Pedigrees Punnett Squares Dihybrid Cross

25% X 25%

• 2.25%

• 6.25%

• 12.5%

• 25%

1/4 X 1/4 =

• 3/8

• 1/2

• 1/16

• 1/8

75% X 50% =

• 6.25%

• 15.5%

• 25%

• 37.5%

1/2 X 3/4 =

• 3/8

• 3/16

• 1/4

• 1/16

25% X 0% =

• 0%

• 25%

• 12.5%

• 37.5%

50% X 50% =

• 250%

• 2.5%

• 25%

• .25%

In flies, red eyes (R) are dominant to brown eyes (r) and brown bodies (B) are dominant to yellow bodies (b). A fly with genotype RrBb is mated with a fly with genotype rrbb. What fraction of offspring will have red eyes and brown bodies?

• 1/4

• 1/8

• 1/2

• 1/16

In pea plants, smooth peas (S) are dominant to wrinkled peas (s) and purple flowers (P) are dominant to white flowers (p). Two plants that are heterozygous for both traits (SsPp) are crossed. How many different genotypes will appear in the offspring?

• 2

• 4

• 6

• 9

In certain birds, yellow feathers (g) are recessive to green feathers (G) and short beaks (l) are recessive to long beaks (L). A bird with genotype ggLl is crossed with a bird with genotype GgLl. What percentage of offspring are expected to have yellow feathers and long beaks?

• 2.5%

• 25%

• 12.5%

• 37.5%

In a certain species of mammals, gray fur (G) is dominant to white fur (g) and brown eyes (B) are dominant to blue eyes (b). An animal with white fur and blue eyes is crossed with an animal that has gray fur and brown eyes (GGBb). What trait will appear in all of the offspring of this mating?

• Gray Fur

• Blue Eyes

• Both

• Neither