UPSC CSE Prelims
Science & Technology Previous Year Questions (PYQs)

Detailed Explanation:

Answer: Option 2 — 1 and 2 only

Pneumococcal Conjugate Vaccines (PCVs) are crucial in India's immunization program as they protect against multiple serious diseases caused by Streptococcus pneumoniae and help combat antibiotic resistance. Statement 3 is incorrect as no vaccine is completely free from side effects or allergic reactions.

✅ Statement 1 – Correct: PCVs are highly effective against pneumonia, meningitis (inflammation of brain and spinal cord membranes), and sepsis (blood infection) caused by Streptococcus pneumoniae bacteria.
✅ Statement 2 – Correct: PCVs reduce dependence on antibiotics by preventing pneumococcal infections, thereby addressing the growing problem of antibiotic-resistant bacterial strains.
❌ Statement 3 – Incorrect: Like all vaccines, PCVs can cause mild side effects (redness, swelling, soreness at injection site) and rare allergic reactions; no vaccine is completely side-effect-free.

📝 Short Notes: Pneumococcal Conjugate Vaccines (PCVs)

• Causative Organism: Streptococcus pneumoniae (pneumococcus) — a bacterium with over 90 serotypes.
• Diseases Prevented: Pneumonia, meningitis, sepsis, otitis media (ear infection), and bacteremia.
• Types of Vaccines: PCV10 (protects against 10 serotypes) and PCV13 (protects against 13 serotypes).
• India's Immunization Program: PCV introduced in Universal Immunization Programme (UIP) in 2017; given at 6, 10, and 14 weeks of age.
• Public Health Impact: Reduces child mortality, prevents pneumococcal diseases (leading cause of death in children under 5), and decreases antibiotic use.
• Antibiotic Resistance: PCVs help combat drug-resistant pneumococcal strains by preventing infections, reducing need for antibiotics.
• Common Side Effects: Mild reactions like fever, irritability, injection site reactions; serious allergic reactions are rare but possible.

Detailed Explanation:

Answer: Option 2 — 1, 3 and 4 only

Cyber insurance for individuals covers digital risks and financial losses arising from cyber incidents. It includes restoration costs for compromised systems, legal defense expenses, and consultant fees for handling cyber extortion, but excludes physical damage to hardware caused by willful acts of vandalism.

✅ Statement 1 – Correct: Cyber insurance covers the cost of restoring computer systems and data corrupted or disrupted by malware attacks.

❌ Statement 2 – Incorrect: Cyber insurance does not cover physical damage to hardware or replacement costs due to willful physical vandalism; it covers only digital risks and cyber-related losses.

✅ Statement 3 – Correct: Cyber insurance covers expenses for hiring specialized consultants to investigate cyber extortion threats (such as ransomware) and minimize associated losses.

✅ Statement 4 – Correct: Cyber insurance provides coverage for legal defense costs when a third party files a lawsuit for privacy breaches, data theft, or defamation resulting from a cyber incident.

Detailed Explanation:

Answer: Option 1 — Functional chromosomes can be created by joining segments of DNA taken from cells of different species.

This statement is incorrect because creating fully functional chromosomes by simply joining DNA segments from different species is not currently feasible. Chromosomes are highly complex structures requiring species-specific regulatory elements, centromeres, telomeres, and structural proteins that cannot be arbitrarily combined from different organisms to create functional units.

✅ Statement 1 – Incorrect: While synthetic chromosomes and chimeric DNA constructs exist, functional chromosomes cannot be simply created by joining segments from different species due to complex species-specific regulatory requirements.
✅ Statement 2 – Correct: Synthetic biology enables the chemical synthesis of artificial functional DNA sequences in laboratories, including synthetic genes and even entire viral genomes.
✅ Statement 3 – Correct: Polymerase Chain Reaction (PCR) is a standard technique that amplifies DNA segments outside living cells in vitro.
✅ Statement 4 – Correct: Cell culture and tissue culture techniques routinely enable plant and animal cells to divide and grow in laboratory petri dishes using nutrient media.

