UPSC Prelims 2012 Science and Technology questions: topic-wise weightage
UPSC Prelims 2012 asked 13 science and technology questions in GS Paper I, spread over 3 topics. See the science and technology weightage for 2012 below, then attempt each question with the official answer and an explanation.
Science and Technology 2012: questions by topic
- Biology, health and biotechnology5
- Space technology1
- Physics and chemistry in daily life; energy and nuclear technology7
Counted from the 13 questions on this page, tagged by topic in the Battle IAS PYQ bank.
Seeing 13 Science and Technology questions spread over 3 topics can feel overwhelming. That's exactly why the Battle IAS PYQ Book maps every question topic by topic, so you know what to study first. Download free sample
Biology, health and biotechnology 5
Consider the following kinds of organisms :
- 1. Bacteria
- 2. Fungi
- 3. Flowering plants
Some species of which of the above kinds of organisms are employed as biopesticides?
Answer (d) & explanation
All three are correct (d). Biopesticides come from living organisms of all three kinds. Bacteria: Bacillus thuringiensis (Bt) makes proteins toxic to caterpillars (1). Fungi: Trichoderma controls soil-borne diseases, and Beauveria and Metarhizium infect insects (2). Flowering plants: neem (azadirachtin) and pyrethrum from chrysanthemum flowers act as natural insecticides (3). So options (a), (b) and (c) leave out real sources.
Notice the advantages: biopesticides are specific, biodegradable and safer for pollinators. Viruses such as NPV (nuclear polyhedrosis virus) are also used. In India they are registered under the Insecticides Act, 1968, and promoted under the National Mission on Natural Farming. Trap: plants are often forgotten as a source.
Answer as per the official UPSC answer key.
With reference to ‘stem cells’, frequently in the news, which of the following statements is/are correct?
- 1. Stem cells can be derived from mammals only.
- 2. Stem cells can be used for screening new drugs.
- 3. Stem cells can be used for medical therapies.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Stem cells are unspecialised cells that can divide and turn into other cell types. They are used to grow tissues in the lab to screen new drugs for safety and effect (2), and in therapies such as bone-marrow transplants for leukaemia (3). Statement 1 is wrong: stem cells exist in all multicellular organisms, including plants (meristems), not only mammals. So (a), (c) and (d) fail.
Notice the types: embryonic (pluripotent), adult (multipotent) and induced pluripotent stem cells (iPSCs), for which Shinya Yamanaka shared the 2012 Nobel Prize. India's ICMR guidelines (2017) permit only approved stem-cell therapies, mainly bone-marrow transplants. Trap: 'mammals only' is too narrow.
Answer as per the official UPSC answer key.
Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
Answer (b) & explanation
Carbon, hydrogen and nitrogen is correct (b). Life's building blocks, amino acids, sugars, fats and nucleic acids, are made mainly of carbon, hydrogen, nitrogen and oxygen, with phosphorus and sulphur. The Miller–Urey experiment (1953) made amino acids by passing sparks through methane, ammonia, hydrogen and water, mimicking the early Earth. (a) and (d) are wrong: sodium and potassium are minerals important for cells but not the core of organic molecules. (c) is wrong: calcium is not primary, and the early atmosphere had little free oxygen.
Notice the related theories: Oparin–Haldane's 'primordial soup', the RNA world, and life near deep-sea hydrothermal vents. Oxygen built up later through cyanobacteria in the Great Oxidation Event (about 2.4 billion years ago). Trap: oxygen is essential now but was not primary then.
Answer as per the official UPSC answer key.
What are the reasons for the people’s resistance to the introduction of Bt brinjal in India?
- 1. Bt brinjal has been created by inserting a gene from a soil fungus into its genome.
- 2. The seeds of Bt brinjal are terminator seeds and therefore, the farmers have to buy the seeds before every season from the seed companies.
- 3. There is an apprehension that the consumption of Bt brinjal may have adverse impact on health.
- 4. There is some concern that the introduction of Bt brinjal may have adverse effect on the biodiversity.
Select the correct answer using the codes given below :
Answer (c) & explanation
Statements 3 and 4 are correct (c). The 2010 moratorium on Bt brinjal followed public fears about possible health effects of eating it (3), and concern that it could contaminate India's many native brinjal varieties, since India is a centre of origin of brinjal (4). Statement 1 is wrong: the Bt gene comes from a bacterium, Bacillus thuringiensis, not a fungus. Statement 2 is wrong: Bt brinjal seeds are not terminator seeds; terminator technology was never commercialised, and public-sector Bt brinjal varieties could be saved. So (a), (b) and (d) fail.
Notice the context: GEAC cleared it in 2009, but Jairam Ramesh imposed the moratorium after public hearings in February 2010. Bangladesh has grown Bt brinjal since 2014. Trap: two plausible myths are mixed with two real concerns.
Answer as per the official UPSC answer key.
Other than resistance to pests, what are the prospects for which genetically engineered plants have been created?
