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 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 the parents​

Answer 1

The genotypes of the parents are:

Explanation:

• As cross between brown male and black female 2 produce all black offspring, so black colour is dominant over brown.
• Let the dominant colour allele be represented as B and recessive colour allele be represented as b.
• Genotype of the black female 2 : BB
• Genotype of the brown male : bb
• Cross between them :

                                                  B               B

                                       b        Bb             Bb

                                                  (B)            (B)

                                       b        Bb             Bb

                                                  (B)            (B)

• (B) represents black phenotype.
• Genotype of black female 1 : Bb.
• Cross between black female 1 (Bb) and brown male(bb) :

                                                     B                   b

                                        b          Bb                 bb

                                                    (B)                  (Brown)

                                         b         Bb                  bb

                                                     (B)                 (Brown)

• (Brown) represents brown phenotype.
• Ratio of Black to Brown obtained in F1 generation is 1 : 1 similar to that stated in the question, 9  :  7 which is also close to 1 : 1.