) The US EPA describes MBRs as a secondary-treatment technology for municipal wastewater that combines a suspended-growth biological reactor with microfiltration, removing nitrogen, phosphorus, bacteria and organic load.
✗ (c) Vaccine and biologics production uses bioreactors (fermenters) too, but the term 'membrane bioreactor' refers to the filtration-based wastewater process.
✗ (b) Nano drug-delivery systems use carriers such as liposomes and nanoparticles; they are not membrane bioreactors.

Remember · Membrane bioreactor = activated-sludge (microbial) treatment + membrane micro/ultrafiltration; compact, high-quality effluent fit for reuse. Used for sewage and industrial wastewater.

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

Sources

US EPA: Wastewater Management Fact Sheet, Membrane Bioreactors ↗ “The membranes can be designed for and operated in small spaces and with high removal efficiency of contaminants such as nitrogen, phosphorus, bacteria”
NCERT Class 12 · Biology, Chapter 8 “A major component of this waste water is human excreta. This municipal waste-water is also called sewage. It contains large amounts of organic matter and microbes.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q92

Medium

Consider the following statements:

Statement-I: India does not import apples from the United States of America.
Statement-II: In India, the law prohibits the import of Genetically Modified food without the approval of the competent authority.

Which one of the following is correct in respect of the above statements?

Answer & explanation

Answer: (d) Statement-I is incorrect, but Statement-II is correct

India does import apples from the United States, so Statement-I is wrong. Statement-II is right: the Food Safety and Standards Act, 2006 bars the import of genetically modified articles of food except as the Act and its regulations permit.

✗ Statement-I The Ministry of Commerce and Industry records apple imports from the USA of US$ 5.27 million in FY 2022-23, down from US$ 145 million in FY 2018-19 after India imposed an additional 20% duty on US apples in 2019. Imports fell but never stopped, and in June 2023 India announced it would remove that extra duty.
✓ Statement-II Section 22 of the Food Safety and Standards Act, 2006 says that, save as otherwise provided under the Act and its regulations, no person shall manufacture, distribute, sell or import genetically modified articles of food. Such food can therefore enter only where the law permits it.

Remember · India does import US apples (US$ 5.27 million in FY 2022-23). Section 22 of the FSS Act 2006 bars import of GM food articles unless the Act and regulations permit.

Sources

The removal of additional retaliatory duties for import of US apples will not result in any negative impact on domestic apple producers (PIB, Ministry of Commerce & Industry, 26 June 2023) ↗ “The import of apples from USA has decreased from US$ 145 million (127,908 Ton) in FY 2018-19 to only US$ 5.27 million (4,486 Ton) in FY 2022-23.”
Food Safety and Standards Act, 2006, Section 22 (FSSAI) ↗ “Save as otherwise provided under this Act and regulations made thereunder, no person shall manufacture, distribute, sell or import any novel food, genetically modified articles of food, irradiated food, organic foods”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q67

Easy

'Wolbachia method' is sometimes talked about with reference to which one of the following?

Answer & explanation

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.

Sources

Call for public consultation: Target Product Profiles for Wolbachia infected Aedes aegypti population replacement intervention (World Health Organization) ↗ “Wolbachia, a symbiotic bacterium that occurs naturally in many insects, has been successfully transferred into the Aedes aegypti mosquito and has been found to reduce the transmission of the dengue virus.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q69

Medium

'Aerial metagenomics' best refers to which one of the following situations?

Answer & explanation

Answer: (a) Collecting DNA samples from air in a habitat at one go

Aerial metagenomics means collecting DNA from the air in a habitat and sequencing it all together to see which organisms are present. Metagenomics studies the combined genetic material of many organisms in one bulk sample, and here the sample is air.

✓ (a) Air carries tiny particles (bioaerosols) shed by microbes, plants and animals. Sampling that air and sequencing the DNA in it at one go reveals the species around, without catching or disturbing any animal.
✗ (b) This describes genetic study of birds only. Metagenomics covers a whole mixed community of organisms in one sample, not one group such as avian species.
✗ (d) Drones collecting physical plant and animal samples from land and water are a sampling method, not a study of DNA collected from air.

Remember · Metagenomics reads the DNA of a whole community from one bulk sample. In aerial metagenomics that sample is air, giving a snapshot of the species around.

Sources

Metagenomics, Talking Glossary of Genomic and Genetic Terms (National Human Genome Research Institute, US NIH) ↗ “Metagenomics is the study of the structure and function of entire nucleotide sequences isolated and analyzed from all the organisms (typically microbes) in a bulk sample.”
AirDNA sampler: airborne environmental DNA for metagenomic applications (PLoS One, 2023, via PubMed Central) ↗ “metagenomic approach has allowed detection of DNA of plants, invertebrate animals, and vertebrate animals from bioaerosols as a comprehensive mean of diversity analysis in a particular environment”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q70

Medium

'Microsatellite DNA' is used in the case of which one of the following?