- 1. To enable them to withstand drought
- 2. To increase the nutritive value of the produce
- 3. To enable them to grow and do photosynthesis in spaceships and space stations
- 4. To increase their shelf life
Select the correct answer using the codes given below :
Answer (c) & explanation
Items 1, 2 and 4 are correct (c). Genetic engineering has produced crops for drought tolerance, such as Argentina's HB4 wheat and drought-tolerant maize (1), better nutrition, such as Golden Rice with beta-carotene, approved in the Philippines (2), and longer shelf life, such as the Flavr Savr tomato (1994) and non-browning Arctic apples (4). Item 3 is wrong: there are no GM plants created to photosynthesise in spaceships; plants are grown in space experiments, but not engineered for that purpose. So (a), (b) and (d) fail.
Notice India's position: Bt cotton remains the only GM crop grown commercially; GM mustard DMH-11 got environmental release approval in 2022 but is in court, and genome-edited rice varieties released in May 2025 are not classed as GM. Trap: space farming exists, but not as a GM aim.
Answer as per the official UPSC answer key.
Space technology 1
Which of the following is/are cited by the scientists as evidence/evidences for the continued expansion of universe?
- 1. Detection of microwaves in space
- 2. Observation of redshift phenomenon in space
- 3. Movement of asteroids in space
- 4. Occurrence of supernova explosions in space
Select the correct answer using the codes given below :
Answer (a) & explanation
Microwaves and redshift are correct (a). Light from distant galaxies is red-shifted: its wavelength is stretched because the galaxies are moving away, faster the farther they are (Hubble's law) (2). The cosmic microwave background radiation, found in 1965, is the cooled afterglow of the Big Bang, spread evenly across the sky (1). Statement 3 is wrong: asteroids move within our solar system and say nothing about expansion. Statement 4 is wrong: supernovae alone are not evidence, though Type Ia supernovae used as distance markers showed in 1998 that expansion is accelerating. So (b), (c) and (d) fail.
Notice the puzzle: this acceleration is blamed on dark energy, and the 'Hubble tension' is a mismatch in measured expansion rates. Trap: (4) hides a partial truth.
Answer as per the official UPSC answer key.
Physics and chemistry in daily life; energy and nuclear technology 7
Biomass gasification is considered to be one of the sustainable solutions to the power crisis in India. In this context, which of the following statements is/are correct?
- 1. Coconut shells, groundnut shells and rice husk can be used in biomass gasification.
- 2. The combustible gases generated from biomass gasification consist of hydrogen and carbon dioxide only.
- 3. The combustible gases generated from biomass gasification can be used for direct heat generation but not in internal combustion engines.
Select the correct answer using the codes given below :
Answer (a) & explanation
Statement 1 only is correct (a). A gasifier partly burns biomass in limited air to make producer gas. Coconut shells, groundnut shells and rice husk are all good feedstocks (1). Statement 2 is wrong: the gas is mainly carbon monoxide, hydrogen and methane, with nitrogen and some CO₂; carbon dioxide does not burn. Statement 3 is wrong: the gas can be used for heat and also to run internal combustion engines for electricity, as in village power plants. So (b), (c) and (d) fail.
Notice the example: Husk Power Systems in Bihar has lit villages using rice-husk gasifiers since 2007. India's SATAT scheme promotes compressed biogas, a different, biological route. Trap: 'only' and 'but not' make statements 2 and 3 false.
Answer as per the official UPSC answer key.
What is the role of ultraviolet (UV) radiation in the water purification systems?
- 1. It inactivates/kills the harmful microorganisms in water.
- 2. It removes all the undesirable odours from the water.
- 3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water.
Which of the statements given above is/are correct?
Answer (a) & explanation
Statement 1 only is correct (a). Ultraviolet light, especially at about 254 nm, damages the DNA of bacteria and viruses, so they cannot multiply; this inactivates harmful microbes (1). Statement 2 is wrong: UV adds no chemicals and does not remove odours; activated carbon filters do that. Statement 3 is wrong: UV does not settle particles or remove turbidity; in fact, cloudy water shields microbes from UV, so water must be filtered first. So (b), (c) and (d) fail.
Notice the related methods: chlorination leaves a residual disinfectant, reverse osmosis removes dissolved salts, and ozonation also disinfects. UV does not remove arsenic or fluoride. Trap: UV is a disinfection step only.
Answer as per the official UPSC answer key.
Graphene is frequently in news recently. What is its importance?
- 1. It is a two-dimensional material and has good electrical conductivity.
- 2. It is one of the thinnest but strongest materials tested so far.
- 3. It is entirely made of silicon and has high optical transparency.
- 4. It can be used as ‘conducting electrodes’ required for touch screens, LCDs and organic LEDs.
Which of the statements given above are correct?
