General Science PYQ – Genetics, Evolution and Biotechnology – Part 1 (Q 1–26)
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The operon model (lac operon) of gene regulation in bacteria was proposed by Francois Jacob and Jacques Monod in 1961.
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General Science PYQ – Genetics, Evolution and Biotechnology – Part 1 (Q 1–26) – 26 questions, subject: 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.
CEGS 2024
The Father of Genetics isCorrect Answer: D [Mendel]
Explanation:
Gregor Mendel discovered the laws of inheritance through pea experiments (1865-66) and is called the Father of Genetics.
2.
VAS AHGS 2020
A cross between F1 hybrid and recessive parent is calledCorrect Answer: A [Test cross]
Explanation:
A cross of the F1 hybrid with the recessive parent is a test cross, used to find the F1 genotype.
3.
Health Officer 2023
The genotypic ratio for monohybrid cross isCorrect Answer: C [1:2:1]
Explanation:
In a monohybrid cross the F2 genotypic ratio is 1:2:1 (TT:Tt:tt), while the phenotypic ratio is 3:1.
4.
VCGS 2022
A single pair of genes produces two or more character is known asCorrect Answer: C [Pleiotropism]
Explanation:
When a single pair of genes affects two or more characters, it is called pleiotropism.
5.
CEGS 2024
Crossing over results inCorrect Answer: B [Recombination of genes]
Explanation:
Crossing over exchanges segments between homologous chromatids during meiosis, resulting in recombination of genes.
6.
PSY 2022
In which animal the polytene chromosomes were discovered for the first time?Correct Answer: C [Chironomus]
Explanation:
Polytene chromosomes were first discovered by Balbiani in 1881 in the salivary glands of Chironomus larvae.
7.
Reason: They are found in the growing oocytes of most animals except mammals
CTS (Non-Interview Posts) 2025
Assertion: Polytene Chromosome contain about 1000 DNA molecules caused by duplication of chromosomesReason: They are found in the growing oocytes of most animals except mammals
Correct Answer: B [Assertion is correct but Reason is wrong]
Explanation:
Polytene chromosomes have about 1000 DNA strands from repeated replication without division, but they occur in salivary glands of dipteran larvae, not growing oocytes, so the reason is wrong.
8.
VAS AHGS 2020
Where the sex chromatin seen in man?Correct Answer: B [Female]
Explanation:
Sex chromatin (Barr body) is seen in the somatic cells of normal females, not males.
9.
Executive Officer Gr. III (HR&CE) 2022
Barr body isCorrect Answer: C [Inactivated 'X' chromosome]
Explanation:
The Barr body is the inactivated, condensed X chromosome found in female cells, discovered by Murray Barr in 1949.
10.
ARGS 2020
How many Barr body is found in normal women?Correct Answer: A [One]
Explanation:
The number of Barr bodies equals the number of X chromosomes minus one, so a normal XX woman has one.
11.
ARGS 2020
Holandric genes are calledCorrect Answer: C [carried by different parts of Y chromosomes]
Explanation:
Holandric genes lie on the non-homologous part of the Y chromosome and are passed only from father to son.
12.
Junior Scientific Officer 2023
Which is an example of sex linked inheritance in man?Correct Answer: D [Haemophilia]
Explanation:
Haemophilia is a sex-linked inherited disease carried by a recessive gene on the X chromosome.
13.
District Educational Officer 2023
Colour blindness is a _____ disease.Correct Answer: D [Hereditary]
Explanation:
Colour blindness is a hereditary disease caused by a recessive X-linked gene.
14.
Group 4 2022
Extra copy of chromosome 21 results inCorrect Answer: B [Down syndrome]
Explanation:
An extra copy of chromosome 21 (trisomy 21) causes Down syndrome.
15.
Executive Officer Gr. I (HR&CE) 2024
Identify the condition of Chromosomal mutation which results in Down's Syndrome.Correct Answer: B [2n+1]
Explanation:
Down's syndrome is trisomy of chromosome 21, which gives a total of 2n + 1 = 47 chromosomes.
16.
Junior Scientific Officer 2023
The number of chromosomes found in 'Turner syndrome' isCorrect Answer: B [45]
Explanation:
Turner syndrome has only one X chromosome (44 + XO), so the total is 45 chromosomes.
17.
(a) Down's syndrome – 1. XXY Male
(b) Patau's syndrome – 2. XO Female
(c) Klinefelter's syndrome – 3. 13–Trisomy
(d) Turner's syndrome – 4. 21 Trisomy
Special Competitive Exam 2025
Match the following(a) Down's syndrome – 1. XXY Male
(b) Patau's syndrome – 2. XO Female
(c) Klinefelter's syndrome – 3. 13–Trisomy
(d) Turner's syndrome – 4. 21 Trisomy
Correct Answer: A [4 3 1 2]
Explanation:
Down's syndrome is 21-trisomy, Patau's 13-trisomy, Klinefelter's XXY male and Turner's XO female, giving 4 3 1 2.
18.
(1) Down's Syndrome – Autosomal trisomy of 21st chromosome
(2) Haemophilia – Sex Linked
(3) Klinefelter Syndrome – XO Complement
(4) Turner Syndrome – Female with retarded growth
Group 2/2A 2025
One of the following is a mismatch:(1) Down's Syndrome – Autosomal trisomy of 21st chromosome
(2) Haemophilia – Sex Linked
(3) Klinefelter Syndrome – XO Complement
(4) Turner Syndrome – Female with retarded growth
Correct Answer: A [(3) only]
Explanation:
Klinefelter syndrome is XXY (47 chromosomes) and XO is Turner syndrome, so pair (3) alone is a mismatch.
19.
(1) Monosomy – 2n – 2
(2) Trisomy – 2n + 1
(3) Tetrasomy – 2n + 2
(4) Nullisomy – 2n + 3
Road Inspector 2023
Which of the following is incorrectly paired?(1) Monosomy – 2n – 2
(2) Trisomy – 2n + 1
(3) Tetrasomy – 2n + 2
(4) Nullisomy – 2n + 3
Correct Answer: D [(1) and (4)]
Explanation:
Monosomy is 2n - 1 and nullisomy is 2n - 2, so pairs (1) and (4) are incorrect.
20.
(i) In the polyploidy condition an organism possesses less than two basic set of chromosomes.
(ii) Polyploidy can be induced in some plants by artificial means such as colchicine treatment.
(iii) Polyploidy condition in plants play a role in the evolution.
CTS (ITI Posts) 2025
Which of the following statements are true about polyploidy in plants?(i) In the polyploidy condition an organism possesses less than two basic set of chromosomes.
(ii) Polyploidy can be induced in some plants by artificial means such as colchicine treatment.
(iii) Polyploidy condition in plants play a role in the evolution.
Correct Answer: B [(ii) and (iii) only]
Explanation:
Polyploidy means more than two basic chromosome sets, can be induced by colchicine and plays a role in plant evolution, so (ii) and (iii) are true.
21.
Group 4 2022
Identify the correct pairing.Correct Answer: C [Purines – Adenine and Guanine]
Explanation:
Purines are adenine and guanine, while a nucleoside is base plus sugar and a nucleotide is nucleoside plus phosphate, so only the purine pair is correct.
22.
Group 1 2022
The enzyme involved in unwinding of DNA isCorrect Answer: B [Helicase]
Explanation:
Helicase unwinds the DNA double helix by breaking hydrogen bonds between strands during replication.
23.
GSCE 2021
In Central dogma of Molecular biology: (X)DNA –Y→ mRNA –Z→ Polypeptide (Protein)Correct Answer: A [X – Replication, Y – Transcription, Z – Translation]
Explanation:
In the central dogma, DNA replicates itself, is transcribed into mRNA, and mRNA is translated into protein.
24.
(i) Genetic code is triplet
(ii) It is degenerate
(iii) It is commaless
(iv) Code is universal
(v) Code is non-ambiguous
CTS (Interview Posts) 2025
The properties of genetic code is given below. Find out the correct statement/statements(i) Genetic code is triplet
(ii) It is degenerate
(iii) It is commaless
(iv) Code is universal
(v) Code is non-ambiguous
Correct Answer: D [(i), (ii), (iii), (iv) and (v) are correct]
Explanation:
The genetic code is triplet, degenerate, commaless, universal and non-ambiguous, so all five statements are correct.
25.
Group 4 2025
What is the crucial role played by noncoding RNA's?Correct Answer: C [gene regulation]
Explanation:
Non-coding RNAs such as microRNAs and long non-coding RNAs are not translated into protein but play a crucial role in regulating gene expression.
26.
Agricultural Officer 2023
The 'Operon model' for Gene regulation was proposed byCorrect Answer: C [Jacob and Monod]
Explanation:
The operon model (lac operon) of gene regulation in bacteria was proposed by Francois Jacob and Jacques Monod in 1961.
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› General Science PYQ – Computers, Technology and Scientists – Part 2 (Q 27–51)
› General Science PYQ – Computers, Technology and Scientists – Part 1 (Q 1–26)
› General Science PYQ – Scientific Temper and Scientific Method
› General Science PYQ – Genetics, Evolution and Biotechnology – Part 2 (Q 27–52)
› General Science PYQ – Diseases, Health and Nutrition
› General Science PYQ – Human Physiology
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