Science — UPSC Prelims practice questions

Question 1

The term 'mRNA vaccine', frequently in the news during the COVID-19 pandemic, refers to a vaccine that:
1. uses messenger RNA to instruct cells to produce a viral protein that triggers an immune response.
2. integrates into the host cell DNA permanently.
3. does not use a live or attenuated virus.
Which of the statements given above is/are correct? (A) 1 only (B) 1 and 3 only (C) 2 and 3 only (D) 1, 2 and 3

Accepted Answer

(B) 1 and 3 only — Correct. mRNA vaccines use synthetic mRNA to instruct cells to make spike protein, triggering immunity, and do not involve live virus. Statement 2 is wrong because mRNA degrades naturally and does not integrate into DNA.

Question 2

The 'DART mission', which was in news in 2022, was primarily aimed at: (A) Studying the composition of an asteroid's interior (B) Testing a kinetic impactor method of planetary defence by deflecting an asteroid's moon (C) Collecting and returning a sample from a near-Earth asteroid (D) Mapping the surface of Mars using radar imaging

Accepted Answer

(B) Testing a kinetic impactor method of planetary defence by deflecting an asteroid's moon — Correct. NASA's Double Asteroid Redirection Test (DART) deliberately impacted Dimorphos, the small moon of asteroid Didymos, to test whether a kinetic impact could alter an asteroid's orbit for planetary defence.

Question 3

Consider the following statements about mitosis:
1. It produces two genetically identical daughter cells.
2. It occurs in somatic cells of the body.
3. It results in halving of the chromosome number.
Which of the statements given above is/are correct? (A) 1 and 2 only (B) 2 and 3 only (C) 1 and 3 only (D) 1, 2 and 3

Accepted Answer

(A) 1 and 2 only — Correct. Mitosis produces two genetically identical daughter cells (statement 1) and occurs in somatic cells for growth and repair (statement 2). Chromosome number is maintained, not halved — halving occurs in meiosis.

Question 4

A bar magnet is broken into two pieces. Which of the following statements is correct? (A) One piece becomes a north pole and the other a south pole (B) Both pieces lose their magnetism (C) Each piece becomes a complete magnet with its own north and south pole (D) The magnetism doubles in each piece

Accepted Answer

(C) Each piece becomes a complete magnet with its own north and south pole — Correct. When a bar magnet is broken, each piece becomes an independent magnet with its own north and south pole. This is because magnetism arises from aligned atomic magnetic moments, and breaking the bar does not disrupt this alignment within each piece.

Question 5

Which of the following is/are correctly matched?
1. Widal test — Typhoid
2. Mantoux test — Tuberculosis
3. ELISA — Malaria
Select the correct answer using the code given below. (A) 1 and 2 only (B) 2 only (C) 1 and 3 only (D) 1, 2 and 3

Accepted Answer

(A) 1 and 2 only — Correct. Widal test detects antibodies against Salmonella typhi (typhoid) and Mantoux test detects TB exposure via tuberculin skin reaction; ELISA is primarily used for HIV detection, not malaria.

Science — UPSC Prelims MCQs

Chapters in Science

Sample Science questions

Practise all of Science

Science — UPSC Prelims MCQs

Chapters in Science

Sample Science questions

Practise all of Science