Name:________________________________ Period: 1 2 3 4 5 6 7 Date:______________
Using Punnett
Squares
Study the following genetics problems. Determine the letters that will be used for each allele,
and then complete the Punnett square for each problem. Give the genotype and phenotype ratio
for the problems that call for them. List them in the correct order of homozygous dominant,
heterozygous, and then homozygous recessive. (Ex: BB, Bb, bb)
1. Tt x tt
2. BB x bb
Genotype Ratio: ________________
Genotype Ratio: ________________
3. Black fur in dogs is dominant over red fur.
Cross a heterozygous dog with a red fur dog.
4. Rolling your tongue is dominant
over the non-rolling trait. Cross a
homozygous roller with a
homozygous non-roller.
_____ x _____
_____ x _____
Genotype Ratio: ________________
Genotype Ratio: ________________
Phenotype Ratio:________________
Phenotype Ratio:________________
5. Silkworms
Dominant Gene: Yellow Cocoon
Recessive Gene: White Cocoon
Cross hybrid with a purebred recessive.
6. Guinea Pigs:
Dominant Gene: Short Fur
Recessive Gene: Long Fur
Cross a purebred dominant with a
purebred recessive.
_____ x _____
_____ x _____
Genotype Ratio: ________________
Genotype Ratio: ________________
Phenotype Ratio:________________
Phenotype Ratio:________________
7. Dimples
Dominant Trait: No Dimples
Recessive Trait: Dimples
Cross a hybrid no dimpled individual with
a hybrid no dimpled individual.
_____ x _____
8. Curly Hair
Dominant Trait: Curly Hair
Recessive Trait: Straight Hair
Cross a hybrid curly haired individual
with a straight haired individual.
_____ x _____
Genotype Ratio: ________________
Genotype Ratio: ________________
Phenotype Ratio:________________
Phenotype Ratio:________________
9. Tigers
Dominant Trait: Orange Fur
Recessive Trait: White Fur
Cross a purebred orange tiger with a
white tiger.
_____ x _____
10. Mice:
Dominant Trait: Black Fur
Recessive Trait: White Fur
Cross a white fur mouse with a white fur
mouse.
_____ x _____
Genotype Ratio: ________________
Genotype Ratio: ________________
Phenotype Ratio:________________
Phenotype Ratio:________________
Genetic Vocabulary Usage:
Use the following genetic vocabulary terms correctly in a complete sentence.
11. Allele
12. Genes
13. Dominant
14. Recessive
15. Heredity