Punnett Squares

Front

What is a Punnett Square used for?

Back

A Punnett Square is used to predict the genotypes and phenotypes of offspring from a genetic cross.

Front

What do the letters in a Punnett Square represent?

Back

The letters represent alleles, where uppercase letters denote dominant alleles and lowercase letters denote recessive alleles.

Front

If a plant has the genotype Rr, what are the possible gametes it can produce?

Back

The possible gametes are R and r.

Front

What is the phenotypic ratio of offspring from a cross between two heterozygous parents (Rr x Rr)?

Back

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

Front

What is the genotypic ratio of offspring from a cross between two heterozygous parents (Rr x Rr)?

Back

The genotypic ratio is 1:2:1 (1 RR : 2 Rr : 1 rr).

Front

What does it mean if an organism is homozygous for a trait?

Back

An organism is homozygous for a trait if it has two identical alleles for that trait (e.g., RR or rr).

Front

What does it mean if an organism is heterozygous for a trait?

Back

An organism is heterozygous for a trait if it has two different alleles for that trait (e.g., Rr).

Front

In a Punnett Square, where are the parent alleles written?

Back

The parent alleles are written outside of the boxes, typically at the top and left side.

Front

What is the probability of obtaining a homozygous recessive offspring from a cross between two heterozygous parents?

Back

The probability is 25%.

Front

What is the significance of dominant and recessive alleles in genetics?

Back

Dominant alleles mask the effect of recessive alleles in heterozygous individuals.