You cross a true breeding pink eyed long nosed Shmoo to a pu

You cross a true breeding pink eyed, long nosed Shmoo to a pure breeding blue eyed, short nosed Shmoo. All of the offspring are blue eyed and long nosed. When you cross some of the F1s you get the following results:

37 pink, long 42 blue, short 98 blue, long How many pink, short Shmoos would you expect? 47.5 O 11.875 35.625 106.875 13 pink, short

Solution

b). 11.875

Assume that the gene coding for pink eyes is P and the gene coding for blue eyes is p; P is dominant over p. Similarly, the gene coding for long nose is L and the gene coding for short nose is l; L is dominant over l.

Now, true breeding parental cross is, PP LL Vs pp ll

PP LL* pp ll ------à Pp Ll (100% pink, long) ---à F1

Cross between F1 will have the progeny with the following genotypes:

Pp Ll* Pp Ll --à P_ L_ (9/16, pink, long), P_ ll (3/16, pink, short), pp L_ (3/16, blue, long), pp ll (1/16, blue, short).

The total number of progeny in the given example is = 98+42+37+13 = 190

Thus, the expected number of pink, short progeny is = 190* 1/16 = 11.875