UPSC Prelims Science & Technology: Repeated Themes and Most Asked Topics

Why Science and Technology Is Crucial for UPSC Prelims GS Paper 1

Science and Technology is a high-weightage, scoring area in the UPSC Prelims GS Paper 1, with repeated themes and most-asked topics appearing almost every year. In the UPSC Civil Services Prelims 2025, the Science & Technology (S&T) section continued its strong presence, contributing around 13–15 questions to General Studies Paper 1. This consistent trend makes UPSC Prelims Science and Technology one of the most crucial subjects for prelims-focused preparation, especially for aspirants aiming to capitalise on predictable, frequently repeated S&T themes.

  

UPSC Prelims Science Questions: Subject-Wise Trend Analysis (2021–2025)

Over the last decade, questions have consistently tested not just factual recall, but conceptual understanding and application of scientific principles in real-world contexts.

Understanding these repeated themes helps aspirants achieve two objectives:

1. Master the most frequently tested areas and
2. Prepare strategy that cuts across static fundamentals and current affairs relevance.

This article analyses these themes and provides clarity on why they matter, how they map to PYQs and how best to prepare.

UPSC Prelims Science and Technology: Repeated Topics, PYQ Analysis

1. Biotechnology and Biological Sciences: Repeated UPSC Prelims Questions and Trends

The biotechnology theme consistently appears in UPSC Prelims. Over the years, candidates have been asked about microorganisms, viruses, immunology, biofilms, probiotics and genetic technologies. Questions range from basic biological phenomena to cutting-edge biological innovations:

• Microorganisms growing in extreme conditions (temperature extremes, acidic environments).
• Concepts like biofilters and nutrient cycles in recirculating aquaculture.
• Biofilms on living and inert surfaces and their antibiotic resistance traits.
• Probiotics, vaccine platforms (mRNA, vector, inactivated platforms) and their modes.

These questions test a range of understanding — from cellular biology and microbiology basics (like roles of viruses and bacteria) to applications (like vaccines and probiotics). Static NCERT biology forms the foundation, but current developments in health technologies form the application layer that UPSC loves.

Why this theme repeats:
Biotechnology is central to modern governance — from public health infrastructure (vaccination strategies) to agriculture (Bt crops) and biodiversity research. This makes it relevant for both static science and current policy frames.

Examples:

2023

1. Consider the following statements:

1. Some microorganisms can grow in environments with temperature above the boiling point of water.
2. Some microorganisms can grow in environments with temperature below the freezing point of water.
3. Some microorganisms can grow in a highly acidic environment with a pH below 3.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

 

2022

1. Consider the following statements in respect of probiotics:
2. Probiotics are made of both bacteria and yeast.
3. The organisms in probiotics are found in foods we ingest but they do not naturally occur in our gut.
4. Probiotics help in the digestion of milk sugars.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) 1 and 3

(d) 2 and 3

 

2021 Question

1. 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?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

2022 Question

1. Consider the following statements:
2. Biofilms can form on medical implants within human tissues.
3. Biofilms can form on food and food processing surfaces.
4. Biofilms can exhibit antibiotic resistance.

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Preparation strategy:

• Start with NCERT Class XI–XII Biology basics (cells, biomolecules, genetics).
• Follow with dynamic current affairs on vaccine development, new biotech tools (like CRISPR) and microbial technologies.

2. Space Science and Technology: ISRO Missions and Astronomy in UPSC Prelims

Space technology is a staple subject repeating across years, focusing on both astronomy and recent space missions:

• Correct matching of cosmic objects and phenomena (Cepheids, nebulae, pulsars).
• Space Mission related questions tie into ISRO achievements — orbiters, lunar missions and probes.

UPSC uses space science questions to test basic scientific knowledge (like stellar classification, celestial phenomena) and to link them with India’s space policy and missions.

 

Examples:

2025:

1. Consider the following space missions: 
2. Axiom-4   
3. SpaDeX   
4. Gaganyaan   

How many of the space missions given above encourage and support microgravity research?    

(a) Only one   

(b) Only two   

(c) All three   

(d) None 

 

2016

1. Consider the following statements:

The Mangalyaan launched by ISRO

1. is also called the Mars Orbiter Mission
2. made India the second country to have a spacecraft orbit the Mars after USA
3. made India the only country to be successful in making its spacecraft orbit the Mars in its very first attempt

Which of the statement(s) given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Preparation strategy:

• Iterate fundamental astronomy concepts (stars, galaxies, space objects).
• Track recent and headline space missions (ISRO missions like Chandrayaan, Aditya-L1, Gaganyaan) through year-long current affairs.

