Ch. 27 Flashcards Preview

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Flashcards in Ch. 27 Deck (21):

Which of the following is an example of a quantitative trait?
A) height
B) rate of glucose metabolism
C) ability to learn a maze
D) all of the above

D) all of the above


Saying that a quantitative trait follows a continuum means that..

Phenotypes are continuous and do not fall into discrete categories


For quantitative traits, genotypes and phenotypes tend to overlap because..

- they are polygenic
- environmental variation affects the trait


A QTL is a ___ where one or more genes affecting a quantitative trait are ___.

Site in a chromosome, located


To map QTLs, strains are crossed that differ with regard to..

A quantitative trait and molecular markers


Normal distribution of a quantitative trait.

Is height a discontinuous (discrete) trait or does it follow a continuum?

In most populations (like this one), height follows a continuum


What does it mean to say that these alleles are additive?

When alleles are additive, this means they contribute in an incremental way to the outcome of a trait.

Having three heavy alleles will make an individual heavier than having two heavy alleles.


Explain how gene number and environmental variation affect the overlaps between phenotypes and different genotypes.

Increases in gene number and more environmental variation tend to cause greater overlaps between different genotypes and the same phenotype.


The general strategy for QTL mapping via molecular markers.

What are the two ways that strains A and B differ?

These two strains differ with regard to a quantitative trait and they differ in their molecular markers.


___ ___ is the study of traits that can be described numerically.

Quantitative genetics


Complex traits-

Usually controlled by more than one gene and are significantly influenced by environmental factors


Anatomical traits

Height, weight, number of bristles Drosophila, ear length in corn, and the degree of pigmentation in flowers and skin


Physiological traits

Metabolic traits, speed of running and flight, ability to withstand harsh temperatures, and milk production in mammals


Behavioral traits

Mating calls, courtship rituals, ability to learn a maze, and the ability to grow or more toward light



Predisposition toward heart disease, hypertension, cancer, diabetes, and arthritis


___ ___ are traits that fall into two or more discrete categories.

Discontinuous traits


___ ___ show a continuum of variation within a group of individuals.

Quantitative traits


An alternative way to describe them is a ___ ___.

Frequency distribution


Often, data fall into a ___ ___.

Normal distribution


___ ___ refers to the transmission of traits that are governed by two or more genes.

Polygenic inheritance


The locations on chromosomes that affect the outcome of quantitative traits are called ___ ___ ___.

Quantitative trait loci (QTLs)