Question

how does the presence of white flowers cahnge from the parent generation to first generation of offspring to the second genration of offsrping

Answer 1

Answer:

P generation:  1 purple flower (AA)  :  1 white flower (aa)

F1 generation:  4 purple flowers (Aa)  :  0 white flowers

F2 generation:  3 purple flowers (AA, Aa)  :  1 white flower

Explanation:

Assuming the parents are AA and aa, the allele for white flowers is recessive, so there needs to be two of them for the trait to be expressed.  Thus, the capital A purple allele that the other parent contributes will mask that white allele and all the flowers will appear purple.  However, all of the offspring are Aa now, so when they are crossed, there's a 25% chance that they'll both contribute the lowercase a allele that codes for white flowers.  Remember that if both of them give the lowercase a allele then the offspring will be aa and appear white.