Basic Monohybrid Genetics

Front

What is a monohybrid cross?

Back

A genetic cross between individuals that involves one pair of contrasting traits.

Front

Define homozygous dominant.

Back

An organism with two identical dominant alleles for a trait (e.g., BB).

Front

Define homozygous recessive.

Back

An organism with two identical recessive alleles for a trait (e.g., bb).

Front

Define heterozygous.

Back

An organism with one dominant and one recessive allele for a trait (e.g., Bb).

Front

What is the phenotypic ratio of a monohybrid cross?

Back

The typical phenotypic ratio is 3:1 for dominant to recessive traits.

Front

What is the genotypic ratio of a monohybrid cross?

Back

The typical genotypic ratio is 1:2:1 for homozygous dominant, heterozygous, and homozygous recessive.

Front

What does a Punnett square illustrate?

Back

A Punnett square is a diagram used to predict the outcome of a genetic cross.

Front

What is the purpose of a test cross?

Back

To determine the genotype of an organism with a dominant phenotype by crossing it with a homozygous recessive.

Front

What is the expected percentage of homozygous dominant offspring from a cross of two heterozygous parents?

Back

25%.

Front

What is the expected percentage of heterozygous offspring from a cross of two heterozygous parents?

Back

50%.