Question

An individual heterozygous for eye color, skin color, and number of eyes mates with an individual who is homozygous recessive for all three characters; what would be the expected phenotypic ratio of their offspring? [Hint: B = black eyes, b = orange eyes; G = green skin, g = white skin; C = two eyes, c = one eye]
A) 9 black eyes, green skin, two eyes : 3 black eyes, green skin, one eye : 3 black eyes, white skin, two eyes : 1black eyes, white skin, one eye : 9 orange eyes, green skin, two eyes : 3 orange eyes, green skin, one eye : 3orange eyes, white skin, twoeyes : 1 orange eyes, white skin, one eye

B) 1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1orange eyes, green skin, two eyes : 1 orange eyes, white skin, two eyes : 1 orange eyes, white skin, one eye

C) 9 black eyes, green skin, two eyes : 3 black eyes, green skin, one eye : 3 black eyes, white skin, two eyes : 1black eyes, white skin, one eye

D) 9 orange eyes, green skin, two eyes : 9 orange eyes, green skin, one eye : 9 orange eyes, white skin, two eyes :1 orange eyes, white skin, one eye

E) 1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1

Answer 1

Answer:

B) 1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1 orange eyes, green skin, two eyes : 1 orange eyes, white skin, two eyes : 1 orange eyes, white skin, one eye

Explanation:

Parentals:                     BbGgCc  x  bbggcc

The punette square diagram of the cross of these two parents is attached.

B = black eyes, b = orange eyes;

G = green skin, g = white skin;

C = two eyes, c = one eye

Progeny with BbGgCc genotype → black eyes, green skin, two eyes = 8

Progeny with BbGgcc genotype → black eyes, green skin, one eye = 8

Progeny with BbggCc genotype → black eyes, white skin, two eyes = 8

Progeny with bbGgCc genotype → orange eyes, green skin, two eyes = 8

Progeny with Bbggcc genotype → black eyes, white skin, one eye = 8

Progeny with bbGgcc genotype → orange eyes, green skin, one eye = 8

Progeny with bbggCc genotype → orange eyes, white skin, two eyes = 8

Progeny with bbggcc genotype → orange eyes, white skin, one eye = 8

So, if we will see them in the form of ratio then each of the genotype will be in the ratio of 1 i.e. black eyes, green skin, two eyes: black eyes, green skin, one eye: black eyes, white skin, two eyes: orange eyes, green skin, two eyes: black eyes, white skin, one eye: orange eyes, green skin, one eye: orange eyes, white skin, two eyes : orange eyes, white skin, one eye = 1:1:1:1:1:1:1:1.

So, in view of above option B is most appropriate.

Note: In a trihybrid cross, a total of 64 progeny types may be produced.