An abnormal human baby with 'XXX' sex chromosomes was born due t

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 Multiple Choice QuestionsMultiple Choice Questions

21.

Fgeneration in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1:2:1. It represents a case of

  • codominance

  • dihybrid cross

  • monohybrid cross with complete dominance

  • monohybrid cross with complete dominance

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22.

A human female with Turner's syndrome

  • has 45 chromosomes with XO

  • has one additional X - chromosome

  • exhibits male characters

  • exhibits male characters

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23.

Which one of the following is a wrong statement regarding mutations?

  • Deletion and insertion of base pairs cause frame-sheft mutations

  • Cancer cells commonly show chromosomal aberrations

  • UV and Gamma rays are mutagens

  • UV and Gamma rays are mutagens

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24.

A test cross is carried out to

  • determine the genotype of a plant at F2

  • predict whether two traits are linked

  • assess the number of alleles of a gene

  • assess the number of alleles of a gene

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25.

A man whose father was colour blind marries a woman, who had a colourblind mother and normal father. What percentage of male children of this couple will be colourblind.

  • 25%

  • 0%

  • 50%

  • 50%

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26.

The idea of mutations was brought forth by

  • Hugo de Vries, who worked on evening primrose

  • Gregor Mendel, who worked on Pisum sativum

  • Hardy Weinberg, who worked on allele frequencies in a population

  • Hardy Weinberg, who worked on allele frequencies in a population

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27.

Represented below is the inheritance pattern of a certain type of traits in humans. Which one of the following conditions could be an example of this pattern?

  • Phenylketonuria

  • Sickle cell anaemia

  • Haemophilia

  • Haemophilia

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28.

Multiple alleles are present

  • On different chromosomes

  • At different loci on the same chromosome

  • at the same locus of the chromosome

  • at the same locus of the chromosome

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29.

An abnormal human baby with 'XXX' sex chromosomes was born due to

  • formation of abnormal sperms in the father

  • formation of abnormal ova in the mother

  • fusion of two ova and one sperm

  • fusion of two ova and one sperm


B.

formation of abnormal ova in the mother

Formation of an abnormal ova usually occurs as an event during the formation of reproductive cells. 
An error in cell division called non-disjunction can result in reproductive cells with additional chromosomes. Any of these cells if contributes in the genetic make up of child leads to trisomy of X-chromosome i.e. the child will have an extra X-chromosome. ZZ+ XX in mother will lead to birth of XXX genotype baby.

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30.

Alleles are 

  • different phenotype

  • true breeding homozygotes

  • different molecular forms of a gene

  • different molecular forms of a gene

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