 

3. Information and Communication Technology (ICT): Computing Concepts

Questions in this category blend IT fundamentals with real applications:

• Terms like qubit, Web 3.0, Software as a Service (SaaS) and Metaverse.
• Communication tech including RFID, CCTV, Wi-Fi short-range systems.

What we see repeatedly is UPSC’s effort to test not only the meaning of terms but also their relevance and implications for public systems and governance. For example, SaaS and Web 3.0 question framing often ties into digital governance platforms and citizen data control paradigms.

Why this theme repeats:
ICT is no longer peripheral — it directly contributes to digital governance, cybersecurity and economic transformation (Digital India initiatives). It’s central to GS syllabus themes like e-governance and digital public infrastructure.

Examples

2022

1. Which one of the following is the context in which the term "qubit" is mentioned?

(a) Cloud Services

(b) Quantum Computing

(c) Visible Light Communication Technologies

(d) Wireless Communication Technologies

Why this theme repeats:
Space exploration illustrates scientific progress and national capability. Its relevance to science and governance (in areas like communications, navigation and national security) makes it perennial.

2022

1. With reference to "Software as a Service (SaaS)", consider the following statements:
2. SaaS buyers can customise the user interface and can change data fields.
3. SaaS users can access their data through their mobile devices.
4. Outlook, Hotmail and Yahoo! Mail are forms of SaaS.

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Preparation strategy:

• Learn basic IT terminologies and their definitions.
• Understand applications in digital systems, cybersecurity and internet evolution.

 

4. Defence Technology and Strategic Systems in UPSC Prelims

The Defence Technology theme has grown stronger, with questions on:

• Missile technologies — ballistic vs cruise missiles, hypersonic systems.
• Fractional Orbital Bombardment Systems (FOBS).
• Use of radar systems in diverse applications.

UPSC asks such questions to gauge whether aspirants can distinguish between different defense technologies, their principles and missions. Questions are rarely about technical depth; rather, they focus on operational principle and policy implication.

Why this theme repeats:
Defense technologies sit at the intersection of science and national security — an area of perennial examination focus.

Examples:

2023

1. Consider the following statements:

1. Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocketpowered only in the initial phase of flight.
2. Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fuelled intercontinental ballistic missile.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

 

2023

1. With reference to India’s defence, consider the following pairs:

Aircraft Type	Description
I. Dornier-228	Maritime patrol aircraft
II. IL-76	Supersonic combat aircraft
III. C-17 Globemaster III	Military transport aircraft

 

How many of the pairs are correctly matched?

(a) Only one   

(b) Only two   

(c) All three   

(d) None  

Preparation strategy:

• Understand basic principles behind missile and radar systems.
• Keep abreast of India’s defense innovations via DRDO, press releases and defense ministry disclosures.

5. Everyday Science and Daily Life Technology in UPSC Prelims

This theme comprises seemingly mundane but conceptually rich questions that often catch aspirants off-guard:

• Accelerometer functions in everyday gadgets.
• Properties of plastics like polyethylene terephthalate (PET) and recycling issues.

These questions highlight how foundational scientific concepts manifest in common technologies — from smartphones to sustainable products.

Examples

1. With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements:
2. Its fibres can be blended with wool and cotton fibres to reinforce their properties.
3. Containers made of it can be used to store any alcoholic beverage.
4. Bottles made of it can be recycled into other products.
5. Articles made of it can be easily disposed of by incineration without causing greenhouse gas emissions.

Which of the statements given above are correct?

(a) 1 and 3

(b) 2 and 4

(c) 1 and 4

(d) 2 and 3

2023

1. In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?

1. Area of the hole in the lid
2. Temperature of the flame
3. Weight of the lid

Select the correct answer using the code given below.

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

2021

1. Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

(a) Low-density polyethylene

(b) Polycarbonate

(c) Polyethylene terephthalate

(d) Polyvinyl chloride

Why this theme repeats:
Such questions evaluate applied science comprehension — not theoretical recall but understanding of how science manifests in daily life. They also reward logical reasoning skills.

Preparation strategy:

• Read up on everyday physics, chemistry and materials science.
• Integrate NCERT fundamentals with current technology developments.

6. Environment, Climate Science and Energy Systems in UPSC Prelims

Science related to environment and energy intersects with biology, chemistry and technology:

• Anthropogenic sources of greenhouse gases like methane and nitrous oxide (e.g., paddy cultivation emissions).
• Concepts like System of Rice Intensification — how it impacts methane emission.

UPSC presents such questions to test both scientific insight and environmental governance awareness.

