Download Unit 1. Classical Genetics. WBC

World Biology
Championship
Classical Genetics
19 September 2011
Rules of the Game
You have been assigned to a team of 5-6 people and
will be asked to sit in a row.
A question will flash on the board and you will have
45 seconds to work the problem on your individual
whiteboard.
At the end of the time, the teacher will call a number
between 1 and 5/6. The person in each group with
the number called will raise his/her board.
Each group with the correct answer will receive one
point for their group.
The Spoils of Winning
The victorious group will receive:
Bonus points on the Classical Genetics Unit
Exam
A group photograph on the World Bio
Championship wall of winners
Bragging rights until the next installment of
the W.B.C.
A mystery prize
Ready...Set...Go!
Question # 1
Explain in one complete sentence the
difference between being homozygous and
being heterozygous.
Question # 2
Mrs. Stefano has freckles (r) but her husband,
George does not (RR). Which of these is the
predicted ratio of children with no freckles to
the children with freckles?
a. 1 : 3
b. 2 : 2
c. 3 : 1
d. 4 : 0
Question # 3
A cross was created between a black guinea pig
and a brown guinea pig. All the offspring ended up
black. Which of the following is the reason for this?
a. Black is recessive so it showed up.
b. Brown is heterozygous so it showed up.
c. Black is dominant so it hid the brown trait.
d. Brown is heterozygous so it was hidden.
Question # 4
How many individuals
in the pedigree to the
right have the trait in
question?
How many of the
affected individuals
are female? Male?
Question # 5
Hemophilia is caused by a sex-linked
recessive trait. What is the genotype of a male
who has hemophilia?
Question # 6
In horses, the allele for straight hair (B) is dominant to
the allele for curly hair (b). Which of the sets of parents
can produce offspring with curly hair?
heterozygous female with straight hair and a
homozygous male with straight hair
homozygous female with curly hair and homozygous
male with straight hair
heterozygous female with straight hair and a
heterozygous male with straight hair
homozygous female with straight hair and
heterozygous male with straight hair
Question # 7
An allele that can be present in a person’s
genes without being expressed is called
__________.
Question # 8
If individual III-4 marries a
man heterozygous for the
trait, what is the probability of
having a child that has the
trait?
0%
25 %
50 %
75 %
Question # 9
Explain in one complete sentence the
difference between a genotype and a
phenotype.
Question # 10
In humans colorblindness (b) is an example of
a sex-linked recessive trait. In this problem, a
male with colorblindness marries a female
who is not colorblind but carries the (b) allele.
Using a Punnett square, determine the
genotypic and phenotypic probabilities for their
potential offspring.
Question # 11
In the pedigree to the
right, is the trait shown
dominant or
recessive? How do
you know?
Question # 12
In dogs, there is hereditary type of deafness
caused by a recessive gene. Two dogs who
carry the gene for deafness but have normal
hearing are mated. What are the possible
genotypes and phenotypes of their offspring
and the percent chance for each?
Question # 13
In beagles, the allele for brown fur (F) is
codominant to the allele for white fur (f). If a
heterozygous beagle is crossed with a white
furred beagle, what will be the genotypic and
phenotypic ratios of their offspring?
Question # 14
How is it possible for two parents to have a
child that has a disease even when neither
parent has the disease?
Question # 15
Explain in one complete sentence the concept
of a sex-linked trait.
Question # 16
If individuals II-1 and
II-2 had another child
together, what is the
probability that it would
have the trait in
question?
Question # 17
In guinea pigs, short hair is dominant over
long hair. If a short haired SS guinea pig is
crossed with a long haired ss guinea pig, what
are the possible genotypes and phenotypes of
their offspring and the percent chance of
each?
Question # 18
Explain in one complete sentence what a
pedigree is and how it can be used.
Question # 19
In rabbits, the allele for black fur (B) is
incompletely dominant with the allele for white
fur (b). If a black rabbit and a white rabbit are
crossed, what will be the genotypic and
phenotypic ratios of their offspring?
Question # 20
Explain in one complete sentence the
difference between codominance and
incomplete dominance.
That’s all folks!