Genetics: Co-Dominance and Incomplete Dominance

The video tutorial covers the concepts of incomplete dominance and co-dominance, which are exceptions to Mendel's laws of inheritance. Incomplete dominance occurs when a dominant allele does not completely mask the recessive allele, resulting in an intermediate phenotype. Examples include snapdragon flowers and Andalusian fowl. Co-dominance is when both alleles in a heterozygote are equally expressed, as seen in the ABO blood group system. The video explains these concepts with examples and highlights the phenotypic and genotypic ratios associated with each.

What is the main characteristic of incomplete dominance?

• The recessive allele is completely expressed.

• The heterozygote shows a blend of both alleles.

• The dominant allele completely masks the recessive allele.

• Both alleles are equally expressed.

Which scientist proposed the concept of incomplete dominance?

• Hugo de Vries

• Charles Darwin

• Karl Correns

• Gregor Mendel

In the example of snapdragons, what color are the flowers of the F1 hybrid?

• Red

• White

• Blue

• Pink

What is the phenotypic ratio observed in the F2 generation of snapdragons?

• 3:1

• 1:2:1

• 2:1

• 1:1

In the Andalusian fowl example, what color are the feathers of the F1 hybrid?

• Blue

• Red

• White

• Black

What is the main feature of co-dominance?

• The phenotype is a blend of both alleles.

• One allele is completely dominant over the other.

• Both alleles are expressed equally in the phenotype.

• The recessive allele is not expressed.

Which blood group system is a classic example of co-dominance?

• Rh factor

• ABO blood group

• MN blood group

• Duffy blood group

In the ABO blood group system, what is the genotype of a person with blood group AB?

• IBIB

• IAIA

• IAIB

• IOIO

What is the phenotypic ratio observed in the offspring when two AB blood group individuals are crossed?

• 1:1

• 3:1

• 2:1

• 1:2:1

Which of the following is true about the alleles in co-dominance?

• Neither allele is expressed.

• Both alleles are dominant.

• Both alleles are recessive.

• One allele is recessive.