UPSC Prelims 2013
Science & Technology Previous Year Questions (PYQs)
Explore 11 solved UPSC Prelims 2013 Science & Technology questions with detailed step-by-step bilingual solutions, option analysis, and answer keys.
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.
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.
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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.
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 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.
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.
UPSC Prelims 2013 - Science & Technology Chapter-wise Distribution
Physics and Applied Technology
5 Qs (45.5%)Biotechnology
4 Qs (36.4%)Agriculture Science & Technology
1 Qs (9.1%)Human Health & Disease
1 Qs (9.1%)UPSC Prelims 2013 - Science & Technology Questions FAQs
Q1 How many Science & Technology questions were asked in UPSC Prelims 2013?
Q2 What is the chapter-wise question distribution for Science & Technology in UPSC Prelims 2013?
- Physics and Applied Technology: 5 questions (45.5%)
- Biotechnology: 4 questions (36.4%)
- Agriculture Science & Technology: 1 questions (9.1%)
- Human Health & Disease: 1 questions (9.1%)