Science and Technology (S&T) in the UPSC CSE Prelims tests awareness of recent developments and applications in fields like space, defense, biotechnology, nanotech, robotics, and ICT. Questions emphasize current affairs, especially Indian initiatives (e.g., ISRO missions, DRDO systems), emerging technologies (AI, quantum tech), and their societal relevance. Unlike theory-heavy subjects, S&T focuses on understanding concepts and their applications rather than deep technical details. NCERTs, newspapers, and sources like PIB, DST, and ISRO websites are key. Prioritizing India-specific advancements and linking them to current news ensures relevance. Static portions are minimal but foundational knowledge aids comprehension of dynamic topics.
As regards S&T and Basic Science in CSE Prelims 2025, the questions were reasonable in number. In S&T, questions featured from all the important topics like space sector, defense, IT, biotech and cutting edge technologies. Except for the two basic science questions, all the questions were based on current affairs. Surprisingly, there were two questions related to Electric Vehicles. And the difficulty level of the questions was moderate to difficult.
Given below is the breakdown of the 100 questions asked in CSE Prelims 2025.
The Detailed Analysis of UPSC Prelims 2025 from Science & Technology section are as follows
UPSC Prelims S&T
Q. Consider the following pairs:
Plant Description
I. Cassava : Woody shrub
II. Ginger : Herb with pseudostem
III. Malabar spinach : Herbaceous climber
IV. Mint : Annual shrub
V. Papaya : Woody shrub
How many of the above pairs are correctly matched?
(a) Only two
(b) Only three
(c) Only four
(d) All the five
Answer: B
Explanation
- Cassava (Manihot esculenta) is a woody shrub native to South America, cultivated primarily for its starchy tuberous roots, which serve as a major source of carbohydrates in tropical and subtropical regions. It is also known as tapioca in parts of India. Hence pair I is correctly matched.
- Ginger (Zingiber officinale), originally from Southeast Asia, is a perennial herb that produces a pseudostem made up of tightly packed leaf bases. Its rhizome is widely used in cooking and traditional medicine. Hence pair II is correctly matched.
- Malabar spinach (Basella alba) is a fast-growing herbaceous climber native to South Asia. It thrives in hot, humid climates and is valued for its edible, mucilaginous leaves and stems, which are rich in nutrients. Hence pair III is correctly matched.
- Mint (Mentha species) is a vigorous perennial herb It spreads rapidly through underground rhizomes and is known for its aromatic leaves, which are widely used in culinary, cosmetic, and medicinal applications. Hence pair IV is not correctly matched.
- Finally, papaya (Carica papaya) is a tropical plant that appears tree-like but is actually a large herb with a soft, non-woody stem. Native to Central America, it is grown for its sweet, nutritious fruit and has several traditional medicinal uses. Despite its size, papaya’s structure classifies it botanically as an herb, not a woody shrub. Hence pair V is not correctly matched.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation: Not current affairs-derived, but mint, ginger, papaya are commonly known plants
Sources:
- Not picked from the NCERT books or any standard newspapers.
UPSC Prelims S&T
Q. GPS-Aided Geo Augmented Navigation (GAGAN) uses a system of ground stations to provide necessary augmentation. Which of the following statements is/are correct in respect of GAGAN?
I. It is designed to provide additional accuracy and integrity.
II. It will allow more uniform and high quality air traffic management.
III. It will provide benefits only in aviation but not in other modes of transportation.
Select the correct answer using the code given below.
(a) I, II and III
(b) II and III only
(c) I only
(d) I and II only
Answer: D
Explanation
- The Indian Space Research Organization (ISRO) and the Airports Authority of India (AAI) have implemented the GAGAN project as a Satellite Based Augmentation System for the Indian Airspace. The primary objective of GAGAN is to establish a certifiable satellite based augmentation system for safety-of-life applications.
- Statement I is correct: GAGAN is designed to enhance the accuracy and integrity of GPS signals over the Indian airspace. It improves positioning accuracy from about 20 meters to 1–2 meters.
- Statement II is correct: GAGAN improves navigation reliability, allowing for more uniform and efficient air traffic management, especially in complex or busy airspace.
- Statement III is not correct: Although developed primarily for aviation, GAGAN also benefits other sectors like railways, road transport, maritime navigation, agriculture, and disaster management.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation: The topic is important as GAGAN and NAVIC always have a high chance to feature in the UPSC CSE
Sources:
Coverage of the topic in the VisionIAS All India Test Series/ Sandhan/Open Test
Sandhan Vision IAS Prelims Test Series Initiative
Consider the following statements regarding the GPS-aided GEO augmented navigation (GAGAN):
1. It is an Indian Satellite Based Augmentation System jointly developed by the Airports Authority of India and the ISRO.