Answer & explanation

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.

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

Sources

NCERT Class 12 · Biology, Chapter 5 “These sequence show high degree of polymorphism and form the basis of DNA fingerprinting.”
Microsatellite, Talking Glossary of Genomic and Genetic Terms (National Human Genome Research Institute, US NIH) ↗ “The number of repeated segments within a microsatellite sequence often varies among people, which makes them useful as polymorphic markers for studying inheritance patterns in families or for creating a DNA fingerprint from crime scene samples.”

Question and answer: UPSC's official GS Paper I (2023, 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 · Q99

Medium

Consider the following statements:

DNA Barcoding can be a tool to:

1.assess the age of a plant or animal.
2.distinguish among species that look alike.
3.identify undesirable animal or plant materials in processed foods.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (d) 2 and 3

DNA barcoding identifies which species a sample belongs to by reading a short, standard piece of DNA. So it can tell apart look-alike (cryptic) species and can spot unwanted or undeclared species in processed food, but it does not tell the age of an organism.

✗ 1. A DNA barcode is a short standardised DNA marker used for detection and identification of species. It says what the organism is, not how old it is.
✓ 2. Barcodes can separate cryptic species, which look alike outwardly; a DNA mini-barcode with next-generation sequencing has been used to detect such species even in mixed seafood.
✓ 3. Processed foods are more likely to be substituted or adulterated with undeclared species, and DNA barcoding is used to check meat, poultry and fish products for such species.

Remember · DNA barcoding = species identification from a short standard DNA sequence (COI in animals). Uses: telling look-alike (cryptic) species apart and checking foods for undeclared species. Not for age.

Sources

Application of DNA barcoding for ensuring food safety and quality (Food Science and Biotechnology, via US National Library of Medicine PMC) ↗ “The DNA barcoding is a detection, identification, and diagnostic technique using a short standardized DNA marker … the newly developed DNA mini-barcode combined with next-generation sequencing (NGS) can detect cryptic species in mixed raw and processed seafood … Furthermore, the processed meat products are more likely to be substituted or adulterated with undeclared species.”

Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2021 · Q65

Medium

With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements:

1.Genetic engineering is applied in the development of these vaccines.
2.Bacteria and viruses are used as vectors.

Which of the statements given above is/are correct?

Answer & explanation

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.

📘 Read it in NCERT: Class 12 Biology, Ch 7 (practise this chapter) · Class 12 Biology, Ch 9 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 7 “Recombinant DNA technology has allowed the production of antigenic polypeptides of pathogen in bacteria or yeast.”
NCERT Class 12 · Biology, Chapter 9 “we have learnt the lesson of transferring genes into plants and animals from bacteria and viruses which have known this for ages”
US National Institute of Allergy and Infectious Diseases (NIH): Vaccine types (Internet Archive copy) ↗ “some vaccines use a harmless virus or bacterium as a vector, or carrier, to introduce genetic material into cells. Several such recombinant vector vaccines are approved to protect animals from infectious diseases, including rabies and distemper.”
WHO: The Sinovac COVID-19 vaccine (what you need to know) ↗ “the WHO EUL COVID-19 vectored vaccines (AstraZeneca Vaxzevria/COVISHIELD or Janssen)”

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2021 · Q66

Medium

In the context of hereditary diseases, consider the following statements:

1.Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
2.A child inherits mitochondrial diseases entirely from mother and not from father.

Which of the statements given above is/are correct?

Answer & explanation

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).

Sources

HFEA (UK regulator): Mitochondrial donation treatment (maternal spindle transfer) ↗ “In MST, your nuclear genetic material is removed from your eggs and transferred into donated eggs which have had their nuclear genetic material removed. The eggs are then fertilised with sperm to create embryos. … In PNT, your eggs are fertilised with sperm in a lab to create embryos. The nuclear genetic material within each embryo is then transferred into embryos created using donated eggs and sperm from the sperm provider.”
MedlinePlus (US National Library of Medicine): Inheritance patterns ↗ “Because only egg cells contribute mitochondria to the developing embryo, only females can pass on mitochondrial variants to their children.”

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2021 · Q67

Easy

Bollgard I and Bollgard II technologies are mentioned in the context of

Answer & explanation

Answer: (b) developing genetically modified crop plants

Bollgard I and Bollgard II are brand names of Bt cotton technology, that is, genetically modified cotton carrying Bt genes that protect it from bollworm pests. So they belong to developing genetically modified crop plants.

