Chapter 2 Reproduction

Question 1

What is a Diploid and haploid

Answer 1

Diploid (2n) cells have two copies of each chromosome;

Haploid (n) cells have one copy.

Question 2

What is interphase?

Answer 2

The cell cycle contains five stages.
The G1, S, and G2 stages are
collectively called interphase, during which the DNA is uncoiled in the
form of chromatin.

Question 3

What is chromatin?

Answer 3

Chromatin is a complex structure made up of DNA tightly wound around protein complexes called histones

Question 4

What is G1?

Answer 4

In the G1
stage (presynthetic gap), cells create organelles for energy and protein production, and increase their size. The restriction
point, during which the DNA is checked for quality, must be passed for the cell to move into the S stage.

Question 5

What is S stage?

Answer 5

In the S stage (synthesis), DNA is replicated. The strands of DNA,
called chromatids, are held together at the centromere.

Question 6

What is G2?

Answer 6

In the G2
stage (postsynthetic gap), there is further cell growth and replication of organelles in preparation for mitosis. Another quality checkpoint must be passed for the cell to enter into mitosis.

Question 7

What is M stage

Answer 7

In the M stage (mitosis), mitosis and cytokinesis occur

Question 8

What is G0?

Answer 8

In the G0 stage, the cell performs its functions without preparing for
division.

Question 9

What is P53 and it’s importance?

Answer 9

p53 plays a role in the two major checkpoints of the cell cycle (G1 to S, and G2 to M).

p53 primarily functions as a transcription factor. A protein that regulates the activity of other genes. Part of the reason that p53 can do so many things is that it controls the expression of many other genes.

Question 10

What is Cyclins and CDK?

Answer 10

Cyclins and cyclin-dependent kinases (CDK) rise and fall during the
cell cycle. Cyclins bind to CDKs, phosphorylating and activating transcription factors for the next stage of the cell cycle

Question 11

What is transcription factors?

Answer 11

Transcription factors are proteins that help turn specific genes “on” or “off” by binding to nearby DNA.

Transcription factors that are activators boost a gene’s transcription. Repressors decrease transcription.

Groups of transcription factor binding sites called enhancers and silencers can turn a gene on/off in specific parts of the body.

Transcription factors allow cells to perform logic operations and combine different sources of information to “decide” whether to express a gene.

Question 12

What is Cancer?

Answer 12

Cancer occurs when cell cycle control becomes deranged, allowing
damaged cells to undergo mitosis without regard to quality or quantity
of the new cells produced. Cancerous cells may begin to produce
factors that allow them to delocalize and invade adjacent tissues or
metastasize ((of a cancer) spread to other sites in the body by metastasis.
“cancers that metastasize to the brain) elsewhere

Question 13

What does mitosis produce?

Answer 13

Mitosis produces two genetically identical diploid daughter cells from a
single cell and occurs in somatic cells.

Question 14

4 phases of Mitosis
PMAT

Answer 14

Prophase Anaphase Metaphase Telophase

Question 15

What is prophase?

Answer 15

Condensation of Chromatin, Breakdown of the nuclear envelope, Assembly of mitotic Spindles

Question 16

What is metaphase?

Answer 16

In metaphase, chromosomes line up along the metaphase plate
(equatorial plate).

Question 17

What is Telphase?

Answer 17

In telophase, the nuclear membrane reforms, spindle apparatus
disappears, and cytosol and organelles are split between the two
daughter cells through cytokinesis.

Question 17

what is anaphase?

Answer 17

In anaphase, sister chromatids are separated and pulled to opposite
poles.
Cleavage Furrow (cell begins to elongate and a shallow groove called the cleavage furrow forms at the cell surface near the original location of the metaphase plate.)

Question 18

What is Meiosis?

Answer 18

Meiosis occurs in gametocytes (germ cells) and produces up to four
nonidentical haploid sex cells (gametes).

Meiosis has one round of replication and two rounds of division (the
reductional and equational divisions).

Question 19

Explain meisosis I and Homologues?

Answer 19

In meiosis I, homologous pairs of chromosomes (homologues) are
separated from each other.

Homologues are chromosomes that are
given the same number, but are of opposite parental origin

Question 20

What is prophase I

Answer 20

In prophase I, the same events occur as in prophase of mitosis, except that homologues come together and intertwine in a process
called synapsis. e four chromatids are referred to as a tetrad, and crossing over exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome. This accounts for Mendel’s second law (of independent assortment).

