Dihybrid Cross Practice Flashcards

Questions and Answers

What is the phenotypic ratio for Aa x Aa (two heterozygous)?

3:1

What is the genotypic ratio for Aa x Aa (two heterozygous)?

1:2:1

What is the phenotypic and genotypic ratio for Aa x aa (1 heterozygous and 1 homozygous)?

1:1

What is the phenotypic ratio for AaBb x AaBb (two pairs of heterozygous cross)?

9:3:3:1 Signup and view all the answers

What is the phenotypic and genotypic ratio for AaBb x aabb (1 pair heterozygous and 1 homozygous)?

1:1:1:1 Signup and view all the answers

How can you identify a dominant trait from a pedigree chart?

Every affected individual has at least one affected parent Signup and view all the answers

Study Notes

Dihybrid Cross Ratios

Phenotypic ratio for a cross between two heterozygous individuals (Aa x Aa) is 3:1, indicating three dominant expressions to one recessive.
Genotypic ratio for the same cross (Aa x Aa) is 1:2:1, showing one homozygous dominant, two heterozygous, and one homozygous recessive genotype.

Monohybrid Cross Ratios

When crossing a heterozygous individual (Aa) with a homozygous recessive individual (aa), both the phenotypic and genotypic ratio result in 1:1, indicating equal chances of dominant and recessive traits appearing.

Dihybrid Cross Ratios with Two Traits

In a dihybrid cross between two individuals heterozygous for both traits (AaBb x AaBb), the phenotypic ratio is 9:3:3:1. This reflects the combinations of traits for two independent genes.
When crossing one individual heterozygous for both traits (AaBb) with one homozygous recessive individual (aabb), the resulting phenotypic and genotypic ratio is 1:1:1:1, indicating equal distribution of the four possible genotype combinations.

Identification of Dominant Traits in Pedigrees

In pedigree charts, a dominant trait can be identified by observing that every affected individual has at least one affected parent.
The trait tends to appear in every generation once it is present, suggesting a direct inheritance pattern.

Description

Test your knowledge of phenotypic and genotypic ratios with these flashcards on dihybrid crosses. Each card presents scenarios using various genetic combinations, allowing for a comprehensive review. Perfect for students studying genetics and Mendelian inheritance.