✓ (b) Bt cotton is a genetically modified crop: a Bt toxin gene from the bacterium Bacillus thuringiensis is expressed in the plant to resist insects. In Bollgard II hybrids, both the Cry1Ac and Cry2Ab proteins are present in the transgenic plant.
✗ (a) Clonal propagation copies plants from cuttings or tissue culture without adding genes; Bollgard involves inserted genes.
✗ (c) Plant growth substances are hormones such as auxins; Bollgard is not a hormone-making technology.
✗ (d) Biofertilizers are living microbes added to soil, whereas Bollgard is a trait built into the cotton plant itself.

Remember · Bollgard I and Bollgard II = Bt cotton (GM cotton); Bollgard II carries two Bt proteins, Cry1Ac and Cry2Ab.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 10 “Bt toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides; in effect created a bio-pesticide. Examples are Bt cotton”
PIB, Ministry of Science & Technology: Rapid diagnostic kits for genetically modified traits (Bollgard I and II) ↗ “Bt cotton ( Bollgard I) with cry1Ac gene was the first GM crop to be commercialized in India in March 2002 and Bt cotton ( Bollgard II) with cry1Ac and cry2Ab for insect resistance has also been commercialized.”

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2021 · Q70

Medium

Consider the following statements:

1.Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
2.Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.

Which of the statements given above is/are correct?

Answer & explanation

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.

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

Sources

NCERT Class 12 · Biology, Chapter 7 “AIDS is caused by the Human Immuno deficiency Virus (HIV), a member of a group of viruses called retrovirus, which have an envelope enclosing the RNA genome”
Gu et al., Molecular characterization of human adenovirus type 55, Virus Genes (2025), PubMed Central (US National Library of Medicine) ↗ “Adenoviruses are non-enveloped, double-stranded deoxyribonucleic acid (DNA) viruses that belong to the family Adenoviridae.”
CDC, About Adenovirus (archived copy) ↗ “Adenoviruses are common and typically cause mild cold or flu-like symptoms.”

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2020 · Q37

Medium

In the context of recent advances in human reproductive technology, "Pronuclear Transfer" is used for

Answer & explanation

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.

Sources

HFEA (UK Human Fertilisation and Embryology Authority), Mitochondrial donation treatment ↗ “Mitochondrial donation treatment can be used by people with severe mitochondrial disease to avoid passing the condition onto their children.”
Mitochondrial replacement to prevent the transmission of mitochondrial DNA disease (peer-reviewed article on PubMed Central, US National Library of Medicine) ↗ “Regulations were passed to enable the Human Fertilisation and Embryology Authority (HFEA) to consider applications to use pronuclear transfer and spindle transfer in clinical treatment to prevent transmission of mtDNA disease.”

Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2020 · Q41

Hard

With reference to carbon nanotubes, consider the following statements:

1.They can be used as carriers of drugs and antigens in the human body.
2.They can be made into artificial blood capillaries for an injured part of human body.
3.They can be used in biochemical sensors.
4.Carbon nanotubes are biodegradable.

Which of the statements given above are correct?

Answer & explanation

Answer: (c) 1, 3 and 4 only

Carbon nanotubes are tiny hollow tubes of rolled-up carbon sheets that are used in medicine to carry drugs and in biochemical sensors, and living systems can break them down with enzymes. Making artificial blood capillaries from them is not an established use, so statement 2 is the one that fails.

✓ 1. Carbon nanotubes are used as carriers, for example to deliver drugs and other payloads in the body, and are studied for bioimaging as well.
✗ 2. The established medical uses are bioimaging, drug delivery and biosensing. Building artificial blood capillaries for an injured body part is not one of them.
✓ 3. Biosensing is one of the main biomedical uses of functionalised carbon nanotubes.
✓ 4. Enzymes such as peroxidases can degrade carbon nanotubes, so they can be cleared from the body after delivering their payload; research is now focused on this route.

Remember · Carbon nanotubes: drug carriers and biosensors, and enzyme-degradable; not used as artificial blood capillaries.

Sources

Peroxidase-mediated biodegradation of carbon nanotubes in vitro and in vivo (review, PubMed Central, NIH author manuscript) ↗ “Biodegradation represents an attractive pathway for the eliminating of CNT carriers post-delivery and may be integral in catalyzing the release of the cargo from the delivery vehicle.”
Applications of Pristine and Functionalized Carbon Nanotubes, Graphene, and Graphene Nanoribbons in Biomedicine (review, PubMed Central) ↗ “The main part of this review includes the description of the applications of functionalized CNMs in bioimaging, drug delivery, and biosensors.”

Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2020 · Q44

Medium

Consider the following statements:

1.Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
2.A person's genome can be edited before birth at the early embryonic stage.
3.Human induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (d) 1, 2 and 3

All three statements describe things that science can already do: edit the genes of egg- and sperm-producing cells, edit the genome of a very early embryo, and inject human stem cells into a pig embryo to make a human-pig chimera. The word 'can' asks about technical possibility, not legal permission.

