Genotype and Phenotype Ratios

The video tutorial explains Punnett squares and lethal alleles, focusing on genotype and phenotype outcomes. It discusses exceptions to dominant phenotype rules, such as lethal allele combinations, and explores the results of crossing heterozygotes and heterozygote with homozygous recessive. The tutorial highlights how these genetic combinations deviate from Mendel's laws.

What is the typical number of phenotype outcomes when considering alleles?

• Four

• One

• Three

• Two

What phenotype results from a homozygous recessive genotype in this example?

• Bald cat

• Hairy dog

• Mexican hairless dog

• Lethal combination

Which genotype results in a Mexican hairless dog?

• Heterozygous

• Homozygous recessive

• Homozygous dominant

• None of the above

What is the outcome of a homozygous dominant genotype in this scenario?

• Spotted dog

• Lethal combination

• Mexican hairless dog

• Hairy dog

What is the genotype ratio when crossing two heterozygotes?

• 1:1:1

• 2:1:1

• 3:1

• 1:2:1

What percentage of offspring die as embryos when two heterozygotes are crossed?

• 75%

• 50%

• 25%

• 0%

What is the phenotype ratio when crossing two heterozygotes?

• 2:2

• 1:1

• 1:2:1

• 3:1

What is the result of crossing a heterozygote with a homozygous recessive?

• All offspring have the lethal combination

• All offspring are hairy

• All offspring are Mexican hairless

• Half are hairy, half are Mexican hairless

What is the phenotype ratio when a heterozygote is crossed with a homozygous recessive?

• 1:1

• 1:2:1

• 3:1

• 2:2

Which genotype combination does not result in any lethal alleles when crossed with a homozygous recessive?

• Heterozygous

• Homozygous dominant

• Homozygous recessive

• None of the above