Dihybrid Crosses

Front

What is a dihybrid cross?

Back

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

Front

What is the phenotypic ratio of a typical dihybrid cross?

Back

9:3:3:1

Front

Define homozygous and heterozygous genotypes.

Back

Homozygous: having two identical alleles for a trait; Heterozygous: having two different alleles for a trait.

Front

What does a Punnett square illustrate?

Back

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

Front

What is the significance of dominant and recessive alleles?

Back

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

Front

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

Back

RY, Ry, rY, ry.

Front

What is the genotype for a plant that is homozygous for round seeds and heterozygous for yellow seeds?

Back

RRYy.

Front

In a dihybrid cross, what fraction of the offspring will be homozygous recessive for both traits?

Back

1/16.

Front

What is the expected phenotypic ratio for a cross between two heterozygous parents (RrYy x RrYy)?

Back

9 round yellow: 3 round green: 3 wrinkled yellow: 1 wrinkled green.

Front

What does the term 'F1 generation' refer to?

Back

The first generation of offspring from a cross of two parental (P) individuals.