Defining Traits and Quantitative Traits

Question 1

Define Trait:

Answer 1

Any observable or measurable characteristic

Question 2

Define phenotype:

Answer 2

A category of a trait

OR

A measurement/observation of a trait

Question 3

Define monogenic trait:

Answer 3

A trait that relies on one or a couple of genes

Question 4

Does environment affect monogenic traits?

Answer 4

NO

Question 5

___________ traits are also known as qualitative and ___________ traits are also known as quantitative traits.

Answer 5

Monogenic ; polygenic

Question 6

Define polygenic trait:

Answer 6

A trait that relies on multiple genes

Question 7

__________ traits do NOT rely on a major gene

Answer 7

polygenic

Question 8

Define major gene:

Answer 8

A gene that explains 1% or more of the genetic variation of the trait

Question 9

What is an example of a polygenic trait?

Answer 9

Litter size, milk production, weaning weight

Question 10

What is an example of a monogenic trait?

Answer 10

Coat color, presence of horns

Question 11

Does Environment affect polygenic traits?

Answer 11

YES

Question 12

Define threshold trait:

Answer 12

A polygenic trait that exhibits categorical phenotypes

Question 13

What is an example of a threshold trait?

Answer 13

Fertility, dystocia, natural gait

Question 14

A normal distribution depends on the ___________.

Answer 14

population

Question 15

A normal distribution is a curve that is symmetrical around its __________.

Answer 15

mean

Question 16

What is the new breeding equation (with quantitative genetics)?

Answer 16

P = u + (A + D + I) + E

Question 17

Define mean.

Answer 17

The sum of all values over the number of values

Question 18

_____________ is the source of genetic change

Answer 18

Variation

**better know this one

Question 19

Define variance:

Answer 19

s^2

The average squared deviation from the mean

Question 20

Define standard deviation.

Answer 20

s

The average deviation from the mean

Question 21

How do you get standard deviation from variance?

Answer 21

Take the square root of the variance.

Question 22

How do you get variance from the standard deviation?

Answer 22

Square the standard deviation

Question 23

Define Coefficient of Variation (CV).

Answer 23

Represents the degree of variation relative to the size of the mean.

Question 24

In animal breeding, we generally select traits that are ___________ the average/curve.

Answer 24

above

Question 25

Is there a difference in selection strategies between monogenic and polygenic traits?

Answer 25

NO

Question 26

Define covariance

Answer 26

Measures the tendency of the two random variables that vary together

Question 27

Covariance represents the ___________ of a relationship of _______ variables

Answer 27

sign or direction ; two

Question 28

Define correlation

Answer 28

Measures the strength (consistency and reliability) of the relationship between two variables

Question 29

Correlation represents the ________ of a relationship between _________ variables.

Answer 29

strength ; two

Question 30

Correlation can range from ____ to ____.

Answer 30

-1 ; +1

Question 31

What are three characteristics of a quantitative trait?

Answer 31

-numerical
-polygenic
-has normal distribution

Question 32

The three measures of covariation are: ___________, ______________, and ___________. Which represent ______________, __________, and ____________ of a relationship between two variables

Answer 32

covariance ; correlation ; regression ;

direction/sign ; strength ; amount of change

Question 33

Define regression.

Answer 33

The expected or average change in one variable (Y) per unit of change of another variable (X).