2024

Which one of the following is synthesised in human body that dilate blood vessels and increases blood flow?

(a) Nitric oxide

(b) Nitrous oxide

(c) Nitrogen dioxide

(d) Nitrogen Pentoxide

2022

1. Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide?

(a) Cotton

(b) Rice

(c) Sugarcane

(d) Wheat

Why this theme repeats:
Environmental science is part of both GS Paper 1 (Prelims) and GS Paper 3 (Mains), with high relevance due to climate change policies and sustainable development goals.

Preparation strategy:

• Cover environment topics from NCERT and static resources.
• Link them with current environmental policies and reports.

7. Nanotechnology and Materials Science: Emerging Areas in UPSC Prelims

Nanotech questions probe applications and implications:

• Uses of carbon nanotubes in medical and sensor technologies.
• Nanotechnology in targeted drug delivery and gene therapy contexts.

While not the most frequent theme, these topics recur enough to demand focused preparation, especially because they bridge fundamental science and applied innovation.

2022

1. Consider the following statements:
2. Other than those made by humans, nanoparticles do not exist in nature.
3. Nanoparticles of some metallic oxides are used in the manufacture of some cosmetics.
4. Nanoparticles of some commercial products which enter the environment are unsafe for humans.

Which of the statements given above is/are correct?

(a) 1 only

(b) 3 only

(c) 1 and 2

(d) 2 and 3

2020

1. With reference to carbon nanotubes, consider the following statements:

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

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2, 3 and 4 only

(c) 1, 3 and 4 only

(d) 1, 2, 3 and 4

 

2021

1. The term ‘ACE2’ is talked about in the context of

(a) genes introduced in the genetically modified plants

(b) development of India’s own satellite navigation system

(c) radio collars for wildlife tracking

(d) spread of viral diseases

 

Why this theme repeats:
Nanoscience sits at the frontier of modern science.. central to major research and innovation sectors.

Preparation strategy:

• Understand core nanoscience principles and common applications.
• Track news about new nanotech applications in medicine and industry.

 

8. Energy Systems and Sustainable Technology in UPSC Prelims

Questions in this category, though fewer, are conceptually significant:

• Fuel cells and alternative vehicle technologies.
• Storage systems like pumped-storage hydropower.

These questions often test understanding of principles, not design details and their relevance to current energy shifts (electric vehicles, hydrogen economy).

Examples

2025

1. Consider the following types of vehicles:  
2. Full battery electric vehicles   
3. Hydrogen fuel cell vehicles   
4. Fuel cell-electric hybrid vehicles   

How many of the above are considered as alternative powertrain vehicles?   

(a) Only one   

(b) Only two   

(c) All the three   

(d) None   

2024

1. Which one of the following is the exhaust Pipe emission from Fuel Cell Electric Vehicles powered by hydrogen?

(a) Hydrogen peroxide

(b) Hydronium

(c) Oxygen

(d) Water vapour

2024

1. Which one of the following is the exhaust Pipe emission from Fuel Cell Electric Vehicles powered by hydrogen?

(a) Hydrogen peroxide

(b) Hydronium

(c) Oxygen

(d) Water vapour

Why this theme repeats:
Energy transitions are central to global climate goals and national commitments to sustainable tech solutions.

Preparation strategy:

• Learn basic energy technology principles, especially those connected to renewables and alternative fuels.

9. Physics and Astronomy Fundamentals in UPSC Prelims Science

This recurring theme tests foundational aspects of physical science:

• Properties of stars (nuclear reaction rates, lifetimes).
• Significance of light-year as a measurement.

These concepts often appear in the context of space missions and celestial questions, but are rooted in basic physics and astronomy.

Examples

1. Consider the following statements:

Statement-I : Giant stars live much longer than dwarf stars.

Statement-II : Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.

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

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

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

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

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

2023

1. Consider the following pairs:

	Objects in space	Description
1.	Cepheids	Giant clouds of dust and gas in space
2.	Nebulae	Stars which brighten and dim periodically
3.	Pulsars	Neutron stars that are formed when massive stars run out of fuel and collapse

 

How many of the above pairs are correctly matched?

(a) Only one

(b) Only two

(c) All three

(d) None

2020

1. In India, why are some nuclear reactors kept under "IAEA safeguards" while others are not?

(a) Some use uranium and others use thorium

(b) Some use imported uranium and others use domestic supplies

(c) Some are operated by foreign enterprises and others are operated by domestic enterprises

(d) Some are State-owned and others are privately-owned

Why this theme repeats:
Physics and astronomy provide the scientific basis for many advanced technological questions; UPSC uses them to assess conceptual grounding.