📝 Short Notes: DNA Technology & Genetic Engineering

• Synthetic DNA: Artificial DNA sequences can be chemically synthesized in laboratories for various applications including gene therapy and research.
• PCR (Polymerase Chain Reaction): A revolutionary technique developed by Kary Mullis that amplifies specific DNA segments millions of times outside living cells.
• Cell Culture: Technique of growing cells in controlled artificial conditions outside their natural environment, fundamental to biotechnology and medical research.
• Chromosomes: Complex structures consisting of DNA wrapped around histone proteins, containing centromeres, telomeres, and species-specific regulatory elements.
• Chimeric DNA: DNA constructs containing sequences from different sources, commonly used in genetic engineering, but different from functional chromosomes.
• Synthetic Biology: The field has achieved milestones like creating synthetic bacterial genomes (Mycoplasma mycoides, 2010) but functional multi-species chromosomes remain beyond current capability.

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

Remote sensing technology uses satellite images to detect and monitor physical characteristics of areas by measuring reflected and emitted radiation. All three parameters mentioned can be effectively measured or estimated using satellite-based remote sensing data.

✅ Statement 1 – Correct: Chlorophyll content in vegetation is estimated by measuring light reflectance, as chlorophyll absorbs specific wavelengths for photosynthesis and the reflected light indicates chlorophyll concentration.

✅ Statement 2 – Correct: Greenhouse gas emissions from rice paddies can be estimated by detecting radiations emitted by methane and other gases, combined with thermal and spectral signatures of waterlogged conditions.

✅ Statement 3 – Correct: Land surface temperatures are directly measured by satellite sensors that detect infrared radiation emitted by the Earth's surface.

📝 Short Notes: Remote Sensing Applications

• Remote Sensing: The science of obtaining information about objects or areas from a distance, typically using satellites or aircraft-mounted sensors.
• Spectral Reflectance: Different surfaces and materials reflect electromagnetic radiation differently; vegetation reflects strongly in near-infrared while absorbing visible light for photosynthesis.
• Thermal Infrared Sensing: Used to measure land surface temperature by detecting heat radiation emitted from the Earth's surface.
• Agricultural Monitoring: Remote sensing helps monitor crop health, soil moisture, irrigation needs, and greenhouse gas emissions from agricultural activities.
• Vegetation Indices: NDVI (Normalized Difference Vegetation Index) and other indices derived from satellite data help assess vegetation vigor and chlorophyll content.
• Methane Detection: Advanced satellite sensors can detect methane emissions from rice paddies, wetlands, and other sources by measuring specific absorption bands in the infrared spectrum.

Detailed Explanation:

Answer: Option 2 — Hepatitis B, unlike Hepatitis C, does not have a vaccine.

This statement is incorrect because a highly effective vaccine for Hepatitis B has been available since 1982, whereas no vaccine exists for Hepatitis C. The question asks for the statement that is NOT correct.

✅ Statement 1 – Correct: Hepatitis B virus is transmitted through similar routes as HIV (blood contact, sexual contact, mother-to-child transmission).
❌ Statement 2 – Incorrect: Hepatitis B has a vaccine; Hepatitis C does not have a vaccine.
✅ Statement 3 – Correct: Globally, Hepatitis B and C infections combined far exceed HIV infections (approximately 325 million vs 38 million).
✅ Statement 4 – Correct: Chronic Hepatitis B and C infections can remain asymptomatic for many years before causing liver damage.

📝 Short Notes: Hepatitis B & C

Detailed Explanation:

Answer: Option 4 — Neither 1 nor 2

Both statements about LTE and VoLTE technologies are incorrect. LTE is marketed as 4G (not 3G) and is a high-speed data technology that can also support voice through circuit-switched fallback, while VoLTE is not voice-only but enables voice calls over the same 4G LTE data network along with simultaneous data services.

❌ Statement 1 – Incorrect: LTE is commonly marketed as 4G technology, not 3G, and VoLTE is an enhancement of 4G LTE for voice services, not advanced 3G.
❌ Statement 2 – Incorrect: LTE is not data-only (it can support voice through fallback mechanisms), and VoLTE is not voice-only (it delivers voice over the data network while allowing simultaneous data usage).

📝 Short Notes: LTE and VoLTE Technologies

Detailed Explanation:

Answer: Option 2 — 3 and 4

This question tests the understanding of the fundamental differences between Augmented Reality (AR) and Virtual Reality (VR). AR enhances the real world by overlaying digital elements, while VR creates a completely immersive simulated environment that replaces the physical world.

❌ Statement 1 – Incorrect: This describes VR, not AR. AR enhances the real world with digital overlays rather than shutting out the physical world completely.

❌ Statement 2 – Incorrect: This describes AR, not VR. VR creates a completely simulated environment that replaces reality, not projects images into real-life objects.

✅ Statement 3 – Correct: AR allows users to remain present in the real world while enhancing their experience through smartphones or PC cameras that overlay digital content onto real surroundings.

✅ Statement 4 – Correct: VR closes out the physical world and transports the user into a fully immersive simulated environment, typically through headsets.

📝 Short Notes: AR vs VR Technologies

Detailed Explanation:

Answer: Option 2 — 2 and 3 only

Multi-drug resistance (MDR) in microbial pathogens arises primarily from improper antibiotic use and environmental exposure to antibiotics. Incorrect dosing and incomplete treatment courses allow resistant strains to survive and multiply, while widespread antibiotic use in livestock farming creates selection pressure for resistant bacteria that can spread to humans through the food chain.

❌ Statement 1 – Incorrect: Genetic predisposition affects individual susceptibility to infections but does not cause multi-drug resistance in pathogens; resistance develops in microbes, not humans.

✅ Statement 2 – Correct: Taking incorrect doses, skipping doses, or not completing antibiotic courses allows partially resistant bacteria to survive and develop full resistance through natural selection.

✅ Statement 3 – Correct: Routine use of antibiotics in livestock for growth promotion and disease prevention creates resistant bacteria that can transfer to humans via food, direct contact, or environmental contamination.

❌ Statement 4 – Incorrect: While chronic diseases may increase infection frequency, they do not directly cause antibiotic resistance in microbial pathogens; resistance is a microbial adaptation, not a patient characteristic.

📝 Short Notes: Antimicrobial Resistance (AMR)

• Definition: AMR occurs when microorganisms evolve mechanisms to survive exposure to antimicrobial drugs that would normally kill them or inhibit their growth.
• Main Causes in India: Irrational use of antibiotics (self-medication, incomplete courses), over-the-counter availability without prescription, use in agriculture and aquaculture, poor infection control in healthcare settings.
• Mechanisms of Resistance: Enzymatic degradation of drugs (e.g., beta-lactamases), alteration of drug targets, reduced drug permeability, efflux pumps that expel antibiotics.
• Agricultural Connection: Antibiotics used as growth promoters in livestock create resistant bacteria; these can transfer resistance genes to human pathogens through horizontal gene transfer.
• Public Health Impact: Makes common infections harder to treat, increases healthcare costs, prolongs hospital stays, increases mortality rates.
• Government Initiatives: National Action Plan on AMR (2017), Red Line Campaign for responsible antibiotic use, regulations on antibiotic sales, AMR surveillance networks.
• WHO Priority: Listed as one of top 10 global public health threats; requires coordinated action across human health, animal health, and environmental sectors (One Health approach).

Detailed Explanation:

Answer: Option 3 — 3 only

A digital signature is a cryptographic mechanism used to authenticate the identity of the sender and ensure that the content of an electronic document has not been altered after signing. Only statement 3 correctly captures this fundamental purpose.

❌ Statement 1 – Incorrect: A digital signature does not identify the certifying authority; instead, it uses a digital certificate issued by a Certificate Authority (CA) to verify the signer's identity, but the signature itself is created by the signer's private key.

❌ Statement 2 – Incorrect: Digital signatures are primarily used for ensuring document integrity and authenticity, not for accessing information or servers on the Internet; access control typically relies on usernames, passwords, tokens, or biometric authentication.

✅ Statement 3 – Correct: A digital signature is indeed an electronic method of signing documents that ensures non-repudiation and integrity by creating a unique cryptographic hash that detects any changes to the original content.

📝 Short Notes: Digital Signatures

• Definition: A digital signature is a cryptographic technique that validates the authenticity and integrity of electronic messages, documents, or software.
• Technology: Based on Public Key Infrastructure (PKI) using asymmetric cryptography—a private key to sign and a public key to verify.
• Key Functions: Authentication (verifies sender identity), Integrity (detects alterations), and Non-repudiation (sender cannot deny signing).
• Process: A hash of the document is created and encrypted with the signer's private key; recipients decrypt it with the public key to verify authenticity.
• Legal Status in India: Digital signatures are legally recognized under the Information Technology Act, 2000, and have the same validity as handwritten signatures.
• Certificate Authority (CA): Trusted third parties (like NIC, eMudhra) issue digital certificates that bind a public key to an individual or organization.
• Common Uses: E-filing of tax returns, online banking, e-governance services, legal documents, and software distribution.

