Question 1

Which of the following best describes the difference between biological sex and gender?

Accepted Answer

Biological sex is determined by chromosomes and anatomy, while gender is assigned based on identity, behavior, or cultural practices.

Question 2

In the XX-XY sex determination system, which of the following statements is correct regarding gamete production?

Accepted Answer

Females produce only X-bearing gametes, while males produce both X- and Y-bearing gametes.

Question 3

Which chromosomal abnormality is characterized by a female with a single X chromosome (XO) and symptoms such as short stature and infertility?

Accepted Answer

Turner syndrome

Question 4

A male child is born with an extra X chromosome (XXY). Which syndrome does this describe, and what is a common symptom?

Accepted Answer

Klinefelter syndrome; often tall stature and sterility

Question 5

In Drosophila melanogaster, what is the expected sexual phenotype of an individual with three X chromosomes and two sets of autosomes (AA XXX)? Use the X:A ratio.

Accepted Answer

Metafemale, because $$\frac{3}{2} = 1.5 \u003e 1$$

Question 6

Which of the following is true about the SRY gene?

Accepted Answer

It is located on the Y chromosome and is responsible for initiating male development.

Question 7

A woman who is heterozygous for an X-linked recessive trait (e.g., color blindness) marries a man with normal vision. What proportion of their sons will be color blind?

Accepted Answer

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

Question 8

Which of the following best explains why females with two X chromosomes do not produce twice as much X-linked gene product as males?

Accepted Answer

One X chromosome is randomly inactivated in each cell, a process known as dosage compensation.

Question 9

Which of the following is a characteristic of Y-linked (holandric) traits?

Accepted Answer

They are passed directly from father to all sons.

Question 10

In birds, which sex is heterogametic and what is the chromosomal composition?

Accepted Answer

Females; ZW

Question 11

A calico cat has patches of black and orange fur. Which genetic mechanism explains this phenotype?

Accepted Answer

Random X-chromosome inactivation in heterozygous females

Question 12

Which of the following is true about genic sex determination?

Accepted Answer

Sex is determined by genes at one or more autosomal loci, not by sex chromosomes.

Question 13

A human embryo with the karyotype XXY will develop as which phenotype, and why?

Accepted Answer

Male, because the presence of a Y chromosome (and SRY gene) determines maleness.

Question 14

Which of the following best describes the inheritance pattern of an X-linked recessive trait?

Accepted Answer

Affected males inherit the allele from their mother and pass it to all daughters but no sons.

Question 15

In the XX-XO sex determination system, which of the following is true for male gametes?

Accepted Answer

Half of the gametes have an X chromosome, and half have no sex chromosome.

Question 16

A Drosophila fly has three sets of autosomes (AAA) and two X chromosomes (XX). What is its X:A ratio and predicted sexual phenotype?

Accepted Answer

$$\frac{2}{3} = 0.67$$, intersex

Question 17

Which of the following is a direct result of meiotic non-disjunction involving sex chromosomes in humans?

Accepted Answer

A child with Turner syndrome (XO)

Question 18

Which of the following statements about dosage compensation in humans is correct?

Accepted Answer

It involves random inactivation of one X chromosome in each female cell, forming a Barr body.

Question 19

A woman with genotype XcXc (where Xc is the allele for color blindness) marries a man with normal vision (X+Y). What is the expected phenotype of their children?

Accepted Answer

All sons will be color blind, all daughters will be carriers.

Sex Determination and Sex-Linked Characteristics: Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards