Question 1

The fold of skin that covers the tip of the penis is the
A) glans penis.
B) prepuce.
C) corpus cavernosum.
D) corpus spongiosum.
E) penile urethra.

Accepted Answer

The fold of skin that covers the tip of the penis is known as the prepuce, or foreskin. The glans penis refers to the rounded head of the penis that is covered by the prepuce. The corpus cavernosum and corpus spongiosum are two of the erectile tissues that fill with blood during an erection, while the penile urethra is the tube that urine and semen pass through.

Question 2

In the condition known as cryptorchidism,
A) the testes fail to descend into the scrotum.
B) the testes are surgically removed.
C) the foreskin has been surgically removed.
D) sperm cells are not produced.
E) the prostate gland is enlarged.

Accepted Answer

Cryptorchidism is a condition in which the testes fail to descend into the scrotum. This can cause infertility and increase the risk of testicular cancer.

Question 3

To avoid down-regulation of GnRH receptors, GnRH is secreted
A) by the testes.
B) in periodic pulses.
C) only under the influence of FSH.
D) by the anterior pituitary.

Accepted Answer

GnRH is secreted in periodic pulses to avoid down-regulation of GnRH receptors. This is because constant exposure to GnRH can lead to desensitization and down-regulation of the GnRH receptors on the anterior pituitary cells, which will result in reduced secretion of FSH and LH. By pulsatile secretion, GnRH can stimulate the synthesis and release of FSH and LH without down-regulating their receptors.

Question 4

Sister chromatids
A) are found in cells called primary gametes.
B) contain twice the normal amount of DNA.
C) occur during ovum formation.
D) are found in cells called primary gametes and contain twice the normal amount of DNA.
E) are found in cells called primary gametes, contain twice the normal amount of DNA, and occur during ovum formation.

Accepted Answer

Sister chromatids are formed during mitosis and meiosis when DNA replication occurs. They are found in cells called primary gametes (cells that will undergo meiosis to form gametes), and they contain twice the normal amount of DNA because they are two identical copies of a single chromosome. However, they do not occur specifically during ovum formation, as they are present during both male and female gamete production.

Question 5

Egg and sperm cells have
A) 46 chromosomes.
B) 23 chromosomes.
C) just 22 pairs of autosomes plus one pair of sex chromosomes.
D) 46 chromosomes and 23 chromosomes.
E) 46 chromosomes, 23 chromosomes, and 22 pairs of autosomes plus one pair of sex chromosomes.

Accepted Answer

Egg and sperm cells, also known as gametes, have half the number of chromosomes as body cells. In humans, this means they have 23 chromosomes, consisting of just one member of each chromosome pair instead of two. Therefore, the correct choice is B.

Question 6

At which stage of gametogenesis does gamete chromosome number reduce from 4N to 2N?
A) during the first meiotic division
B) during the second meiotic division
C) prior to the first meiotic division
D) prior to the first mitotic division

Accepted Answer

During the first meiotic division, homologous chromosomes are separated, reducing the chromosome number from 4N to 2N. This process is known as reductional division.

Question 7

Mitotic divisions in germ cells
A) are complete before birth.
B) begin at puberty.
C) continue throughout life.
D) end at andropause or menopause.
E) The answer depends on gender.

Accepted Answer

Mitotic divisions in germ cells vary by gender. In females, mitotic divisions are complete before birth, and the number of germ cells (oocytes) is set for life. In males, mitotic divisions begin at puberty and continue throughout life to produce sperm.

Question 8

When allowed to develop, the Müllerian ducts become the
A) fallopian tubes, uterus, and upper vagina.
B) distal vagina, clitoris, and labia.
C) epididymis, vas deferens, and seminal vesicles.
D) penis and scrotum.
E) fallopian tubes, uterus, upper vagina, distal vagina, clitoris, and labia.

Accepted Answer

The Müllerian ducts develop into the fallopian tubes, uterus, and upper vagina in females.

Question 9

The erectile tissue that immediately surrounds the urethra is the
A) membranous urethra.
B) penile urethra.
C) glans penis.
D) corpus spongiosum.
E) corpus cavernosum.

Accepted Answer

The erectile tissue that immediately surrounds the urethra is the corpus spongiosum. This tissue helps to keep the urethra open during ejaculation to allow for passage of semen.

Question 10

Sperm production occurs in the
A) ductus deferens.
B) seminiferous tubules.
C) epididymis.
D) seminal vesicles.
E) rete testis.

Accepted Answer

Sperm production occurs in the seminiferous tubules, which are located within the testes. The ductus deferens carries mature sperm from the epididymis to the urethra, the epididymis is a highly coiled tube where sperm mature and are stored, the seminal vesicles secrete fluids that make up semen along with sperm, and the rete testis is a network of tiny tubes within the testes that transport sperm to the epididymis.

