Question 1

In a genetic cross between an AaBb mouse and an Aabb mouse, what is the expected phenotypic ratio for coat color, assuming no ghost mice and using the product law?

Accepted Answer

8 white; 4 yellow; 2 agouti; 2 black

Question 2

Which of the following best describes a hemizygous individual in the context of X-linked recessive diseases?

Accepted Answer

An individual with only one copy of the gene, typically on the X chromosome (e.g., affected son)

Question 3

A group of students planted seeds from a tube labeled Rr x Rr and observed 78 round peas and 42 wrinkled peas. What is the expected ratio for round to wrinkled peas in this cross?

Accepted Answer

3:1

Question 4

Given the observed counts of 78 round and 42 wrinkled peas from an Rr x Rr cross, what is the calculated chi-square value ($$\$$chi^2$$)?

Accepted Answer

$$\$$chi^2$$ = 6.4$$

Question 5

What is the formula for the chi-square statistic used to compare observed and expected genetic ratios?

Accepted Answer

$$\$$chi^2$$ = \sum \frac{(O-E)^2$}{E}$$

Question 6

If the calculated $$\$$chi^2$$ value is 6.4 and the critical value for 1 degree of freedom at p = 0.05$ is 3.84, what conclusion should be drawn?

Accepted Answer

Reject the null hypothesis; the data do not fit the expected ratio

Question 7

In a chi-square test, what does a p-value less than 0.05 indicate?

Accepted Answer

The null hypothesis should be rejected

Question 8

How many degrees of freedom are there in a chi-square test comparing two phenotypic categories?

Accepted Answer

1

Question 9

Which of the following is the correct null hypothesis for a cross between Rr x Rr pea plants?

Accepted Answer

The observed segregation ratio of round to wrinkled peas will fit the expected 3:1 ratio

Question 10

A carrier mother for an X-linked recessive disease has children with an unaffected father. Which child is most likely to be affected?

Accepted Answer

Affected son

Question 11

In the context of genetic testing, which scenario best illustrates the use of a Punnett square?

Accepted Answer

Predicting the probability of a child inheriting a recessive genetic disorder from carrier parents

Question 12

If a cross produces 8 white, 4 yellow, 2 agouti, and 2 black mice, what is the total number of offspring, and what fraction are white?

Accepted Answer

Total: 16; Fraction white: $$\frac{1}{2}$$

Question 13

Which of the following is NOT a plausible outcome when the p-value from a chi-square test is greater than 0.05?

Accepted Answer

Reject the null hypothesis

Question 14

In a Punnett square for Rr x Rr, what is the probability of obtaining a wrinkled pea plant?

Accepted Answer

$$\frac{1}{4}$$

Question 15

Which equation correctly calculates the expected number of round peas in a sample of 120 plants from an Rr x Rr cross?

Accepted Answer

$$120 	imes \frac{3}{4}$$

Question 16

A geneticist performs a chi-square test and obtains $$\$$chi^2$$ = 2.5$$ with 1 degree of freedom. What is the correct interpretation if the critical value at $$p = 0.05 is 3.84$$?

Accepted Answer

Fail to reject the null hypothesis; the data fit the expected ratio

Question 17

Which of the following best describes the purpose of chi-square analysis in genetics?

Accepted Answer

To determine whether observed results deviate significantly from expected results

Question 18

If a genetic cross produces offspring with a ratio that does not fit the expected 3:1 ratio and the p-value is less than 0.05, what should be concluded?

Accepted Answer

The null hypothesis should be rejected

Question 19

Which of the following is a real-world application of genetic testing discussed in class?

Accepted Answer

Using genetic testing to determine a dog's breed and health risks

Genetics Study Notes: Sep 12

Study Guide - Practice Questions

Study Guide - Flashcards