UPSC Prelims Science and Technology: Previous Year Questions from 2012 to 2023 – Solved With Explanations

UPSC Prelims Science and Technology: Previous Year Questions from 2012 to 2023 – Solved With Explanations. The Union Public Service Commission (UPSC) civil services examination stands as one of the most rigorous and prestigious tests of merit in India.

Attracting hundreds of thousands of aspirants each year, the exam serves as the gateway to the esteemed Indian Civil Services, a cadre of professionals tasked with the administration and governance of one of the world’s most diverse and populous nations.

One cannot underscore enough the significance of the Science and Technology (S&T) section within this examination. In a rapidly evolving world, where the boundaries of what we know are constantly being pushed, S&T plays a pivotal role. It is the backbone of modern development, a catalyst for policy decisions, and a key influencer of geopolitical strategies.

For a civil servant, understanding the nuances of S&T is not just an academic exercise, but a necessity. This understanding aids in policy formulation, governance, and international diplomacy, especially in an era where technological prowess is tantamount to national strength.

This compilation seeks to provide a comprehensive resource to UPSC aspirants targeting the S&T segment. It amalgamates questions, answers, and explanations from the years 2012 to 2023, offering a deep dive into the patterns, complexities, and recurrent themes of the section.

However, it is imperative for the reader to approach this compilation with a discerning mind. While every effort has been made to ensure accuracy and completeness, there might be instances where certain questions are not included. Additionally, the nature of many questions in the UPSC exam is such that they can have multiple interpretations, leading to potential variations in the answers. Hence, readers are encouraged to treat this as a guiding resource rather than an exhaustive or definitive manual.

Your journey through the vast expanse of Science and Technology, as seen through the lens of the UPSC, begins here. It promises to be enlightening, challenging, and most importantly, instrumental in shaping the future custodians of India’s governance.

The Union Public Service Commission’s (UPSC) Civil Services Examination (CSE) stands as a testament to the vast and varied knowledge base expected of India’s future civil servants. Over the years, the prominence of Science and Technology (S&T) in the CSE has grown, reflecting its increasing significance in contemporary governance, policy-making, and global issues.

This compilation provides a curated selection of S&T questions from the CSE spanning the years 2012 to 2023, serving as an invaluable resource for aspirants and educators alike.

Through the lens of the past decade, this book captures the evolving nature of the S&T domain in the CSE. The questions encompass a wide array of topics, from foundational scientific concepts to cutting-edge technological advancements. Notably, the CSE’s emphasis on applied science and its societal implications shines through, reflecting the multidisciplinary approach that the examination is renowned for.

For the aspirant looking to master the domain of Science and Technology in the UPSC examination, it is imperative to understand the varied fields that constitute this vast subject.

Areas such as: 1. Basic Sciences: Fundamental concepts in Physics, Chemistry, and Biology lay the groundwork.

2. Medical and Biotechnology: Emerging diseases, healthcare technologies, genetic research, and other related topics.

3. Space and Astronomy: India’s space missions, astronomical phenomena, and global space research initiatives.

4. Environment and Ecology: Climate change, sustainable technologies, environmental conservation, and biodiversity.

5. Information and Communication Technology: Digital governance, cyber security, and the role of information technology in administration.

6. Nuclear and Renewable Energy: The nuances of nuclear energy, solar power, wind energy, and India’s energy security.

7. Defense and Strategic Technologies: Defense technologies, missiles, and the role of science in national security.

8. Innovations and Technological Advancements: Contemporary and future-forward technologies that are likely to shape the global and national landscape.

As aspirants delve into this collection, it’s essential to approach these questions not merely as queries to be answered but as a reflection of the broader scientific discourse shaping the world. Engaging with the explanations will further enrich one’s understanding, providing depth and context to the answers.

In conclusion, this book aims to empower its readers with a comprehensive understanding of the S&T domain as envisaged by the UPSC CSE. By combining rigorous study with a keen sense of curiosity, aspirants can navigate the complexities of science and technology, translating their knowledge into effective governance and policy-making for the betterment of society.

1. Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?

(a) Butterflies

(b) Dragonflies

(c) Honeybees

(d) Wasps

Answer: (c) Honeybees

Explanation: Honeybees perform the waggle dance to communicate the direction and distance of a food source to other members of the hive. This dance is an intricate series of movements that conveys information about the location of resources.

2. Consider the following statements:

1. Some mushrooms have medicinal properties.

2. Some mushrooms have psychoactive properties.

3. Some mushrooms have insecticidal properties.

4. Some mushrooms have bioluminescent properties.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) Only three

(d) All four

Answer: (d) All four

Explanation: Many mushrooms, like Reishi or Shiitake, have medicinal properties and have been used in traditional medicine for their health benefits.

Some mushrooms, often called” magic mushrooms”, contain psychoactive compounds like psilocybin, leading to hallucinations.

Certain mushrooms have compounds that can act as insecticides.

Bioluminescent mushrooms, such as the species found in the Mycena genus, emit light in the dark.

3. Consider the following statements regarding the Indian squirrels:

1. They build nests by making burrows in the ground.

2. They store their food materials like nuts and seeds in the ground.

3. They are omnivorous.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (b) Only two

Explanation:

Indian squirrels, especially the tree squirrels, usually build nests in trees, not by making burrows in the ground.

They do store food, like nuts and seeds, often burying them in the ground.

They are mainly herbivores but can sometimes eat small insects, making them omnivorous.

