149 UPSC previous-year questions in Science, with answers and concise explanations, grouped by topic. Showing the 120 most recent — open a topic for the rest.
Read the Science notesConsider the following statements: I. It is expected that Majorana 1 chip will enable quantum computing. II. Majorana 1 chip has been introduced by Amazon Web Services (AWS). III. Deep learning is a subset of machine learning. Which of the statements given above are correct?
Why
Majorana 1 is Microsoft's topological quantum chip, not AWS; deep learning is indeed a subset of machine learning.
Which one of the following words/phrases is most appropriately used to denote "an interoperable network of 3D virtual worlds that can be accessed simultaneously by millions of users, who can exert property rights over virtual items"?
Why
The metaverse is defined as a persistent, shared network of 3D virtual spaces where users interact and own virtual assets.
Consider the following activities:
In how many of the above activities can the radars be used?
Why
Radars can detect concealed objects including narcotics, are widely used in weather monitoring for precipitation, and wildlife tracking radars are used to monitor animal migrations.
Consider the following actions:
In how many of the above actions is the function of accelerometer required?
Why
An accelerometer measures changes in velocity and orientation; all three scenarios, airbag deployment, hard drive protection, and screen rotation, rely on accelerometer data.
With reference to "Software as a Service (SaaS)", consider the following statements:
Which of the statements given above are correct?
Why
SaaS allows UI customisation, is accessible from any device including mobiles, and web-based email services like Outlook and Hotmail are classic SaaS examples.
Consider the following communication technologies:
Which of the above are considered Short-Range devices/technologies?
Why
CCTV, RFID, and Wi-Fi (WLAN) all operate over short to medium ranges and are classified as short-range communication technologies.
With reference to Non-Fungible Tokens (NFTs), consider the following statements:
Which of the statements given above are correct?
Why
NFTs can represent physical assets digitally and are unique blockchain-based tokens, but they are non-fungible and cannot be exchanged at equivalency unlike currencies.
With reference to Web 3.0, consider the following statements:
Which of the statements given above are correct?
Why
Web 3.0 is decentralised, built on blockchain, user-controlled, and enables decentralised social networks, so all three statements are correct.
With reference to Visible Light Communication (VLC) technology, which of the following statements are correct?
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Why
VLC operates in visible light wavelengths (375–780 nm), is a short-range (not long-range) technology, is faster than Bluetooth, and uses light so it has no electromagnetic interference.
Consider the following activities:
At the present level of technology, which of the above activities can be successfully carried out by using drones?
Why
Drones are currently used for precision agriculture spraying, volcanic crater inspection in hazardous environments, and aerial whale breath sampling for DNA research.
In India, under cyber insurance for individuals, which of the following benefits are generally covered, in addition to payment for the loss of funds and other benefits?
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Why
Cyber insurance covers malware restoration, cyber extortion consultant costs, and legal defence costs, but physical damage to hardware by a miscreant is typically covered under property insurance, not cyber insurance.
With the present state of development, Artificial Intelligence can effectively do which of the following?
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Why
AI effectively optimises industrial energy use, diagnoses diseases, and converts text to speech, but wireless electrical energy transmission is a separate physics technology unrelated to AI.
With reference to "Blockchain Technology", consider the following statements:
Which of the statements given above is/are correct?
Why
Blockchain is a decentralised public ledger with permissionless development capability, but it is not limited to cryptocurrency, it supports smart contracts, supply chains, and more.
With reference to communication technologies, what is/are the difference/differences between LTE (Long-Term Evolution) and VoLTE (Voice over Long-Term Evolution)?
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Why
LTE is marketed as 4G (not 3G) and supports both data and voice; VoLTE adds voice capability over LTE networks, so both statements are incorrect.
In the context of digital technologies for entertainment, consider the following statements:
Which of the statements given above is/are correct?
Why
AR overlays digital content onto the real world (not shut it out) while VR creates full immersion; statements 3 and 4 correctly describe AR and VR respectively.
In the context of wearable technology, which of the following tasks is/are accomplished by wearable devices?
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Why
Wearable devices accomplish all three, GPS-enabled smartwatches track location, fitness bands monitor sleep cycles, and hearing aids are wearable devices for the hearing impaired.
