Practice: Monohybrid Crosses

Front

What does it mean to be homozygous for a trait?

Back

Having two of the same alleles for the trait (sometimes called purebred).

Front

What is the term for the physical expression of a genetic trait?

Back

Phenotype.

Front

What is the difference between genotype and phenotype?

Back

Genotype refers to the genetic makeup (alleles), while phenotype refers to the physical expression of that genetic trait.

Front

In a monohybrid cross, what is the expected phenotypic ratio of offspring?

Back

Typically, the expected phenotypic ratio is 3:1 for dominant to recessive traits.

Front

What is a genotype?

Back

The genetic makeup of an organism, represented by the alleles it possesses.

Front

If one brother has the genotype BB and the other has Bb, what can be said about their phenotypes?

Back

They have the same phenotype (brown eyes) but different genotypes.

Front

What is the genotypic ratio resulting from a cross between a red flower (Rr) and a white flower (rr)?

Back

0 RR; 2 Rr; 2 rr.

Front

In a genetic cross, what does a dominant allele do?

Back

A dominant allele masks the effect of a recessive allele in the phenotype.

Front

What is the expected percentage of homozygous dominant offspring from a cross between a homozygous dominant mother (AA) and a heterozygous father (Aa)?

Back

50% of the offspring will be homozygous dominant (AA).

Front

What is the definition of a recessive allele?

Back

An allele that is masked by the presence of a dominant allele and only expressed in a homozygous condition.