Genotypes and Phenotypes

What is a genotype?

• A genotype is the physical appearance of an organism.

• A genotype is the genetic makeup of an organism, represented by the alleles it possesses.

• A genotype is the environment in which an organism lives.

• A genotype is a type of mutation that occurs in DNA.

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., *)

What does it mean if an organism is homozygous?

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

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

• An organism has one allele for a particular gene.

• An organism has no 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 the phenotype of a homozygous dominant genotype (AA)?

• The phenotype of a homozygous dominant genotype is the recessive trait.

• The phenotype of a homozygous dominant genotype is the dominant trait.

• The phenotype of a homozygous dominant genotype is a blend of traits.

• The phenotype of a homozygous dominant genotype is an intermediate trait.

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 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 its trait in the presence of a recessive allele.

• An allele that is always expressed regardless of the genotype.

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

• The dominant trait

• The recessive trait

• A blend of traits

• No observable trait

How are dominant alleles represented?

• By lowercase letters (e.g., a)

• By capital letters (e.g., A)

• By numbers (e.g., 1)

• By symbols (e.g., *)