GATE XL Genetics PYQs & Answers

Questions 1–10 of 26. Imported answers require independent review unless marked reviewed.

Below are the numbers of individuals of migratory green warblers and the frequencies of three genotypes at a single locus for this species. F refers to the allele for faster migration and S to the allele for slower migration.

	FF	FS	SS	Total
Number of individuals	35	20	10	65
Genotype frequencies	0.54	0.30	0.16	1

What are the allele frequencies of F and S? (round off to 2 decimal places)

Your answerChoose one option.

Allele frequency of F = 0.69 and allele frequency of S = 0.31

Allele frequency of F = 0.59 and allele frequency of S = 0.41

Allele frequency of F = 0.31 and allele frequency of S = 0.69

Allele frequency of F = 0.50 and allele frequency of S = 0.50

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Imagine a population of diploid species in Hardy-Weinberg equilibrium. The population has two alleles for a gene which are ‘a’ and ‘A’. The number of individuals with ‘aa’ genotype in this population is 1 in 1000. The frequency of the allele ‘A’ in the population is ______ (up to two decimal places)

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What would be the number of genotypes and phenotypes, respectively, from a cross between genotypes AaBbCcDd and AaBBCcDd? Assume independent assortment and simple dominant-recessive relationship in each gene pair.

Your answerChoose one option.

8 and 4

12 and 4

27 and 8

14 and 8

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Which of the following genetic disorders is/are caused by trinucleotide repeat expansions?

Your answerSelect all correct options. You can choose more than one.

Huntington’s disease

β-thalassemia

Fragile X syndrome

Cystic fibrosis

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The mother and the father of five children are carriers (heterozygous) of an autosomal recessive allele that causes cystic fibrosis. The probability of having exactly three normal children among five is _____ (up to two decimal places)

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The human genetic code is triplet in nature with 64 codons made using four nucleotides. If the human genetic code was doublet in nature, the number of codons theoretically possible from four nucleotides is ______. (Answer in integer)

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In a population of 1000 wild dogs in a grassland, 360 and 480 dogs had black body colour with genotypes BB and Bb, respectively. In the same population, remaining dogs were white in colour with a genotype of bb. Based on this data, the frequency of allele “b” in the population is ______ (round off to one decimal place).

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Match the syndromes listed in Column I with the cause/symptoms listed in Column II

Column I: P. Prader-Willi syndrome; Q. Down syndrome; R. Cushing syndrome; S. Turner syndrome; T. Fanconi syndrome

Column II: (i) a collection of signs and symptoms due to prolonged exposure to corticosteroids like cortisol; (ii) a syndrome of inadequate reabsorption in the proximal renal tubule of the kidney; (iii) a genetic disorder usually caused by the deletion of a part of chromosome 15; (iv) a genetic disorder caused by the presence of all or part of a third copy of chromosome 21; (v) a genetic condition in which a female has partially or completely missing an X chromosome

Your answerChoose one option.

P – (ii) ; Q – (v) ; R – (iv) ; S – (iii) ; T – (i)

P – (iv) ; Q – (ii) ; R – (i) ; S – (iii) ; T – (v)

P – (iii) ; Q – (iv) ; R – (i) ; S – (v) ; T – (ii)

P – (v) ; Q – (iv) ; R – (ii) ; S – (i) ; T – (iii)

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Among the following statements, which is/are TRUE regarding the replication of DNA?

Your answerSelect all correct options. You can choose more than one.

Replication is bidirectional and conservative in nature.

Replication in eukaryotes takes place at multiple Ori sites simultaneously.

Both the strands replicate in discontinuous manner.

One strand replicates in continuous while the other replicates in discontinuous manner.

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Mendel deduced the genetic principle of inheritance by experimenting on sweet pea plants. One of the experiments involved crossing plants with two contrasting characters, tall (dominant) and dwarf (recessive), which yielded all tall plants in the first generation. When the same genetic cross was independently repeated by a researcher, only short plants were obtained. Which one of the following can possibly explain the altered outcome?

Your answerChoose one option.

Tall plants were heterozygous

An enhancer for the tall allele is present in the dwarf plant

A suppressor for the tall allele is present in the dwarf plant

Dwarf plants are homozygous

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GATE XL Genetics PYQs

How to practice Genetics

Question 98

Question 91

Question 96

Question 101

Question 102

Question 92

Question 91

Question 95

Question 100

Question 89