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 based on their genotypes.

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

What is the genotype of an organism?

Back

The genotype is the genetic constitution of an organism, represented by the alleles it possesses.

Front

What is the phenotype of an organism?

Back

The phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Front

What is a homozygous genotype?

Back

A homozygous genotype has two identical alleles for a particular gene (e.g., BB or bb).

Front

What is a heterozygous genotype?

Back

A heterozygous genotype has two different alleles for a particular gene (e.g., Bb).

Front

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

Back

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

Front

What is the probability of homozygous recessive offspring from a cross of Bb x Bb?

Back

The probability is 25%.

Front

What does it mean if an organism has a dominant phenotype?

Back

It means that the organism has at least one dominant allele for that trait, which masks the effect of any recessive alleles.

Front

What is the significance of a test cross?

Back

A test cross is used to determine the genotype of an organism with a dominant phenotype by crossing it with a homozygous recessive organism.