Question 1

Which of the following occurs during the process of labor?
A)positive feedback involving oxytocin and prostaglandins
B)negative feedback involving oxytocin and prostaglandins
C)positive feedback involving estrogen and human chorionic gonadotropin
D)negative feedback involving estrogen and human chorionic gonadotropin

Accepted Answer

During labor, positive feedback mechanisms involving oxytocin and prostaglandins are triggered. Oxytocin stimulates uterine contractions, which produce more oxytocin and prostaglandins, leading to stronger contractions and further stimulation of labor. This process continues until the baby is delivered.

Question 2

The discovery of ________ explains embryonic pattern formation in a wide variety of organisms.
A)the three-dimensional forms of animals
B)gastrulation
C)homeotic genes
D)programmed cell death

Accepted Answer

Homeotic genes are master control genes that regulate the development of the body plan of an organism. They are responsible for determining the identity and positioning of body regions and segments during embryonic development. This discovery helps to explain embryonic pattern formation in a wide variety of organisms.

Question 3

What would happen if the chorion failed to secrete human chorionic gonadotropin?
A)The maternal elements of the placenta would fail to develop.
B)The fetal elements of the placenta would fail to develop.
C)Neural tube formation would not occur, and the embryo would have no central nervous system.
D)The embryo would be aborted.

Accepted Answer

The chorion plays a critical role in the secretion of human chorionic gonadotropin (hCG), which is essential for maintaining the pregnancy during the early stages. If the chorion fails to secrete hCG, the embryo would not be able to implant and establish a connection with the maternal blood supply, leading to a miscarriage or abortion.

Question 4

Asthenozoospermia is a medical condition that is characterized by reduced sperm motility. What structure of the sperm is likely affected in a man who has asthenozoospermia?
A)acrosome
B)head
C)middle piece
D)flagellum

Accepted Answer

Asthenozoospermia is characterized by reduced sperm motility, which is primarily due to a defect in the flagellum or tail of the sperm. The flagellum is responsible for the movement of the sperm, so a defect in this structure can result in reduced motility or asthenozoospermia.

Question 5

A vasectomy is a form of male sterilization in which each vas deferens is cut, but most of the male's reproductive physiology remains intact. Which of the following will not continue to occur in a male who has had a vasectomy?
A)Sperm will be produced in the seminiferous tubules.
B)Seminal fluid will be ejaculated from the penis during orgasm.
C)Glandular secretions will be ejaculated from the penis during orgasm.
D)Sperm will be ejaculated from the penis during orgasm.

Accepted Answer

A vasectomy involves cutting the vas deferens, preventing sperm from being ejaculated from the penis during orgasm. However, seminal fluid and glandular secretions will still be ejaculated from the penis during orgasm as these fluids are produced by other glands, such as the prostate and seminal vesicles. Sperm will still be produced in the seminiferous tubules, but will be reabsorbed by the body since they cannot be ejaculated.

Question 6

Which of the following structures contributes to the structure of the placenta as well as completely surrounding the embryo?
A)chorion
B)amnion
C)yolk sac
D)allantois

Accepted Answer

The chorion is the outermost membrane that completely surrounds the embryo and contributes to the structure of the placenta. The amnion is an inner membrane that encloses the embryo in fluid. The yolk sac and allantois are also membranes that play a role in early embryonic development, but they do not contribute to the structure of the placenta or completely surround the embryo.

Question 7

Contractions in uterine smooth muscle during labor are initiated by
A)epinephrine.
B)estrogen.
C)oxytocin.
D)prolactin.

Accepted Answer

Contraction of the uterine smooth muscle during labor is initiated by the release of the hormone oxytocin. Oxytocin is produced by the hypothalamus and released by the posterior pituitary gland in response to stretching of the cervix and uterus. Oxytocin stimulates the contraction of the smooth muscle in the uterus, leading to labor and delivery. Epinephrine and estrogen do not play a direct role in initiating contractions, and prolactin is primarily involved in milk production after delivery.

Question 8

Which of the following statements regarding infertility and fertilization procedures is true?
A)Embryos fertilized through assisted reproductive technologies cannot be frozen for later use, as they degrade rapidly.
B)In GIFT, sperm are injected into an embryo in vitro, and the embryo is placed into the oviducts.
C)In IVF, fertilization occurs in a dish. The embryo is allowed to develop for several days, and then the embryo is placed into the uterus.
D)Children conceived using reproductive technologies such as IVF and ICSI display a high rate of abnormalities resulting from these procedures.

