Phenotypic Ratios in Genetics

The video tutorial by Nikolaj covers a genetics lesson focusing on the observation of a 1:2:1 ratio of phenotypes in the F2 generation of a cross between two homozygous lines of corn. It explains the genetic basis of this ratio, involving a single gene with two alleles, and discusses the concept of incomplete dominance. The tutorial walks through the parental, F1, and F2 generations, using Punnett squares to illustrate the genetic outcomes. The lesson concludes with identifying the correct answer to the posed question, emphasizing the role of incomplete dominance in the observed phenotypic ratio.

What is the observed phenotypic ratio in the F2 generation of a cross between two homozygous lines of corn?

• 1:2:1

• 2:1

• 3:1

• 1:1

What does the dominant allele produce in the corn plants?

• White pigment

• No pigment

• Blue pigment

• Red pigment

In the F1 generation, what is the expected genotype of the offspring?

• None of the above

• Homozygous recessive

• Homozygous dominant

• Heterozygous

What type of dominance is exhibited in the F1 generation?

• No dominance

• Co-dominance

• Incomplete dominance

• Complete dominance

What color do the flowers appear in the F1 generation due to incomplete dominance?

• Pink

• Pale red

• White

• Bright red

How many phenotypes are observed in the F2 generation?

• One

• Two

• Three

• Four

What is the phenotypic ratio of red, pink, and white flowers in the F2 generation?

• 2:1

• 3:1

• 1:1:1

• 1:2:1

What is the correct statement about the gene involved in the cross?

• Three alleles are involved

• A single gene with two allelic forms is involved

• Two genes are involved

• No gene is involved

What type of dominance is shown by the alleles in the F2 generation?

• Complete dominance

• Incomplete dominance

• No dominance

• Co-dominance

Which of the following is NOT true about the F2 generation?

• Three phenotypes are observed

• The alleles show complete dominance

• The ratio is 1:2:1

• It is a result of crossing F1 generation