Dihybrid Crosses

Front

What is a dihybrid cross?

Back

A genetic cross that involves two traits, each represented by two alleles.

Front

What does heterozygous mean?

Back

An organism with two different alleles for a specific trait (e.g., Bb).

Front

What does homozygous mean?

Back

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

Front

What is a Punnett square?

Back

A diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles.

Front

What fraction of offspring will have a dominant phenotype in a typical dihybrid cross?

Back

9/16 will show the dominant phenotype for both traits.

Front

What is the genotype for a pea plant homozygous for round seeds (R) and heterozygous for yellow seeds (Y)?

Back

RRYy.

Front

What is the genotype for a pea plant heterozygous for round seeds (R) and homozygous recessive for green seeds (y)?

Back

Rryy.

Front

In a dihybrid cross, how many different gametes can be produced by a plant with genotype RrYy?

Back

4 different gametes: RY, Ry, rY, and ry.

Front

What is the phenotypic ratio of a dihybrid cross?

Back

The typical phenotypic ratio is 9:3:3:1.

Front

What does the term 'allele' refer to?

Back

An allele is a variant form of a gene that can produce different traits.