2. India is the only country to have such a space based augmented navigation system.
3. It will allow aircrafts to land in low-visibility scenarios.
Which of the statements given above is/are not correct?
(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 only
(d) 1, 2 and 3
UPSC Prelims S&T
Q. Consider the following statements regarding Al Action Summit held in Grand Palais, Paris in February 2025:
- 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.
- Along with other countries, the US and UK also signed the declaration on inclusive and sustainable Al.
Which of the statements given above is/are correct?
(a) I only
(b) II only
(c) Both I and II
(d) Neither I nor II
Answer: A
Explanation:
- Statement I is correct: The AI Action Summit held at the Grand Palais in Paris on February 10–11, 2025, was co-chaired by France and India. It built upon the progress made at the Bletchley Park Summit in 2023 and the Seoul Summit in 2024, aiming to advance global cooperation on AI governance and development.
- Statement II is not correct: While the summit introduced a declaration on "inclusive and sustainable" AI, the United States and the United Kingdom declined to sign it. Their refusal was based on concerns over national security and the belief that the declaration did not adequately address global AI governance.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation
- The event took place recently and was co-hosted by India.
Sources
VisionIAS Current Affairs Source
- "PT 365 Updated Part : Article 2.2.3. INDIA-FRANCE
- PT 365 Updated Part : Article 4.10.8. COALITION FOR ENVIRONMENTALLY SUSTAINABLE AI
- Daily News Summary, Date- 13-02-2025- One Size Won’t Fit All, Find Common Ground"
UPSC Prelims S&T
Q. Consider the following statements:
Statement I:
Some rare earth elements are used in the manufacture of flat television, screens and computer monitors,
Statement II:
Some rare earth elements have phosphorescent properties.
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 not correct
(d) Statement I is not correct but Statement II is correct
Answer: A
Explanation:
- Rare earth elements (REEs) are a group of 17 metallic elements, including the lanthanides, scandium, and yttrium, known for their unique properties like magnetism, luminescence, and conductivity. These elements are crucial components in various technologies, from consumer electronics to clean energy and medical devices. While relatively abundant in the Earth's crust, they are often dispersed and difficult to extract in concentrated quantities, hence the term "rare earth".
- Statement I is correct: Rare earth elements such as europium, terbium, and yttrium are used in the manufacture of flat-screen TVs and computer monitors, particularly in the color displays.
- Statement II is correct and explains statement I: These rare earths have phosphorescent (or luminescent) properties, which means they emit light when excited by energy—this property is essential for producing vivid colors in display technologies.
- Hence option (a) is the correct answer.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation:
- REE is an important topic. The US-China trade war made this topic even more important as China is the leading REE exporter, but the properties of REE come under S&T and not IR or geography. That is why it was tough.
Sources:
- https://www.bbc.com/news/articles/c1drqeev36qo
UPSC Prelims S&T
Q. Consider the following statements:
I. Indian Railways have prepared a National Rail Plan (NRP) to create a future ready railway system by 2028.
II. ‘Kavach’ is an Automatic Train Protection system developed in collaboration with Germany.
III. ‘Kavach’ system consists of RFID tags fitted on track in the station section.
Which of the statements given above are not correct?
(a) I and II only
(b) II and III only
(c) I and III only
(d) I, II and III
Answer: A
Explanation:
- Indian Railways have prepared a National Rail Plan (NRP) for India – 2030. The Plan is to create a 'future ready' Railway system by 2030 and not 2028. Hence, statement 1 is not correct.
- Kavach is an Automatic Train Protection system which was developed indigenously by the Research Design and Standards Organisation (RDSO) in collaboration with the Indian industry. Hence, statement 2 is not correct.
- Key activities involved in the implementation of Kavach include:
- Installation of Station Kavach: Kavach is being installed at each and every station and block section along the tracks. These installations allow the system to monitor and manage train movements, ensuring safe operations.
- RFID Tag Installation: Radio Frequency Identification (RFID) tags are placed throughout the entire track length to enable the Kavach system to track train positions and detect any potential safety issues along the route. Hence, statement 3 is correct.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation:
- Kavach has been in the news because of the train accidents.
Sources:
VisionIAS Current Affairs Source:
- "PT 365 Economy 9.7 – Indian Railway safety PT-365 2025 (S&T): 9.7.1. KAVACH
- Monthly Current Affairs May 2024: Article 3.3. 3.3. LOGISTICS SECTOR OF INDIA
- Newstoday (18th June 2024): Train accident in West Bengal draws attention to the Railway Safety in India"
UPSC Prelims S&T
Q. Consider the following pace missions :
I. Axiom-4
II. SpaDeX
III. Gaganyaan
How many of the space missions given above encourage and support micro-gravity research?
