Genetics: Punnett Square

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the genotype and phenotype combinations of a genetic cross.

Front

What does 'heterozygous' mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Gg).

Front

What does 'homozygous' mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., gg or GG).

Front

What is the genotype of a green pea plant with the alleles Gg?

Back

The genotype is heterozygous.

Front

What is the phenotype of a homozygous recessive plant?

Back

The phenotype is the recessive trait, which in this case is yellow.

Front

If a tall plant (Tt) is crossed with a short plant (tt), what are the possible offspring genotypes?

Back

The possible offspring genotypes are 50% Tt (tall) and 50% tt (short).

Front

What is the expected phenotype ratio from a cross between two heterozygous rabbits (Bb)?

Back

The expected phenotype ratio is 75% white (dominant) and 25% brown (recessive).

Front

What does it mean if a trait is dominant?

Back

A dominant trait is expressed in the phenotype even if only one allele is present (e.g., G in Gg).

Front

What is the expected genotype of offspring from a cross between a homozygous black rabbit (BB) and a heterozygous white rabbit (Bb)?

Back

The expected genotype is 50% BB and 50% Bb.

Front

How do you determine the phenotype from a genotype?

Back

The phenotype is determined by the expression of the dominant allele in the genotype.