Detailed Explanation:

Answer: Option 1 — 1, 2 and 4

RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression by neutralizing targeted mRNA molecules. This technology has gained popularity for its applications in gene silencing therapies, cancer treatment, and developing disease-resistant crops.

✅ Statement 1 – Correct: RNAi technology is extensively used in developing gene silencing therapies by targeting and reducing specific gene expressions to treat various diseases.
✅ Statement 2 – Correct: RNAi-based therapies are being actively researched and developed for cancer treatment by silencing genes responsible for tumor growth and proliferation.
❌ Statement 3 – Incorrect: RNAi is not used for hormone replacement therapies; it works by silencing genes rather than introducing hormones into the body.
✅ Statement 4 – Correct: RNAi technology is successfully applied in agriculture to produce crop plants resistant to viral pathogens by targeting and degrading viral RNA.

📝 Short Notes: RNA Interference (RNAi) Technology

• Definition: RNAi is a natural cellular process where double-stranded RNA molecules trigger the degradation of specific mRNA, thereby silencing gene expression.
• Discovery: First discovered in the 1990s by Andrew Fire and Craig Mello, who won the Nobel Prize in 2006 for their work.
• Mechanism: Small interfering RNAs (siRNAs) or micro RNAs (miRNAs) bind to complementary mRNA sequences, leading to their degradation or translational repression.
• Medical Applications: Used in treating genetic disorders, viral infections, and cancer by silencing disease-causing genes; several RNAi-based drugs are in clinical trials or approved.
• Agricultural Applications: Development of virus-resistant crops, enhanced nutritional content, and improved stress tolerance in plants.
• Limitations: Off-target effects, delivery challenges to specific tissues, and potential immune responses remain areas of ongoing research.

Detailed Explanation:

Answer: Option 1 — A molecular scissors used in targeted gene editing

Cas9 is an RNA-guided endonuclease enzyme that functions as molecular scissors, capable of cutting DNA at precise locations within a genome. It is the key component of the CRISPR-Cas9 gene editing system, which has revolutionized genetic engineering by enabling targeted modifications to DNA sequences in living organisms.

📝 Short Notes: CRISPR-Cas9 Gene Editing Technology

• CRISPR-Cas9 stands for Clustered Regularly Interspaced Short Palindromic Repeats associated with Cas9 protein.
• Mechanism: The system uses a guide RNA (gRNA) to direct the Cas9 enzyme to a specific DNA sequence, where it makes a precise cut.
• Function: After cutting, the cell's natural DNA repair mechanisms can be harnessed to add, delete, or replace genetic material at the targeted location.
• Applications: Treatment of genetic diseases, development of disease-resistant crops, creation of genetically modified organisms, and basic research in genomics.
• Advantages: More precise, efficient, and cost-effective compared to earlier gene editing technologies like zinc finger nucleases and TALENs.
• Nobel Prize 2020: Emmanuelle Charpentier and Jennifer Doudna were awarded the Nobel Prize in Chemistry for developing CRISPR-Cas9 gene editing.
• Ethical Concerns: Potential misuse in human germline editing, unintended off-target effects, and ecological impacts of genetically modified organisms.

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

Wearable technology devices are capable of performing all three mentioned tasks through integrated sensors and connectivity features. Modern wearables combine GPS, biometric sensors, and audio processing capabilities to assist users in various ways.

✅ Statement 1 – Correct: Smartwatches and fitness trackers with GPS functionality can identify and track a person's real-time location for navigation, safety, and fitness tracking purposes.
✅ Statement 2 – Correct: Wearable devices equipped with accelerometers and heart rate sensors can monitor sleep patterns, including duration, stages (REM, deep, light sleep), and overall sleep quality.
✅ Statement 3 – Correct: Hearing aid wearables and some smartwatches can amplify sounds and process audio to assist hearing-impaired persons by improving sound clarity and volume.

📝 Short Notes: Wearable Technology

• Definition: Electronic devices worn on the body that incorporate sensors, processors, and wireless connectivity to collect data and provide services.
• Common Types: Smartwatches, fitness trackers, smart glasses, hearing aids, health monitors, and smart clothing.
• Key Features: Real-time health monitoring (heart rate, blood oxygen, ECG), GPS tracking, notifications, activity tracking, and biometric authentication.
• Health Applications: Continuous glucose monitoring for diabetics, fall detection for elderly, stress monitoring, and remote patient monitoring.
• Technology Components: Sensors (accelerometer, gyroscope, heart rate, GPS), Bluetooth/Wi-Fi connectivity, battery management, and companion mobile apps.
• Examples: Apple Watch, Fitbit, Google Glass, Cochlear implants, Samsung Galaxy Watch, and Garmin fitness trackers.

