Download Basic Genetics Problems File

Basic Genetics Problems
1. Let's say that in seals, the gene for the length of the whiskers has two alleles. The dominant
allele (L) codes long whiskers & the recessive allele (l) codes for short whiskers. Show how
the following will be represented:
Genotype
Phenotype
Homozygous dominant alleles
Homozygous recessive alleles
Heterozygous alleles
a) What percentage of offspring would be expected to have long whiskers from the
cross of a homozygous long-whiskered seals and a short-whiskered seal?
Draw a Punnett square to support your answer.
b) What ratio of offspring - both phenotype and genotype - would result from a cross
between the seals produced by part (a)
2. Tall (T) is dominant to short (t) in peas. Give the genotypic and phenotypic ratios resulting
from the cross between a heterozygous tall plant and a short plant.
3. Black hair (B) and white hair (W) are codominant in a breed of rat. Describe the
phenotype(s) resulting from a cross between two heterozygous individuals.
4. Red hair (R) and white hair (W) exercise incomplete dominance in a breed of parrot.
Describe the phenotype(s) resulting from a cross between two heterozygous individual.
5. A man with heterozygous B blood has children with a woman with O blood.
Show the proportions of all genotypes and phenotypes for their children.
6. A woman with AB blood has children with a man heterozygous for A blood.
Show the proportions of all genotypes and phenotypes for their children.
7. The disorder of being an albino is called albinism. Albinism is inherited as a recessive
trait (aa). An albino man marries a pigmented woman (normal). They have nine children
together and all of them are normally pigmented. What can you assume about the
genotypes of the mother and the children?
8. The color of the fur of Jackalopes is expressed through incomplete dominance conditions, R
for red and W for white with the heterozygous being expressed as pink. You are starting a
jackalope-breeding business and someone wants to buy a white jackalope. The problem is,
you only have a red jackalope (female) and a pink jackalope (male). How are you going
to meet your customer’s needs? Draw Punnett squares to help explain your answer.
9. Johnny Depp claims to be the illegitimate son of Elvis and wants to claim Graceland as his
new home. The King was type O blood and Johnny Depp is type AB blood. Is Johnny the
son of the King? Will he move into Graceland? Why or why not? Show punnett/proof.