Unit 5 Test – Genetics
Study Guide
Make sure you know the meaning of the following terms: (They can all be found in your notes and on
the Power Point which is posted online)
The Chromosome Theory of Inheritance
Heredity
Phenotype
Genetics
P Generation
Probability
Purebred
F1 Generation
Independence of Events
Hybrid
F2 Generation
Co dominance
Homozygous Dominant
Chromosome
Incomplete Dominance
Homozygous Recessive
Trait
Sex-linked traits
Heterozygous
Gene
Genotype
Allele
Make sure you know how to use a Punnett Square to determine the probability of different
phenotypes and genotypes.
Classic Punnett Squares:
In pea plants green pods are dominant to yellow pods.
What is the phenotype of a yellow podded plant? _____________________________
Show a Punnet square that crosses a Homozygous Dominant plant with a Homozygous Recessive plant.
What are the genotypes of the offspring (with percentages)? __________________________________
What are the phenotypes of the offspring (with percentages)? _________________________________
Incomplete Dominance Punnett Squares:
In Snapdragons, red and white flower color show incomplete dominance. Crossing a homozygous red
flower with a homozygous white flower will produce pink flowered offspring.
What is the genotype of pink flowered offspring? _____________________________
Show a Punnett Square that crosses a Pink Snapdragon with a white snapdragon.
What are the genotypes of the offspring (with percentages)? __________________________________
What are the phenotypes of the offspring (with percentages)? _________________________________
Co-Dominant Punnett Squares:
In house cats, tan and black fur color are co-dominant. Crossing a tan and a black cat will produce a tan
and black stripped offspring referred to as tabby.
How would you write the genotype for a black cat? _________________________
Show a Punnett Square that crosses two tabby cats.
What are the genotypes of the offspring (with percentages)? __________________________________
What are the phenotypes of the offspring (with percentages)? ________________________________
Sex Linked Punnett Squares:
Colorblindness is a sex-linked trait. It is carried on the X chromosome. People that are homozygous
recessive are colorblind.
Show a Punnett square that crosses a man with normal vision with a female who is a carrier for
colorblindness.
What percentage of the offspring are colorblind? ________________
What is the gender of the colorblind offspring? __________________
Pedigrees:
Albinism is a recessive disorder. In order to be albino your genotype must be homozygous recessive. Use
the pedigree shown below to answer the questions
What is the gender of the albino person? _______________________________
Does the albino person have offspring? _______________________________
Are the people in the first generation albino? _______________________________
How many women in the pedigree are carriers for albinism? _______________________________
How many brothers and sisters does the albino person have? _______________________________
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