Detailed Explanation:

Answer: Option 2 — 'Gravitational waves' were detected.

The merger of black holes is expected to generate powerful gravitational waves, which are ripples in spacetime caused by accelerating massive objects. Detecting these waves with instruments like LIGO (Laser Interferometer Gravitational-Wave Observatory) allows scientists to study these cosmic events even when they are too far away or obscured to observe directly with traditional telescopes. This observation opened a revolutionary new window for astronomical observations and confirmed a major prediction of Einstein's General Theory of Relativity.

❌ Option 1 – Incorrect: Higgs boson particles are detected in particle accelerators like the Large Hadron Collider (LHC), not through astronomical observations of black hole mergers.

❌ Option 3 – Incorrect: While wormholes are theoretical concepts in physics, no observation of black hole mergers has confirmed the possibility of intergalactic space travel through wormholes.

❌ Option 4 – Incorrect: While black hole mergers provide insights into extreme gravity, understanding the singularity (the point of infinite density at the center of a black hole) remains beyond current observational capabilities.

📝 Short Notes: Gravitational Waves

• Definition: Gravitational waves are ripples in the fabric of spacetime caused by violent cosmic events involving massive accelerating objects.
• Prediction: First predicted by Albert Einstein in 1916 as part of his General Theory of Relativity.
• First Detection: Directly detected for the first time in 2015 by LIGO (Laser Interferometer Gravitational-Wave Observatory).
• Sources: Merging black holes, colliding neutron stars, supernovae, and rotating neutron stars with asymmetries.
• Speed: Travel at the speed of light through spacetime.
• Significance: Opens a new field of gravitational wave astronomy, allowing observation of events invisible to electromagnetic telescopes.
• Nobel Prize: The 2017 Nobel Prize in Physics was awarded to Rainer Weiss, Barry Barish, and Kip Thorne for the LIGO detector and observation of gravitational waves.

Detailed Explanation:

Answer: Option 3 — 3 only

Only Statement 3 is correct. Plant varieties cannot be patented under the Indian Patents Act, though they receive protection under a separate sui generis system (PPVFR Act, 2001). Statement 1 is incorrect because biological processes for seed production are explicitly excluded from patenting under Section 3(j) of the Patents Act. Statement 2 is incorrect because the Intellectual Property Appellate Board (IPAB) existed in India at the time this question was asked in 2019 (it was later abolished in 2021).

❌ Statement 1 – Incorrect: Section 3(j) of the Indian Patents Act explicitly excludes biological processes for the propagation or production of plants (including seeds) from being patented.

❌ Statement 2 – Incorrect: The Intellectual Property Appellate Board (IPAB) was established in 2003 and was functional when this question was set in 2019; it was abolished only in 2021 through the Tribunals Reforms Act.

✅ Statement 3 – Correct: Plant varieties are not eligible for patents under the Patents Act; instead, they are protected under the Protection of Plant Varieties and Farmers' Rights Act, 2001.

📝 Short Notes: Intellectual Property Protection for Biological Innovations in India

Detailed Explanation:

Answer: Option 4 — WTO

India enacted the Geographical Indications of Goods (Registration and Protection) Act, 1999 to comply with its obligations under the TRIPS (Trade-Related Aspects of Intellectual Property Rights) Agreement of the WTO. TRIPS mandates all WTO member countries to provide legal protection for Geographical Indications, which identify products originating from specific geographical locations whose qualities or reputation are essentially attributable to that origin.

📝 Short Notes: Geographical Indications in India

• GI Act, 1999: Enacted to comply with TRIPS Agreement (Articles 22-24) under WTO framework
• Definition: GI identifies goods as originating from a specific territory where quality, reputation, or other characteristics are essentially attributable to geographical origin
• Duration: GI registration is valid for 10 years and can be renewed indefinitely
• Examples: Darjeeling Tea (first Indian GI), Basmati Rice, Kanchipuram Silk, Tirupati Laddu, Kashmir Pashmina
• Authority: Controller General of Patents, Designs and Trademarks under the Department for Promotion of Industry and Internal Trade (DPIIT) administers GI registration
• Benefits: Legal protection against unauthorized use, promotes rural and agricultural development, preserves traditional knowledge