UPSC Prelims 2013 Question Paper
Explore the complete solved question paper for UPSC Prelims 2013 featuring 100 solved questions with bilingual (English & Hindi) explanations, official answer key, and subject weightage breakdown.
With reference to the National Legal Services Authority, consider the following statements :
- Its objective is to provide free and competent legal services to the weaker sections of the society on the basis of equal opportunity.
- It issues guidelines for the State Legal Services Authorities to implement the legal programs and schemes throughout the country.
Which of the statements given above is/are correct?
Detailed Explanation:
✅ Statement 1 – Correct: NALSA's primary objective is to provide free and competent legal services to weaker sections including women, children, SC/ST, and persons with disabilities on the basis of equal opportunity as mandated by Article 39A of the Constitution.
✅ Statement 2 – Correct: NALSA is the apex body that issues guidelines, principles, and policies for State Legal Services Authorities (SLSAs) to implement legal aid programs and schemes uniformly throughout the country under the Legal Services Authorities Act, 1987.
Priority Sector Lending by banks in India constitutes the lending to:
Detailed Explanation:
Priority Sector Lending (PSL) mandates banks to allocate 40% of Adjusted Net Bank Credit (ANBC) to designated sectors including agriculture and allied activities, micro and small enterprises, weaker sections (low-income groups, students for education, housing), export credit, renewable energy, and social infrastructure.
All three options – agriculture, micro and small enterprises, and weaker sections – are explicitly covered under the RBI's PSL guidelines, making option 4 the correct answer.
To obtain full benefits of demographic dividend, what should India do?
Detailed Explanation:
Demographic dividend refers to economic growth potential when the working-age population (15-64 years) exceeds the non-working-age population.
Promoting skill development is essential to transform this large workforce into productive and employable human capital. Without adequate technical and vocational skills, a large working-age population leads to unemployment and social instability rather than economic growth. Social security schemes provide safety nets but don't directly enhance productivity. Reducing infant mortality affects future demographics, not current workforce quality. Privatization of higher education alone doesn't ensure skill-based employability across all economic sectors.
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The known forces of nature can be divided into four classes, viz, gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
Detailed Explanation:
❌ Statement 1 – Incorrect: Gravity is the weakest of the four fundamental forces, not the strongest.
✅ Statement 2 – Correct: Electromagnetism acts only on particles with electric charge (positive or negative).
✅ Statement 3 – Correct: Weak nuclear force is responsible for radioactivity and beta decay.
✅ Statement 4 – Correct: Strong nuclear force holds protons and neutrons together inside the atomic nucleus.
With reference to the usefulness of the by-products of the sugar industry, which of the following statements is/are correct?
- Bagasse can be used as biomass fuel for the generation of energy.
- Molasses can be used as one of the feedstocks for the production of synthetic chemical fertilizers.
- Molasses can be used for the production of ethanol.
Select the correct answer using the codes given below.
Detailed Explanation:
✅ Statement 1 – Correct: Bagasse (fibrous residue after sugarcane crushing) is widely used as biomass fuel for co-generation of electricity in sugar mills, making them energy self-sufficient.
❌ Statement 2 – Incorrect: Molasses is not a feedstock for synthetic chemical fertilizers; these are produced through Haber-Bosch process (ammonia) and phosphate/potash mining, not from sugar by-products.
✅ Statement 3 – Correct: Molasses serves as a key feedstock for ethanol production through fermentation, supporting India's Ethanol Blending Programme (EBP) for fuel.
Fruits stored in a cold chamber exhibit longer storage life because -
Detailed Explanation:
Cold storage lowers the temperature, which directly reduces the rate of respiration in fruits.
Slower metabolic and enzymatic processes delay ripening, reduce microbial activity, and extend storage life significantly.
Which of the following statements is/are correct?
- Viruses lack enzymes necessary for the generation of energy.
- Viruses can be cultured in any synthetic medium.
- Viruses are transmitted from one organism to another by biological vectors only.
Select the correct answer using the codes given below.
Detailed Explanation:
✅ Statement 1 – Correct: Viruses lack metabolic machinery and enzymes for ATP generation; they depend entirely on host cells for energy production.
❌ Statement 2 – Incorrect: Viruses cannot be cultured in synthetic or artificial media; they require living host cells (bacteria, plants, animals, or cell cultures) for replication.
