Exam 23: Quantitative Genetics and Multifactorial Traits

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

As used in twin studies in mammals, distinguish between the terms concordant and discordant.

Assume that a cross is made between tall and dwarf tobacco plants. The F₁ generation showed intermediate height, while the F₂ generation showed a distribution of height ranging from tall to dwarf, like the original parents, and many heights between the extremes. These data are consistent with which one of the following modes of inheritance?

Concordance refers to the frequency with which members of a twin pair express a different trait.

When a trait is polygenic, but distinguished from continuous and meristic traits by having a small number of discrete classes, it is said to be a(n) ________ trait.

Environmental factors typically influence inheritance of ________.

Continuous inheritance is often related to the term quantitative inheritance. Why?

List at least three statistical values often used to represent a sample.

Which two relatively recent extensions to QTL mapping center on molecular definitions of phenotypes with quantitative traits?

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

Define the term broad-sense heritability (H²⁾. What is implied by a relatively high value of H²? Express aspects of broad-sense heritability in equation form

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?