SSC CGL Science – Genetics, Evolution & Plant Biology – Tier II Level · Marathon

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SSC CGL Science – Genetics, Evolution & Plant Biology – Tier II Level · Marathon – 11 questions, subject: General Science. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.

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1.  
The experiment that proved DNA is the genetic material using radioactive phosphorus and sulphur was done by:

Correct Answer: D [Hershey and Chase]

Explanation:

Answer: Hershey and Chase. 1952, bacteriophages.

2.  
Semi-conservative replication of DNA was shown by:

Correct Answer: A [Meselson and Stahl]

Explanation:

Answer: Meselson and Stahl. Heavy nitrogen (¹⁵N) in E.

3.  
In the Watson–Crick model, one full turn of the helix contains how many base pairs?

Correct Answer: B [10]

Explanation:

Answer: 10. Pitch 3.4 nm ÷ 0.34 nm = 10.

4.  
In a population in Hardy–Weinberg equilibrium, the frequency of the recessive phenotype (q²) is 0.16. The frequency of heterozygotes (2pq) is:

Correct Answer: D [0.48]

Explanation:

q = 0.4, p = 0.6 → 2pq = 0.48.

5.  
Which of these does NOT disturb Hardy–Weinberg equilibrium?

Correct Answer: B [Random mating in a very large population]

Explanation:

The five disturbing factors are migration, drift, mutation, recombination and selection.

6.  
Fill in the blankSickle-cell anaemia results from the substitution of glutamic acid by ______ at the sixth position of the β-globin chain.

Correct Answer: C [valine]

Explanation:

Answer: valine. Glu → Val.

7.  
The endosperm of flowering plants is formed by the fusion of a male gamete with:

Correct Answer: A [two polar nuclei]

Explanation:

Triple fusion → triploid primary endosperm nucleus.

8.  
Griffith's experiment (1928) with Streptococcus pneumoniae demonstrated:

Correct Answer: A [transformation of bacteria]

Explanation:

Heat-killed S strain transformed live R strain.

9.  
The founder effect is a kind of:

Correct Answer: D [genetic drift]

Explanation:

A small founding group's allele frequencies drift by chance.

10.  
The requirement of a low-temperature period for flowering in some plants is called:

Correct Answer: C [vernalisation]

Explanation:

Winter wheat needs vernalisation.

11.  
Pleiotropy – one gene affecting several characters – is illustrated by:

Correct Answer: B [phenylketonuria]

Explanation:

Answer: phenylketonuria. NCERT example of pleiotropy.

➤ Full notes, shortcuts and every answer explained – SSC CGL 2026 General Science book (₹149): www.shanmugamiasacademy.in/study-materials/ssc-cgl-general-science

📘 SSC CGL 2026 – General Science (Tier I + Tier II)
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