Question 1

Which phase of meiosis best explains Mendel’s law of segregation, and what key event occurs during this phase?

Accepted Answer

Anaphase I; homologous chromosomes separate to different daughter cells.

Question 2

T.H. Morgan’s experiments with Drosophila melanogaster provided evidence for which of the following conclusions?

Accepted Answer

Genes are located on chromosomes, and some genes are sex-linked.

Question 3

In humans, the presence of which gene on the Y chromosome determines male development?

Accepted Answer

SRY gene

Question 4

Why are X-linked recessive diseases, such as hemophilia, more common in males than in females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will cause the disease.

Question 5

A woman who is a carrier for color blindness (X	extsuperscript{N}X	extsuperscript{n}) and a man with normal vision (X	extsuperscript{N}Y) have a son. What is the probability that their son will be color blind?

Accepted Answer

$$0.25$$

Question 6

Which of the following best explains the tortoiseshell coloration in female cats?

Accepted Answer

Random inactivation of one X chromosome in each cell during embryonic development.

Question 7

Linked genes tend to be inherited together because:

Accepted Answer

They are located near each other on the same chromosome.

Question 8

If two genes are linked, which of the following is most likely to occur in the offspring?

Accepted Answer

Parental phenotypes will be more common than recombinant phenotypes.

Question 9

Crossing over during meiosis can result in which of the following?

Accepted Answer

Unlinking of genes that are located close together on the same chromosome.

Question 10

A nondisjunction event during meiosis II in a human female produces an egg with two copies of chromosome 21. If this egg is fertilized by a normal sperm, what is the resulting zygote’s chromosome 21 status?

Accepted Answer

Trisomy 21

Question 11

Which chromosomal alteration is responsible for cri du chat syndrome?

Accepted Answer

Deletion on chromosome 5

Question 12

Which of the following best describes polyploidy?

Accepted Answer

Having more than two complete sets of chromosomes

Question 13

A patient is diagnosed with chronic myelogenous leukemia (CML). Which chromosomal event is most likely responsible?

Accepted Answer

Reciprocal translocation between chromosomes 9 and 22

Question 14

Which of the following karyotypes would be found in a person with Turner syndrome?

Accepted Answer

$$45,\,X$$

Question 15

A child is born with Klinefelter syndrome. Which of the following is the correct chromosomal composition?

Accepted Answer

$$47,\,XXY$$

Question 16

Which of the following best distinguishes between linked genes and sex-linked genes?

Accepted Answer

Linked genes are on the same chromosome; sex-linked genes are specifically on sex chromosomes.

Question 17

Which chromosomal abnormality is associated with Down syndrome?

Accepted Answer

Trisomy 21

Question 18

A geneticist observes a chromosome with a segment that has been reversed end to end. What type of chromosomal alteration is this?

Accepted Answer

Inversion

Question 19

Which of the following best describes the consequence of a duplication event in a chromosome?

Accepted Answer

A segment of the chromosome is present in two copies.

Question 20

A woman with genotype $$X^N X^n ($$carrier for hemophilia) and a man with genotype $$X^n Y ($$hemophiliac) have a daughter. What is the probability that their daughter will have hemophilia?

Accepted Answer

$$0.25$$

Chapter 15: The Chromosomal Basis of Inheritance – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards