Morgan coined the term _______ to describe the physical association of genes on a chromosome.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Linkage
• Recombination
• Assortment
• Segregation
Correct Option: A  [ Linkage ]

Remark: Morgan coined the term linkage to describe this physical association of genes on a chromosome.

The genes white and yellow in Drosophila were very tightly linked and showed only _______ per cent recombination.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• 1.3
• 37.2
• 50
• 98.7
Correct Option: A  [ 1.3 ]

Remark: The genes white and yellow were very tightly linked and showed only 1.3 per cent recombination.

The genes white and miniature wing in Drosophila showed _______ per cent recombination, indicating looser linkage.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• 37.2
• 1.3
• 50.0
• 12.5
Correct Option: A  [ 37.2 ]

Remark: White and miniature wing genes showed 37.2 per cent recombination.

Traits generally controlled by three or more genes, such as human height or skin colour, are called as _______ traits.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Polygenic
• Monogenic
• Pleiotropic
• Multiple allelic
Correct Option: A  [ Polygenic ]

Remark: Traits generally controlled by three or more genes are called as polygenic traits.

Besides the involvement of multiple genes, polygenic inheritance also takes into account the influence of the _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Environment
• Genotype
• Factor
• Mutation rate
Correct Option: A  [ Environment ]

Remark: Polygenic inheritance also takes into account the influence of environment.

A single gene that can exhibit multiple phenotypic expression is called a _______ gene.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Pleiotropic
• Polygenic
• Dominant
• Recessive
Correct Option: A  [ Pleiotropic ]

Remark: A single gene can exhibit multiple phenotypic expression, and such a gene is called a pleiotropic gene.

_______ is an example of XO type of sex determination in which the males have only one X-chromosome besides the autosomes.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Grasshopper
• Human
• Bird
• Drosophila
Correct Option: A  [ Grasshopper ]

Remark: Grasshopper is an example of XO type of sex determination.

The sex determination mechanism where males produce two different types of gametes (e.g., X or Y) is designated as male _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Heterogamety
• Homogamety
• Polymorphism
• Monogamety
Correct Option: A  [ Heterogamety ]

Remark: The production of two different types of gametes by males is designated to be the example of male heterogamety.

In birds, females produce two different types of gametes (Z and W), a mechanism known as female _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Heterogamety
• Homogamety
• Polymorphism
• Autogamety
Correct Option: A  [ Heterogamety ]

Remark: In organisms like birds, the female produces two different types of gametes in terms of sex chromosomes (Z and W), representing female heterogamety.

In the haplodiploid sex-determination system of honey bees, females are _______ having 32 chromosomes.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Diploid
• Haploid
• Triploid
• Aneuploid
Correct Option: A  [ Diploid ]

Remark: In honey bees, the females are diploid having 32 chromosomes.