Download File - Science with Ms. Tantri

SBI3U: Genetics In-Class Assignment
Name:
__
APPLICATION [30 marks]
Answer the following questions on a SEPARATE piece of paper. Show ALL your work. You may work in
partners, but each person must hand-in their own work. (Remember to define the alleles (letters), parent
genotypes, gamete possibilities, and Punnett Squares)
1) Brown eye colour in humans is dominant to blue-eyed colour. A brown-eyed man marries a blue-eyed
woman and all their children are brown-eyed. [2 marks]
a. What is the genotype of the brown-eyed man?
b. What would be the genotypes of the children?
2) In humans, the gene for curly hair is dominant to straight hair. Fred has curly hair but Fred’s mother had
straight hair. Fred marries Lisa, who has straight hair. What proportion of their children would have curly
hair? [3 marks]
3) A pea plant with terminal flowers is crossed with a pea plant with axial flowers. All of the F1 are axialflowered plants. When the F1 was self-fertilized, 400 seeds were produced (F2 generation). When these
seeds were planted, 300 of the F2 generation produced axial flowers and 100 produced terminal flowers.
How many of the F2 axial flowered plants were homozygous? SHOW YOUR WORK! [5 marks]
4) A homozygous purple-terminal flowered plant was crossed with a homozygous white-axial-flowered plant.
The purple flower is dominant to white flowers and axial flower position is dominant to terminal flower
position.
a. What would the genotype be for the F1 generation? [1 mark]
b. Show the results of a cross between two F1 plants and give the phenotype ratio of the F2 plants.
[4 marks]
5) What is the phenotype ratio of offspring produced by a cross between a heterozygous black, short-haired
guinea pig and a homozygous white, long-haired guinea pig? Assume black colour and short hair are
dominant. [2 marks]
6) In Cocker Spaniels, a black coat is governed by a dominant allele, and the red coat by its recessive allele.
Solid pattern is dominant over spotted pattern. A solid-patterned black male is mated to a solid-patterned
red female and produces a litter of six pups: two solid-patterned black, two solid-patterned red, one
spotted black, and one spotted red. Determine the genotype of the parents. [3 marks]
7)
The color of fruit for plant "X" is determined by two alleles. When two plants with orange fruits are
crossed the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit, 25%
yellow fruit. What are the genotypes of the parent orange-fruited plants?
[2 marks]
8)
A homozygous red/terminal-flowered plant was crossed with a homozygous white/axial-flowered plant.
Red and white flowers exhibit incomplete dominance and axial flowers are dominant to terminal. What
are the possible genotypes and phenotypes of the F1 generation? What is the phenotype ratio for the F2
generation? [8 marks]