$$f = \frac{\text{number of nondisjunction events}}{\text{total number of meiotic divisions}}$$

Question 1

Which of the following best describes the outcome of nondisjunction during meiosis I, as shown in the image?

Accepted Answer

Half of the gametes will have an extra chromosome, and half will be missing a chromosome.

Question 2

In the diagram, what is the chromosomal composition of the gametes produced after nondisjunction in meiosis II?

Accepted Answer

Two normal gametes, one with an extra chromosome, and one missing a chromosome.

Question 3

If a human egg with two X chromosomes (XX) is fertilized by a normal Y sperm, what syndrome could result?

Accepted Answer

Klinefelter syndrome (XXY)

Question 4

Which equation correctly represents the calculation for the expected frequency of nondisjunction events in a population?

Accepted Answer

$$f = \frac{	ext{number of nondisjunction events}}{	ext{total number of meiotic divisions}}$$

Question 5

Which of the following is a possible result of nondisjunction during meiosis II, as depicted in the image?

Accepted Answer

One gamete is nullisomic (O), one is disomic (XX), and two are normal (X).

Question 6

If nondisjunction occurs during meiosis I, what is the chromosomal composition of the resulting gametes?

Accepted Answer

Two gametes with XX, two gametes with O

Question 7

Which syndrome is most likely to result from fertilization of an O egg (no X chromosome) by a normal X sperm?

Accepted Answer

Turner syndrome (XO)

Question 8

What is the main difference between nondisjunction in meiosis I and meiosis II?

Accepted Answer

Nondisjunction in meiosis I affects all gametes, while in meiosis II only half are affected.

Question 9

Which of the following best describes the normal segregation of X chromosomes during meiosis, as shown in the image?

Accepted Answer

Each gamete receives one X chromosome.

Question 10

If a sperm with no sex chromosome (O) fertilizes a normal X egg, what is the resulting genotype?

Accepted Answer

XO (Turner syndrome)

Genetics Study Guide: Foundations, Mendelian Inheritance, Sex Linkage, Maternal Inheritance, Linkage & Recombination

Study Guide - Practice Questions