✓ 1. Gene editing of germ-line stem cells and gametes (eggs and sperm) is possible. India's stem cell guidelines name it and restrict such work to laboratory (in vitro) studies.
✓ 2. Germline editing means changing genes in eggs, sperm or very early embryos, and the change is heritable. So a person's genome can be edited at the early embryonic stage.
✓ 3. Human induced pluripotent stem cells (iPSCs, adult cells reprogrammed to an embryo-like state) have been injected into pig embryos. Some of the human iPSCs took part in the pig embryos' development, giving a chimera.

Remember · Germline and embryo editing and human-animal chimeras are technically possible today, though India restricts them to regulated laboratory work.

Sources

ICMR and DBT, National Guidelines for Stem Cell Research 2017 (glossary) ↗ “Germline Editing: It is a form of genetic modification that involves changing genes in eggs, sperm, or very early embryos. … Genome modification including gene editing (for example by CRISPR-Cas9 technology) of stem cells, germ-line stem cells or gamete and human embryos is restricted only to in vitro studies.”
Wu et al., Interspecies chimerism with mammalian pluripotent stem cells, Cell 2017 (PubMed Central) ↗ “Chimerism is observed with some human iPSCs in post-implantation pig embryos”

Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2019 · Q57

Medium

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 & explanation

Answer: (c) 3 only

Only statement 3 is correct. Section 3(j) of the Patents Act, 1970 rules out plants, seeds, varieties and essentially biological processes as patentable inventions. An Intellectual Property Appellate Board did exist when the question was set in 2019.

✗ 1. Section 3(j) treats seeds, varieties and species, and processes that are essentially biological, as non-inventions, so a biological method of making a seed cannot be patented.
✗ 2. In 2019 the Intellectual Property Appellate Board (IPAB) was still in existence, so the statement was wrong at the time.
✓ 3. Section 3(j) excludes plant varieties from patenting. New plant varieties are protected under the separate Protection of Plant Varieties and Farmers' Rights Act, 2001.
• Since then The Tribunals Reforms Act, 2021 (13 August 2021) lists the IPAB among the bodies it wound up, with pending cases transferred to the courts. Statement 2 would now read differently, but the answer for the 2019 paper stands.

Remember · Patents Act, section 3(j): plants, seeds, varieties and essentially biological processes are not patentable; plant varieties go to the PPV&FR Act, 2001.

Sources

The Patents Act, 1970, section 3(j) (as amended up to 1 August 2024), Indian Patent Office ↗ “plants and animals in whole or any part thereof other than micro-organisms but including seeds, varieties and species and essentially biological processes for production or propagation of plants and animals”
The Tribunals Reforms Act, 2021, Second Schedule, Department of Revenue ↗ “Intellectual Property Appellate Board under Trade Marks Act, 1999 (47 of 1999). … Any appeal, application or proceeding pending before the Tribunal, Appellate Tribunal or other Authorities specified in the Second Schedule”

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 ·

Prelims 2019 · Q92

Easy

The word 'Denisovan' is sometimes mentioned in media in reference to

Answer & explanation

Answer: (b) an early human species

Denisovans are an early human group (an archaic hominin population of the Late Pleistocene) first identified from DNA taken from a finger bone found in Denisova Cave in southern Siberia. The name has nothing to do with dinosaurs, a cave system in North-East India or a geological period.

✓ (b) In 2010 researchers sequenced the genome of an archaic hominin from a finger bone found in Denisova Cave in southern Siberia, and named this hominin population 'Denisovans'. Their DNA shows they shared a common origin with Neanderthals.
✗ (a) Denisovans were hominins, that is, relatives of modern humans, not dinosaurs.
✗ (c) Denisova Cave lies in southern Siberia, not in North-East India.
✗ (d) 'Denisovan' names a human population, not a geological period.

Remember · Denisovans: an archaic early human group, first identified in 2010 from DNA of a finger bone in Denisova Cave, southern Siberia; related to Neanderthals.

Sources

Reich et al., Genetic history of an archaic hominin group from Denisova Cave in Siberia, Nature 468 (2010) (NIH PMC copy), abstract ↗ “Using DNA extracted from a finger bone found in Denisova Cave in southern Siberia, we have sequenced the genome of an archaic hominin to about 1.9-fold coverage. … We designate this hominin population ‘Denisovans’ and suggest that it may have been widespread in Asia during the Late Pleistocene epoch.”

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2019 · Q93

Hard

With reference to the recent developments in science, which one of the following statements is not correct?

Answer & explanation

Answer: (a) Functional chromosomes can be created by joining segments of DNA taken from cells of different species.