Accepted Answer

In vitro fertilization (IVF) involves fertilization in a dish, with the resulting embryo being allowed to develop for several days before being transferred to the uterus. This is the most commonly used fertilization procedure for couples with infertility issues. The other statements are incorrect: embryos can be frozen successfully with cryopreservation, GIFT involves placing the embryo into the oviducts, not injecting sperm into an embryo, and while there may be slightly higher rates of certain types of birth defects among children conceived through IVF or ICSI, overall rates of abnormalities are still very low.

Question 9

The human embryo's first blood cells arise in the
A)developing liver.
B)developing bone marrow.
C)yolk sac.
D)allantois.

Accepted Answer

The human embryo's first blood cells arise in the yolk sac. It is the site of blood cell formation until the liver and bone marrow develop later in embryonic development.

Question 10

Which of the following would be the most likely outcome if androgen receptors on cells in the hypothalamus and anterior pituitary suddenly could not bind androgen?
A)Sperm production would increase.
B)Sperm production would decrease.
C)FSH production would decrease.
D)HCG production would increase.

Accepted Answer

If androgen receptors in the hypothalamus and anterior pituitary cannot bind androgen, negative feedback on these glands would be reduced, leading to increased production of gonadotropins like FSH, which would stimulate sperm production.

Question 11

Which of the following options correctly lists the three stages of labor in the order in which they occur?
A)dilation, expulsion, delivery of the placenta
B)dilation, crowning, expulsion
C)contractions, dilation, expulsion
D)dilation, crowning, delivery of the placenta

Accepted Answer

The three stages of labor are dilation, expulsion, and delivery of the placenta. Dilation is the opening of the cervix, expulsion is when the baby is pushed through the birth canal, and delivery of the placenta is when the placenta is delivered after the baby. Option A correctly lists these stages in the correct order.

Question 12

Suppose that diploid cells of the seminiferous tubules encounter errors during the cell cycle and mitosis. This results in the primary spermatocytes having a 4n number of chromosomes. Assuming that meiosis proceeds normally, which of the following would be true?
A)Sperm cells would have an n number of chromosomes.
B)Sperm cells would have a 2n number of chromosomes.
C)Secondary spermatocytes would have a 4n number of chromosomes.
D)Secondary spermatocytes would have an n number of chromosomes.

Accepted Answer

If primary spermatocytes have a 4n number of chromosomes, then after the first meiotic division, secondary spermatocytes will have a 2n number of chromosomes. After the second meiotic division, spermatids will have an n number of chromosomes, resulting in sperm cells with a haploid (n) number of chromosomes. Therefore, the correct answer is B.

Question 13

The yolk sac of humans
A)stores nutrients to support the developing embryo.
B)is evidence of humans' relationships with egg-laying vertebrates.
C)secretes HCG.
D)absorbs nutrients from, and releases waste to, the mother's blood.

Accepted Answer

The human yolk sac does not store nutrients for the embryo, secrete HCG, or exchange nutrients and wastes with the mother's blood. Instead, it serves as evidence of the evolutionary history of humans, indicating a common ancestry with egg-laying vertebrates. This is because the yolk sac is a vestigial structure that in egg-laying animals would store nutrients for the developing embryo. In humans, it is involved in early blood cell formation and development of the gut, but its presence reflects evolutionary history rather than a functional role in nutrition.

Question 14

Suppose that during the embryonic development of a hand, homeotic gene expression is altered such that the dorsal-ventral axis is switched. What is the most likely outcome of this scenario?
A)The palm and back of the hand will be switched.
B)The pinky and thumb would be switched.
C)The shoulder and hand would be switched.
D)The foot and hand would be switched.

Accepted Answer

The dorsal-ventral axis determines the top-bottom orientation of a limb, so switching it would result in a flip-flop of the palm and back of the hand. This means that the fingers and thumb would likely also be reversed. Switching other axes (such as the proximal-distal or anterior-posterior axes) would result in different outcomes, but the question specifically asks about the dorsal-ventral axis.

Question 15

When does the human blastocyst implant in the wall of the uterus?
A)within a few hours of fertilization
B)about a day after conception
C)about a week after conception
D)only after all four extraembryonic membranes become established

Accepted Answer

The human blastocyst implants in the wall of the uterus about a week after conception.

Question 16

Home pregnancy test kits work by detecting the presence of a hormone in a woman's urine. Recently developed test kits include an indicator of how long the women has been pregnant (1-2, 2-3, or 3+ weeks). The presence of ________ would indicate that a woman is pregnant, and ________ levels of this hormone would indicate that she is farther along in her pregnancy.
A)HCG; low
B)HCG; high
C)FSH; low
D)FSH; high

Accepted Answer

Home pregnancy tests detect the hormone HCG (human chorionic gonadotropin), which is present during pregnancy. Higher levels of HCG indicate that the pregnancy is further along.

