Download Genetics Assignment

SBI3U
Genetics In-Class Assignment
Name: ___________________
For each of the questions below, answer neatly on lined paper and show ALL of your work.
You may use your notes, however, absolutely no group work is allowed.
1.
In rabbits, black coat (B) is dominant to brown coat (b). Long hair (L) is dominant to short hair (l).
a) Determine the phenotype to be expected when a homozygous black long haired rabbit is mated with a brown
short haired rabbit. [4]
b) When the rabbits of the F1 generation are inbred, what is the resulting phenotypic ratio of the F2 offspring? [5]
2.
In watermelons, the green colour gene (G) is dominant over the striped colour gene (g), and round shape (R) is dominant
over long shape (r). A heterozygous round striped watermelon plant is crossed with a long heterozygous green colour plant.
Determine the expected phenotypic ratio of the F1 generation. [5]
3.
In some breeds of dogs, a dominant allele controls the characteristic of barking (B) while on a scent trail. The allele for nonbarking trailing dogs is (b). In these dogs an independent gene (E) produces pointy ears which are dominant over drooping
ears (e). For each of the following mating situations, calculate the phenotypic ratio of the offspring.
a) A non-barking trailer with pointy ears (heterozygous) is mated with a heterozygous barking trailer with drooping
ears. [4]
b) A non-barking trailer with drooping ears is mated with a heterozygous barking trailer with drooping ears. [4]
4.
What is the probability of a couple (XX and XY) having five daughters in a row? [4]
5.
A geneticist notices that crossing a round radish with a long radish produces oval radishes in the F1 generation. Two oval
radishes are crossed:
a) What are the phenotypic and genotypic ratios of the F 2 generation? [5]
b) Which type of inheritance is this? [1]
6.
A woman of blood type A is suing a man of blood type B for paternity. The woman’s child is type O.
a) Could this man be the father of this child? If this man is actually the father of this child, specify the genotypes of
both parents. [2]
b) If it was impossible for this man to be the father of a type O child, regardless of the mother’s genotype, specify his
genotype. [1]
c) If a man was blood type AB, could he be the father of a type O child? [1]
7.
In a recent study done at Waterloo Oxford, it was determined that the ability to fall asleep in class was dependent on a
gene that was incompletely dominant to the gene that controlled wakefulness in class. It was found that the heterozygous
condition produced dozing in class with one eye open!
If a male W-O graduate who slept through classes in high school married a female W-O graduate who managed to doze
through high school, what are the chances of their children sleeping all the way through high school? [4]
8.
Red-green colour-blindness is a relatively common condition caused by an X-linked recessive gene. A woman with colour
vision (whose father was red-green colour-blind) and a man with colour vision, have a family.
a) State the genotypes for the woman, her father and her husband. [3]
b) What are the possible phenotypes and genotypes of their children? [3]
c) What is the probability of producing a colour vision daughter? [1]
d) If the woman’s second husband is red-green colour-blind, what is the probability that they could have a son with
colour vision? [4]
e) Could there be a colour-blind daughter from the first marriage? The second marriage? Explain. [2]
9.
A man is heterozygous for one autosomal gene pair Tt and he carries a recessive X-linked gene k. What proportion of his
sperm will be tXk? Show your work. [2]
10. A research lab at the University of Waterloo had an incident where some of the mouse cages were left open. The mice that
were heterozygous and homozygous dominant for the grey coat colour got mixed up. Recessive mice are white. What can
the students do to determine the unknown genotypes of the mice that were let loose? Explain your answer clearly. [3]
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