UPSC's official answer: (a) · the answer UPSC accepted, and the one that counts in the exam

What we believe: no option fits strictly

Statements (b), (c) and (d) are textbook techniques: recombinant DNA 'created in vitro', PCR copying DNA 'in vitro', and cell culture. By elimination (a) is the only candidate, which is how UPSC's key arrives at it.
But (a) is also an established fact. A yeast artificial chromosome (YAC) joins yeast centromere, telomere and origin sequences to DNA from another organism, and the yeast cell copies the construct as a chromosome: 'as the yeast cells grow and divide, they amplify the YAC DNA' (NHGRI).
NCERT itself names YACs as working vectors of the Human Genome Project: 'the vectors were called as BAC (bacterial artificial chromosomes), and YAC (yeast artificial chromosomes)'. A chromosome built from yeast and foreign DNA that replicates in a cell is a functional chromosome made from the DNA of different species.
On a strict reading none of the four statements is incorrect; UPSC's key stands by elimination, treating (a) as the overstatement.

UPSC's key marks (a), and in the exam (a) is the option to mark, since the other three are familiar textbook techniques. Exam lesson: when three options are standard textbook facts, the fourth, least familiar claim is the one UPSC will mark.

NIH National Human Genome Research Institute, Talking Glossary: Yeast Artificial Chromosome (YAC) ↗“Yeast artificial chromosome (YAC) is a human-engineered DNA molecule used to clone DNA sequences in yeast cells. YACs are often used in connection with the mapping and sequencing of genomes.”
NIH National Human Genome Research Institute, Talking Glossary: YAC, how the construct replicates in yeast ↗“The YACs, with their inserted DNA, are then taken up by yeast cells. As the yeast cells grow and divide, they amplify the YAC DNA”
NCERT Class 12 Biology, Ch 5 Molecular Basis of Inheritance (Human Genome Project) ↗“The commonly used hosts were bacteria and yeast, and the vectors were called as BAC (bacterial artificial chromosomes), and YAC (yeast artificial chromosomes).”

This box is Minimalist IAS's analysis, with its sources; it does not change UPSC's answer.

UPSC's key treats statement (a) as the one that is not correct. Statements (b), (c) and (d) each name an established laboratory technique: recombinant DNA made in vitro, copying of DNA outside a cell by PCR, and plant and animal cell culture. Statement (a) claims more, that a working chromosome is created simply by joining DNA pieces from different species; the key treats that as an overstatement, since such splicing yields recombinant DNA, a molecule, not by itself a functioning chromosome.

✓ (a) UPSC's key marks this as the statement that is not correct. The key's reading: joining DNA segments from different species is the making of recombinant DNA, whereas a functional chromosome is an organised structure of DNA and proteins with its own origins, centromere and telomeres, and a splice of foreign DNA is not treated as creating one. By elimination too, (a) is the only candidate, since the other three are textbook techniques.
✗ (b) This statement is true. NCERT describes recombinant DNA, a new combination of DNA made in vitro by joining cut DNA pieces with the enzyme DNA ligase.
✗ (c) This statement is true. In the polymerase chain reaction (PCR), multiple copies of a DNA segment are synthesised in vitro, that is, outside a living cell.
✗ (d) This statement is true. Plant and animal cells can be grown outside the body in a nutrient-rich medium, where they grow and multiply; this is cell culture.

Remember · Lab techniques that are real: recombinant DNA (joined in vitro), PCR (copying DNA outside cells) and cell culture (cells dividing in dishes). UPSC's key treats 'creating a functional chromosome by splicing DNA from different species' as the overstatement.

📘 Read it in NCERT: Class 12 Biology, Ch 9 (practise this chapter) · Class 12 Biology, Ch 9 (practise this chapter) · Class 9 Exploration, Ch 2 (practise this chapter) · Class 12 Biology, Ch 5 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 9 “This makes a new combination of circular autonomously replicating DNA created in vitro and is known as recombinant DNA.”
NCERT Class 12 · Biology, Chapter 9 “PCR stands for Polymerase Chain Reaction. In this reaction, multiple copies of the gene (or DNA) of interest is synthesised in vitro”
NCERT Class 9 · Exploration, Chapter 2 “Scientists have developed methods to grow plant and animal cells outside the body in special conditions. This is called cell culture.”
NCERT Class 12 · Biology, Chapter 5 “The commonly used hosts were bacteria and yeast, and the vectors were called as BAC (bacterial artificial chromosomes), and YAC (yeast artificial chromosomes).”
NIH National Human Genome Research Institute, Talking Glossary: Yeast Artificial Chromosome (YAC) ↗ “Yeast artificial chromosome (YAC) is a human-engineered DNA molecule used to clone DNA sequences in yeast cells.”