Question 17

Your friend tells you that as long as you can track the exact day that a woman ovulates, and as long as a woman does not have sexual intercourse on this day, then she will not get pregnant even if no form of contraception is used. Is your friend correct? Why or why not?
A)Yes. Sperm can only fertilize an egg on the day that ovulation occurs, so as long as sexual intercourse does not occur on this day, the woman will not become pregnant.
B)Yes. High levels of FSH and LH are needed for fertilization to occur, and the levels of FSH and LH do not rise until the exact day that ovulation occurs.
C)No. Even after ovulation occurs, a woman's egg remains in the uterus for at least a week and is able to be fertilized by sperm during this time period.
D)No. Sperm can survive in the female reproductive tract, so having sexual intercourse a few days before ovulation can result in pregnancy.

Accepted Answer

Sperm can survive in the female reproductive tract for up to five days, so having sexual intercourse a few days before ovulation can still result in pregnancy. Additionally, the egg can be fertilized within 12-24 hours of ovulation, but it can also survive for up to 24-48 hours after ovulation. Therefore, abstaining from sexual intercourse only on the day of ovulation is not an effective method of birth control.

Question 18

Another term for gestation is
A)conception.
B)fertilization.
C)development.
D)pregnancy.

Accepted Answer

Gestation refers specifically to the period of time between conception and birth. While conception refers to the moment when an egg and sperm unite to form a zygote, and fertilization refers to the process of the sperm penetrating the egg, neither of these terms encompasses the whole period of gestation. Development is a more general term that encompasses growth and change over time, but does not specifically refer to the process of gestation. Therefore, pregnancy is the most appropriate term, as it specifically denotes the period of gestation in a human or animal.

Question 19

Which of the following processes dominates the third trimester of human development?
A)formation of external features such as arms and legs
B)formation of hair and fingernails
C)rapid growth
D)organ formation

Accepted Answer

The third trimester of human development is characterized by rapid growth, as the fetus undergoes significant weight gain and development of body systems (such as the digestive, respiratory, and nervous systems). While external features such as arms and legs continue to develop during this time, they are already formed in the earlier stages of pregnancy. Hair and fingernails also begin to form earlier in pregnancy and primarily grow during the second trimester. Organ formation occurs mainly during the first trimester, although some final maturation and development of organs occurs in the second and third trimesters.

Question 20

At which gestational age does a developing human fetus first look obviously human and not like other vertebrate embryos?
A)2 weeks
B)4 weeks
C)9 weeks
D)4 months

Accepted Answer

At 9 weeks gestational age, the developing human fetus has distinct human-like features, such as the formation of the face, limbs, and fingers, as well as the development of external genitalia. Prior to this point, the developing embryo resembles embryos of other vertebrates.

Quiz 27: Reproduction and Embryonic Development

Which of the following occurs during the process of labor?

The discovery of ________ explains embryonic pattern formation in a wide variety of organisms.

What would happen if the chorion failed to secrete human chorionic gonadotropin?

Asthenozoospermia is a medical condition that is characterized by reduced sperm motility. What structure of the sperm is likely affected in a man who has asthenozoospermia?

A vasectomy is a form of male sterilization in which each vas deferens is cut, but most of the male's reproductive physiology remains intact. Which of the following will not continue to occur in a male who has had a vasectomy?

Which of the following structures contributes to the structure of the placenta as well as completely surrounding the embryo?

Contractions in uterine smooth muscle during labor are initiated by

Which of the following statements regarding infertility and fertilization procedures is true?

The human embryo's first blood cells arise in the

Which of the following would be the most likely outcome if androgen receptors on cells in the hypothalamus and anterior pituitary suddenly could not bind androgen?

Which of the following options correctly lists the three stages of labor in the order in which they occur?

Suppose that diploid cells of the seminiferous tubules encounter errors during the cell cycle and mitosis. This results in the primary spermatocytes having a 4n number of chromosomes. Assuming that meiosis proceeds normally, which of the following would be true?

The yolk sac of humans

Suppose that during the embryonic development of a hand, homeotic gene expression is altered such that the dorsal-ventral axis is switched. What is the most likely outcome of this scenario?

When does the human blastocyst implant in the wall of the uterus?

Your friend tells you that as long as you can track the exact day that a woman ovulates, and as long as a woman does not have sexual intercourse on this day, then she will not get pregnant even if no form of contraception is used. Is your friend correct? Why or why not?

Another term for gestation is

Which of the following processes dominates the third trimester of human development?

At which gestational age does a developing human fetus first look obviously human and not like other vertebrate embryos?