Download Punnett Squares Worksheet

Punnett Square Worksheet
Before you begin….remember this…
- Choose one letter for a trait. The Dominant allele is a capital letter, the Recessive allele is a lower-case letter.
1. In rabbits, black fur is dominant over white fur. Show the cross of a heterozygous black
male with a homozygous white female.
Genotype Ratio:
Phenotype Ratio:
2. Tall is dominant over short in pea plants. Show the cross of a homozygous short plant is
crossed with a homozygous tall plant.
Genotype Ratio:
Phenotype Ratio:
3. Wrinkled seed are recessive to smooth seeds. Show a plant that can only pass down
wrinkled seeds crossed with a heterozygous smooth seeds producing plant.
Genotype Ratio:
Phenotype Ratio:
4. As in the previous problem… Show a heterozygous smooth plant crossed with another
heterozygous smooth seed producing plant.
Genotype Ratio:
Phenotype Ratio:
5. Blue eyes are dominant to red eyes in rabbits. Show a heterozygous blue-eyed rabbit
crossed with a red-eyed rabbit.
Genotype Ratio:
Phenotype Ratio:
6. In fruit flies, red eyes are dominant over white eyes. Show a cross between two whiteeye fruit flies.
Genotype Ratio:
Phenotype Ratio:
Use the following for questions 7-11:
In dogs, there is a hereditary deafness caused by a recessive gene, “d.” A kennel owner
has a male dog (Gilbert) that she wants to use for breeding purposes if possible. Gilbert can hear.
7) What are the two possible genotypes of Gilbert?
__________ and _________
8) If the dog’s genotype is Dd, the owner does not wish to use him for breeding so that
the deafness gene will not be passed on. This can be tested by breeding the dog to a deaf female
(dd). Draw two Punnett squares to illustrate the two possible crosses between Gilbert and the
deaf female using the possible genotypes of Gilbert that you gave in number 7.
9) In each case from number 8, what percentage of the offspring would be expected to be
able to hear? ___________ to be deaf? ___________
10) How will the owner know the genotype of Gilbert?
11) Using a Punnett square, show how two hearing dogs could produce deaf offspring.