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2019 · Q96

Medium

'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 & explanation

Answer: (a) 1, 2 and 4

RNA interference is a natural process in which a small RNA switches off a specific gene, so it is used for gene-silencing therapies, is being developed for cancer, and can make plants resist viruses. It is a way of switching genes off, not of supplying a hormone, so statement 3 does not fit.

✓ 1. Synthetic small interfering RNAs use RNAi to modulate gene function. The world's first RNAi drug, for a rare genetic liver disorder, has been approved.
✓ 2. Anticancer RNAi drugs are in development and have reached early clinical trials, although delivering them to tissues other than the liver remains a challenge.
✗ 3. Hormone replacement therapy supplies a hormone the body lacks. RNAi works by silencing a specific gene or mRNA, so it is not the basis of such therapies.
✓ 4. Plants can be engineered to carry sequences that target viral genes, so that RNAi silences the invading virus. NCERT notes that RNAi is a cellular defence that can be triggered by infection with RNA-genome viruses, and describes transgenic RNAi used to make plants resistant to a nematode pest.

Remember · RNAi silences a specific mRNA. Uses: gene-silencing drugs, cancer therapies under development, and virus-resistant crops; it does not supply hormones.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 12 Biology, Ch 10 (practise this chapter) · Class 12 Biology, Ch 10 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 10 “RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing).”
NCERT Class 12 · Biology, Chapter 10 “The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.”
NCERT Class 12 · Biology, Chapter 10 “The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA.”
Mary Ann Liebert / NIH PMC, RNA Interference-Based Cancer Drugs: The Roadblocks, and the Delivery of the Promise, abstract ↗ “Nucleic acid-based therapeutics like synthetic small interfering RNAs have been exploited to modulate gene function, taking advantage of RNA interference (RNAi), an evolutionally conserved biological process. Recently, the world's first RNAi drug was approved for a rare genetic disorder in the liver. … In this study, we discuss the critical design considerations in anticancer RNAi drug development, insights gained from initial clinical trials”
RNA Interference: Promising Approach to Combat Plant Viruses (NIH PMC), abstract ↗ “This natural RNAi pathway could introduce transgenes targeting various viral genes to induce gene silencing.”

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2019 · Q99

Easy

What is Cas9 protein that is often mentioned in news?

Answer & explanation

Answer: (a) A molecular scissors used in targeted gene editing

Cas9 is an enzyme that cuts DNA at a spot chosen by a guide RNA, which is why it is called molecular scissors. It is the cutting tool of CRISPR-Cas9 gene editing.

✓ (a) The guide RNA carries the address of the target DNA and Cas9 makes the cut there. Once the DNA is cut, the cell's repair process can be used to change the gene.
✗ (b) Cas9 is a cutting enzyme, not a sensor. Some diagnostic tests borrow it, but the protein itself is not a biosensor.
✗ (c) Cas9 is a protein (an enzyme), not a gene. It can be used to edit genes, including those that help plants resist pests, but it is not that gene.

Remember · CRISPR-Cas9: a guide RNA finds the DNA address and the Cas9 enzyme, the 'molecular scissors', cuts it.

Sources

PIB, Ministry of Science & Technology: CRISPR gene-editing possible in temperature sensitive organisms, plants & crop varieties (3 Nov 2022) ↗ “the associated Cas9 enzyme, which acts as molecular scissors to cut DNA at a location specified by a guide RNA, can bind to and cut the target DNA at very low temperatures.”

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 ·

Prelims 2018 · Q63

Medium

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 & explanation

Answer: (b) 2 only

Only statement 2 is correct. India's GM mustard hybrid (DMH-11) carries the barnase, barstar and bar genes, which give a pollination-control system for producing hybrid seed. It was developed at the University of Delhi, not by IARI and Punjab Agricultural University, and its genes do not give pest resistance.

✗ 1. The transgenes are barnase (makes the plant male-sterile), barstar (restores fertility) and bar (tolerance to the herbicide Basta, and a marker for selecting transformed lines). None is a pest-resistance gene like Bt.
✓ 2. The barnase-barstar system controls pollination, so two chosen diverse parent lines can be cross-pollinated to make a high-yielding hybrid.
✗ 3. It was developed by the Centre for Genetic Manipulation of Crop Plants (CGMCP), University of Delhi South Campus, and cleared by the GEAC in 2022, not by IARI and Punjab Agricultural University.

Remember · GM mustard DMH-11 (Delhi University's CGMCP) uses the barnase-barstar-bar genes for hybrid seed production through pollination control, not for pest resistance.