Consider the following statements: A digital signature is
Which of the statements given above is/are correct?
Why
A digital signature specifically ensures the integrity and authenticity of an electronic document; it is not an identity record of the certifying authority nor a general internet access credential.
"3D Printing" has applications in which of the following?
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Why
3D printing has applications across all these domains, food, automotive prototyping, medical implants, and even data-processing hardware components.
The terms "WannaCry, Petya and Eternal Blue" sometimes mentioned in the news recently are related to:
Why
WannaCry and Petya are ransomware and EternalBlue is an exploit used to spread them, all are associated with major cyber attacks in 2017.
When the alarm of your smartphone rings in the morning, you wake up and tap it to stop the alarm which causes your geyser to be switched on automatically. The smart mirror in your bathroom shows the day's weather and also indicates the level of water in your overhead tank. After you take some groceries from your refrigerator for making breakfast, it recognises the shortage of stock in it and places an order for the supply of fresh grocery items. When you step out of your house and lock the door, all lights, fans, geysers and AC machines get switched off automatically. On your way to office, your car warns you about traffic congestion ahead and suggests an alternative route, and if you are late for a meeting, it sends a message to your office accordingly. In the context of emerging communication technologies, which one of the following terms best applies to the above scenario?
Why
The scenario describes interconnected everyday devices communicating and automating actions, which is the defining characteristic of the Internet of Things (IoT).
Consider the following pairs: Terms seen in news — Context/Topic
Which of the pairs given above is/are correctly matched?
Why
Belle II is a particle physics experiment at KEK in Japan, and CRISPR-Cas9 is a gene-editing tool in biology; only Blockchain Technology correctly pairs with Digital/Cryptocurrency.
In India, it is legally mandatory for which of the following to report on cyber security incidents?
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Why
Under India's IT (Amendment) Act and CERT-In regulations, service providers, data centres, and body corporates are all mandated to report cyber security incidents.
With reference to 'Li-Fi', recently in the news, which of the following statements is/are correct?
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Why
Li-Fi transmits data using visible light from LEDs and can achieve speeds several times faster than Wi-Fi due to the wider bandwidth of the visible light spectrum.
With reference to 'Near Field Communication (NFC) Technology', which of the following statements is/are correct?
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Why
NFC uses electromagnetic radio fields for contactless communication and supports encryption, but it is designed for very short ranges (typically under 20 cm), not up to a metre.
In addition to fingerprint scanning, which of the following can be used in the biometric identification of a person?
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Why
Biometric identification encompasses all unique biological characteristics including iris patterns, retinal patterns, and voice, so all three are valid biometric identifiers.
What is the difference between blue-tooth and Wi-Fi devices?
Why
Bluetooth operates exclusively on the 2.4 GHz band for short-range personal area networking, while Wi-Fi operates on both 2.4 GHz and 5 GHz bands for local area networking.
What is "virtual private network"?
Why
A VPN extends a private network over a public internet connection, allowing secure remote access to an organisation's resources by encrypting the data tunnel.
Consider the following substances: I. Ethanol II. Nitroglycerine III. Urea Coal gasification technology can be used in the production of how many of them?
Why
Coal gasification produces syngas (CO + H₂), which serves as a feedstock for synthesising ethanol, nitroglycerine (via glycerol route), and urea, all three compounds.
Consider the following statements:
Which of the statements given above is/are correct?
Why
Carbon fibres are widely used in lightweight structural components for automobiles and aircraft, but recycling processes for carbon fibre composites do exist, making statement 2 incorrect.
With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements:
Which of the statements given above are correct?
Why
PET fibres are blended with wool and cotton to improve textile durability, and PET bottles are recyclable; however, PET is not recommended for high-alcohol beverages and incineration of PET releases CO₂.
Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
Why
BPA is a monomer used in the polymerisation of polycarbonate plastics and epoxy resins, and its endocrine-disrupting properties have raised health concerns.
In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned?
Why
Pyrolysis (thermal decomposition without oxygen) and plasma gasification are both waste-to-energy technologies that convert municipal solid waste into usable fuel gases or electricity.
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?
Why
Monoclonal antibodies are synthetic proteins designed to bind specific antigens, and they are used therapeutically against various viral infections including Nipah, making all three statements correct.
