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In Antirrhinum (dog flower), phenotypic ...

In Antirrhinum (dog flower), phenotypic ratio in `F_(2)` generation for the inheritance of flower colour would be

A

`3:1`

B

`1:2:1`

C

`1:1`

D

`2:1`

Text Solution

Verified by Experts

The correct Answer is:
B
The inheritance of flower colour in the Antirrhinum majus (snapdragon or dog flower) is an example of incomple or partial dominance. Imcomplete dominance is the phenomenon in which neither of the two alleles of a gene is completely dominant over the other. In a cross between true-breeding red-flowered (RR) and true-breeding white-flowered plants (rr)m the `F_(1)` plants obtained were pink (Rr) coloured. When the `F_(1)` plants were self-pollinated, the `F_(2)` generation resulted in the ratio, 1 (RR) Red : 2 (Rr) Pink : 1 (rr) white. The phenotypic ratios had changed from the normal 3 : 1 dominant : recessive ratio to `1:2:1` R. was not completelt dominant over r and this made it possible to distinguish Rr (pink) from RR (red) and rr (white).
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In the case of snapdragon (Antirrhinum majus) a plant with red flowers was crossed with another plant with white flowers. Trace the inheritance of flower colour up to the F_(2) generation indicating the genotypes and phenotypes at each level. What special features do you notice in the genotypic and phenotypic ratio in F_(1) generations?

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Knowledge Check

  • Phenotypic dihybrid ratio in "F"_(2) generation is:

    A
    `1 : 3`
    B
    `9 : 3 : 3 : 1`
    C
    `1 : 2 : 1`
    D
    `1 : 1 : 1 : 1`

  • Phenotypic and genotypic ratio in F_(2) generation in incomplete dominance is

    A
    1:2:1 and 1:2:1
    B
    3:1 and 1:2:1
    C
    9:6 and 3:1
    D
    9:3:3:1 and 1:2:1:4:1:1:2:1:2:1

  • Phenotypic ratio of dominant epistasis In F_(2) generation is

    A
    `12 : 3 : 1`
    B
    `9 : 7`
    C
    `9 : 3 : 4`
    D
    `9 : 3 : 3 : 1`

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    In Antirrhinum (Snapdragon). A red flower was crossed with a white flower and in F_(1) generation pink flowers were obtained. When pink flowers were selfed, the F_(2) generation showed white, red and pink flowers. Choose the incorrect statement from the following:

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    If Aabb x aaBB, then phenotypic ratio of its progeny ( F_(2) -generation) will be

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