Practice problems for monohybrid crosses

Problem Set 1: Practice problems for monohybrid crosses. 

7. White fruit is dominant to yellow fruit in squash. Pollen from a white-fruited plant that is known to be heterozygous is placed on the stigma of the flower of a yellow-fruited plant.

What is the genotype of the white-fruited plant?

WW (W) = dominant allele

What gamete(s) will this plant make?

(W), (w)

What is the genotype of the yellow-fruited plant?

ww (w) = recessive allele

What gametes will this plant make?

(W), (w)

Make a Punnett square illustrating this cross.

(W) (w)

(W)

(w)

Give the expected genotypic ratio of the offspring of this cross.

WW: ww = 3:1

Give the expected phenotypic ratio of the offspring of this cross.

W: w = 0.5: 0.5

Problem Set 3: Crosses involving 2 or more genes (Practice on dihybrid crosses). 

In guinea pigs, black fur is dominant to white fur and rough coat is dominant to smooth coat. These genes exhibit independent assortment. A white, smooth female is mated to a black, rough coated male. The male is heterozygous at both loci.

What letter will you use to represent each trait?

Color:

Black: B 

White: b 

Coat texture

Smooth: r 

Rough: R 

Genotype of the male:__RrBb___ gametes produced by the male: __RrBb, RRBb, rrbb___

Genotype of the female ___Rrbb__ gametes produced by the female: ____Rrbb, Rrbb, rrbb_