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. Which of the statements given above are correct?
Why
All three statements are false: viruses (bacteriophages) infect bacteria, marine viruses are abundant in oceans, and many viruses hijack host transcriptional machinery.
With reference to the 'Pradhan Mantri Surakshit Matritva Abhiyan', consider the following statements:
Which of the statements given above is/are correct?
Why
Only statement 2 is correct; the scheme does not cover post-delivery care for six months, it focuses on fixed-day antenatal checkups, and private specialists can volunteer at government health facilities.
In which of the following are hydrogels used?
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Why
Hydrogels are used in controlled drug delivery, as desiccants and coolants in air-conditioning systems, and as lubricants in industrial applications, so all three uses are valid.
Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow?
Why
Nitric oxide (NO) is endogenously produced by endothelial cells and acts as a vasodilator by relaxing smooth muscle in blood vessel walls.
'Wolbachia method' is sometimes talked about with reference to which one of the following?
Why
The Wolbachia method involves infecting mosquitoes with Wolbachia bacteria to block transmission of dengue, Zika, and other viral diseases.
Consider the following statements in relation to Janani Suraksha Yojana:
How many of the statements given above are correct?
Why
Statements 2 and 3 are correct core objectives, and statement 1 is partially correct as a Central scheme implemented through States, but statement 4 is incorrect, JSY does not cover infant healthcare.
Consider the following statements in the context of interventions being undertaken under Anaemia Mukt Bharat Strategy:
How many of the statements given above are correct?
Why
Statements 2, 3, and 4 are correct interventions under Anaemia Mukt Bharat; statement 1 is incorrect because the strategy provides iron and folic acid supplementation, not calcium.
Consider the following statements:
How many of the above statements are correct?
Why
Extremophiles include thermophiles (living above 100°C in hydrothermal vents), psychrophiles (living below 0°C), and acidophiles (thriving at pH < 3), so all three statements are correct.
Consider the following statements:
Statement-I: India's public sector health care system largely focuses on curative care with limited preventive, promotive and rehabilitative care.
Statement-II: Under India's decentralized approach to health care delivery, the States are primarily responsible for organizing health services. Which one of the following is correct in respect of the above statements?
Why
Both statements are independently correct facts about India's health system, but decentralization (Statement-II) is not the reason for the curative-care bias (Statement-I), so it is not the correct explanation.
In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements:
Which of the statements given above are correct?
Why
Covishield uses a viral vector (ChAdOx1), not an mRNA platform; Sputnik V is vector-based; and COVAXIN is an inactivated whole-virion vaccine, so statements 2 and 3 are correct.
With reference to Ayushman Bharat Digital Mission, consider the following statements:
Which of the statements given above is/are correct?
Why
Only statement 3 is correct; adoption by hospitals is voluntary (not mandatory), and while universal coverage is an aspiration, participation is not compulsory for every citizen.
Which one of the following statements best describes the role of B cells and T cells in the human body?
Why
B cells and T cells are lymphocytes that form the adaptive immune response, collectively defending the body against pathogen-caused diseases through antibody production and cell-mediated immunity.
Consider the following statements in respect of probiotics:
Which of the statements given above is/are correct?
Why
Probiotics contain live bacteria and yeasts (statement 1 correct) and many strains produce lactase to help digest lactose/milk sugars (statement 3 correct); probiotic organisms do naturally occur in the gut, making statement 2 false.
Consider the following statements:
Which of the statements given above are correct?
Why
Biofilms are communities of bacteria that adhere to surfaces including medical implants and food-contact surfaces, and their matrix confers significant resistance to antibiotics.
Consider the following: 1) Bacteria 2) Fungi 3) Virus Which of the above can be cultured in artificial/synthetic medium?
Why
Bacteria and fungi are cellular organisms that can be grown on synthetic nutrient media, whereas viruses are obligate intracellular parasites that require living host cells to replicate.
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?
Why
Adenoviruses actually have double-stranded DNA and retroviruses have single-stranded RNA genomes, making statement 1 false; statement 2 is correct as adenoviruses cause some cold cases and HIV (a retrovirus) causes AIDS.
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?
Why
Recombinant vector vaccines use genetic engineering to insert antigen-coding genes into bacterial or viral vectors, so both statements are correct.
