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Solution
The correct option is D Rr; Incomplete dominance
With respect to the inheritance
of flower colour in snapdragon, allele ‘R’ imparts red colour to the petals of the flower and the allele ‘r’ imparts white colour to the petals of the flower.
However, the allele ‘R’ is not completely dominant over ‘r’ and due to this, a cross between true-breeding red-flowered [RR] and white -flowered plants [rr] results in pink-flowered plants [Rr].
Hence, the progeny of this cross does not resemble either of the two parents with respect to the flower colour, rather an intermediate phenotype is seen. This phenomenon is known as incomplete dominance.
In the case of co-dominance, the F1 generation resembles both the parents.
Generally, a gene has two alleles, but certain genes have more than two alleles and these are called multiple alleles. However, in an individual, only two alleles are present.
Hence, inheritance of flower colour in snapdragon is an example of incomplete dominance.
Problem 10: Disappearance of parental phenotypes in the F1 generation
A genetic cross of inbred snapdragons with red flowers with inbred snapdragons with white flowers resulted in F1-hybrid offspring that all had pink flowers. When the F1 plants were self-pollinated, the resulting F2-generation plants had a phenotypic ratio of 1 red: 2 pink: 1 white. The most likely explanation is:
Tutorial
Incomplete dominance
The
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Correct option [c] 1:2:1 and 1:2:1
Explanation:
Son.retimes two genes of the allelomorphic pair do not show a dominant-recessive relationship, but when presents together, they show intermediate trait or incomplete dominance. Incomplete dominance is not blending inheritance because parental characters reappear in F2 generation. ln Mirabilis jalapa, there are two types of pure breeding plants, red flowered and white flowered. On crossing them the F1 plants or hybrids possess pink flowers. On selfing them, F2 generation has plants in the ratio of 1 red: 2 pinks: 1 white-flowered plants with the phenotypic ratio being the same as a genotypic ratio.
Genotypic ratio= 1RR: 2Rr: 1rr
Phenotypic ratio: 1 Red : 2 Pink : 1 White
Both genotypic ratio and phenotypic ratio are same,
i.e., 1 :2 :1.
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Video Solution: When red and white flowered Mirabilis plants are crossed, all pink flowers are produced in F_[1] generation. When F_[1] progeny is selfed , the expected phenotypic and genotypic ratios are, respectively .
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Text Solution
`1 : 2 : 1 and 3 : 1``3 : 1 and 1 : 2 : 1``1 : 2 : 1 and 1 : 2 : 1``1 : 1 and 1 : 1: 1`
Answer : C
Answer
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Question Details till 08/10/2022
Question | |
Chapter Name | 5 Principles Of Inheritance And Variation |
Subject | Biology [more Questions] |
Class | 12th |
Type of Answer | Video |
Question Language | In Video - English In Text - English |
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Question Video Duration | 2m39s |
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