Let’s try some Punnett Squares



Punnett Squares Practice Worksheet

1. In guinea pigs, long hair is dominant to short hair. A pure bred short haired guinea pig is bred with a hybrid long haired. What does each of those look like? (use H)

Pure bred (homozygous) _______________

Hybrid (heterozygous) _________________

Set up the Punnett square:

What percent of the babies will have Hh as their alleles? ______________

What percent of the babies will be long haired? _____________________

What percent of the babies will be short haired? ____________________

What is the genotypic ratio? _______________________

What is the phenotypic ratio? ______________________

2. In rabbits, black fur is dominant to white fur. If you cross a BB male with a Bb female, what are the possible genotypes and phenotypes of the offspring? What is the percent chance for each type? Include genotypic and phenotypic ratios.

| |Possible combinations |Percent chance |Ratios |

|Genotypes | | | |

| | | | |

|Phenotypes | | | |

| | | | |

3. In cabbage butterflies, White wings are dominant to yellow wings. If a Ww butterfly is crossed with a ww butterfly, what are the possible genotypes and phenotypes of the offspring and the percent chance for each? Include genotypic and phenotypic ratios.

| |Possible combinations |Percent chance |Ratios |

|Genotypes | | | |

| | | | |

|Phenotypes | | | |

| | | | |

4. In dogs, there is a hereditary type of deafness caused by a recessive gene. Two dogs that carry the gene for deafness but have normal hearing are mated. What are the possible genotypes and phenotypes of their offspring and the percent chance for each? Include genotypic and phenotypic ratios.

| |Possible combinations |Percent chance |Ratios |

|Genotypes | | | |

| | | | |

|Phenotypes | | | |

| | | | |

5. Tongue-curling in humans is a dominant genetic trait. Suppose a man who is Tt for tongue-curling marries a woman who is also Tt for this trait. What are the possible genotypes and phenotypes of their children and the percent chance for each? Include genotypic and phenotypic ratios.

| |Possible combinations |Percent chance |Ratios |

|Genotypes | | | |

| | | | |

|Phenotypes | | | |

| | | | |

6. In guinea pigs, rough coats (with lots of swirly cowlicks) are dominant over smooth coats. If an RR guinea pig is crossed with an Rr guinea pig, what are the possible genotypes and phenotypes of the offspring? What are the chances of each? Include genotypic and phenotypic ratios.

| |Possible combinations |Percent chance |Ratios |

|Genotypes | | | |

| | | | |

|Phenotypes | | | |

| | | | |

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download