Exam 23: Quantitative Genetics and Multifactorial Traits

We often refer to the host of genetic factors in the genome that have an influence on a particular gene's expression as its genetic background.What influence does genetic background have over the phenotype of the organism?

Name two human traits that would be expected to have high concordance.

Heritability is a measure of the degree to which the phenotypic variation of a given trait is due to genetic factors.

The 9:3:3:1 ratio is typical of a dihybrid cross in which complete dominance and independent assortment occur.What is the dihybrid ratio with independent assortment of polygenes?

What are QTLs and RFLPs?

Bell-shaped distributions produced by plotting results of F₂ and F₃ crosses are typical of which type of inheritance?

Describe the value of using twins in the study of questions relating to the relative impact of heredity versus environment.

Polygenes are involved in determining continuously varying or multiple-factor traits.

Name the three components of phenotypic variance.

Provide a brief definition of the terms additive variance,dominance variance,and interactive variance.

What is meant by the term heritability? Describe the components of heritability and provide a brief explanation of each.Of what interest is heritability to animal and plant breeders?

Interpret the meaning of an H² (broad-sense heritability)value that approaches 1.0.