Genotypes and Phenotypes

What is a dominant allele?

• An allele that expresses its trait only when two copies are present in the genotype.

• An allele that expresses its trait even when only one copy is present in the genotype.

• An allele that does not express any trait in the genotype.

• An allele that can only be inherited from one parent.

Give an example of a homozygous genotype.

• AA or aa

• Aa or Bb

• AB or CD

• Aa or AA

What is the relationship between genotype and phenotype?

• The genotype has no effect on the phenotype.

• The phenotype is determined solely by environmental factors.

• The genotype determines the phenotype, but the phenotype is also influenced by environmental factors.

• Genotype and phenotype are unrelated.

What does it mean if an organism is heterozygous?

• An organism has two identical alleles for a particular gene (e.g., AA).

• An organism has two different alleles for a particular gene (e.g., Aa).

• An organism has no alleles for a particular gene.

• An organism has three different alleles for a particular gene.

What is the phenotype of a homozygous recessive genotype (aa)?

• The dominant trait

• The recessive trait

• A blend of traits

• No observable trait

Give an example of a heterozygous genotype.

• AA

• Aa

• aa

• AABb

What does it mean if an organism is homozygous?

• An organism has two identical alleles for a particular gene (e.g., AA or aa).

• An organism has two different alleles for a particular gene (e.g., Aa).

• An organism has one allele for a gene and no other alleles.

• An organism has three alleles for a particular gene.

In a heterozygous genotype (Aa), which allele determines the phenotype?

• The recessive allele (a) determines the phenotype.

• The dominant allele (A) determines the phenotype.

• Both alleles equally determine the phenotype.

• Neither allele determines the phenotype.

What is a phenotype?

• The genetic makeup of an organism.

• The observable physical or biochemical characteristics of an organism, determined by its genotype.

• The process by which organisms adapt to their environment.

• The evolutionary history of a species.

How are recessive alleles represented?

• By uppercase letters (e.g., A)

• By lowercase letters (e.g., a)

• By numbers (e.g., 1)

• By symbols (e.g., *)