Exploring Types of Dominance in Genetics

The video tutorial explains the concept of dominance in genetics, focusing on how alleles interact to determine phenotypes. It covers three types of dominance: complete dominance, where one allele completely masks another; incomplete dominance, where the phenotype is a blend of both alleles; and codominance, where both alleles are equally expressed. Examples from nature, such as pea plants, 4o’ clock plants, and human traits like hair type, illustrate these concepts. The tutorial also discusses how incomplete and codominance are exceptions to Mendelism.

What does dominance in genetics refer to?

• The blending of two genes

• The suppression of one gene by another

• The physical appearance of an organism

• The interaction between two alleles of a gene

Which type of dominance results in offspring that only show the dominant trait?

• None of the above

• Incomplete Dominance

• Codominance

• Complete Dominance

Can you name a natural example of complete dominance?

• Blood type in humans

• Flower color in peas

• None of the above

• Coat color in cattle

What genotype results from a cross between a homozygous dominant and a homozygous recessive in complete dominance?

• None of the above

• Homozygous recessive

• Heterozygous

• Homozygous dominant

What is observed in incomplete dominance?

• Only one allele is expressed

• Both alleles are fully expressed

• Traits skip generations

• Both alleles blend to form a new trait

Which human trait is an example of incomplete dominance?

• Skin color

• Hair type

• Blood type

• Eye color

In incomplete dominance, crossing a homozygous dominant with a homozygous recessive results in what phenotype?

• Dominant

• Recessive

• Intermediate

• Variable

What happens when two dominant alleles are present in codominance?

• Both alleles are partially expressed

• One allele hides the other

• Neither allele is expressed

• Both alleles are fully expressed

Which example illustrates codominance in nature?

• Height in pea plants

• None of the above

• Blood groups in humans

• Wavy hair in humans

What is a key characteristic of codominance?

• Complete suppression of one allele

• Partial expression of both alleles

• Full expression of both alleles

• Random expression of alleles