15 Science & Technology MCQs for UPSC Prelims 2025

Time’s up

1. Which of the following is used in CRISPR-Cas9 technology?

A) RNA
B) DNA
C) Protein
D) Both RNA and Protein

Answer: D) Both RNA and Protein
Explanation: CRISPR-Cas9 is a gene-editing tool that uses a guide RNA to identify the target DNA sequence and a Cas9 protein to cut the DNA, enabling precise modifications.

2. Graphene is known for:

A) Being radioactive
B) High electrical conductivity
C) Absorbing X-rays
D) Being soluble in water

Answer: B) High electrical conductivity
Explanation: Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It exhibits excellent electrical and thermal conductivity and is extremely strong.

3. Which Indian organization launched Chandrayaan-3?

A) ISRO
B) DRDO
C) NASA
D) ROSCOSMOS

Answer: A) ISRO
Explanation: The Indian Space Research Organisation (ISRO) launched Chandrayaan-3 to explore the Moon’s south pole region, aiming to demonstrate the ability to perform a soft landing on the lunar surface.

4. What is a Qubit in quantum computing?

A) Classical bit
B) Quantum bit
C) Memory chip
D) Logic gate

Answer: B) Quantum bit
Explanation: A qubit is the basic unit of quantum computation, which can exist in 0, 1, or both states simultaneously (superposition), enabling quantum computers to process complex computations more efficiently than classical computers.

5. James Webb Space Telescope (JWST) primarily observes:

A) X-rays
B) Infrared spectrum
C) Gamma rays
D) Ultraviolet rays

Answer: B) Infrared spectrum
Explanation: JWST is designed to observe distant galaxies and stars in the infrared region, allowing us to see the early universe and phenomena obscured by cosmic dust.

6. Polylactic acid (PLA) is an example of:

A) Non-biodegradable plastic
B) Biodegradable plastic
C) Conductive polymer
D) Synthetic fiber

Answer: B) Biodegradable plastic
Explanation: PLA is made from plant sources like corn starch or sugarcane and decomposes naturally, unlike conventional plastics, making it environmentally friendly.

7. Which of the following is a recent room-temperature superconductor?

A) Copper
B) Hydrogen sulfide under high pressure
C) Silicon
D) Iron

Answer: B) Hydrogen sulfide under high pressure
Explanation: Scientists achieved superconductivity at near room temperature by compressing hydrogen sulfide under extremely high pressure, a significant breakthrough in material science.

8. Artificial Intelligence (AI) mainly relies on:

A) Photosynthesis
B) Machine Learning
C) Quantum Entanglement
D) Blockchain

Answer: B) Machine Learning
Explanation: AI systems learn from data patterns using machine learning, improving performance without being explicitly programmed, enabling them to make decisions and predictions.

9. Which organelle is known as the “powerhouse of the cell”?

A) Nucleus
B) Ribosome
C) Mitochondria
D) Lysosome

Answer: C) Mitochondria
Explanation: Mitochondria produce ATP, the energy currency of the cell, through cellular respiration, hence called the powerhouse.

10. Which Indian satellite is dedicated to weather forecasting?

A) INSAT-3D
B) Chandrayaan-1
C) Astrosat
D) Cartosat-2

Answer: A) INSAT-3D
Explanation: INSAT-3D is an Indian meteorological satellite providing data for weather prediction, cyclone tracking, and climate studies, enhancing India’s disaster management capabilities.

11. Quantum entanglement refers to:

A) Two particles sharing the same charge
B) Two particles instantly affecting each other’s state
C) Splitting an atom
D) Light traveling faster than speed of light

Answer: B) Two particles instantly affecting each other’s state
Explanation: Entangled particles are connected quantum mechanically. A change in one affects the other instantly, regardless of distance, a phenomenon that Einstein famously referred to as “spooky action at a distance.”

12. Which of the following is NOT an application of nanotechnology?

A) Targeted drug delivery
B) Solar cells improvement
C) Water purification
D) Classical fossil fuel burning

Answer: D) Classical fossil fuel burning
Explanation: Nanotechnology is used in medicine, energy, and environment, such as improving solar cells, purifying water, and delivering drugs precisely, but it is not related to fossil fuel burning.

13. Which of the following diseases can be transmitted from one person to another through tattooing?

A) Chikungunya
B) Hepatitis B
C) HIV-AIDS
D) Both B and C

Answer: D) Both B and C
Explanation: Hepatitis B and HIV-AIDS can be transmitted through contaminated needles or equipment used in tattooing, highlighting the importance of sterilization.

14. Which of the following is a biodegradable polymer used in medical implants?

A) Polyethylene
B) Polylactic acid (PLA)
C) PVC
D) Polystyrene

Answer: B) Polylactic acid (PLA)
Explanation: PLA is biocompatible and biodegradable, widely used in stents, screws, and other medical implants, as it breaks down within the body over time without causing harm.

15. Which gas causes ozone layer depletion?

A) CO₂
B) CFCs
C) Methane
D) Nitrogen

Answer: B) CFCs
Explanation: Chlorofluorocarbons (CFCs) release chlorine atoms in the atmosphere, which destroy ozone molecules, causing the ozone hole, leading to increased UV radiation reaching Earth’s surface.