Dihybrid Cross Problem Set

A dihybrid cross involves a study of inheritance patterns for organisms differing in two traits. Mendel invented the dihybrid cross to determine if different traits of pea plants, such as flower color and seed shape, were inherited independently. Our objective is to understand the principles that govern inheritance of different traits in a dihybrid cross that led Mendel to propose that alleles of different genes are assorted independently of one another during the formation of gametes.

Instructions: The following problems have multiple choice answers. Correct answers are reinforced with a brief explanation. Incorrect answers are linked to tutorials to help solve the problem.
  1. Predicting combinations of alleles in gametes of plants heterozygous for two traits.
  2. When does a phenotype ratio of 9:3:3:1 occur?
  3. A genetic cross yielding a 9:3:3:1 ratio of offspring.
  4. Predicting gametes of an SsYy plant.
  5. A SsYy x ssyy test cross.
  6. Offspring of a SsYy x ssyy test cross.
  7. Homozygous offspring of a dihybrid cross.
  8. Heterozygous offspring of a dihybrid cross.
  9. Homozygous offspring of a dihybrid cross, again.
  10. Exceptions to the 9:3:3:1 ratio of offspring?
  11. Incomplete dominance in a dihybrid cross.
  12. What is the genotype of the agouti parent?
  13. AaBb dihybrid cross involving epistasis.


The Biology Project
University of Arizona
Tuesday, August 13, 1996
Contact the Development Team

All contents copyright © 1996. All rights reserved.