In the context of hereditary diseases, consider the following statements:
Which of the statements given above is/are correct?
Why
Mitochondria are maternally inherited, so mitochondrial diseases pass only from mother; mitochondrial replacement therapy (MRT) can prevent this transmission before or after IVF.
In the context of recent advances of human reproductive technology, 'Pronuclear Transfer' is used for:
Why
Pronuclear transfer involves moving the nuclear genetic material from a fertilised egg with defective mitochondria into an enucleated donor egg, preventing the inheritance of mitochondrial diseases.
What is the importance of using Pneumococcal Conjugate Vaccines in India?
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Why
Pneumococcal vaccines protect against pneumonia, meningitis, and sepsis and reduce antibiotic dependence, but like all vaccines they can have side effects and allergic reactions in some individuals.
With reference to carbon nanotubes, consider the following statements:
Which of the statements given above are correct?
Why
Carbon nanotubes can carry drugs and antigens, function in biosensors, and certain types are biodegradable, but they cannot yet be fabricated into functional blood capillaries.
Which one of the following statements is not correct?
Why
A safe and effective vaccine for Hepatitis B has existed since the 1980s; it is Hepatitis C that currently has no licensed vaccine, making option (b) false.
Which of the following are the reasons for the occurrence of multi-drug resistance in microbial pathogens in India?
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Why
Multi-drug resistance develops primarily due to incomplete or incorrect antibiotic use (2) and sub-therapeutic antibiotic use in livestock that promotes resistant strains (3); genetic predisposition and chronic diseases are not causes of antibiotic resistance.
Consider the following:
Which of the above spread plant diseases?
Why
Plant pathogens (fungal spores, bacteria, viruses) can be dispersed by all of these vectors, birds, dust, rain splash, and wind, so all four spread plant diseases.
Consider the following statements:
Which of the statements given above is/are correct?
Why
Both statements are correct, Aedes aegypti transmits both Zika and dengue, and sexual transmission of Zika has been documented.
'Mission Indradhanush' launched by the Government of India pertains to:
Why
Mission Indradhanush aims to achieve full immunization coverage for children and pregnant women against seven vaccine-preventable diseases by reaching every unimmunized and partially immunized child.
Which of the following statements is/are correct? Viruses can infect:
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Why
Viruses infect all cellular life: bacteriophages infect bacteria, mycoviruses infect fungi, and plant viruses infect plants, so all three are correct.
With reference to the use of nanotechnology in health sector, which of the following statements is/are correct?
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Why
Nanoparticles are used both for targeted drug delivery to specific cells and as vectors in gene therapy to deliver nucleic acids into cells.
H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases?
Why
H1N1 is the influenza A strain responsible for swine flu, which caused the 2009 pandemic.
Consider the following diseases:
Which of the above diseases has/have been eradicated in India?
Why
Smallpox was eradicated globally by 1980 (and from India earlier); diphtheria and chickenpox still occur and are only controlled, not eradicated.
Consider the following pairs: Vitamin — Deficiency disease:
Which of the pairs given above is/are correctly matched?
Why
Vitamin C deficiency causes scurvy and Vitamin D deficiency causes rickets; night blindness is caused by Vitamin A deficiency, not Vitamin E.
Which of the following statements is/are correct?
Select the correct answer using the codes given below.
Why
Viruses lack metabolic enzymes for energy production (1 correct); they cannot be cultured on synthetic media without a host (2 false); and they can be transmitted by non-biological vectors like contaminated water or air (3 false).
Consider the following minerals:
Which of the minerals given above is/are required by human body for the contraction of muscles?
Why
Calcium triggers the actin-myosin interaction for contraction, sodium is essential for generating the action potential that initiates it, and iron (in myoglobin) supports the oxygen supply to muscles, all three are required.
Which of the following diseases can be transmitted from one person to another through tattooing?
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Why
Hepatitis B and HIV can be transmitted via blood-contaminated tattooing needles; Chikungunya is vector-borne and not transmitted through blood contact in tattooing.
With reference to the usefulness of the by-products of sugar industry, which of the following statements is/are correct?
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Why
Bagasse is burned as biomass fuel in sugar mills (1 correct) and molasses is fermented to produce ethanol (3 correct); molasses is not a feedstock for synthetic chemical fertilizers (2 incorrect).
Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxin which are not generally destroyed by normal cooking process. Aflatoxin are produced by?
Why
Aflatoxins are mycotoxins produced by Aspergillus moulds (especially A. flavus and A. parasiticus) that grow on stored grains and oilseeds under warm, humid conditions.
With reference to National Rural Health Mission, which of the following are the jobs of 'ASHA', a trained community health worker?
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Why
ASHA workers escort women for antenatal checkups, use pregnancy test kits, and provide nutrition and immunization information, but they are not trained to conduct deliveries.
With reference to 'stem cells' frequently in the news, which of the following statements is/are correct?
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Why
Stem cells have been derived from non-mammalian organisms as well, so statement 1 is wrong; statements 2 and 3 are correct as stem cells are used in drug testing and therapeutic applications.
With reference to radioisotope thermoelectric generators (RTGs), consider the following statements:
Which of the statements given above are correct?
Why
RTGs convert heat from radioactive decay (not fission) into electricity, so statement 1 is wrong; statements 2 and 3 are correct, they power spacecraft and can use Pu-238 derived from weapons programs.
Consider the following statements:
Statement-I: India, despite having Uranium deposits, depends on coal for most of its electricity production.
Statement-II: Uranium, enriched to the extent of at least 60%, is required for the production of electricity. Which of the following is correct in respect of the above statements?
Why
India does rely heavily on coal despite having uranium deposits (Statement-I true), but nuclear reactors require only low enrichment (~3–5%), not 60%, making Statement-II false.
India is an important member of the 'International Thermonuclear Experimental Reactor'. If this experiment succeeds, what is the immediate advantage for India?
Why
ITER is a nuclear fusion experiment; its success would enable participating nations, including India, to develop commercial fusion reactors for clean power generation.
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?
Which of the statements given above is/are correct?
Why
All three advantages are correct, thorium is more abundant, yields more energy per unit of mined mineral (via the thorium-232 to uranium-233 cycle), and generates shorter-lived, less harmful radioactive waste.
The function of heavy water in a nuclear reactor is to?
Why
Heavy water (D₂O) acts as a moderator in nuclear reactors, slowing fast neutrons to thermal speeds so they can sustain the fission chain reaction more efficiently.
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?
Why
India does import apples from the USA, so Statement I is wrong; however, the law (Environment Protection Act) does prohibit import of GM food without competent authority approval, making Statement II correct.
'Aerial metagenomics' best refers to which one of the following situations?
Why
Aerial metagenomics involves capturing environmental DNA (eDNA) directly from air samples to study the genetic diversity of organisms in a habitat.
'Microsatellite DNA' is used in the case of which one of the following?
Why
Microsatellite DNA (short tandem repeats) shows high variability between individuals and species, making it a key molecular marker for phylogenetic and evolutionary studies.
Consider the following statements: DNA Barcoding can be a tool to:
Which of the statements given above is/are correct?
Why
DNA barcoding uses short standardised gene sequences to distinguish species and detect adulteration in food, but it cannot determine an organism's age.
Bollgard I and Bollgard II technologies are mentioned in the context of:
Why
Bollgard I and Bollgard II are Bt cotton technologies where Bacillus thuringiensis genes are introduced into cotton to confer resistance against bollworm pests.
Consider the following statements:
Which of the statements given above is/are correct?
Why
All three are established or demonstrated possibilities in modern genetic and stem cell research, including germline editing and human-animal chimera experiments.
'RNA interference (RNAi)' technology has gained popularity in the last few years. Why?
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Why
RNAi silences specific genes and is used in gene therapy, cancer treatment, and engineering virus-resistant crops, but it is not related to hormone replacement therapy.
With reference to the recent developments in science, which one of the following statements is not correct?
Why
You cannot create fully functional chromosomes simply by joining DNA segments from different species; the other statements describe verified techniques in synthetic biology and cell culture.
What is Cas9 protein that is often mentioned in news?
Why
Cas9 is the endonuclease enzyme used in the CRISPR-Cas9 system to make precise cuts in DNA at targeted genomic locations.
With reference to the Genetically Modified mustard (GM Mustard) developed in India, consider the following statements:
Which of the statements given above is/are correct?