4. 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

Answer: (c) All three

Explanation:

There are extremophilic microorganisms known as thermophiles that can thrive at temperatures above the boiling point of water.

Psychrophiles are microorganisms that can grow in extremely cold conditions, even below the freezing point of water.

Acidophiles are microorganisms that thrive in highly acidic environments, even with a pH below 3.

5. Which one of the following makes a tool with a stick to scrape insects from a hole in a tree or a log of wood?

(a) Fishing cat

(b) Orangutan

(c) Otter

(d) Sloth bear

Answer: (b) Orangutan

Explanation: Orangutans are known for their intelligence and ability to use tools. They sometimes use sticks as tools to scrape insects or honey from tree holes.

6. Consider the following:

1. Aerosols

2. Foam agents

3. Fire retardants

4. Lubricants

In the making of how many of the above are hydrofluorocarbons used?

(a) Only one

(b) Only two

(c) Only three

(d) All four

Answer: (d) All four

Explanation: Hydrofluorocarbons (HFCs) are synthetic compounds used in various applications due to their properties. They can be found in aerosols, foam agents, fire retardants, and lubricants.

7. Consider the following statements:

1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.

2. Carbon fibres once used cannot be recycled.

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

Answer: (a) 1 only

Explanation:

Carbon fibres have high strength-to-weight ratios making them ideal for use in automobiles and aircraft components.

Carbon fibres can be recycled, though the process might be challenging and not as widespread as other recycling processes.

8. Consider the following actions:

1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously

2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive

3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode In how many of the above actions is the function of accelerometer required?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (c) All three

Explanation: An accelerometer is a device that measures changes in gravitational acceleration. It is used in: Cars, to detect sudden stops or collisions, which will trigger the airbags.

Laptops, to detect free-falls and help protect the hard drive from potential damage

Smartphones, to detect the orientation and adjust the display accordingly

9. With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements:

1. Biofilters provide waste treatment by removing uneaten fish feed.

2. Biofilters convert ammonia present in fish waste to nitrate.

3. Biofilters increase phosphorus as nutrient for fish in water.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (b) Only two

Explanation:

Biofilters are primarily used to convert toxic ammonia from fish waste into less harmful nitrate through nitrifying bacteria.

They don’t specifically remove uneaten feed; other systems like mechanical filtration take care of solid wastes.

Biofilters don’t increase phosphorus; rather, they help in nitrogen conversion.

10. Consider the following pairs:

1. Cepheid’s – 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

Answer: (a) Only one

Explanation:

Cepheid’s are stars which brighten and dim periodically, not giant clouds of dust and gas.

Nebulae are giant clouds of dust and gas in space.

Pulsars are correctly described.

11. Which one of the following countries has its own Satellite Navigation System?

(a) Australia

(b) Canada

(c) Israel

(d) Japan

Answer: (d) Japan

Explanation: Japan has its own regional satellite navigation system known as QZSS (Quasi-Zenith Satellite System). It is primarily designed to improve GPS accuracy in the Asia-Oceania regions, especially in urban areas where buildings can obstruct signals from satellites.

12. Consider the following statements:

1. Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocket-powered only in the initial phase of flight.

2. Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fueled 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

Answer: (d) Neither 1 nor 2

Explanation:

Ballistic missiles are rocket-powered and follow a ballistic trajectory.

Cruise missiles can be jet or rocket-powered and fly closer to the ground.

Agni-V is an intercontinental ballistic missile (ICBM) developed by India. BrahMos, on the other hand, is a supersonic cruise missile, a joint venture between India and Russia.

13. Consider the following statements regarding mercury pollution:

 1. Gold mining activity is a source of mercury pollution in the world.

2. Coal-based thermal power plants cause mercury pollution.

3. There is no known safe level of exposure to mercury.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (c) All three

Explanation:

Mercury is often used in gold mining (especially in small-scale or artisanal mining) to amalgamate with gold, thus becoming a significant source of mercury pollution.

Coal contains trace amounts of mercury. When coal is burned in thermal power plants, this mercury is released into the atmosphere, leading to pollution.

Mercury is a neurotoxin. Even at low exposure levels, it can have harmful effects, especially on fetuses and young children.

14. With reference to green hydrogen, consider the following statements:

1. It can be used directly as a fuel for internal combustion.

2. It can be blended with natural gas and used as fuel for heat or power generation.

3. It can be used in the hydrogen fuel cell to run vehicles.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (c) All three

Explanation:

Green hydrogen is hydrogen produced using renewable energy sources, such as wind or solar, through the electrolysis of water.

Green hydrogen can indeed be used in internal combustion engines as a direct fuel. While not as common as hydrogen fuel cells for vehicles, it’s feasible.

It can also be blended with natural gas to reduce the carbon content of the gas used for power or heat generation.

Hydrogen fuel cells convert hydrogen into electricity. Green hydrogen can be used in these fuel cells to power vehicles, providing a zero-emission transport solution.

1. S&T Questions From Year 2023

2. S&T Questions From Year 2022

3. S&T Questions From Year 2021

4. S&T Questions From Year 2020

5. S&T Questions From Year 2019

6. S&T Questions From Year 2018

7. S&T Questions From Year 2017

8. S&T Questions From Year 2016

9. S&T Questions From Year 2015

10. S&T Questions From Year 2014

11. S&T Questions From Year 2013

12. S&T Questions From Year 2012


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