Question

Two black female mice are crossed with a brown male later female1 produced 9 black and 7 brown offsprings female 2 produced 57 black offsprings during first filial generation then with the help of chakkar board 1)what inference can you make concerning inheritance of black and brown coloured mice 2)with the help of phenotype given find out what are the genotypes of parents

Answer 1

ANSWER

1) According to law of inheritance black is a dominant trait

2) female 1- Bb

female 2- BB

male mice- bb

Answer 2

1 Inference can you make concerning inheritance of black and brown coloured mice -

-First inference that can be drawn that Black color is the dominant trait and brown color is the recessive trait, as the second female produces only black offsprings.

Had the brown color been dominant, then female 2 would definitely have produced brown colored mice.

Now, let us denote the black color trait with 'B' and brown color with 'b'

Possible genotypes of dominant black color mice - 'BB' and 'Bb'

Possible genotypes of recessive brown mice - 'bb'

If the genotype of female 1 is homozygous, 'BB' then crossing with 'bb' gives us all black offsprings with genotype 'Bb' but this is not the case.

Therefore, the genotype of Female 1 mouse must be 'Bb' so offsprings of both colors are produced.

-In case of female 2, only black offsprings are obtained. Therefore, she must have a homozygous genotype, 'BB' which results in all dominant black colored offsprings.

Genotype of brown male mouse - 'bb'

Draw Punnet's squares wherever necessary and the answer will be clear to you.