Punnett Practice
For each of the problems below, show the punnett square.
1. In silkworms, the yellow cocoon allele is dominant (Y). The white allele is recessive(y). Two silkworms
have 100 offspring and all have yellow cocoons. The male parent has a white caccoon. What is the genotype of
the female parent.
2. In guinea pigs the dominant allele "F" produces short fur. The recessive allele "f" produces long fur.
Assuming a heterozygous male fertilizes a homozygous recessive female, what percentage of their children will
have short fur? What percentage will have long fur?
3. In mice, the black eyes allele is dominant (E). The red eye allele is recessive (e). A male and female mouse
have 200 offspring and 87 have red eyes. If the female has black eyes what are the genotypes of the parents?
4. In fruit flies the allele for normal size wings (W) is dominant over the allele for small wings (w). A
heterozygous male mates with a female of unknown genotype. 39 of their 100 offspring have small wings.
What is the female’s genotype?
5. In certain trees, smooth bark (B) is dominant over wrinkled (b). When two heterozygous trees are crossed
how many of the 200 offspring will have wrinkled bark? Show your square!
6.
Two heterozygous parent have 4 offspring. 3 of the offspring have large noses and 1 of the offspring
has a small nose. Which trait is recessive? Show a punnett square to support your claim.
Punnett Practice
For each of the problems below, show the punnett square.
1. In silkworms, the yellow cocoon allele is dominant indicated by "Y". The white allele is recessive, and
indicated by "y". Two silkworms have 100 offspring and all have yellow cocoons. The male parent has a white
caccoon. What is the genotype of the female parent.
2. In guinea pigs the dominant allele "F" produces short fur. The recessive allele "f" produces long fur.
Assuming a heterozygous male (Ff) fertilizes a homozygous recessive female (ff), what percentage of their
children will have short fur? What percentage will have long fur?
3. In mice, the black eyes allele is dominant (E). The red eye allele is recessive (e). A male and female mouse
have 200 offspring and 87 have red eyes. If the female has black eyes what are the genotypes of the parents?
4. In fruit flies the allele for normal size wings (W) is dominant over the allele for small wings (w). A
heterozygous male mates with a female of unknown genotype. 39 of their 100 offspring have small wings.
What is the female’s genotype?
5. In certain trees, smooth bark (B) is dominant over wrinkled (b). When two heterozygous trees are crossed
how many of the 200 offspring will have wrinkled bark? Show your square!
6. Two heterozygous parent have 4 offspring. 3 of the offspring have large noses and 1 of the offspring has a
small nose. Which trait is recessive? Show a punnett square to support your claim.