❌ Statement 3 – Incorrect: Viral transmission occurs through multiple routes – direct contact, respiratory droplets, contaminated water/food, airborne particles, fomites, and biological vectors (mosquitoes, ticks); vectors are not the only mode.
Which of the following diseases can be transmitted from one person to another through tattooing?
- Chikungunya
- Hepatitis B
- HIV-AIDS
Select the correct answer using the codes given below.
Detailed Explanation:
❌ Statement 1 – Incorrect: Chikungunya is a mosquito-borne viral disease transmitted by Aedes mosquitoes, not through blood contact or tattooing.
✅ Statement 2 – Correct: Hepatitis B is a bloodborne viral infection that can be transmitted through contaminated tattooing needles and equipment.
✅ Statement 3 – Correct: HIV-AIDS spreads through contact with infected blood, making transmission possible via unsterilized tattooing equipment.
Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?
- Dispersion
- Refraction
- Internal reflection
Select the correct Solution using the codes given below.
Detailed Explanation:
Refraction occurs when sunlight enters and exits the raindrop, bending light at air-water boundaries.
Dispersion separates white light into constituent colours as different wavelengths refract at different angles inside the droplet.
Internal reflection bounces the dispersed light off the rear inner surface of the raindrop back toward the observer, creating the visible rainbow arc.
All three phenomena—Dispersion, Refraction, and Internal Reflection—work together to form a rainbow.
During a thunderstorm, the thunder in the skies is produced by the
- Meeting of cumulonimbus clouds in the sky
- Lightning that separates the nimbus clouds
- Violent upward movement of air and water particles
Select the correct answer using the codes given below
Detailed Explanation:
❌ Statement 1 – Incorrect: The meeting of cumulonimbus clouds does not produce thunder; thunder is caused by lightning, not cloud collision.
❌ Statement 2 – Incorrect: Lightning does not separate clouds; rather, the intense heat from lightning causes rapid air expansion, which produces thunder.
❌ Statement 3 – Incorrect: Violent upward movement of air and water particles creates storm conditions and lightning, but thunder itself is the sound wave from lightning-heated air expansion.
Correct mechanism: Thunder is produced when lightning heats the surrounding air to approximately 30,000°C, causing it to expand explosively and create a shock wave heard as sound.
Ball bearings are used in bicycles, cars, etc., because
Detailed Explanation:
Ball bearings reduce the effective area of contact between the wheel and axle, replacing sliding friction with rolling friction.
Reduced contact area means lower friction and higher efficiency, as rolling balls have a much lower coefficient of friction than flat surfaces sliding against each other.
Recombinant DNA technology (Genetic Engineering) allows genes to be transferred
- Across different species of plants.
- From animals to plants.
- From microorganisms to higher organisms.
Select the correct Solution using the codes given below.
Detailed Explanation:
✅ Statement 1 – Correct: Recombinant DNA technology enables gene transfer across different plant species to introduce desirable traits like disease resistance.
✅ Statement 2 – Correct: Animal genes can be transferred to plants; for example, antifreeze protein genes from cold-water fish have been introduced into tomatoes and strawberries for frost tolerance.
✅ Statement 3 – Correct: Genes from microorganisms are routinely transferred to higher organisms; Bacillus thuringiensis (Bt) genes from soil bacteria are transferred to crops like cotton and corn for pest resistance.
Consider the following animals:
- Sea cow
- Sea horse
- Sea lion
Which of the above is/are mammal/mammals?
Detailed Explanation:
Sea Cow (Dugong): A herbivorous marine mammal found in coastal waters of the Indian and Pacific Oceans; classified under class Mammalia.
Sea Horse: A carnivorous fish (not a mammal) belonging to class Osteichthyes; found in shallow tropical and temperate waters.
Sea Lion: A carnivorous marine mammal of family Otariidae; breeds on Pacific and Atlantic coasts; classified under class Mammalia.
Therefore, only Sea Cow (1) and Sea Lion (3) are mammals.
Consider the following minerals -
- Calcium
- Iron
- Sodium
Which of the minerals given above is/are required by the human body for the contraction of muscles?
Detailed Explanation:
Calcium triggers muscle contraction by binding to troponin, which allows actin-myosin interaction.
Iron enables oxygen transport via myoglobin and supports ATP production in mitochondria for sustained muscle contraction.
Sodium maintains membrane potential and initiates action potentials that trigger muscle fiber contraction.
All three minerals (Calcium, Iron, Sodium) are essential for muscle contraction. Hence, option 4 is correct.
