Lecture 28

Question 1

What is a quantitative trait?

Answer 1

Phenotypes that vary continuously (height, mass); exhibit complex relationship between genotype/phenotype, likely polygenic, may have environmental influences, ranges may overlap

Question 2

Define continuous characteristics/traits

Answer 2

Characteristics vary along a scale of measurement with many overlapping phenotypes; usually quantitative

Question 3

Define discontinuous characteristics/traits

Answer 3

Traits that possess only a few phenotypes (red or white petals); usually qualitative

Question 4

What are threshold characteristics?

Answer 4

Measured by presence or absence; susceptibility to disease

Question 5

Define standard deviation

Answer 5

Square root of the variance

Question 6

What is an appropriate sample?

Answer 6

Subset of the population that should be representative of the larger population and unbiased (not tailored to support your hypothesis)

Question 7

What is a GWAS (Genome Wide Association Study)?

Answer 7

Examination of many common genetic variants in different individuals to see if any variant is associated (co-segregates) with a trait

Question 8

Define polygenic inheritance

Answer 8

Occurs when one characteristic is controlled by two or more genes

Question 9

Define variance

Answer 9

Variability within a group of measurements

Question 10

The measurements of a distribution with a higher _____ will be more spread out.

a. Mean
b. Variance
c. Standard deviation
d. Both b and c

Answer 10

D. Both B and C since they are related

Question 11

Define the correlation coefficient

Answer 11

Statistical measure of the strength of the association; perfect correlation is 1, negative coefficient indicates an inverse relationship

Question 12

Define regression and regression coefficient

Answer 12

Regression: predicting the value of one variable, if the value of the other is given

Regression Coefficient: represents the slope of the regression line, indicating how much one value changes on average per increase in the value of another variable

Question 13

In Lubbock, TX, rainfall and temperature exhibit a significant correlation of -0.7. Which conclusion is correct?

a. There is usually more rainfall when the temperature is high
b. There is usually more rainfall when the temperature is low
c. Rainfall is equally likely when the temperature is high or low

Answer 13

B. There is usually more rainfall when the temperature is low

Question 14

How do calculate broad-sense heritability and narrow-sense heritability?

Answer 14

Broad: ratio of total genetic variance to total phenotypic variance

Narrow: ratio of additive genetic variance to the total phenotypic variance