Exam 21: Quantitative Genetics and Multifactorial Traits

If the proportion of F₂ individuals resembling either of the two most extreme parental phenotypes can be determined,which formula can be applied to determine the number of gene pairs involved?

The multiple factor hypothesis suggests that many factors or genes contribute to the phenotype in a cumulative or quantitative manner.

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?

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?

Assume that a cross is made between tall and dwarf tobacco plants.The F₁ generation showed intermediate height,whereas 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?

What is the term given to a random subset of individuals who are selected for measurement in a particular study?

What is the name of the process of selecting a specific group of organisms from an initially heterogeneous population for future breeding purposes?

Additive alleles are those that are epistatic over nonallelic genes that influence the same phenotypic characteristic.

To estimate how much the means of a variety of like samples drawn from the same population might vary,which statistic is often used and what is its formula?

Provide a formal equation for h² (narrow-sense heritability).

Assume that in the F₂ of a series of crosses,1/64 of the offspring resemble one of the parents (P).How many gene pairs are involved in producing these results?

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