1. In guinea pigs, black fur (F) is dominant and white fur (f) is recessive. Show the cross between two heterozygous black guinea pigs. Fill in the punnett square. What will be the probable genotypic and phenotypic ratios of their offspring?

Parent 1 genotype:

Parent 2 genotype:

Parent 1 possible sex cells:

Parent 2 possible sex cells:

Draw a punnet square

Genotypic Ratio:

Phenotypic Ratio:

1. Eye color in guinea pigs is determined by the presence of a dominant allele for black eyes and a recessive allele for red eyes. If two red-eyed guinea pigs mate, what will be the genotypic and phenotypic ratios of their offspring? Fill in the punnett square.

Parent 1 genotype:

Parent 2 genotype:

Parent 1 possible sex cells:

Parent 2 possible sex cells:

Draw a punnet square

Genotypic Ratio:

Phenotypic Ratio:

Test Cross

1. An animal breeder wants to know if a black guinea pig is homozygous or heterozygous for coat color. He test crosses the black guinea pig with a homozygous recessive white guinea pig. If one of the offspring is white, what is the genotype of the black guinea pig?

Pedigree

1. The ability to taste a chemical called PTC (phenolthiocarbimide) is controlled by a dominant gene (T). Use (t) for non-tasters. Shaded individuals cannot taste PTC. For unknown heterozygous dominant individuals use (T?). Draw a pedigree.

Dihybrid Crosses

1. If a purebred thorny plant (T) with red flowers (R) were crossed with a plant that was purebred for yellow flowers (r) and no thorns (t), what would be the ratio for the F₂ Generation?

Parent 1 genotype:

Parent 2 genotype:

Parent 1 possible sex cells:

Parent 2 possible sex cells:

Draw a punnet square

F₁ Phenotypic Ratio:

For the F₂ Generation

F₁ Parent 1 genotype:

F₁ Parent 2 genotype:

F₁ Parent 1 possible sex cells:

F₁ Parent 2 possible sex cells:

Draw a punnet square

F₂ Phenotypic Ratio: Click here to enter text.

6. Widow’s peak is a dominant trait in humans and hitchhiker’s thumb is recessive. Cross a person who is homozygous dominant for widow’s peak and heterozygous for hitchhiker’s thumb with a person who is heterozygous for widow’s peak and homozygous recessive for hitchhiker’s thumb. What si the phenotypic ratio for the possible offspring?

Parent 1 genotype:

Parent 2 genotype:

Parent 1 possible sex cells:

Parent 2 possible sex cells:

Draw a punnet square

Phenotypic Ratio: Click here to enter text.

Incomplete Dominance

7. Snapdragon flowers can be red, white, or pink. Pink flowers result when red and white flowers cross-pollinate. Red snapdragons are homozygous red (RR) and white snapdragons are homozygous white (R’R’). Show the cross between a red snapdragon and a white snapdragon.

Draw a punnet square

Genotypic Ratio:

Phenotypic Ratio:

Codominance

1. In Erminette chickens, one allele produces black feathers (B) and the other produces white feathers (W). Heterozygous individuals have some black feathers and some white feathers, giving them a speckled appearance. If a black rooster and a white hen mate, what would be the ratio of phenotypes in the F2 generation?

Draw a punnet square

Phenotypic Ratio:

Blood Typing

1. Suppose two newborn babies were accidentally mixed up at the hospital. To determine the parents of each baby, the blood types of each baby and both couples were tested. First identify the possible genotypes of each individual, and then determine which baby belongs to each couple. (HINT: Draw as many Punnett squares as you wish.)

Person	phenotype	Genotype
Baby #1	Type O
Baby #2	Type A
Mr. Brown	Type B
Mrs. Brown	Type AB
Mr. Smith	Type B

Mrs. Smith

Type A

Baby #1belongs to Mr. and Mrs.

Baby #2 belongs to Mr. and Mrs.

Sex-linked

10. Hemophilia in humans is caused by a recessive mutation on the X-chromosome. What will be the outcome of mating between a homozygous normal female (X ^H X ^H ) and a hemophilic male (X ^h Y)?

Draw a punnet square

Genotypic Ratio:

Phenotypic Ratio:

11. What will be the results of a cross between a female with hemophilia and a normal male?

Draw a punnet square

Genotypic Ratio:

Phenotypic Ratio: