Punnett Squares

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents.

Front

What does the term 'allele' mean?

Back

An allele is a variant form of a gene that can produce different traits.

Front

What is the difference between genotype and phenotype?

Back

Genotype refers to the genetic makeup of an organism (the alleles), while phenotype refers to the observable physical traits.

Front

What does homozygous mean?

Back

Homozygous means having two identical alleles for a particular gene (e.g., RR or rr).

Front

What does heterozygous mean?

Back

Heterozygous means having two different alleles for a particular gene (e.g., Rr).

Front

What is a dominant allele?

Back

A dominant allele is one that expresses its trait even when only one copy is present (e.g., R in Rr).

Front

What is a recessive allele?

Back

A recessive allele is one that only expresses its trait when two copies are present (e.g., rr).

Front

How do you determine the genotype of a red-flowering plant?

Back

A red-flowering plant can be either homozygous dominant (RR) or heterozygous (Rr).

Front

What is the expected phenotype ratio from a cross of two heterozygous parents (Rr x Rr)?

Back

The expected phenotype ratio is 3:1 (3 red-flowering plants to 1 white-flowering plant).

Front

What is the expected phenotype from crossing a homozygous dominant (DD) with a homozygous recessive (dd)?

Back

The expected phenotype is 100% dominant trait (all offspring will show dimples).