Ch. 27

Question 1

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

Answer 1

D) all of the above

Question 2

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

Answer 2

Phenotypes are continuous and do not fall into discrete categories

Question 3

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

Answer 3

• they are polygenic

- environmental variation affects the trait

Question 4

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

Answer 4

Site in a chromosome, located

Question 5

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

Answer 5

A quantitative trait and molecular markers

Question 6

Normal distribution of a quantitative trait.

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

Answer 6

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

Question 7

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

Answer 7

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.

Question 8

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

Answer 8

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

Question 9

The general strategy for QTL mapping via molecular markers.

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

Answer 9

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

Question 10

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

Answer 10

Quantitative genetics

Question 11

Complex traits-

Answer 11

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

Question 12

Anatomical traits

Answer 12

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

Question 13

Physiological traits

Answer 13

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

Question 14

Behavioral traits

Answer 14

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

Question 15

Diseases

Answer 15

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

Question 16

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

Answer 16

Discontinuous traits

Question 17

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

Answer 17

Quantitative traits

Question 18

An alternative way to describe them is a ___ ___.

Answer 18

Frequency distribution

Question 19

Often, data fall into a ___ ___.

Answer 19

Normal distribution

Question 20

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

Answer 20

Polygenic inheritance

Question 21

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

Answer 21

Quantitative trait loci (QTLs)