Why
India's GM Mustard (DMH-11) was developed by Delhi University using barnase-barstar genes from soil bacteria to enable hybridization, not for pest resistance, and was not jointly developed with Punjab Agricultural University.
What is the application of Somatic Cell Nuclear Transfer Technology?
Why
Somatic Cell Nuclear Transfer (SCNT) involves transferring a somatic cell nucleus into an enucleated egg to produce a genetically identical clone, as demonstrated with Dolly the sheep.
With reference to agriculture in India, how can the technique of 'genome sequencing', often seen in the news, be used in the immediate future?
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Why
Genome sequencing identifies resistance markers, accelerates breeding programmes, and helps understand how pathogens interact with crop hosts, making all three applications valid.
In the context of the developments in Bioinformatics, the term 'transcriptome', sometimes seen in the news, refers to:
Why
The transcriptome is the complete set of RNA transcripts (primarily mRNA) produced by the genome of an organism under specific conditions.
The Genetic Engineering Appraisal Committee is constituted under the:
Why
The Genetic Engineering Appraisal Committee (GEAC) was set up under the Environment (Protection) Act, 1986 to regulate the use of GMOs in India.
Consider the following techniques/phenomena:
Which of the above is/are used to create transgenic crops?
Why
Cytoplasmic male sterility and gene silencing are tools used to create transgenic or hybrid crops, while budding and grafting are conventional vegetative propagation methods that do not alter the genome.
Recombinant DNA technology (genetic engineering) allows genes to be transferred:
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Why
Recombinant DNA technology enables gene transfer across all biological kingdoms, between plant species, from animals to plants, and from microorganisms to higher organisms.
Other than resistance to pests, what are the prospects for which genetically engineered plants have been created?
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Why
Genetically engineered crops have been developed for drought tolerance, enhanced nutrition (e.g., Golden Rice), and extended shelf life, but engineering plants for photosynthesis in space is not a current application.
What are the reasons for the people's resistance to the introduction of Bt brinjal in India?
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Why
Resistance to Bt brinjal centres on health safety concerns and potential harm to biodiversity; the gene is from a bacterium (not fungus) and the seeds are not terminator seeds, so only statements 3 and 4 correctly reflect the resistance.
At present, scientists can determine the arrangement or relative positions of genes or DNA sequences on a chromosome. How does this knowledge benefit us?
Which of the statements given above is/are correct?
Why
Chromosome mapping allows pedigree analysis of livestock and identification of genes for disease resistance in breeding programmes, but it cannot reveal the causes of all human diseases.
A genetically engineered form of brinjal, known as the Bt-brinjal, has been developed. The objective of this is?
Why
Bt brinjal carries the Bacillus thuringiensis Cry1Ac gene, which produces a protein toxic to fruit and shoot borers, making the plant pest-resistant.
Which one of the following is the context in which the term "qubit" is mentioned?
Why
A qubit (quantum bit) is the basic unit of information in quantum computing, exploiting superposition and entanglement.
Organic Light Emitting Diodes (OLEDs) are used to create digital display in many devices. What are the advantages of OLED displays over Liquid Crystal displays?
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Why
OLEDs are self-emissive and can be deposited on flexible plastic, enabling roll-up and transparent displays, all three advantages over rigid, backlit LCDs are correct.
With reference to technology for solar power production, consider the following statements:
Which of the statements given above is/are correct?
Why
Only statement 1 is correct, photovoltaics directly converts light to electricity (DC) while solar thermal converts solar heat; statement 2 reverses the current types and statement 3 is factually wrong.
What is the difference between a CFL and an LED lamp?
Which of the statements given above is/are correct?
Why
Statements 1 and 3 are correct, CFLs use mercury vapour and phosphor while LEDs use semiconductors, and LEDs are more energy-efficient; however, LEDs last significantly longer than CFLs, making statement 2 wrong.
In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
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Why
The cooking temperature in a pressure cooker is determined by the internal pressure, which depends on the size of the steam-release hole and the weight of the lid, not the external flame temperature.
The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?
Why
Water reaches maximum density at 4°C and sinks to the bottom, insulating deeper layers from freezing even as the surface temperature drops below 0°C.
With reference to street-lighting, how do sodium lamps differ from LED lamps?
