Genetics

Front

What is the definition of dominant alleles?

Back

Dominant alleles are versions of a gene that can mask the presence of recessive alleles in an organism's phenotype.

Front

What does it mean to be heterozygous?

Back

An organism is heterozygous when it has two different alleles for a specific gene, one inherited from each parent.

Front

What does it mean to be homozygous?

Back

An organism is homozygous when it has two identical alleles for a specific gene, either both dominant or both recessive.

Front

What is the genotype of a plant with round seeds if R = round and r = wrinkled?

Back

The genotype can be either homozygous dominant (RR) or heterozygous (Rr).

Front

What is the phenotype of a plant with the genotype rr?

Back

The phenotype will be wrinkled seeds, as the recessive trait is expressed.

Front

In a Punnett square, what does each box represent?

Back

Each box represents a possible genotype of the offspring resulting from the combination of alleles from the parents.

Front

What is the expected percentage of offspring with short arms when two heterozygous cacti (Aa) are crossed?

Back

25% of the offspring are expected to have short arms (aa).

Front

What is the expected genotype ratio from a cross between a homozygous dominant (BB) and a heterozygous (Bb) organism?

Back

The expected genotype ratio is 50% BB and 50% Bb.

Front

What is the definition of a recessive allele?

Back

A recessive allele is a version of a gene that is masked by the presence of a dominant allele and is only expressed in the phenotype when two copies are present.

Front

What is a Punnett square used for?

Back

A Punnett square is used to predict the genetic makeup of offspring from a cross between two parents.