Question 1

Which phase of meiosis is most directly responsible for Mendel’s principle of segregation, and what event occurs during this phase?

Accepted Answer

Anaphase I; homologous chromosomes separate to opposite poles

Question 2

T.H. Morgan’s experiments with Drosophila melanogaster provided evidence for the chromosomal theory of inheritance. Which observation from his experiments best supported this theory?

Accepted Answer

The inheritance of eye color was linked to the X chromosome

Question 3

In humans, the SRY gene is crucial for sex determination. What is the primary function of the SRY gene?

Accepted Answer

It triggers the formation of testes in males

Question 4

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

Accepted Answer

Males inherit only one X chromosome, so a single recessive allele causes the disease

Question 5

A woman who is a carrier for color blindness (an X-linked recessive trait) marries a man with normal vision. What is the probability that their son will be color blind?

Accepted Answer

$$\frac{1}{2}$$

Question 6

Which statement best distinguishes between linked genes and sex-linked genes?

Accepted Answer

Linked genes are located close together on the same chromosome, while sex-linked genes are specifically located on sex chromosomes

Question 7

In female mammals, X inactivation leads to mosaic expression of X-linked genes. Which real-world example illustrates this phenomenon?

Accepted Answer

Tortoiseshell coloration in cats

Question 8

Linked genes do not assort independently during meiosis. What is the primary reason for this?

Accepted Answer

They are located close together on the same chromosome

Question 9

During meiosis, crossing over can result in recombinant phenotypes. Which outcome is most likely when crossing over occurs between two linked genes?

Accepted Answer

Some offspring display recombinant phenotypes not seen in the parents

Question 10

A geneticist observes two traits in Drosophila that are inherited together more frequently than expected by independent assortment. What does this suggest about the genes controlling these traits?

Accepted Answer

The genes are linked and located close together on the same chromosome

Question 11

Which chromosomal alteration is responsible for Down syndrome in humans?

Accepted Answer

Trisomy of chromosome 21

Question 12

A patient is diagnosed with chronic myelogenous leukemia (CML). Which chromosomal alteration is most commonly associated with this disorder?

Accepted Answer

Translocation between chromosomes 9 and 22

Question 13

Which of the following best defines polyploidy?

Accepted Answer

The presence of more than two complete sets of chromosomes

Question 14

A child is born with Turner syndrome. Which chromosomal abnormality is responsible for this condition?

Accepted Answer

Monosomy X ($$XO)$$

Question 15

Which chromosomal alteration is most likely to result in cri du chat syndrome?

Accepted Answer

Deletion of the short arm of chromosome 5

Question 16

If a cell undergoes nondisjunction during meiosis I, what is the expected outcome for the gametes produced?

Accepted Answer

Half the gametes will have an extra chromosome, and half will have one less chromosome

Question 17

Which chromosomal alteration is most likely to result in a duplication?

Accepted Answer

A segment of a chromosome is copied and inserted into the same chromosome

Question 18

A genetic counselor is analyzing a pedigree for hemophilia, an X-linked recessive disorder. If a carrier mother and a normal father have a daughter, what is the probability that the daughter will be a carrier?

Accepted Answer

$$\frac{1}{2}$$

Question 19

Which chromosomal alteration is most likely to result in an inversion?

Accepted Answer

A segment of a chromosome is reversed end to end

Question 20

A male with an extra Y chromosome ($$XYY) is $$diagnosed. Which syndrome does this represent, and what is the chromosomal basis?

Accepted Answer

Extra Y syndrome; XYY

Chapter 15: The Chromosomal Basis of Inheritance – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards