UPSC Prelims 2022
Science & Technology Previous Year Questions (PYQs)

Detailed Explanation:

Answer: Option 3 — 1 and 3

This question tests knowledge about probiotics, which are live microorganisms beneficial for gut health. Statements 1 and 3 are correct as probiotics include both bacteria and yeast, and certain strains help digest lactose (milk sugar).

✅ Statement 1 – Correct: Probiotics consist of both bacteria (like Lactobacillus, Bifidobacterium) and yeast (like Saccharomyces boulardii).

❌ Statement 2 – Incorrect: Probiotic organisms naturally occur in our gut as part of the normal gut microbiome; probiotics supplement these beneficial microbes.

✅ Statement 3 – Correct: Some probiotic strains produce lactase enzyme, which helps break down lactose (milk sugar), aiding digestion especially in lactose-intolerant individuals.

📝 Short Notes: Probiotics

• Definition: Live microorganisms that provide health benefits when consumed in adequate amounts, particularly for gut health.
• Common Types: Bacteria (Lactobacillus, Bifidobacterium, Streptococcus thermophilus) and Yeast (Saccharomyces boulardii).
• Natural Sources: Yogurt, kefir, sauerkraut, kimchi, tempeh, miso, pickles, and other fermented foods.
• Benefits: Improve digestive health, enhance immune function, aid lactose digestion, synthesize vitamins (B and K), prevent diarrhea and constipation.
• Gut Microbiome: Human gut naturally contains trillions of microorganisms; probiotics supplement beneficial strains already present.
• vs Prebiotics: Probiotics are live organisms; prebiotics are non-digestible food components that feed beneficial gut bacteria.

Detailed Explanation:

Answer: Option 2 — 2 and 3 only

This question tests knowledge about different COVID-19 vaccine platforms used in India. Statement 1 is incorrect because Covishield is a viral vector vaccine (using chimpanzee adenovirus), not an mRNA vaccine. Statements 2 and 3 are correct as they accurately describe the platforms used for Sputnik V and COVAXIN respectively.

❌ Statement 1 – Incorrect: Covishield is a viral vector vaccine using chimpanzee adenovirus (ChAdOx1), not an mRNA platform vaccine.
✅ Statement 2 – Correct: Sputnik V uses a vector-based platform with two different human adenovirus vectors (rAd26 and rAd5) in a two-dose regimen.
✅ Statement 3 – Correct: COVAXIN, developed by Bharat Biotech, is an inactivated pathogen-based vaccine using the whole-virion inactivated Vero cell platform.

📝 Short Notes: COVID-19 Vaccine Platforms

Detailed Explanation:

Answer: Option 1 — 1 and 2 only

Non-Fungible Tokens (NFTs) are unique cryptographic tokens on blockchain that enable digital representation of physical or digital assets. However, unlike fungible assets, NFTs cannot be traded at equivalency since each token has a unique value and characteristics, making them unsuitable as a standard medium of commercial transactions.

✅ Statement 1 – Correct: NFTs enable digital representation of physical assets through tokenization, allowing real-world items like real estate, artwork, or luxury goods to be represented on blockchain, facilitating ownership transfer and reducing fraud.

✅ Statement 2 – Correct: NFTs are unique cryptographic tokens that exist on a blockchain with distinct identification codes and metadata that differentiate each token from others, unlike fungible cryptocurrencies like Bitcoin.

❌ Statement 3 – Incorrect: NFTs are non-fungible by definition, meaning they cannot be traded or exchanged at equivalency; each NFT has unique characteristics and value, unlike fungible assets (fiat currency, Bitcoin) that can serve as standard medium of exchange.

📝 Short Notes: Non-Fungible Tokens (NFTs)

• Definition: Unique digital identifiers recorded on blockchain that certify ownership and authenticity of specific digital or physical assets
• Key Characteristic: Non-fungibility means each token is unique and cannot be replaced or exchanged on a one-to-one basis
• Technology: Built on blockchain platforms like Ethereum, using smart contracts to enforce ownership and transfer rules
• Applications: Digital art, collectibles, gaming assets, virtual real estate, music rights, and tokenization of physical assets
• Difference from Cryptocurrency: Cryptocurrencies are fungible (interchangeable), while NFTs are unique with distinct values
• Tokenization: Process of converting rights to an asset into a digital token on blockchain
• Limitations: Cannot function as medium of exchange due to non-fungibility; high energy consumption concerns; speculation and volatility issues

Detailed Explanation:

Answer: Option 2 — Quantum Computing

A qubit (quantum bit) is the fundamental unit of information in quantum computing, analogous to the classical bit. Unlike classical bits that exist in either 0 or 1 state, qubits can exist in a superposition of both states simultaneously, enabling quantum computers to perform complex calculations exponentially faster for certain problems.

📝 Short Notes: Quantum Computing Fundamentals

• Qubit (Quantum Bit): The basic unit of quantum information that can exist in superposition of |0⟩ and |1⟩ states simultaneously.
• Superposition: A quantum phenomenon where a qubit exists in multiple states at once until measured, unlike classical bits which are deterministic.
• Quantum Entanglement: Qubits can be entangled such that the state of one instantly affects another, regardless of distance.
• Quantum Gates: Operations that manipulate qubits, analogous to logic gates in classical computing but exploiting quantum properties.
• Decoherence: The main challenge in quantum computing where qubits lose their quantum properties due to environmental interference.
• Applications: Cryptography, drug discovery, optimization problems, artificial intelligence, and financial modeling.
• Major Players: IBM, Google, Microsoft, and various research institutions are developing quantum computers with increasing qubit counts.

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

All three statements correctly describe the characteristics and examples of Software as a Service (SaaS). SaaS is a cloud computing model where software is hosted remotely and accessed via the internet, eliminating the need for local installation.

✅ Statement 1 – Correct: Most SaaS platforms allow users to customize the user interface and modify data fields according to their business requirements, providing flexibility within the hosted environment.

✅ Statement 2 – Correct: A fundamental advantage of SaaS is platform-independent accessibility, enabling users to access their data and applications from any device with internet connectivity, including mobile devices.

✅ Statement 3 – Correct: Outlook (web version), Hotmail, and Yahoo! Mail are classic examples of SaaS applications where email services are delivered over the internet without requiring local software installation.

📝 Short Notes: Software as a Service (SaaS)

• Definition: SaaS is a cloud computing service model where applications are hosted by a service provider and made available to users over the internet.
• Key Characteristics: No local installation required, subscription-based pricing, automatic updates, multi-tenant architecture, and accessibility from anywhere.
• Advantages: Lower upfront costs, scalability, automatic maintenance and updates, cross-platform compatibility, and reduced IT infrastructure burden.
• Common Examples: Google Workspace (Gmail, Docs, Sheets), Microsoft 365, Salesforce, Dropbox, Slack, Zoom, and Adobe Creative Cloud.
• Cloud Service Models: SaaS (Software), PaaS (Platform as a Service), and IaaS (Infrastructure as a Service) form the three main cloud computing service models.
• Security Considerations: Data is stored on third-party servers, requiring trust in the provider's security measures and compliance standards.

Detailed Explanation:

Answer: Option 4 — 2 and 3

This question tests understanding of nanoparticles, their natural occurrence, applications, and potential safety concerns. Statement 1 is incorrect as nanoparticles occur naturally through various processes, while statements 2 and 3 are correct regarding their use in cosmetics and potential environmental risks.

❌ Statement 1 – Incorrect: Nanoparticles exist naturally in the environment through volcanic eruptions, forest fires, ocean spray, and biological processes (e.g., viruses, protein complexes).

✅ Statement 2 – Correct: Nanoparticles of metallic oxides like zinc oxide (ZnO) and titanium dioxide (TiO₂) are commonly used in sunscreens and cosmetics for UV protection and improved texture.

✅ Statement 3 – Correct: Many nanoparticles from commercial products can enter the environment and may pose health risks due to their ability to penetrate biological barriers and accumulate in organs.

📝 Short Notes: Nanoparticles

• Definition: Particles with at least one dimension between 1-100 nanometers (nm)
• Natural Sources: Volcanic ash, sea spray, forest fires, mineral weathering, and biological entities (viruses, ferritin)
• Cosmetic Applications: Zinc oxide and titanium dioxide nanoparticles in sunscreens provide broad-spectrum UV protection without visible white residue
• Other Applications: Drug delivery, electronics, catalysis, water purification, antibacterial coatings
• Safety Concerns: High surface area-to-volume ratio allows interaction with biological systems; can cross blood-brain barrier and cell membranes; potential for bioaccumulation
• Environmental Impact: Persistence in environment, toxicity to aquatic organisms, unknown long-term effects on ecosystems
• Regulation: Many countries are developing specific guidelines for nanomaterial safety assessment in consumer products

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

All three technologies—CCTV, RFID, and WLAN—are classified as short-range communication devices. Short-range technologies typically operate within a few centimeters to a few hundred meters, unlike long-range technologies such as cellular networks or satellite communication.

✅ Closed-Circuit Television (CCTV) – Short-Range: CCTV systems use cables or wireless connections with limited range, typically confined to a building or specific premises, operating within tens to hundreds of meters.

✅ Radio Frequency Identification (RFID) – Short-Range: RFID uses radio waves for identification and tracking, with typical reading ranges from a few centimeters to about 10 meters depending on the tag type (passive, active, or semi-passive).

✅ Wireless Local Area Network (WLAN/Wi-Fi) – Short-Range: WLAN networks typically operate within 20-100 meters indoors and up to 300 meters outdoors, making them short-range compared to wide-area networks like cellular or satellite systems.

📝 Short Notes: Short-Range Communication Technologies

• Short-range vs Long-range: Short-range technologies operate within localized areas (centimeters to hundreds of meters), while long-range technologies like cellular networks (kilometers) and satellite communication (global coverage) serve wider geographical areas.
• Power consumption: Short-range devices typically consume less power, making them suitable for battery-operated applications.
• Data rate: Generally, shorter ranges allow for higher data transfer rates (e.g., Wi-Fi offers Mbps to Gbps speeds).
• Applications: Short-range technologies are ideal for home automation, personal devices, local networking, surveillance, and proximity-based services.

Detailed Explanation:

Answer: Option 4 — 2 and 3

DNA barcoding is a molecular technique that uses short, standardized gene sequences to identify species. It is particularly effective for distinguishing morphologically similar species and detecting species composition in processed materials, but it cannot determine the age of organisms.

❌ Statement 1 – Incorrect: DNA barcoding identifies species based on genetic sequences but cannot assess the age of a plant or animal, as age determination requires other methods like dendrochronology or carbon dating.

✅ Statement 2 – Correct: DNA barcoding excels at distinguishing among species that look morphologically similar by comparing their unique genetic barcodes (typically COI gene in animals, rbcL or matK in plants).

✅ Statement 3 – Correct: DNA barcoding is extensively used in food safety to identify undeclared or undesirable animal/plant materials in processed foods, helping detect food adulteration and mislabeling.

📝 Short Notes: DNA Barcoding

• Definition: A molecular tool that uses short, standardized DNA sequences to rapidly identify species
• Gene Markers: COI (Cytochrome C Oxidase I) for animals; rbcL, matK, ITS for plants
• Applications: Species identification, biodiversity assessment, food authentication, detection of illegal wildlife trade, identification of medicinal plants
• Advantages: Works with small tissue samples, identifies cryptic species, useful for immature/damaged specimens
• Limitations: Cannot determine age, recent speciation may show similar sequences, requires reference database
• Global Initiative: International Barcode of Life (iBOL) project maintains comprehensive DNA barcode libraries

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

Web 3.0 represents the next generation of the internet built on decentralization, blockchain technology, and user ownership. All three statements correctly describe key features of Web 3.0 technology.

✅ Statement 1 – Correct: Web 3.0 enables users to control their own data through decentralization, eliminating the need for centralized platforms to store and manage personal information.
✅ Statement 2 – Correct: Blockchain technology is fundamental to Web 3.0 and enables the creation of decentralized social networks where users own their content and interactions.
✅ Statement 3 – Correct: Web 3.0 operates on a decentralized model where users collectively maintain and control the network, rather than a single corporate entity.

📝 Short Notes: Web 3.0

• Definition: The third generation of internet services focusing on decentralization, blockchain technology, and semantic web capabilities
• Core Technologies: Blockchain, artificial intelligence, machine learning, and decentralized protocols
• Key Features: User data ownership, permissionless access, trustless interactions, and tokenization
• Differences from Web 2.0: Web 2.0 is centralized (controlled by corporations), while Web 3.0 is decentralized (user-controlled)
• Applications: Decentralized finance (DeFi), NFTs, decentralized autonomous organizations (DAOs), and blockchain-based social networks
• Advantages: Enhanced privacy, data security, censorship resistance, and direct peer-to-peer interactions
• Challenges: Scalability issues, high energy consumption, regulatory uncertainty, and user adoption barriers

Detailed Explanation:

Answer: Option 4 — They protect the body from the diseases caused by pathogens.

B cells and T cells are both lymphocytes and key components of the adaptive immune system that specifically defend the body against pathogens like viruses, bacteria, fungi, and parasites. B cells produce antibodies that recognize and neutralize specific antigens on pathogens, while T cells either directly kill infected cells (cytotoxic T cells) or help coordinate the immune response (helper T cells).

❌ Option 1 – Incorrect: While immune cells can respond to allergens, the primary role of B and T cells is pathogen defense, not allergen protection.
❌ Option 2 – Incorrect: Pain and inflammation alleviation is not the primary function of B and T cells; they are involved in immune response.
❌ Option 3 – Incorrect: B and T cells are immunoactive, not immunosuppressants; they enhance rather than suppress immune function.
✅ Option 4 – Correct: This accurately describes the primary role of B and T cells in adaptive immunity against pathogenic diseases.

📝 Short Notes: B Cells and T Cells

Detailed Explanation:

Answer: Option 3 — A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.

The Fractional Orbital Bombardment System (FOBS) is a nuclear weapons delivery system that launches a warhead into a low Earth orbit trajectory instead of a traditional high-arc ballistic path. The key characteristic is that the missile completes only a fraction of an orbit before deorbiting to strike its target, making it harder to detect by early warning systems designed for conventional ballistic missiles. This orbital approach allows the weapon to approach from unexpected directions and reduces warning time significantly.

❌ Option 1 – Incorrect: FOBS is not designed for asteroid defense but for delivering weapons to Earth-based targets via orbital trajectory.
❌ Option 2 – Incorrect: This describes planetary landing maneuvers, not FOBS which is specifically about weapon delivery systems orbiting Earth.
✅ Option 3 – Correct: Accurately describes FOBS as a missile placed in orbit that deorbits over a terrestrial target.
❌ Option 4 – Incorrect: This describes a comet rendezvous mission, unrelated to FOBS weapons systems.

📝 Short Notes: Fractional Orbital Bombardment System (FOBS)

• Concept: A weapons delivery system developed during the Cold War era, primarily by the Soviet Union in the 1960s
• Trajectory: Uses a low Earth orbit (LEO) path rather than a high ballistic arc, completing only a fraction of an orbit before deorbiting
• Strategic Advantage: Can approach targets from unexpected directions (including over the South Pole), bypassing radar systems oriented toward traditional ballistic missile trajectories
• Detection Challenge: Early warning systems designed to detect high-arc ballistic missiles may fail to identify low-orbit FOBS until late in the attack sequence
• Reduced Warning Time: The orbital path and lower altitude mean less time between detection and impact compared to intercontinental ballistic missiles (ICBMs)
• Modern Context: Recent reports suggest renewed interest in FOBS technology by certain nations, making it relevant to contemporary strategic discussions
• Treaty Status: The Outer Space Treaty (1967) prohibits placing weapons of mass destruction in orbit, though FOBS occupies a grey area as it doesn't complete a full orbit

Detailed Explanation:

Answer: Option 3 — 1, 3, 4, 6 and 7 only

Solar storms (solar flares and coronal mass ejections) release charged particles and electromagnetic radiation that interact with Earth's magnetosphere and ionosphere, causing various technological and atmospheric disturbances. The correct effects include disruption to satellite-based navigation, power grid damage, enhanced auroral displays, satellite orbital changes, and radio communication interference.

✅ Statement 1 – Correct: Solar storms disrupt the ionosphere, causing GPS signal delays and navigation system failures.
❌ Statement 2 – Incorrect: Tsunamis are caused by seismic or volcanic activity underwater, not by solar storms which affect electromagnetic and particle environments.
✅ Statement 3 – Correct: Geomagnetically induced currents (GICs) from solar storms can overload transformers and damage power grids, causing blackouts.
✅ Statement 4 – Correct: Enhanced solar wind energizes particles in the magnetosphere, creating intense auroras visible at lower latitudes than normal.
❌ Statement 5 – Incorrect: Solar storms do not directly cause widespread forest fires; they affect electromagnetic systems, not ignition sources on such a scale.
✅ Statement 6 – Correct: Increased atmospheric drag from heating during solar storms can alter satellite orbits, especially in low Earth orbit.
✅ Statement 7 – Correct: Ionospheric disturbances disrupt shortwave (HF) radio communications, particularly affecting polar routes where ionospheric effects are strongest.