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Why
Sodium lamps emit omnidirectionally (360°) and produce near-monochromatic yellow light, while LEDs have a much longer lifespan than sodium lamps, making statement 2 wrong.
Consider the following phenomena:
Which of the above are optical illusions?
Why
The enlarged appearance of the sun at dusk (atmospheric refraction/illusion), its reddish colour at dawn (scattering), and the twinkling of stars (atmospheric scintillation) are optical phenomena/illusions; moon visibility at dawn and Polestar visibility are real observations.
Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?
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Why
A rainbow requires all three: refraction (bending of light as it enters/exits the drop), dispersion (splitting into colours), and total internal reflection (inside the drop).
Water can dissolve more substances than any other liquid because:
Why
The polar O–H bonds give water a dipole moment that allows it to stabilise ions and polar molecules through electrostatic interactions, making it the universal solvent.
Which of the following statements are correct regarding the general difference between plant and animal cells?
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Why
Plant cells have cellulose cell walls (1 correct) and a large central vacuole (3 correct), but both plant and animal cells have plasma membranes, making statement 2 false.
Consider the following pairs: Commonly used / consumed materials and Unwanted or controversial chemicals likely to be found in them:
Which of the pairs given above is/are correctly matched?
Why
Lead can be found as a contaminant in some lipsticks, brominated vegetable oils are used in some citrus-flavoured soft drinks as emulsifiers, and monosodium glutamate is a common flavour enhancer in Chinese fast food, all three matches are correct.
With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements:
Which of the statements given above is / are correct?
Why
Hydrogen fuel cells emit only heat and water, making statement 1 correct; they can power small portable devices (not just buildings) and produce direct current (DC), making statements 2 and 3 false.
Which of the following is/are the example/examples of chemical change?
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Why
Souring of milk involves bacterial fermentation that converts lactose into lactic acid, a chemical change, while crystallisation and melting are physical changes.
Fruits stored in cold chamber exhibit long storage life because ___:
Why
Low temperatures slow down the enzymatic reactions that drive cellular respiration in fruits, thereby slowing ripening and decay and extending shelf life.
What is the role of ultraviolet (UV) radiation in the water purification systems?
Which of the statements given above is/are correct?
Why
UV radiation disrupts the DNA of microorganisms, inactivating them; it does not remove odours or accelerate sedimentation, so only statement 1 is correct.
Among the following organisms, which one does not belong to the class of other three?
Why
Mites, scorpions, and spiders are all arachnids (class Arachnida), whereas crabs are crustaceans (class Malacostraca), making the crab the odd one out.
Which one of the following is the process involved in photosynthesis?
Why
Photosynthesis captures light (free energy) and stores it as chemical potential energy in glucose molecules, making option b the correct description of the process.
Many transplanted seedlings do not grow because?
Why
Root hairs are delicate, short-lived structures responsible for water and mineral absorption; they are easily torn off during transplantation, severely limiting the seedling's ability to absorb water and nutrients.
Which of the following statements is/are correct regarding vegetative propagation of plants?
Select the correct answer using the code given below.
Why
Vegetative propagation produces genetically identical clones (1 correct) and can be practiced through much of the year (3 correct), but it does not eliminate viruses, it actually perpetuates them in the clonal lines (2 incorrect).
Ball bearings are used in bicycles, cars, etc., because:
Why
Ball bearings replace sliding friction with rolling friction by reducing the effective contact area between wheel and axle, thereby lowering friction and energy loss.
The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
Why
Gravity is actually the weakest of the four fundamental forces; the strong nuclear force is the strongest, making statement (a) incorrect.
Consider the following statements. If there were no phenomenon of capillarity:
Which of the statements given above are correct?
Why
Capillarity drives fuel up a lamp wick, allows blotting paper to absorb ink, and draws water up from roots to leaves in tall trees; drinking through a straw relies on pressure difference, not capillarity.
Aspartame is an artificial sweetener sold in the market. It consists of amino acids and provides calories like other amino acids. Yet, it is used as a low-calorie sweetening agent in food items. What is the basis of this use?
Why
Aspartame is about 200 times sweeter than sucrose, so only a tiny amount is needed to achieve the same sweetness, resulting in far fewer total calories despite each gram yielding the same energy as other amino acids.