Question 11

Meiosis of one cell results in production of
A) four gametes.
B) one gamete.
C) four gametes if male, one if female.
D) four gametes if female, one if male.

Accepted Answer

The answer of Meiosis of one cell results in production...

Question 12

Gametes are produced by
A) internal genitalia.
B) external genitalia.
C) gonads.
D) autosomes.
E) sex chromosomes.

Accepted Answer

Gametes are produced by the gonads, which are the ovaries in females and the testes in males.

Question 13

Interstitial cells produce
A) sperm.
B) inhibin.
C) nutrients.
D) androgens.
E) androgen-binding protein.

Accepted Answer

Interstitial cells, also known as Leydig cells, produce androgens, mainly testosterone.

Question 14

The enzyme responsible for converting androgens to estrogens is
A) 5α-reductase.
B) TDF.
C) aromatase.
D) AMH.

Accepted Answer

The enzyme responsible for converting androgens to estrogens is aromatase. Aromatase is responsible for the conversion of testosterone to estradiol and androstenedione to estrone. 5α-reductase is responsible for converting testosterone to its more potent form, dihydrotestosterone (DHT). TDF (testis-determining factor) is a gene on the Y chromosome that is responsible for initiating male development during embryogenesis. AMH (anti-Müllerian hormone) is produced by the Sertoli cells in the testes and is responsible for inhibiting the development of the Müllerian ducts in males, which later develop into female reproductive organs.

Question 15

X-linked genes are expressed
A) more often in males.
B) more often in females.
C) at equal rates in the two genders.

Accepted Answer

X-linked genes are found on the X chromosome, and males only have one X chromosome while females have two. Therefore, X-linked genes are expressed more often in males because they do not have a second copy of the gene to mask any possible traits or mutations.

Question 16

A zygote with the genotype XO will
A) develop into a female.
B) have Turner's syndrome.
C) develop into a male.
D) die.
E) develop into a female and have Turner's syndrome.

Accepted Answer

The XO genotype leads to the development of a female phenotype due to the absence of the Y chromosome, which is necessary for male development. Additionally, this genotype is associated with Turner's syndrome, a condition characterized by the presence of a single X chromosome in females, leading to various physical and developmental features.

Question 17

Bipotential gonads develop into testes under the influence of
A) androgens.
B) estrogens.
C) peptide or protein hormones.
D) None of the answers are correct.

Accepted Answer

The development of bipotential gonads into testes is primarily influenced by the SRY gene on the Y chromosome, which triggers the production of testis-determining factor (TDF), not directly by androgens, estrogens, or peptide/protein hormones.

Question 18

The product of the SRY gene is
A) testosterone.
B) anti-Müllerian hormone.
C) dihydrotestosterone.
D) 5-α reductase.
E) testis-determining factor.

Accepted Answer

The product of the SRY gene is testis-determining factor, which plays a crucial role in determining male sex in mammals. This protein is responsible for initiating the development of testes in male embryos by directing the differentiation of the gonadal ridge into testicular tissue. It is not involved in the production of testosterone, anti-Müllerian hormone, dihydrotestosterone, or 5-α reductase.

Question 19

The small paired glands at the base of the penis that produce a lubricating secretion are the
A) seminal vesicles.
B) prostate glands.
C) preputial glands.
D) Bartholin's glands.
E) bulbourethral glands.

Accepted Answer

The bulbourethral glands, also known as Cowper's glands, are located at the base of the penis and produce a lubricating secretion that helps to neutralize any acidic urine residue in the urethra, which could be harmful to the sperm that will eventually pass through. The other gland options listed either are not located at the base of the penis, do not produce a lubricating secretion, or do not exist in males (Bartholin's glands).

Question 20

A zygote with the genotype YO will
A) develop into a male.
B) develop into a female.
C) have Turner's syndrome.
D) have Kleinfelter's syndrome.
E) die.

Accepted Answer

A zygote with the genotype YO (having only one Y chromosome and no second sex chromosome) is not viable and will not develop into a fetus. Humans typically need at least one X chromosome to survive because the X chromosome carries essential genes for development.

Quiz 26: Reproduction and Development

The fold of skin that covers the tip of the penis is the

In the condition known as cryptorchidism,

To avoid down-regulation of GnRH receptors, GnRH is secreted

Sister chromatids

Egg and sperm cells have

At which stage of gametogenesis does gamete chromosome number reduce from 4N to 2N?

Mitotic divisions in germ cells

When allowed to develop, the Müllerian ducts become the

The erectile tissue that immediately surrounds the urethra is the

Sperm production occurs in the

Meiosis of one cell results in production of

Gametes are produced by

Interstitial cells produce

The enzyme responsible for converting androgens to estrogens is

X-linked genes are expressed

A zygote with the genotype XO will

Bipotential gonads develop into testes under the influence of

The product of the SRY gene is

The small paired glands at the base of the penis that produce a lubricating secretion are the

A zygote with the genotype YO will