Consider the following phenomena:
- Size of the sun at dusk
- Colour of the sun at dawn
- Moon being visible at dawn
- The twinkle of stars in the sky
- Polestar being visible in the sky
Which of the above are optical illusions?
Detailed Explanation:
1. Size of the sun at dusk – Optical illusion: The sun appears larger near the horizon due to the moon illusion, a psychological effect where our brain misinterprets distance cues, though its actual angular size remains constant.
2. Colour of the sun at dawn – Optical illusion: The sun appears red/orange because its light travels through more atmosphere, causing Rayleigh scattering that removes blue light, creating a perceived color change.
3. Moon being visible at dawn – NOT an illusion: This is a real astronomical event where the moon's orbital position allows it to be visible during daylight hours.
4. Twinkle of stars – Optical illusion: Stars don't actually twinkle; their light is refracted by turbulent atmospheric layers, causing rapid brightness fluctuations.
5. Polestar being visible – NOT an illusion: The Pole Star (Polaris) is genuinely visible due to its alignment with Earth's rotational axis, making it appear stationary.
Answer: Option 3 (1, 2 and 4) are optical illusions.
Mycorrhizal Biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to -
- Resist drought and increase absorptive area
- Tolerate extremes of pH
- Resist disease infestation
Select the correct answer using the codes given below:
Detailed Explanation:
✅ Statement 1 – Correct: Mycorrhizal fungi form symbiotic associations with plant roots, greatly increasing the effective absorptive surface area (fungal hyphae extend beyond roots) and improving water uptake, enabling plants to resist drought stress.
✅ Statement 2 – Correct: Mycorrhizae help plants tolerate extreme pH conditions (both acidic and alkaline soils) by facilitating nutrient acquisition even when pH levels reduce nutrient availability.
✅ Statement 3 – Correct: Mycorrhizae provide bioprotection against disease infestation by competing with soil-borne pathogens, producing antimicrobial compounds, and enhancing plant immune responses.
Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by
Detailed Explanation:
Aflatoxins are poisonous carcinogens produced by certain moulds, specifically Aspergillus flavus and Aspergillus parasiticus.
These moulds grow in soil, decaying vegetation, hay, and improperly stored grains and are not destroyed by normal cooking temperatures.
Many transplanted seedlings do not grow because -
Detailed Explanation:
Root hairs are delicate, thin-walled extensions of the root epidermis responsible for water and mineral absorption.
During transplantation, these fragile root hairs are easily broken or damaged, severely reducing the seedling's ability to absorb water and causing transplant failure.
The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is /are the importance/importances of discovering this particle?
- It will enable us to understand as to why elementary particles have mass.
- It will enable us in the near future to develop the technology to transferring matter from one point to another without traversing the physical space between them.
- It will enable us to create better fuels for nuclear fission.
Select the correct answer using the codes given below:
Detailed Explanation:
✅ Statement 1 – Correct: The Higgs boson discovery confirms the Higgs field mechanism that explains why elementary particles acquire mass through interaction with this field.
❌ Statement 2 – Incorrect: Matter teleportation (transferring matter without traversing physical space) is not related to the Higgs boson; this particle explains mass, not quantum teleportation or matter transport technologies.
❌ Statement 3 – Incorrect: The Higgs boson is a fundamental particle in the Standard Model of physics unrelated to nuclear fission fuels; it does not improve fuel efficiency or reactor technology.
The demand for the Tebhaga Peasant Movement in Bengal was for:
Detailed Explanation:
The Tebhaga movement (1946-47) was a peasant agitation in Bengal led by the Kisan Sabha.
The core demand was to reduce the landlord's share from one-half (50%) to one-third (33%) of the crop, allowing sharecroppers (bargadars) to retain two-thirds instead of half.
UPSC Prelims 2013 Questions Paper - Subject-wise Question Distribution
UPSC Prelims 2013 Question Paper - FAQs & Analysis
Q1 How many total questions were asked in UPSC Prelims 2013?
Q2 What is the subject-wise question breakdown for UPSC Prelims 2013?
- Environment & Ecology: 21 questions (21%)
- Indian Economy: 20 questions (20%)
- Indian Polity: 17 questions (17%)
- Science & Technology: 11 questions (11%)
- World Geography: 9 questions (9%)
- Indian Art & Culture: 8 questions (8%)
- Indian Geography: 6 questions (6%)
- Modern History: 6 questions (6%)
- Ancient History: 2 questions (2%)