Explain the mechanism of ‘sex determination’ in birds

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 Multiple Choice QuestionsShort Answer Type

131.

give a scientific term:
Functional unit of gene

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132.

Name the scientist who is associated with the following:
Mutation

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133.

Explain sex determination in bees.

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134.

Name the type of cross that would help to find the genotype of a pea plant bearing violet flowers.

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135.

Both Haemophilia and Thalassemia are blood related disorders in humans. Write their causes and the difference between the two. Name the category of genetic disorder they both come under.

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136.

(a) Write the desirable characters a farmer looks for in his sugarcane crop. (b) How did plant breeding techniques help north Indian farmers to develop cane with desired characters ?

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137.

Explain the mechanism of ‘sex determination’ in birds. How does it differ from that of human beings?


In birds, sex determination is of ZW – ZZ type.

In this type, the males are homogametic and have ZZ sex chromosomes, and females are heterogametic with ZW pair of sex chromosomes.

Parents: Male X Female
  ZZ   ZW
Gametes: (Z)(Z)   (Z)(W)
F1: ZW   ZZ
  Female   Male

whereas, in human beings, the chromosomal mechanism of sex determination is of XX – XY type. The human male is heterogametic and has XY sex chromosomes and the human female is homogametic with XX sex chromosomes.


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138.

a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.

b) How did Sturtevant explain gene mapping while working with Morgan?


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 Multiple Choice QuestionsMultiple Choice Questions

139.

Assertion: A middle aged woman is reported to have small breasts and undersized uterus.

Reason: Her genotypic analysis shows XO condition of allosomes.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false


140.

A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the F1 plants were selfed the resulting genotypes were in ratio of 

  • 1:2:1 :: Tall heterozygous: Tall homozygous: Dwarf

  • 3:1:: Tall: Dwarf

  •  3:1:: Dwarf: Tall

  •  3:1:: Dwarf: Tall

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