Punnett Squares

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the genetic makeup of offspring from a cross between two parents.

Front

What does it mean if an allele is dominant?

Back

A dominant allele is one that expresses its trait even when only one copy is present in the genotype.

Front

What does it mean if an allele is recessive?

Back

A recessive allele is one that only expresses its trait when two copies are present in the genotype.

Front

In a Punnett Square, what does each box represent?

Back

Each box represents a possible genotype of the offspring and the probability of that genotype occurring.

Front

If brown eyes (B) are dominant over blue eyes (b), what is the genotype of a person with blue eyes?

Back

The genotype of a person with blue eyes is bb.

Front

What is the probability of having brown eyes if one parent is BB and the other is bb?

Back

100% of the offspring will have brown eyes (Bb).

Front

What is the probability of having brown eyes if both parents are heterozygous (Bb)?

Back

75% of the offspring will have brown eyes.

Front

What is the genotype of a plant that is homozygous tall (TT)?

Back

The genotype of a homozygous tall plant is TT.

Front

What is the probability of producing a short plant from a Tt x Tt cross?

Back

25% of the offspring will be short (tt).

Front

In a heterozygous genotype, which allele is expressed in the phenotype?

Back

The dominant allele is expressed in the phenotype.