Question 1

Which of the following best describes the purpose of the chi-square ($\chi^2$) test in genetics experiments?

Accepted Answer

To determine the probability that observed deviations from expected results are due to chance.

Question 2

Given the formula for the chi-square test: $\chi^2 = \sum \frac{(O - E)^2}{E}$, what do the variables $O$ and $E$ represent?

Accepted Answer

$O$ is the observed value and $E$ is the expected value.

Question 3

A geneticist performs a monohybrid cross and observes 5474 round seeds and 1850 wrinkled seeds. The expected ratio is 3:1. Calculate the expected number of round and wrinkled seeds if the total is 7324.

Accepted Answer

Round: 5493, Wrinkled: 1831

Question 4

If a chi-square test yields a $P$ value of 0.03, what is the correct interpretation?

Accepted Answer

The deviation between observed and expected results is statistically significant; the hypothesis of chance is rejected.

Question 5

Which of the following statements about X-linked recessive inheritance is correct?

Accepted Answer

Males are always affected if they inherit the mutant allele from their mother.

Question 6

A woman who is a carrier for hemophilia (X-linked recessive) and a normal male have a child. What is the probability that their son will have hemophilia?

Accepted Answer

$\frac{1}{2}$

Question 7

Which chromosomal combination results in a male in humans?

Accepted Answer

XY

Question 8

What is the role of the SRY gene in sex determination?

Accepted Answer

It triggers male development by initiating testis formation.

Question 9

Which of the following is a characteristic of Y-linked inheritance?

Accepted Answer

Only males are affected and the trait is passed from father to son.

Question 10

A pedigree shows a trait that appears only in males and is passed from father to all sons. What is the most likely mode of inheritance?

Accepted Answer

Y-linked

Question 11

Which of the following diseases is NOT typically associated with sex-linked inheritance?

Accepted Answer

Marfan syndrome

Question 12

In a chi-square test with 2 degrees of freedom, what is the critical $\chi^2$ value at $P = 0.05$?

Accepted Answer

$5.99$

Question 13

A female with Turner syndrome has which chromosomal composition?

Accepted Answer

XO

Question 14

Which of the following best explains why X-linked dominant disorders are often more severe in males?

Accepted Answer

Males have only one X chromosome, so a single mutant allele is expressed without a second normal allele to compensate.

Question 15

A man with hairy ears (a proposed Y-linked trait) has children with a woman who does not have hairy ears. What is the expected outcome for their sons?

Accepted Answer

All sons will have hairy ears.

Question 16

Which of the following is a correct statement about the inheritance of X-linked recessive traits?

Accepted Answer

Affected males inherit the trait from their mothers.

Question 17

A woman who is homozygous for an X-linked dominant disorder and a normal male have children. What is the probability that their daughter will be affected?

Accepted Answer

1

Question 18

Which of the following best describes the difference between the homogametic and heterogametic sexes in humans?

Accepted Answer

Females are homogametic (XX), males are heterogametic (XY).

Question 19

Which of the following is a real-world example of an X-linked recessive disorder?

Accepted Answer

Hemophilia

Chi-Square Analysis and Sex-Linked Inheritance in Genetics

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