Principles of Inheritance and Variation
- The linkage map of X-chromosome of fruit fly has 66 units, with yellow body gene (y) at one end and bobbed hair
(b) gene at the other end. The recombination frequency between these two genes (y and b) should be
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Mapping of genes on chromosomes is based on the assumption that genes are arranged on the chromosome and that the percentage of crossing over (recombination frequency) between two genes is an index of their distance apart. Distances between genes is expressed as map units, where one map unit is defined as 1 per cent recombination.
Correct Option: B
Mapping of genes on chromosomes is based on the assumption that genes are arranged on the chromosome and that the percentage of crossing over (recombination frequency) between two genes is an index of their distance apart. Distances between genes is expressed as map units, where one map unit is defined as 1 per cent recombination.
- Two crosses between the same pair of genotypes or phenotypes in which the source of the gametes are reversed in one cross, is known as
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Dihybrid cross is made between individuals having contrasting traits in order to study the inheritance of two pairs of alleles. Test cross is a back cross between individual with a dominant trait and its recessive parent to know whether the individual is homozygous or heterozygous for the trait.
Correct Option: C
Dihybrid cross is made between individuals having contrasting traits in order to study the inheritance of two pairs of alleles. Test cross is a back cross between individual with a dominant trait and its recessive parent to know whether the individual is homozygous or heterozygous for the trait.
- The genes controlling the seven pea characters studied by Mendel are now known to be located on how many different chromosomes?
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The seven traits are now know to be present on 4 chromosome. But they do not show linkage, because of large distances between them on the chromosome.
Correct Option: A
The seven traits are now know to be present on 4 chromosome. But they do not show linkage, because of large distances between them on the chromosome.
- Which one of the following traits of garden pea studied by Mendel was a recessive feature?
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Yellow seed colour is dominant over green seed colour.
Correct Option: C
Yellow seed colour is dominant over green seed colour.
- Nicotiana sylvestris flowers only during long days and N. tabacum flowers only during short days. If raised in the laboratory under different photoperiods, they can be induced to flower at the same time and can be cross fertilized to produce self – fertile offspring. What is the best reason for considering N. sylvestris and N. tabacum to be separate species?
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Similar species show interbreeding characters, i.e., two organisms which breed freely in nature to produce fertile offsprings belong to the same species. The two species are considered separate because they are reproductively distinct.
Correct Option: C
Similar species show interbreeding characters, i.e., two organisms which breed freely in nature to produce fertile offsprings belong to the same species. The two species are considered separate because they are reproductively distinct.
