Question 1

Which of the following best describes a chromosome?

Accepted Answer

A single molecule of DNA and associated proteins containing thousands of genes.

Question 2

How many autosomes are present in a human sperm cell?

Accepted Answer

22

Question 3

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry the same genes but may have different alleles.

Question 4

What is the chromosomal composition of a human male?

Accepted Answer

44 autosomes + XY

Question 5

During which phase of meiosis does crossing over occur?

Accepted Answer

Prophase I

Question 6

If an organism has a diploid number of 6 (2n = 6), how many genetically unique gametes can it produce due to independent assortment alone?

Accepted Answer

$$2^3 = 8$

Question 7

Which event during meiosis increases genetic diversity by creating new combinations of alleles?

Accepted Answer

Crossing over between nonsister chromatids

Question 8

A person with Klinefelter syndrome has which of the following karyotypes?

Accepted Answer

XXY

Question 9

What is the most common cause of Down syndrome?

Accepted Answer

Trisomy of chromosome 21

Question 10

Which of the following best explains why the chance of having a child with Down syndrome increases with maternal age?

Accepted Answer

Older eggs have a higher risk of nondisjunction during meiosis.

Question 11

Which of the following is NOT a mechanism that increases genetic diversity during sexual reproduction?

Accepted Answer

Replication of DNA during S phase

Question 12

A human zygote with the genotype XØ will most likely develop which syndrome?

Accepted Answer

Turner syndrome

Question 13

Which of the following best describes aneuploidy?

Accepted Answer

An abnormal number of chromosomes resulting from nondisjunction.

Question 14

If a human egg cell contains 24 chromosomes, what is the most likely outcome after fertilization with a normal sperm?

Accepted Answer

A zygote with trisomy (47 chromosomes)

Question 15

Which of the following is true about the X and Y chromosomes?

Accepted Answer

They are not homologous to each other.

Question 16

Which process is responsible for the separation of homologous chromosomes?

Accepted Answer

Anaphase I of meiosis

Question 17

A geneticist observes a karyotype with three copies of chromosome 18. What is the correct term for this condition?

Accepted Answer

Trisomy 18

Question 18

Which of the following equations correctly represents the number of possible gametes due to independent assortment in humans?

Accepted Answer

$$2^{23}$$

Question 19

Which of the following is a direct result of nondisjunction during meiosis?

Accepted Answer

A gamete with an abnormal number of chromosomes

Question 20

Which of the following best explains why loss of an autosome is not compatible with life?

Accepted Answer

Essential genes are missing, leading to nonviable development.

Chromosomes, Meiosis, and Genetic Disorders: Study Notes

Study Guide - Practice Questions