Question 21

What is metaphase I

Answer 21

In metaphase I, homologous chromosomes line up on opposite sides
of the metaphase plate.

Question 22

What is anaphase I

Answer 22

In anaphase I, homologous chromosomes are pulled to opposite poles of the cell. is accounts for Mendel’s first law (of segregation)

[Mendel’s first law, also known as the “Law of Segregation,” states that during the formation of gametes (sex cells), the two alleles for a given trait separate from each other, so that each gamete only receives one allele, ensuring genetic diversity in offspring; essentially, each parent contributes only one copy of each gene to their offspring. ]

Question 23

What is telephase I

Answer 23

In telophase I, the chromosomes may or may not fully decondense,
and the cell may enter interkinesis after cytokinesis.

Question 24

What is interkinesis?

Answer 24

a period of rest that cells of some species enter during meiosis, between meiosis I and meiosis II. No DNA replication occurs.

Question 25

What is meiosis II

Answer 25

In meiosis II, sister chromatids are separated from each other in a
process that is functionally identical to mitosis

Question 26

What are sister chromatids?

Answer 26

Sister chromatids are
copies of the same DNA held together at the centromere.

Question 27

How is chromosomal sex determined?

Answer 27

Chromosomal sex is determined by the 23rd pair of chromosomes in
humans, with XX being female and XY being male.

Question 28

What is the X chromosome?

Answer 28

The X chromosome carries a sizeable amount of genetic information;

mutations of X-linked genes can cause sex-linked disorders.

Males are hemizygous with respect to the unpaired genes on the X chromosome, so they will express sex-linked disorders, even if they
only have one recessive disease-carrying allele.

Females with only one
copy of the affected allele are called carriers.

Question 29

What is the Y chromosome

Answer 29

The Y chromosome carries little genetic information, but does contain the SRY (sex-determining region Y) gene, which causes the
gonads to differentiate into testes.

Question 30

Where does sperm develop?

Answer 30

Sperm develop in the seminiferous tubules in the testes. They are
nourished by Sertoli cells.

Question 31

What is the Interstitial cells of Leydig?

Answer 31

Interstitial cells of Leydig, in the testes, secrete testosterone and other male sex hormones (androgens).

Question 32

Where are the testes and what does it do.

Answer 32

The testes are located in the scrotum, which hangs outside of the
abdominal cavity and has a temperature 2°C to 4°C lower than the
rest of the body.

Question 33

Where does spem gain motility?

Answer 33

Once formed, sperm gain motility in the epididymis and are stored
there until ejaculation.

Question 34

During ejaculation, sperm travel through the _____ ________ to the
ejaculatory duct, and then to the _______ and out through the penis.

Answer 34

During ejaculation, sperm travel through the vas deferens to the
ejaculatory duct, and then to the urethra and out through the penis.

Question 35

What is The seminal vesicles?

Answer 35

The seminal vesicles contribute fructose to nourish sperm and
produce alkaline fluid

Question 36

what is The prostate gland

Answer 36

The prostate gland also produces alkaline fluid.

Question 37

What is the bulbourethral glands?

Answer 37

The bulbourethral glands produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual
arousal.

Question 38

What is semen composed of?

Answer 38

Semen is composed of sperm and seminal fluid from the glands
above.

Question 39

What happens in spermatogenesis?

Answer 39

In spermatogenesis, four haploid sperm are produced from a spermatogonium.

Question 40

After S stage, the germ cells are called ________ ___________

Answer 40

After S stage, the germ cells are called primary spermatocytes

Question 41

After meiosis I, the germ cells are called secondary spermatocytes.

Answer 41

After meiosis I, the germ cells are called ________ ____________

Question 42

After meiosis II, the germ cells are called _________

Answer 42

After meiosis II, the germ cells are called spermatids

Question 43

After maturation, the germ cells are called _________.

Answer 43

After maturation, the germ cells are called spermatozoa.

Question 44

Anatomy of a sperm:

Answer 44

Sperm contain a head, midpiece, and flagellum.

Question 45

The head of a sperm contains:

Answer 45

The head contains the genetic material and is covered with an
acrosome—a modified Golgi apparatus that contains enzymes that
help the sperm fuse with and penetrate the ovum

Question 46

The midpiece of sperm does what?

Answer 46

The midpiece generates ATP from fructose and contains many mitochondria.

Question 47

The flagellum promotes _________

Answer 47

The flagellum promotes motility

Question 48

The Ova (eggs) are produced in ________ in the ________.

Answer 48

The Ova (eggs) are produced in follicles in the ovaries.

Question 49

When an egg is ovulated what happens?

Answer 49

Once each month, an egg is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct.

Question 50

Where are the fallopian tubes are connected?

Answer 50

The fallopian tubes are connected to the uterus,
the lower end of
which is the cervix.

Question 51

What is the vaginal canal?

Answer 51

The vaginal canal lies below the cervix and is the site where sperm are deposited during intercourse.

The vaginal canal also can be the site of childbirth.

Question 52

What is oogenesis?

Answer 52

In oogenesis, one haploid ovum and a variable number of polar bodies
are formed from an oogonium.

Question 53

Whats the vulva?

Answer 53

The external parts of the female genital organs are collectively known
as the vulva.

Question 54

What is primary oocytes?
(part of oogenesis)

Answer 54

At birth, all oogonia have already undergone replication and are
considered primary oocytes. They are arrested in prophase I.

Question 55

What is secondary oocytes?
(part of oogenesis)

Answer 55

The ovulated egg each month is a secondary oocyte, which is
arrested in metaphase II.

If the oocyte is fertilized, it will complete meiosis II to become a true
ovum.

Question 56

What is a polar body in Oogenesis?

Answer 56

Cytokinesis is uneven in oogenesis. The cell receiving very little cytoplasm and organelles is called a polar body.

Question 57

Oocytes are surrounded by the ____ _________, an acellular mixture
of glycoproteins that protects the oocyte and contains the
compounds necessary for sperm binding;

And the _______ _______,
which is a layer of cells that adheres to the oocyte during ovulation.

Answer 57

Oocytes are surrounded by the zona pellucida, an acellular mixture
of glycoproteins that protects the oocyte and contains the
compounds necessary for sperm binding;

And the corona radiata,
which is a layer of cells that adheres to the oocyte during ovulation.

Question 58

Where do Gonadotropin releasing hormone (GnRH) happen? And What do they do?

Answer 58

Gonadotropin-releasing hormone (GnRH) from the hypothalamus
causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the functions of which depend on the sex
of the individual.

Question 59

Explain follicle-stimulating hormone (FSH) in Men?

Answer 59

In males, FSH stimulates the Sertoli cells and triggers
spermatogenesis, while LH causes the interstitial cells to produce testosterone.

Testosterone is responsible for the maintenance and
development of the male reproductive system and male secondary
sex characteristics (facial and axillary hair, deepening of the voice,
and increased bone and muscle mass)

Question 60

Explain follicle-stimulating hormone (FSH) in females?

Answer 60

In females, FSH stimulates development of the ovarian follicles, while LH causes ovulation. These hormones also stimulate production of
estrogens and progesterone.

Question 61

Name the phases of menstural cycle:

Answer 61

Follicular phase, Ovulation, Luteal phase, Ovulation, Menstruation

Question 62

Describe the Follicular phase:

Answer 62

In the follicular phase, GnRH secretion stimulates FSH and LH secretion, which promotes follicle development. Estrogen is released, stimulating vascularization and glandularization of the decidua.

[The decidua is the modified uterine lining during pregnancy that supports the embryo and placenta. Glandularization of the decidua refers to the growth of glands that secrete nutrients for the developing embryo.]

Question 63

What is the Ovulation phase?

Answer 63

Ovulation is stimulated by a sudden surge in LH. is surge is triggered when estrogen levels reach a threshold and switch from
negative to positive feedback effects.

Question 64

What is Luteal phase?

Answer 64

In the luteal phase, LH causes the ruptured follicle to become the. corpus luteum, which secretes progesterone that maintains the uterine lining. High estrogen and progesterone levels cause negative
feedback on GnRH, LH, and FSH.

Question 65

What is menstruation?

Answer 65

Menstruation occurs if there is no fertilization. As the estrogen and progesterone levels drop, the endometrial lining is sloughed off, and
the block on GnRH production is removed.

Question 66

If fertilization does occur, the blastula produces _______ _________ ________ (___)
which, as an LH analog, can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production.

Answer 66

If fertilization does occur, the blastula produces human chorionic
gonadotropin (hCG)
which, as an LH analog, can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production.

Question 67

What is Menopause?

Answer 67

Menopause occurs when the ovaries stop producing estrogen and progesterone, usually between ages 45 and 55. Menstruation stops and FSH and LH levels rise. Physical and physiological changes accompanying menopause include flushing, hot flashes, bloating, headaches, and irritability.

Question 68

Name the Cell Cycle stages and features

Answer 68

G: 1Cell grows and performs its normal functions. DNA is examined and
repaired

S: DNA is replicated.

G2: Cell continues to grow and replicates organelles in preparation for
mitosis. Cell continues to perform its normal functions.

M: Mitosis (cell division) occurs.

G0: The cell performs its normal functions and is not preparing to divide.

Question 69

What is the Mitotic phases and features

Answer 69

Prophase:
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite poles and begin forming the
spindle apparatus

Metaphase:
Chromosomes gather along the metaphase plate in the center of the cell under the guidance of the spindle apparatus

Anaphase:
Sister chromatids separate, and a copy of each chromosome migrates
to opposite poles

Telophase and Cytokenseis:

Chromosomes decondense, nuclear membrane reforms, nucleoli reappear, spindle apparatus breaks down, cell divides into two
identical daughter cells

Question 70

What is the number and ploidy of the daughter cells produced from meiosis I? From meiosis II?

Answer 70

After meiosis I, there are two haploid daughter cells.

After meiosis II, there are up to four haploid gametes.

Question 71

What is the difference between homologous chromosomes and sister
chromatids?

Answer 71

Homologous chromosomes are related chromosomes of opposite parental origin (such as maternal chromosome 15 and paternal chromosome 15, or—in males—the X and Y chromosomes)

Sister chromatids are identical copies of the same DNA that are held together at the centromere. Aer S phase, a cell contains 92 chromatids, 46 chromosomes, and 23 homologous pairs.

Question 72

What is the Meiotic I phases and features

what are the differences from the analogous phase of mitosis?

Answer 72

Prophase I:
Homologous chromosomes come together as tetrads during synapsis; crossing over

Metaphase I:
Homologous chromosomes line up on opposite sides of the metaphase plate, rather than individual chromosomes lining up on the metaphase plate

Anaphase I:
Homologous chromosomes separate from each other; centromeres do not break

Telophase I: Chromatin may or may not decondense; interkinesis occurs as the cell prepares for meiosis II

Question 73

What are the functions of interstitial cells of Leydig and Sertoli cells?

Answer 73

The interstitial cells of Leydig secrete testosterone and other male sex
hormones (androgens). Sertoli cells nourish sperm during their development

Question 74

During which phase of meiosis is a primary oocyte arrested?
VS
During which phase of meiosis is a secondary oocyte arrested?

Answer 74

A primary oocyte is arrested in prophase I, while a secondary oocyte is
arrested in metaphase II.

Question 75

What is the acrosome? What organelle forms the acrosome?

Answer 75

The acrosome contains enzymes that are capable of penetrating the corona radiata and zona pellucida of the ovum, permitting fertilization to occur.

It is a modified Golgi apparatus.

Question 76

Which hormones are key to sexual differentiation in a fetus with XY genotype? Describe the expected phenotype if receptors to these hormones are absent.

Answer 76

Androgens, such as testosterone, lead to male sexual differentiation.
Absence of androgen receptors, a condition known as androgen
insensitivity syndrome, leads to an XY genotype with phenotypically female characteristics.

Question 77

Name the phases and how it effects hormones

Answer 77

Follicular:
Egg develops, endometrial
lining becomes vascularized
and glandularized
(FSH =↑) (LH remained =) (Estrogen ↓ then ↑) (Progesterone = ↓)

Ovulation:
Egg is released from follicle
into peritoneal cavity
(FSH =↑) (LH =↑) (Estrogen =↑) (Progesterone = ↓)

Luteal:
Luteal Corpus luteum produces progesterone to maintain endometrium
(FSH =↑) (LH remained =) (Estrogen = ↑) (Progesterone = ↑)

Menses:
Shedding of endometrial
lining
(FSH =↑) (LH =↑) (Estrogen =↑) (Progesterone = ↓)

Question 78

Which of the following is the correct sequence of the development of a
mature sperm cell?

A. Spermatid→ 1° spermatocyte→spermatogonium→2°
spermatocyte→spermatozoan
B. Spermatogonium→1° spermatocyte→2°
spermatocyte→spermatid→spermatozoan
C. Spermatozoan→1° spermatocyte→2°
spermatocyte→spermatogonium→spermatid
D. Spermatogonium→1° spermatocyte→2°
spermatocyte→spermatozoan→spermatid

Answer 78

B
Diploid cells called spermatogonia differentiate into primary spermatocytes, which undergo the first meiotic division to yield two haploid secondary spermatocytes.

These undergo a second meiotic division to become immature spermatids. e
spermatids then undergo a series of changes leading to the production of mature
sperm, or spermatozoa.

Question 79

Which of the following correctly pairs the stage of development of an egg cell
with the relevant point in a woman’s life cycle?
A. From birth to menarche—prophase II
B. At ovulation—metaphase I
C. At ovulation—metaphase II
D. At fertilization—prophase II

Answer 79

C
From the time of birth until shortly before ovulation, all egg cells are arrested at the
prophase stage of meiosis I. ese cells are referred to as primary oocytes. At
ovulation, the egg cell has completed meiosis I and is now arrested in metaphase II as a haploid cell called a secondary oocyte. When a sperm penetrates the outer layers of the secondary oocyte, it completes meiosis II to become a mature ovum.

Question 80

Some studies suggest that in patients with Alzheimer’s disease, there is a
defect in the way the spindle apparatus attaches to the kinetochore fibers. At
which stage of mitotic division would one first expect to be able to visualize
this problem?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Answer 80

A
The spindle apparatus first interacts with the kinetochore fibers near the end of prophase. While the spindle apparatus aligns the chromosomes at the equatorial plate
during metaphase, (B), the initial connection of the microtubule to the kinetochore
occurs in prophase.

Question 81

A researcher wishes to incorporate a radiolabeled deoxyadenine into the
genome of one of the two daughter cells that would arise as a result of
mitosis. What is the latest stage of cellular development during which the
radiolabeled deoxyadenine could be added to achieve this result?
A. G1
B. G2
C. M
D. S

Answer 81

D
To ensure that the labeled deoxyadenine will be incorporated into the DNA of one of
the daughter cells, we have to insert the nucleotide before DNA replication has been
completed. Because replication occurs during S stage, we could introduce the
deoxyadenine during G1 or S stage. Because G1 precedes S, the latest point at which
the deoxyadenine could be added is the S stage.

Question 82

Certain ovarian tumors called granulosa cell tumors are known to produce
excessive levels of estrogen. A physician who diagnoses a granulosa cell
tumor should look for a secondary cancer in which of the following parts of
the reproductive tract?
A. Fallopian tube
B. Cervix
C. Endometrium
D. Vagina

Answer 82

C
Estrogen is known to cause growth of the endometrial lining during the follicular
phase of the menstrual cycle, and its levels stay high during the luteal phase to
promote vascularization and glandularization of this tissue. Excessive levels of
estrogen may provide a strong enough signal for cell growth to promote tumor
formation or even cancer.

The other tissues listed in this question require estrogen for development, but are not strongly dependent on estrogen for growth.

Question 83

Upon ovulation, the oocyte is released into the:
A. fallopian tube.
B. follicle.
C. abdominal cavity.
D. uterus.

Answer 83

C
This subtle point about ovulation is missed by most students and remains hard to believe until the organs are examined in anatomy class in medical school. e
ruptured ovarian follicle releases an oocyte into the abdominal cavity, close to the entrance of the fallopian tube. With the aid of beating cilia, the oocyte is drawn into the fallopian tube, through which it travels until it reaches the uterus. If it is fertilized in the fallopian tube, it will implant in the uterine wall. If fertilization does not occur, it will be expelled along with the uterine lining during menstruation.

Question 84

Cancer cells are cells in which mitosis occurs continuously, without regard to quality or quantity of the cells produced. For this reason, most chemotherapies attack rapidly dividing cells. At which point(s) in the cell cycle could chemotherapy effectively prevent cancer cell division?
I. S stage
II. Prophase
III. Metaphase

A. I only
B. I and II only
C. II and III only
D. I, II, and III

Answer 84

D
The question is asking us to determine at which points in the cell cycle we can prevent
or at least lower the number of cells undergoing mitosis. One idea would be to
prevent DNA synthesis during the S stage of the cell cycle. Without the DNA being replicated, two viable daughter cells could not be formed. Other ideas would be preventing the mitotic cycle from forming altogether in prophase by preventing spindle apparatus formation, preventing the nuclear membrane from dissolving, or interfering with other processes during this phase. Similarly, a treatment that would act on cells in the metaphase stage of the cell cycle would also interfere with the mitotic cycle. Therefore, any of the three solutions presented would be a viable option

Question 85

Which of the following INCORRECTLY pairs a structure of the male
reproductive system with a feature of the structure?
A. Seminal vesicles—produce alkaline fructose-containing secretions
B. Prostrate gland—surrounded by muscle to raise and lower the testes
C. Vas deferens—tube connecting the epididymis to the ejaculatory duct
D. Cowper’s glands—produce a fluid to clear traces of urine in the urethra

Answer 85

B
The prostrate gland, along with the seminal vesicles and the bulbourethral gland, secretes seminal fluid that combines with sperm to produce semen. It is the cremaster muscle which surrounds the testes that raises and lowers the testes in response to changes in temperature

Question 86

What is the last point in the meiotic cycle in which the cell has a diploid
number of chromosomes?
A. During interphase
B. During telophase I
C. During interkinesis
D. During telophase II

Answer 86

B
the first meiotic division (reductional division) pulls homologous chromosomes to opposite poles of the cell during anaphase I. Near the end of telophase I, cytokinesis occurs, resulting in two haploid (n) daughter cells.

Thus, during interkinesis and anaphase II, the daughter cells are already haploid, eliminating (C) and (D). The cell
is diploid during interphase, (A), but remains diploid up until the end of telophase I.

Question 87

Which of the following does NOT likely contribute to genetic variability?
A. Random fertilization of an egg by a sperm
B. Random segregation of homologous chromosomes
C. Crossing over between homologous chromosomes during meiosis
D. Replication of the DNA during S stage

Answer 87

D
The safest way to answer this question correctly is to go through each answer choice and eliminate the ones that contribute to genetic variability. e random fertilization
of an egg by a sperm, the random segregation of homologous chromosomes during anaphase I, and crossing over between homologous chromosomes during prophase I all contribute to genetic variability during sexual reproduction because they result in novel combinations of genetic material, eliminating (A), (B), and (C). S stage, (D), should not cause increased genetic variability; the DNA should be copied precisely,
without error, meaning that both strands of DNA should be identical.

Question 88

Which of the following statements correctly identifies a key difference
between mitosis and meiosis?

A. In metaphase of mitosis, replicated chromosomes line up in single file; in
metaphase II of meiosis, replicated chromosomes line up on opposite
sides of the metaphase plate.
B. During anaphase of mitosis, homologous chromosomes separate; during anaphase of meiosis I, sister chromatids separate.
C. At the end of telophase of mitosis, the daughter cells are identical to each
other; at the end of meiosis I, the daughter cells are identical to the parent
cell.
D. During metaphase of mitosis, centromeres are present directly on the
metaphase plate; during metaphase of meiosis I, there are no
centromeres on the metaphase plate.

Answer 88

D
e key differences between mitosis and meiosis primarily appear during meiosis I.
Of note, synapsis and crossing over occur during prophase I, and homologous
chromosomes are separated during meiosis I (rather than sister chromatids, as in
mitosis). While the location of the centromeres relative to the metaphase plate may
seem trivial, it is representative of the fact that homologous chromosomes line up on
opposite sides of the equatorial plate in meiosis, in contrast to the positioning of each
chromosome directly upon the metaphase plate in mitosis.

Question 89

Which of the following is true regarding prophase?
A. The chromosomes separate and move to opposite poles of the cell.
B. The spindle apparatus disappears.
C. The chromosomes uncoil.
D. The nucleoli disappear

Answer 89

D
In prophase, the chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear. (A) describes anaphase,
whereas (B) and (C) describe telophase.

Question 90

An individual who is phenotypically female is found to have only one copy of
a disease-carrying recessive allele on the X chromosome, yet demonstrates
all of the classic symptoms of the disease. Geneticists determine that the
individual has a genotype that likely arose from nondisjunction in one parent.
What is the likely genotype of this individual?
A. 46,XX (46 chromosomes, with XX for sex chromosomes)
B. 46,XY
C. 45,X
D. 47,XXY

Answer 90

C
Nondisjunction refers to the incorrect segregation of homologous chromosomes
during anaphase I, or of sister chromatids during anaphase II. In either case, one daughter cell ends up with two copies of related genetic material, while the other
receives zero. Immediately, this should eliminate (A) and (B), which show a normal
complement of chromosomes (46). An individual who has only one recessive diseasecarrying allele, and yet still expresses the disease, likely does not have a dominant
allele for the given trait. is is seen in males, who are hemizygous for many X-linked
genes, and can also be seen in females who have Turner syndrome (45,X) and only
one X chromosome. us, (C) is the answer.

Question 91

During which phase of the menstrual cycle does progesterone concentration
peak?
A. Follicular phase
B. Ovulation
C. Luteal phase
D. Menses

Answer 91

C
Progesterone peaks during the luteal phase, as it supports the endometrium for potential implantation of a blastula. Progesterone levels are relatively low during the follicular phase and ovulation, eliminating (A) and (B). Withdrawal of progesterone
actually causes menses, eliminating (D).

Question 92

Which of the following would NOT be seen during pregnancy?
A. High levels of hCG in the first trimester
B. High levels of progesterone throughout the pregnancy
C. Low levels of FSH in the first trimester
D. High levels of GnRH throughout the pregnancy

Answer 92

D
During the first trimester of pregnancy, the corpus luteum is preserved by human chorionic gonadotropin (hCG); hence, progesterone secretion by the corpus luteum is
maintained during the first trimester. is eliminates (A). During the second
trimester, hCG levels decline, but progesterone levels rise because the hormone is
now secreted by the placenta itself, eliminating (B). High levels of progesterone and
estrogen inhibit GnRH secretion, thus preventing FSH and LH secretion and the
onset of a new menstrual cycle. This eliminates (C) and validates (D).

Question 93

Female chromosome pairs are [XX or XY]

Answer 93

Female chromosome pairs are XX

Question 94

In [mitosis phase], chromosomes meet in middle of the cell

Answer 94

In metaphase, chromosomes meet in middle of the cell

Metaphase = “meet in middle” at the metaphase plate

Question 95

A/an [… protein] is any protein that acts as an agent to bind two or more molecules together

Answer 95

A/an binding protein is any protein that acts as an agent to bind two or more molecules together

Examples include:
DNA-binding protein
Single-strand binding protein
Telomere-binding protein

Question 96

[Hormone] develops the female reproductive tract and thickens the uterine wall

Answer 96

Estrogen develops the female reproductive tract and thickens the uterine wall

“Estrogen establishes and progesterone protects the endometrium”

Estrogen responds to FSH

Question 97

In males with an X-linked recessive mutation, the mutation [will or will not] be expressed

Answer 97

In males with an X-linked recessive mutation, the mutation will be expressed

This is because males only have one X chromosome

Question 98

The phases of meiosis:

Answer 98

The phases of meiosis:

Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II

PMAT x 2

Question 99

Male chromosome pairs are [XX or XY]

Answer 99

Male chromosome pairs are XY

Question 100

[…] is when two chromosomes of a homologous pair exchange segments with each other

Answer 100

Crossing over is when two chromosomes of a homologous pair exchange segments with each other

Question 101

The […] have follicles that produce ova

Answer 101

The ovaries have follicles that produce ova

Question 102

In females with an X-linked recessive mutation, the mutation [will or will not] be expressed

Answer 102

In females with an X-linked recessive mutation, the mutation will not be expressed

Females have two X chromosomes, so the mutation is carried but not expressed. The normal X chromosome will be expressed because this is a recessive trait

Question 103

[Organs] are controlled by FSH and LH

Answer 103

Ovaries are controlled by FSH and LH

Question 104

[…] and the […] make alkaline fluid to help sperm survive the acidic environment of the female reproductive tract

Answer 104

Seminal vesicles and the prostate gland make alkaline fluid to help sperm survive the acidic environment of the female reproductive tract

Question 105

The number of complete sets of chromosomes in a cell is referred to as the […] of a cell

Answer 105

The number of complete sets of chromosomes in a cell is referred to as the ploidy of a cell

Haploid (N) Diploid (2N)

Question 106

The process of fertilization involves the following 4 steps:

1. […]
2. […]
3. […]
4. […]

Answer 106

The process of fertilization involves the following 4 steps:

1. Sperm binding
2. Acrosome reaction
3. Cortical reaction
4. Genetic transfer

Question 107

In [mitosis phase], chromosomes decondense, the nuclear membrane forms, and cytokinesis occurs

Answer 107

In telophase, chromosomes decondense, the nuclear membrane forms, and cytokinesis occurs

Question 108

Female egg pathway:

[…]

Answer 108

Female egg pathway:

Ovary → Oviduct or fallopian tube → Uterus → Cervix → Vagina

Note: If unfertilized, the egg will leave through the cervix and vagina, otherwise it implants into the uterus as an embryo

Question 109

The four phases of Mitosis:

[…]
[…]
[…]
[…]

Answer 109

The four phases of Mitosis:

