Punnett Squares

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the genetic makeup of offspring from two parents. It shows all possible combinations of alleles.

Front

What do the letters in a Punnett Square represent?

Back

The letters represent different alleles of a gene. Uppercase letters indicate dominant alleles, while lowercase letters indicate recessive alleles.

Front

What is the difference between dominant and recessive traits?

Back

Dominant traits are expressed when at least one dominant allele is present. Recessive traits are only expressed when two recessive alleles are present.

Front

If a plant has the genotype Tt, what does this mean?

Back

The plant has one dominant allele (T) for tallness and one recessive allele (t) for shortness.

Front

What is the probability of getting a dominant trait from a Tt x Tt cross?

Back

The probability is 75% for a dominant trait (T) and 25% for a recessive trait (t).

Front

In a cross between two heterozygous parents (Tt), what fraction of the offspring will be short?

Back

1 out of 4 offspring, or 25%, will be short.

Front

What is the likelihood that the offspring will be yellow if yellow is a recessive trait?

Back

If yellow is recessive, the likelihood of yellow offspring is 25% when both parents are heterozygous.

Front

What does it mean if an organism is homozygous?

Back

An organism is homozygous if it has two identical alleles for a trait, either dominant (AA) or recessive (aa).

Front

What does it mean if an organism is heterozygous?

Back

An organism is heterozygous if it has two different alleles for a trait, one dominant and one recessive (Aa).

Front

If round seeds (R) are dominant over wrinkled seeds (r), what is the probability of getting wrinkled seeds from a cross of Rr x Rr?

Back

The probability of getting wrinkled seeds (rr) is 25%.