Genetics: Dominance and Phenotypes

The video tutorial reviews complete dominance in Mendelian genetics, where one allele masks another. It introduces incomplete dominance, where alleles blend to create an intermediate phenotype, and codominance, where both alleles are fully expressed. Examples include cattle coat colors and flower petal colors, using Punnett squares to predict offspring outcomes.

In complete dominance, what happens to the phenotype of the offspring when a homozygous dominant is crossed with a homozygous recessive?

• Offspring show a new phenotype

• Offspring show a mix of both phenotypes

• All offspring show the dominant phenotype

• All offspring show the recessive phenotype

What is the result of mixing alleles in incomplete dominance?

• A dominant trait

• An intermediate trait

• A completely new trait

• A recessive trait

When crossing a homozygous red carnation with a homozygous white carnation, what is the phenotype of the offspring?

• Pink

• White

• Red

• Red and white

If two pink carnations are crossed, what percentage of the offspring are expected to be pink?

• 50%

• 25%

• 100%

• 75%

In codominance, how are the alleles expressed in the phenotype?

• Both alleles are fully expressed

• Both alleles are partially expressed

• Only the recessive allele is expressed

• Only the dominant allele is expressed

What is an example of codominance in animals?

• A pink flower from red and white parents

• A gray coat in cattle

• A solid black coat in cattle

• A black and white spotted coat in cattle

How does codominance differ from incomplete dominance?

• Codominance results in a blend of traits

• Codominance results in a new trait

• Codominance shows both traits fully

• Codominance shows only one trait

Which gene interaction results in an intermediate phenotype?

• Complete dominance

• Incomplete dominance

• Codominance

• Recessive dominance

In which type of dominance do both alleles contribute equally to the phenotype?

• Recessive dominance

• Codominance

• Incomplete dominance

• Complete dominance

What is the phenotype of a heterozygous organism in codominance?

• Only one trait expressed

• Both traits fully expressed

• A new trait

• A blend of both traits