Prophase
Metaphase
Anaphase
Telophase

Acronym: PMAT

Note: Interphase precedes mitosis, it is not part of mitosis

Question 110

A cell will enter [cell cycle phase] if it does not need to divide

Answer 110

A cell will enter G0 phase if it does not need to divide

Question 111

The [gene] is responsible for initiation of male sex determination and codes for testicles

Answer 111

The SRY gene is responsible for initiation of male sex determination and codes for testicles

“Sorry you’re a male”

Question 112

Crossing over occurs in [meiosis phase]

Answer 112

Crossing over occurs in prophase I

Question 113

A/an […] is one half of a chromosome

Answer 113

A/an chromatid is one half of a chromosome

One of the chromatids is an identical copy of the other

Question 114

[…] is the production of female gametes

Answer 114

Oogenesis is the production of female gamete

Question 115

[…] is when sister chromatids don’t separate properly during anaphase

Answer 115

Nondisjunction is when sister chromatids don’t separate properly during anaphase

Results in aneuploidy. (Aneuploidy is when a cell has too many or too few chromosomes. Instead of the normal number, it can have extra or missing ones, which can cause health problems.)

Question 116

Mitosis and cytokinesis occur in the [cell cycle phase]

Answer 116

Mitosis and cytokinesis occur in the M phase

Question 117

In the [cell cycle phase], cells grow and make organelles

Answer 117

In the G2 phase, cells grow and make organelles

Question 118

Eukaryotes have [#] chromosome(s)

Prokaryotes have [#] chromosome(s)

Answer 118

Eukaryotes have multiple chromosome(s)

Prokaryotes have one chromosome(s)

Note:
1.The prokaryotic chromosome is circular
2. Plasmids are different from chromosomes and contain DNA that is not essential for survival

Question 119

The […] makes viscous fluid to clean out the urethra

Answer 119

The bulbourethral gland makes viscous fluid to clean out the urethra

Question 120

Pathway of sperm during ejaculation:

[…]

Answer 120

Pathway of sperm during ejaculation:

SEVE(N) UP mnemonic

Seminiferous Tubules
Epididymis
Vas Defens
Ejaculatory ducts
(Nothing)
Urethra
Penis

Question 120

[…] states that two alleles of each gene become separated and only one allele from each parent will be passed to the offspring

Answer 120

The law of segregation states that two alleles of each gene become separated and only one allele from each parent will be passed to the offspring

Parent Offspring
YY. →. Y or Y
Yy → Y or y
yy →. y or y

Question 121

At the […] checkpoint, cells choose whether or not to divide

Answer 121

At the G1 checkpoint, cells choose whether or not to divide

P53 is in charge

Question 122

Eukaryotic cells reproduce via […]

Answer 122

Eukaryotic cells reproduce via mitosis

Question 123

Interphase includes [cell cycle phases]

Answer 123

Interphase includes G1, S, and G2 phases

Phase where the cell spends most of its life

Question 124

In [mitosis phase], the DNA condenses, centrioles migrate to opposite poles, and microtubules form

Answer 124

In prophase, the DNA condenses, centrioles migrate to opposite poles, and microtubules form

Question 125

Semen is a combination of […] and […]

Answer 125

Semen is a combination of sperm and seminal fluid

Question 126

Humans have [#] pairs of chromosomes, for a total of [#] chromosomes

Answer 126

Humans have 23 pairs of chromosomes, for a total of 46 chromosomes

Question 127

DNA is replicated in the [cell cycle phase]

Answer 127

DNA is replicated in the S phase

S = synthesis phase

Question 128

Fertilization occurs in the […]

Answer 128

Fertilization occurs in the fallopian tube

Question 129

At the […] checkpoint, the cell will check that the DNA has replicated correctly

Answer 129

At the G2 checkpoint, the cell will check that the DNA has replicated correctly

Question 130

[…] refers to genetic conditions associated with mutations in genes on the X chromosome

Answer 130

X-linked recessive inheritance refers to genetic conditions associated with mutations in genes on the X chromosome

Question 131

During the [cell cycle phase], cells synthesize mRNA and proteins

Answer 131

During the G1 phase, cells synthesize mRNA and proteins

This is to prepare for subsequent steps leading to mitosis

G1 stands for “Gap 1”

Question 132

In [mitosis phase], sister chromatids separate and move to opposite poles

Answer 132

In anaphase, sister chromatids separate and move to opposite poles

Anaphase = “Apart”