Download genetics practice 3

Biology 9
Genetics Practice Problems and Extra Credit (15 points)
•
For each of the following genotypes, give all possible gametes.
o WWSs
o Tt
o Ttgg
o AaBb
•
For each of the following, state whether a genotype or a gamete is represented.
o D
o Ll
o Pw
o LlGg
Be sure to show or explain your work for each of the following in order to get full credit.
• A man with a widow’s peak has a mother with a straight hairline. Widow’s peak (W) is dominant over
straight hairline (w). What is the genotype of the man?
•
Both a man and a woman are heterozygous for freckles. Freckles (F) are dominant over no freckles (f).
What is the chance that their child will have freckles?
•
Both you and your sister or brother have attached earlobes, yet your parents have unattached earlobes.
Unattached earlobes (E) are dominant over attached earlobes (e). What are the genotypes of your
parents?
•
Two cats are mated. One of the parent cats is long-haired (recessive allele). The resulting litter contains
two short-haired and three long-haired kittens. What does the second parent look like, and what is its
genotype?
1
•
Woody Guthrie was a folk singer that was diagnosed with a genetic disorder called Huntington’s
disease. A dominant autosomal gene causes Huntington’s disease. If Woody Guthrie was heterozygous
for this gene, then what are the chances his children will have the disorder. Assume his wife is
homozygous normal for this condition.
•
What genotype do children have if one parent is homozygous recessive for earlobes and homozygous
dominant for hairline, and the other is homozygous dominant for unattached earlobes and homozygous
recessive for hairline?
•
If an individual from this cross reproduces with another of the same genotype, what are the chances that
they will have a child with a straight hairline and attached earlobes?
•
Attached earlobes and straight hairline are recessive. What genotype does a man with unattached
earlobes and a widow’s peak have if his mother has attached earlobes and a straight hairline?
•
A child who does not have dimples or freckles is born to a man who has dimples and freckles (both
dominant) and a woman who does not. What are the genotypes of all persons concerned?
2
•
Most house cats have long tails, but some are stumpies (bob-tailed) and some are rumpies (no tail, or
manx). Two stumpies are bred together and produce nine kittens, three with long tails, five stumpies,
and one rumpie. From these results, how would you conclude that tail length is inherited? Show
genotypes of all cats to support your conclusion (mother, father and three groups of kittens).
•
In shorthorn cattle, the hybrid between red and white is roan, having red and white hairs intermingled.
If a roan is bred with a white, what will the phenotypic ratio be?
•
A multifactorial trait is controlled by three pairs of alleles. What are the two extreme genotypes for this
trait? (Use letters A,B, and C)
•
What is the genotype of the lightest child that could result from a mating between two medium-brown
individuals?
•
A child with type O blood is born to a mother with type A blood.
o What is the genotype of the child? The mother? What are the possible genotypes of the father?
• From the following blood types, determine which baby belongs to which parents:
Baby 1, type O
Ms. Doe, type A
Baby 2, type B
Mr. Doe, type A
Ms. Jones, type A
Mr. Jones, type AB
3
•
This pedigree chart pertains to color blindness. The genotype of the individual at the * is?
• Does the following pedigree represent an autosomal dominant trait, an autosomal recessive trait, or an
X-linked recessive trait?
4