(a) Only one
(b) Only two
(c) All the three
(d) None
Answer: C
Explanation:
- Recently, India has shortlisted 2 astronaut-designates for the upcoming Axiom-4 mission to the International Space Station. Axiom Mission 4 (Axiom-4): A private spaceflight mission to the International Space Station (ISS) operated by Axiom Space.
- Axiom-4: A private mission to the International Space Station (ISS), Axiom-4 supports microgravity research by carrying experiments related to medicine, materials science, and biology in space conditions. Hence option I is correct.
- SpaDeX (Space Docking Experiment): An Indian mission to demonstrate autonomous docking. While its primary goal is technological, microgravity effects are often studied during such missions, especially in maneuvering and system validation in orbit. Hence option II is correct.
- Gaganyaan: India’s first human spaceflight program. It aims to send humans into space, where microgravity research is a key scientific objective, especially in life sciences and space medicine. Hence option III is correct.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation:
- All the three missions have been in the news
Sources:
VisionIAS Current Affairs Source:
- "PT 365 2025 SnT: Article 5.1.2. Bharatiya Antariksh Station (BAS)
- News Today (30 Nov 2024): Axiom Mission 4 (Ax-4)"
UPSC Prelims S&T
Q. 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 Globe- : Military transport aircraft
master III
How many of the pairs given above are correctly matched?
(a) Only one
(b) Only two
(c) All the three
(d) None
Answer: B
Explanation:
- Pair I is correctly matched: The Dornier-228 aircraft is used by the Indian Navy and Coast Guard for maritime surveillance and patrol. The Dornier 228 is a versatile, twin-engine turboprop aircraft, known for its short takeoff and landing (STOL) capabilities and multi-mission utility. Manufactured by Hindustan Aeronautics Limited (HAL) in India and Dornier Flugzeugwerke in Germany, it's used for various roles including passenger transport, cargo, surveillance, and research.
- Pair II is not correctly matched: The IL-76 is a strategic airlifter, not a supersonic combat aircraft. It is used for heavy cargo and troop transport. The Ilyushin Il-76 is a Russian-designed, four-engine turbofan strategic airlifter, primarily used as a heavy-lift cargo aircraft. It was initially developed in the late 1960s for commercial cargo transport and later adapted for military roles. The Il-76 is known for its robust design and ability to carry heavy payloads over long distances.
- Pair III is correctly matched: The C-17 is a large military transport aircraft used by the Indian Air Force for strategic and tactical airlift missions. The Boeing C-17 Globemaster III is a large military transport aircraft developed by McDonnell Douglas for the United States Air Force. It is a versatile airlifter capable of strategic and tactical missions, including cargo and troop transport, aeromedical evacuation, and airdrop operations.
MOTIVATION, SOURCES AND COVERAGE OF PRELIMS QUESTION IN THE VISIONIAS SOURCES
Motivation:
- All the three aircrafts were in the news in the last 6-7 months in the context of India
Sources:
- https://timesofindia.indiatimes.com/india/c-17-aircraft-lands-at-kargil-in-a-major-boost-to-strategic-airlift-capabilities/articleshow/118765295.cms
- https://www.thehindu.com/news/national/medium-transport-aircraft-to-be-procured-will-replace-an-32-and-il-76-fleets-of-iaf/article68722466.ece
- https://m.economictimes.com/news/defence/india-targets-global-defence-market-with-dornier-228-offer-for-malaysian-coast-guard-including-tech-transfer/articleshow/117309015.cms
VisionIAS Current Affairs Sources:
As can be seen from the above analysis, questions from S&T in CSE Prelims 2025, were a mix of conceptual and factual type. Most of the themes were drawn from the VisionIAS Sandhan Initiative, All India Test Series 2025 and the various components of VisionIAS Current Affairs.
As the importance of the Previous Year Questions (PYQs) cannot be overstated, it is always an indispensable source for every serious aspirant to go ahead with a well–guided strategy.
The VisionIAS 10-year strategy document for S&T is a sought-after source for the PYQ analysis.
TO WATCH THE CSE PRELIMS 2025 ANALYSIS VIDEO, CLICK ON THE FOLLOWING LINK
UPSC Prelims 2025 Analysis | GS Paper 1 - YouTube
TO WATCH THE VISIONIAS 10 Year PYQ ANALYSIS VIDEO, CLICK ON THE FOLLOWING
GS Prelims Analysis / Discussion | 10 Years (2015 - 2024) UPSC PYQ | Science & Technology | Part 1
Further, understand the UPSC Prelims with VisionIAS's Master Classes on PYQ of UPSC Prelims. This program transforms 13 years of UPSC previous year question papers into a powerful strategy- building resource. Designed to enhance your accuracy, speed, and conceptual clarity, it's a smart way to turn UPSC PYQs into your strongest preparation tool