20.3 Dihybrid inheritance

Question 1

What’s dihybrid inheritance

Answer 1

The inheritance of two different characteristics which are controlled by two genes, which may be located on different pairs of homologous chromosomes.Each of these genes can have two or more alleles

Question 2

How does a dihybrid cross differ from a monogenetic cross

Answer 2

Four alleles (two for each characteristic) are shown at each stage instead of two

Question 3

What would the ratio be for a dihybrid heterozygous cross for F1 genotypes?

Answer 3

9:3:3:1

Question 4

Work through a dihybrid genetic cross between a pea plant which produces green wrinkled seeds and a heterozygous pea plant which produces yellow round seeds to determine the expected ratio of the F1 offspring

Answer 4

1:1:1:1

Question 5

What’s epistatis

Answer 5

the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another.

Question 6

Why can the actual ration of offspring differ from the expected

Answer 6

-random fertilisation
- autosomal linkage may occur when the genes being studied are both on the same chromosome so no crossing over occurs and they are both inherited together

Question 7

What’s autosomal linkage

Answer 7

may occur when the genes being studied are both on the same chromosome so no crossing over occurs and they are both inherited together