Answer (c) & explanation
Statements 1, 2 and 4 are correct (c). Graphene is a single layer of carbon atoms arranged in a honeycomb, so it is two-dimensional and conducts electricity very well (1). It is one atom thick yet about 200 times stronger than steel (2). Being nearly transparent and conductive, it suits conducting electrodes in touch screens, LCDs and OLEDs (4). Statement 3 is wrong: it is made of carbon, not silicon. So (a), (b) and (d) fail.
Notice the history: Andre Geim and Konstantin Novoselov won the 2010 Nobel Prize in Physics for isolating it with sticky tape. India set up the India Graphene Engineering and Innovation Centre in Kerala. Trap: 'silicon' comes from the link with electronics.
Answer as per the official UPSC answer key.
A team of scientists at Brookhaven National Laboratory including those from India created the heaviest anti-matter (anti-helium nucleus). What is/are the implication/implications of the creation of anti-matter?
- 1. It will make mineral prospecting and oil exploration easier and cheaper.
- 2. It will help probe the possibility of the existence of stars and galaxies made of anti-matter.
- 3. It will help understand the evolution of the universe.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). The anti-helium-4 nucleus, the heaviest antimatter nucleus then made, was detected at the RHIC collider at Brookhaven (2011), with Indian scientists in the STAR team. Such work helps search for antimatter stars and galaxies (2) and understand why the early universe ended up with more matter than antimatter (3). Statement 1 is wrong: antimatter has no use in mineral or oil exploration; it is made in tiny amounts and vanishes on contact with matter. So (a), (c) and (d) fail.
Notice the related tools: the Alpha Magnetic Spectrometer on the ISS searches for cosmic antimatter. Positrons (anti-electrons) are used in medical PET scans. Trap: practical-sounding uses are attached to basic physics.
Answer as per the official UPSC answer key.
To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium?
- 1. Thorium is far more abundant in nature than uranium.
- 2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium.
- 3. Thorium produces less harmful waste compared to uranium.
Which of the statements given above is/are correct?
Answer (d) & explanation
All three are correct per UPSC's key (d). Thorium is about three to four times more abundant than uranium in the Earth's crust, and India holds about a quarter of world reserves in monazite sands of Kerala, Tamil Nadu and Odisha (1). Nearly all mined thorium-232 can be bred into fissile uranium-233, unlike the 0.7% U-235 in natural uranium, so it can yield more energy per tonne mined (2). The thorium cycle produces far fewer long-lived transuranic wastes such as plutonium (3). So (a), (b) and (c) leave out real advantages.
Notice India's plan: thorium is stage three of Bhabha's three-stage programme; the Prototype Fast Breeder Reactor at Kalpakkam began core loading in 2024. Thorium is not fissile itself, so it needs a starter fuel. Trap: 'more energy' holds only via breeding.
Answer as per the official UPSC answer key.
Recently, there has been a concern over the short supply of a group of elements called ‘rare earth metals’. Why?
- 1. China, which is the largest producer of these elements, has imposed some restrictions on their export.
- 2. Other than China, Australia, Canada and Chile, these elements are not found in any country.
- 3. Rare earth metals are essential for the manufacture of various kinds of electronic items and there is a growing demand for these elements.
Which of the statements given above is/are correct?
Answer (c) & explanation
Statements 1 and 3 are correct (c). In 2010, China, which then produced over 90% of the world's rare earths, cut export quotas (1), just as demand was rising for magnets, phones, batteries, wind turbines and electric vehicles (3). Statement 2 is wrong: rare earths are found in many countries, including India (monazite sands), the USA, Brazil, Vietnam and Russia. So (a), (b) and (d) fail.
Notice the recent turn: China imposed export controls on several rare earths and magnets in April 2025 and widened them in October 2025, hurting automakers. India launched a National Critical Mineral Mission (2025) and a scheme for rare earth permanent magnets (November 2025); IREL handles domestic output. Trap: 'rare' refers to concentration, not scarcity.
Answer as per the official UPSC answer key.
Consider the following statements :
If there were no phenomenon of capillarity
- 1. it would be difficult to use a kerosene lamp
- 2. one would not be able to use a straw to consume a soft drink
- 3. the blotting paper would fail to function
- 4. the big trees that we see around would not have grown on the Earth
Which of the statements given above are correct?
Answer (b) & explanation
Statements 1, 3 and 4 are correct (b). Capillarity draws liquid up narrow spaces because of adhesion and surface tension. It lifts kerosene up a lamp wick (1), soaks ink into blotting paper (3), and helps raise water up the narrow xylem vessels of trees, along with transpiration pull and cohesion (4). Statement 2 is wrong: drinking through a straw works by air pressure; sucking lowers the pressure inside, and atmospheric pressure pushes the drink up. So (a), (c) and (d) fail.
Notice the related examples: water rising in soil and in a towel, and the meniscus in thin tubes. Mercury shows capillary fall, not rise, because cohesion exceeds adhesion. Trap: the straw is about pressure, not capillarity.
Answer as per the official UPSC answer key.
All years by topic
Every question from 2011 to 2026, grouped by syllabus topic, with year-wise trends.