In chickens, the crested hen dominates the simple comb, and the colored plumage over the black.

In chickens, the crested hen dominates the simple comb, and the colored plumage over the black. We crossed a heterozygous crested chicken with colored feathers with a homozygous rooster with a simple comb and black. A) What is the probability (in%) of the birth of a chick with colored plumage? B) What is the probability (in%) of the birth of a chicken without a crest?

Let’s designate the gene for crested chickens as B, then the gene that causes the development of a simple ridge will be b.

Let’s designate the gene that causes colored plumage in chickens as C, then the gene for black plumage will be c.

The chicken, according to the condition of the problem, is crested, has colored plumage and is heterozygous. Let’s write it down as ВbСс. This chicken produces eggs BC, bc, bC and Bc.

The cock has black plumage and a simple comb. He is homozygous. Let’s write it bbcc. Such a cock will produce the same type of sperm cells.

The offspring from crossing the described rooster and chicken will look like this:

25% – ВbСс: crested chickens with colored plumage;

25% – bbcc: black chickens with a simple comb;

25% – bbСс: colored chickens with simple combs;

25% – Bbcc: black crested chickens.

Answer: A). fifty%; B). fifty%.



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