Punnett Squares: Predicting Genetic Traits

Punnett Squares: Predicting Genetic Traits

Read each question carefully and answer to the best of your ability. Use the provided Punnett Squares to show your work when necessary.

1. A Punnett Square is a diagram that is used to predict the outcome of a particular cross or breeding experiment. It helps to determine the probability of an offspring inheriting a specific  .

2. In genetics, an allele is one of two or more versions of a gene. A   allele will always express its trait if present, while a   allele will only express its trait if two copies are present.

3. If 'B' represents the allele for black fur (dominant) and 'b' represents the allele for white fur (recessive), which genotype would result in an organism with white fur?

4. In pea plants, tall (T) is dominant over short (t). Cross a heterozygous tall plant with a short plant. Fill in the Punnett Square below and state the genotypic and phenotypic ratios of the offspring.

Genotypic Ratio:  

Phenotypic Ratio:  

5. A homozygous dominant individual has two different alleles for a particular trait.

6. In guinea pigs, rough coat (R) is dominant over smooth coat (r). If you cross two heterozygous rough-coated guinea pigs (Rr x Rr), what percentage of the offspring would you expect to have a smooth coat?