Genetics Review
• In Fruit flies, dumpy wings are
shorter and broader than normal
wings. The allele for normal
wings is dominant to the allele for
dumpy wings. Two normalwinged flies were mated and
produced 300 normal-winged flies
and 100 dumpy-winged flies.
What were the parents’
genotypes.
Dd X Dd
In the following dihybrid cross
concerning the traits of tongue rolling
and unattached earlobes.
TtEe X TtEe
What is the probability that an offspring
would be a tongue roller with
unattached earlobes?
9/16
In snapdragons, the allele for tall plants
is dominant to the allele for dwarf
plants, and the allele for red flowers is
incompletely dominant with white
flowers (a red flower mated with a
white flower has all pink offspring). If
a dwarf pink snapdragon is mated
with a heterozygous tall white
snapdragon, what is the phenotypic
ratio of their offspring?
¼ Tall Pink
¼ Tall White
¼ Dwarf Pink
¼ Dwarf White
When a black lab is mated with a
yellow lab and half of their pups are
chocolate and half are yellow labs,
what must the genotypes of the
parents be?
This type of inheritance is called
____________.
EeBb X eebb
Epistasis
Red headed people frequently have
freckles. This is best explained by which
of the following?
a. The genes for these two traits are
linked on the same chromosome.
b. The genes for these two traits are sexlinked.
c. Alleles for these two traits are codominant.
d. Both parents have red hair and
freckles.
A
Hemophilia is linked to the X
chromosome. A Normal man’s father
is hemophiliac and his wife has no
family history of hemophilia. What is
the probability that they will have a
child with hemophilia?
0%
For the following pedigree what is the
pattern of inheritance? List the genotypes
of as many people as possible.
Autosomal Recessive
If a father is heterozygous A+ and the
mother is O-, what are the possible
phenotypes and in what percents for
their children?
25% A+
25% A25% O+
25% O-
Who can donate blood to a person with
A- blood?
People with A- or O- blood.
Describe how Gregory Mendel studied
heredity.
By working with pea plants, he was able to
see how traits were passed down from
one generation to the next. One of his first
experiments was to test tall pea plants
with short. He expected the offspring to
be medium in height but he found out that
some were tall and some were short.
Through more studies he was able to
identify dominant and recessive traits.
Challenge problem – worth 2 points
A woman’s grandmother had cystic fibrosis
and her husband has no known cases of
cystic fibrosis in his family but we know
there is a 1 in 20 chance that he is a
carrier. What is the probability that this
couple will have a cystic fibrosis child?