Sources

ICAR: Genetically modified (GM) Mustard hybrid will boost production and productivity ↗ “A robust pollination control system is required that would facilitate cross-pollination to help develop hybrids between any two selected diverse parental lines.”
PIB: Statement by Secretary DARE and DG ICAR on GM mustard ↗ “In India, the Centre for Genetic Manipulation of Crop Plants (CGMCP), University of Delhi South Campus, New Delhi has made a successful attempt with some alterations in the barnase/ barstar system”

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2018 · Q64

Easy

Consider the following pairs:

	Terms sometimes seen in news	Context/Topic
1.	Belle II experiment	Artificial Intelligence
2.	Blockchain technology	Digital/Cryptocurrency
3.	CRISPR – Cas9	Particle Physics

Which of the pairs given above is/are correctly matched?

Answer & explanation

Answer: (b) 2 only

Only the blockchain pair is right. Blockchain is the technology behind cryptocurrencies such as Bitcoin. Belle II is a particle-physics experiment in Japan, and CRISPR-Cas9 is a gene-editing tool used in biotechnology.

✗ 1. Belle II is a particle-physics experiment at the SuperKEKB collider at KEK, Tsukuba, Japan. It studies rare decays of B and D mesons and tau leptons, with an Indian team led by TIFR.
✓ 2. Blockchain is a shared, distributed ledger. NITI Aayog notes that it is the Bitcoin paper of 2008 that is most credited for the advent of the technology, so it is closely tied to digital currency.
✗ 3. CRISPR-Cas9 is a genome-editing technology; the Cas9 enzyme cuts DNA at a location set by a guide RNA. It belongs to biotechnology, not particle physics.

Remember · Belle II = particle physics (KEK, Japan); blockchain = ledger behind cryptocurrencies; CRISPR-Cas9 = gene editing.

Sources

Tata Institute of Fundamental Research (DAE): Belle (II) Collaboration ↗ · reference work “The Belle experiment at the KEK B-factory in Tsukuba (about 50 km northeast of Tokyo) was built to study that phenomenon, called charge-parity (CP) violation, in the decays of B mesons”
NITI Aayog: Blockchain: The India Strategy, Part I ↗ “it is the paper on the Bitcoin that is most credited for the advent of the new technology.”
PIB, Ministry of Science & Technology: CRISPR gene-editing possible in temperature sensitive organisms, plants & crop varieties (3 November 2022) ↗ “the associated Cas9 enzyme, which acts as molecular scissors to cut DNA at a location specified by a guide RNA”

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2017 · Q14

Medium

In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation technique?

1.It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature.
2.Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms.
3.Genetic engineering can be used to create microorganisms specifically designed for bioremediation.

Select the correct answer using the code given below:

Answer & explanation

Answer: (c) 1 and 3 only

Bioremediation speeds up the natural breakdown of pollutants by microbes, and microbes can be genetically engineered for the job. But microbes break down organic compounds; metals such as cadmium and lead are elements that cannot be degraded, only changed in form or immobilised, so statement 2 overclaims.

✓ 1. It uses microorganisms that feed on or co-metabolise contaminants, boosting the same biodegradation that happens in nature by supplying nutrients, oxygen or other electron acceptors.
✗ 2. Bioremediation is described as degrading organic contaminants. Heavy metals cannot be broken down by microbes, so 'readily and completely treated' is wrong; at best microbes change their chemical form.
✓ 3. Biotechnology uses genetically modified microbes for bioremediation; in 1971 Ananda Mohan Chakrabarty developed a bacterium that could break down oil spills.

Remember · Bioremediation = microbes degrading organic pollutants (oil, solvents, pesticides); engineered microbes help. Heavy metals cannot be degraded, only transformed or immobilised.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 8 Curiosity, Ch 2 (practise this chapter)

Sources

US EPA, CLU-IN: Bioremediation Overview ↗ · reference work “Bioremediation uses microorganisms to degrade organic contaminants in soil, groundwater, sludge, and solids. The microorganisms break down contaminants by using them as an energy source or cometabolizing them with an energy source.”
NCERT Class 12 · Biology, Chapter 10 “using genetically modified microbes, fungi, plants and animals. The applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production.”
NCERT Class 8 · Curiosity, Chapter 2 “In 1971, he developed a special bacterium that could break down oil spills, helping to clean the environment.”

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 ·

Prelims 2017 · Q45

Easy

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 & explanation

Answer: (d) 1, 2 and 3

All three uses are correct. Reading a crop's full DNA reveals markers for traits such as drought tolerance and disease resistance, cuts the years needed to breed a new variety, and shows how crops and their disease-causing organisms interact.

✓ 1. When 90 chickpea genomes were sequenced, the work gave millions of genetic markers that can be used to breed varieties with better drought tolerance and disease resistance.
✓ 2. Breeding a new chickpea variety normally takes 4–8 years; the scientists behind the chickpea genome said the sequence could cut this to half.
✓ 3. Sequencing crop and pathogen genomes lets researchers study plant–pathogen interactions and plant resistance at gene level.

Remember · Genome sequencing in crops: finds trait markers (drought, disease resistance), speeds up breeding (chickpea: 4–8 years cut to about half) and reveals host–pathogen interactions.

Sources

Global research team decodes genome sequence of 90 chickpea lines, ICAR ↗ · reference work “Re-sequencing of additional 90 genotypes provided millions of genetic markers and low diversity genome regions that may be used in the development of superior varieties with enhanced drought tolerance and disease resistance. … At the moment, it takes 4-8 years to breed a new chickpea variety. This genome sequence could reduce to half the time to breed for a new variety with market-preferred traits.”
Integrated Molecular and Bioinformatics Approaches for Disease-Related Genes in Plants, PMC (US National Library of Medicine) ↗ “The progress in the sequencing of agriculturally important crops has made it possible to develop a better understanding of plant–pathogen interactions and plant resistance.”

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 ·

Prelims 2017 · Q78

Easy

What is the application of Somatic Cell Nuclear Transfer Technology?

Answer & explanation

Answer: (c) Reproductive cloning of animals

Somatic Cell Nuclear Transfer (SCNT) is the technique used for reproductive cloning of animals. The nucleus of an ordinary body (somatic) cell is placed into an egg cell whose own nucleus has been removed, and the egg develops into an animal genetically identical to the donor.

✓ (c) Dolly the sheep (1997), the most famous cloned animal, was made this way. In India, NDRI Karnal has used a hand-guided version of the method to clone buffalo calves.
✗ (a) Biolarvicides are biological agents used to kill mosquito larvae. They have no link with moving cell nuclei.
✗ (b) Biodegradable plastics are made from natural or microbial polymers through chemistry and fermentation, not by nuclear transfer.
✗ (d) SCNT copies the donor's genome, including any inherited fault; it does not make an organism disease-free.

Remember · SCNT = nucleus of a body cell put into an enucleated egg. It is the method of reproductive cloning, as with Dolly the sheep.

Sources

US National Human Genome Research Institute (NIH): Cloning Fact Sheet ↗ “They then transfer the DNA of the donor animal's somatic cell into an egg cell, or oocyte, that has had its own DNA-containing nucleus removed.”
ICAR-National Dairy Research Institute, Karnal: Animal Biotechnology ↗ · reference work “Rajat was produced through Hand-guided cloning using somatic cells isolated from the frozen-thawed semen of a highly ranked progeny-tested Murrah buffalo bull”

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 ·

Prelims 2016 · Q31

Medium

In the context of the developments in Bioinformatics, the term 'transcriptome', sometimes seen in the news, refers to

Answer & explanation

Answer: (b) the full range of mRNA molecules expressed by an organism

Just as the genome is the full set of an organism's DNA, the transcriptome is the full set of RNA transcripts copied from that DNA, the 'gene readouts' in a cell. Of the options, 'the full range of mRNA molecules expressed' is the one that names this collection; the others describe tools, processes or mutations rather than a set of molecules.

✓ (b) Transcription copies genes into RNA; these gene readouts are called transcripts, and the transcriptome is the collection of all of them in a cell, with messenger RNA (mRNA) as the major type.
✗ (c) The transcriptome is a set of molecules, not an account of how gene expression works; reading it shows which genes are being expressed, but it is not the mechanism itself.
✗ (a) Genome-editing tools such as CRISPR-Cas9 nucleases are enzymes; they have nothing to do with the term transcriptome.

Remember · -ome words: genome = all DNA; transcriptome = all RNA transcripts (mainly mRNA) expressed in a cell; proteome = all proteins. The transcriptome changes with tissue, stage and condition.

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

Sources

NCERT Class 12 · Biology, Chapter 5 “The process of copying genetic information from one strand of the DNA into RNA is termed as transcription.”
US National Human Genome Research Institute (NIH): Transcriptome Fact Sheet ↗ “These gene readouts are called transcripts, and a transcriptome is a collection of all the gene readouts present in a cell. … The major type, called messenger RNA (mRNA), plays a vital role in making proteins.”

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 ·

The same topic in Mains

IT, space, robotics, biotech & IPRGS 3 syllabus

Read it in NCERT

Class 12 Biology, Chapter 10cited in 7 explanations
Class 12 Biology, Chapter 5cited in 5 explanations
Class 12 Biology, Chapter 9cited in 3 explanations
Class 12 Biology, Chapter 7cited in 2 explanations
Class 12 Biology, Chapter 8cited in 1 explanation
Class 9 Exploration, Chapter 2cited in 1 explanation

Biotechnology & genetics

The same topic in Mains

Read it in NCERT

More in Science & technology