Genetics Test

1
Genetics Test

• Review

2

• The allele for brown eye color is dominant over
  blue. A brown-eyed woman (whose father had blue
  eyes) married a man with blue eyes (whose mother
  was brown-eyed). What genotypic and phenotypic
  ratios would you expect in their children?

3

• Nystagmus is a condition in humans in which those
  affected have eyeballs that roll involuntarily.
  The genes for this trait are incompletely
  dominant. A normal man marries a woman who is
  slightly nystagmus. What is the chance that
  their children will be affected?

4

• A woman with blood type B marries a man. They
  have 3 kids. One is type B, the other 2 are type
  O. What are the genotypes of everyone in the
  family?

5

• A dominant gene is responsible for the gray body
  color of fruit flies its recessive allele
  produces black body color. A cross of a gray
  female with a black male produces 52 black and 58
  gray flies. What are the genotypes of the
  parents?

6

• In humans the size of mouth is codominant. There
  are 3 sizes, small, medium and large. Assign the
  symbols for the alleles and do the following
  crosses and tell the expected phenotypes.
• small x medium
• medium x large
• What would the genotypes of the parents have to
  be so that the parents could have 3 children with
  different phenotypes?

7

• In pea, plants tall is dominant over short. A
  tall plant is crossed with a short one producing
  offspring of which about ½ are tall and ½ are
  short. What are the genotypes of the parents?

8

• Some miscellaneous, but related questions
• How many chromosomes do you have per trait
• What is a gene?
• How many chromosomes do you have in each cell?