📝 Short Notes: Solar Storms and Earth Effects

• Solar Storm Components: Solar flares (electromagnetic radiation) and Coronal Mass Ejections (CME - charged particles) that reach Earth in 1-3 days.
• Magnetosphere Interaction: Charged particles compress Earth's magnetosphere, inducing geomagnetic storms.
• Ionospheric Disruption: Solar radiation alters ionosphere density, affecting radio wave propagation and satellite communications.
• Geomagnetically Induced Currents (GICs): Magnetic field fluctuations induce currents in long conductors like power lines and pipelines.
• Aurora Formation: Charged particles collide with atmospheric gases (oxygen, nitrogen), producing light displays typically at 60-70° latitude, but extending to lower latitudes during major storms.
• Space Weather Monitoring: Organizations like NOAA's Space Weather Prediction Center track solar activity to issue warnings for critical infrastructure protection.
• Historical Events: Carrington Event (1859) caused widespread telegraph failures; Quebec blackout (1989) affected 6 million people for 9 hours.

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

All three statements about biofilms are correct. Biofilms are complex microbial communities encased in a self-produced protective matrix that can form on various surfaces, including medical implants, food processing equipment, and biological tissues, exhibiting significant antibiotic resistance.

✅ Statement 1 – Correct: Biofilms readily form on medical implants like catheters, heart valves, and artificial joints within human tissues, leading to chronic infections that are difficult to treat.

✅ Statement 2 – Correct: Biofilms commonly form on food and food processing surfaces, contaminating food products and contributing to spoilage while being resistant to standard cleaning methods.

✅ Statement 3 – Correct: Bacteria within biofilms exhibit 10-1000 times greater antibiotic resistance than planktonic (free-floating) bacteria due to the protective matrix barrier, altered metabolic states, and horizontal gene transfer mechanisms.

📝 Short Notes: Biofilms

• Definition: Biofilms are structured communities of microorganisms encased in a self-produced extracellular polymeric substance (EPS) matrix, adhering to surfaces.
• Medical Implications: Responsible for 65-80% of all microbial infections in humans; form on indwelling medical devices, teeth (dental plaque), and in chronic wounds.
• Resistance Mechanisms: EPS matrix acts as a barrier to antimicrobials; slow growth rate in biofilms reduces antibiotic efficacy; persister cells survive treatment; gene transfer promotes resistance spread.
• Industrial Impact: Contaminate water pipes, ship hulls (biofouling), heat exchangers, and food processing equipment; cause economic losses and efficiency reduction.
• Food Safety: Biofilms in food industry harbor pathogens like Listeria, Salmonella, and E. coli; resistant to standard sanitization procedures.
• Control Strategies: Include mechanical removal, enzymatic disruption of EPS, quorum sensing inhibitors, and combination antimicrobial therapies.

Detailed Explanation:

Answer: Option 3 — 1 and 2

Gucchi (Morchella esculenta) is a rare and expensive wild mushroom fungus found in the Himalayan regions. It grows naturally in temperate forest areas following snowmelt but cannot be commercially cultivated, making statements 1 and 2 correct while statement 3 is incorrect.

✅ Statement 1 – Correct: Gucchi is a fungus (Morchella esculenta) belonging to the Morchellaceae family, known for its distinctive honeycomb-like appearance and prized culinary value.

✅ Statement 2 – Correct: It grows naturally in the temperate conifer forest areas of the Himalayas, particularly in Jammu and Kashmir, Himachal Pradesh, and Uttarakhand during spring after snowmelt.

❌ Statement 3 – Incorrect: Gucchi mushrooms cannot be commercially cultivated due to their complex mycorrhizal associations with trees; they are wild-harvested, and they primarily grow in the Western Himalayas, not the north-eastern foothills.

📝 Short Notes: Gucchi (Morchella Mushroom)

• Scientific Name: Morchella esculenta, belonging to family Morchellaceae
• Appearance: Distinctive honeycomb or sponge-like cap structure, light brown to dark brown color
• Habitat: Temperate conifer forests of Western Himalayas (J&K, Himachal Pradesh, Uttarakhand) at altitudes of 2,500-3,500 meters
• Season: Grows in spring (March-May) following snowmelt in moist, shaded forest floors
• Economic Value: One of the most expensive mushrooms globally, fetching ₹10,000-30,000 per kg; major export item
• Cultivation Status: Cannot be commercially cultivated due to complex symbiotic relationship with tree roots; only wild-harvested by local communities
• Nutritional Value: Rich in protein, vitamins (especially Vitamin D), minerals, and antioxidants
• Conservation Concern: Over-harvesting threatens wild populations; sustainable harvesting practices needed