Q: Which equation is used to calculate the variance ($$s^2) of a $$sample?

$$s^2$$ = \sum (X - \text{mean}$$)^2 / (n - 1$$)$$

Q: Which formula is used to calculate the correlation coefficient ($$r) $$between two traits X and Y?

$$r = \frac{\text{cov}(X, Y)}{S_x S_y}$$

Question 1

Which of the following best describes a quantitative trait in genetics?

Accepted Answer

A trait that is influenced by multiple genes and environmental factors, showing continuous variation.

Question 2

A researcher measures the heights of 100 plants and finds the mean height is 50 cm. The sum of squared differences from the mean is 400. What is the variance ($$s^2) of $$the sample?

Accepted Answer

$$s^2$$ = \frac{400}{99}$$

Question 3

Which graph type is most appropriate for displaying the frequency distribution of a quantitative trait in a population?

Accepted Answer

Histogram

Question 4

A bell-shaped curve in the distribution of a quantitative trait indicates:

Accepted Answer

The trait follows a normal (Gaussian) distribution.

Question 5

If the standard deviation ($$s) of a $$sample is 4 and the sample size ($$n) is 16$$, what is the standard error of the mean?

Accepted Answer

$$\frac{4}{\sqrt{16}} = 1$$

Question 6

Which of the following statements about polygenic inheritance is correct?

Accepted Answer

Polygenic traits result from the additive effects of multiple genes.

Question 7

What does the covariance between two traits measure in quantitative genetics?

Accepted Answer

The degree of association between the two traits.

Question 8

A population of chickens shows variation in the number of eggs laid per year. This trait is best described as:

Accepted Answer

A meristic trait

Question 9

Which equation is used to calculate the variance ($$s^2) of a $$sample?

Accepted Answer

$$s^2$$ = \sum (X - 	ext{mean}$$)^2 / (n - 1$$)$$

Question 10

In a study of grain color in corn, four distinct phenotypic categories are observed. If the number of additive alleles is $$n$$, which equation can be used to determine the number of phenotypic categories?

Accepted Answer

$$2n + 1$$

Question 11

Which of the following is NOT a component of genetic variation in quantitative genetics?

Accepted Answer

Meristic variance

Question 12

A threshold trait is best described as:

Accepted Answer

A trait that is expressed only when a combination of alleles exceeds a certain limit.

Question 13

Which of the following best explains why quantitative traits often show a normal distribution in populations?

Accepted Answer

They result from the additive effects of many genes and environmental factors.

Question 14

If the correlation coefficient ($$r) $$between two traits is 0.9, how would you describe the relationship?

Accepted Answer

Strong association

Question 15

Which formula is used to calculate the correlation coefficient ($$r) $$between two traits X and Y?

Accepted Answer

$$r = \frac{	ext{cov}(X, Y)}{S_x S_y}$$

Question 16

Which of the following is a plausible reason for greater genetic variation in F2 compared to F1 in a polygenic inheritance experiment?

Accepted Answer

F2 individuals have more combinations of alleles due to segregation and recombination.

Question 17

Which of the following is NOT a measure of central tendency used in quantitative genetics?

Accepted Answer

Variance

Question 18

A scatter plot is most useful for studying:

Accepted Answer

The association between two quantitative traits

Question 19

If the largest phenotype value in a population is 10 and the smallest is 2, and there are 4 contributing alleles, what is the average effect per allele?

Accepted Answer

$$(10 - 2) / 4 = 2$$

Quantitative Genetics: Polygenic Inheritance, Variation, and Statistical Analysis

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