Preparation strategy:

• Cover basic physical science topics in NCERT.
• Link them to space phenomena and modern astrophysics developments.

10. Artificial Intelligence, Automation and Emerging Technologies in UPSC Prelims

This is a rapidly consolidating theme in UPSC Prelims, where questions are framed around conceptual understanding of emerging technologies, not coding or engineering depth.

UPSC increasingly tests:
• Core principles behind AI, Machine Learning, Deep Learning and automation
• Applications in governance, healthcare, finance and public systems
• Distinctions between closely related terms (AI vs ML, algorithm vs model)

Recent trends show that UPSC prefers definition-based conceptual traps, often mixed with governance relevance.

Key areas repeatedly touched upon:

• Artificial Intelligence vs Machine Learning vs Deep Learning
• Algorithms, neural networks and data-driven decision-making
• Automation in services, robotics and smart systems
• Ethical and governance dimensions (bias, explainability — without philosophy)

2025

1. Consider the following statements regarding AI Action Summit held in Grand Palais, Paris in February 2025:
2. Co-chaired with India, the event builds on the advances made at the Bletchley Park Summit held in 2023 and the Seoul Summit held in 2024.  
3. Along with other countries, the US and UK also signed the declaration on inclusive and sustainable AI.  

Which of the statements given above is/are correct?  

(a) I only  

(b) II only  

(c) Both I and I   

(d) Neither I nor II  

2020

1. With the present state of development, Artificial Intelligence can effectively do which of the following?

1. Bring down electricity consumption in industrial units
2. Create meaningful short stories and songs
3. Disease diagnosis
4. Text-to-Speech Conversion
5. Wireless transmission of electrical energy

Select the correct answer using the code given below:

(a) 1, 2, 3 and 5 only

(b) 1, 3 and 4 only

(c) 2, 4 and 5 only

(d) 1, 2, 3, 4 and 5

 

2020

1. With reference to “Blockchain Technology”, consider the following statements:

1. It is a public ledger that everyone can inspect, but which no single user controls.
2. The structure and design of blockchain is such that all the data in it are about cryptocurrency only.
3. Applications that depend on basic features of blockchain can be developed without anybody’s permission.

Which of the statements given above is/are correct?

(a) 1 only

(b) 1 and 2 only

(c) 2 only

(d) 1 and 3 only

 

Why this theme repeats:
AI and automation are now integral to digital governance, national missions and economic transformation. UPSC treats AI as an extension of ICT but increasingly tests it as a standalone scientific domain.

Summary of Repeated Science and Technology Themes in UPSC Prelims

To make this even clearer, here’s a recurring theme map based on PYQs and trend analysis across years:

Theme	Why It Repeats
Biotechnology & Life Sciences	Relevance to health, governance, disease control policies
Space Science & Astronomy	Technological achievements and India’s space mission narratives
ICT & Computing	Digital governance, cybersecurity, modern tech lexicon
Defence Technologies	National security applications, DRDO innovations
Everyday Technology	Applied science in daily life, conceptual clarity
Environment & Energy	Climate change policy relevance
Nanotechnology & Materials	Frontier innovation and application
Physics & Astronomy Fundamentals	Conceptual science foundation
Artificial Intelligence (AI), Automation & Emerging Digital Technologies	Innovation ecosystem and governance

 

How to Prepare Science and Technology for UPSC Prelims Using PYQ Trends

1. Start with NCERTs: Build a strong foundation in basic physics, chemistry and biology. Static knowledge helps clarify answers for concept-based questions.
2. Stay Updated with Current Affairs: Most S&T questions derive from recent scientific developments or news items. Regularly read science sections of major newspapers and government releases.
3. Leverage PYQ Analysis: Patterns emerge only when past questions are analysed together. The recurring pan-India themes listed here reflect those patterns.
4. Link Science to Society: UPSC rewards understanding of how science impacts policy and society e.g., vaccine platforms, renewable energy goals or digital platforms like SaaS.
5. Use Reliable Sources: Apart from NCERT, sources like IASGYAN and standard notes from reputed coaching platforms help bridge static and dynamic contexts.

Conclusion: How Repeated Science & Technology Themes Can Be a Scoring Advantage

Science and Technology in UPSC Prelims is much more than a collection of random facts. It is an integrated domain where science principles, recent innovations and governance implications converge. Over the years, UPSC has consistently tested aspirants on conceptual clarity, application ability and awareness of real-world technological progress. By recognising the recurring themes outlined above and preparing with a strategic blend of static fundamentals and dynamic current affairs, aspirants can not only crack this section but also transform it into a scoring advantage.