Question 1

Most organ systems are fully formed and ready to function in the fetus by the sixth month. Which of the following systems is the exception to this generalization because it takes longer to finish development?
A) the respiratory system
B) the urinary system
C) the circulatory system
D) the integumentary system

Accepted Answer

The respiratory system continues to develop until the end of the pregnancy, with full maturation occurring in the first few years of life.

Question 2

The bodyʹs axis of development is determined by the
A) primitive streak.
B) notochord.
C) blastomeres.
D) epiblast.

Accepted Answer

The notochord is a key structure in determining the body's axis of development, as it provides a signaling center for the development of the neural tube and other body structures. The primitive streak and blastomeres are involved in early stages of development, while the epiblast forms the embryonic disc but does not directly determine the body axis.

Question 3

The primary germ layer that ultimately produces the hair, fingernails, and toenails is
A) neural crest.
B) mesoderm.
C) ectoderm.
D) endoderm.

Accepted Answer

The ectoderm is the primary germ layer that gives rise to structures such as the hair, fingernails, and toenails. This layer also produces the skin, nervous system, and other structures derived from the neural crest, such as the adrenal medulla and some cranial bones. The mesoderm gives rise to structures such as the muscles, bones, and most organs, while the endoderm gives rise to the internal lining of organs such as the digestive and respiratory systems.

Question 4

Male and female fetuses can first be distinguished by their genitalia at
A) 1 week.
B) 3 months.
C) 7 months.
D) 3 weeks.

Accepted Answer

At around 3 months, the genitalia of the male and female fetuses are visibly different and can be distinguished by ultrasound.

Question 5

Implantation of the blastocyst on the uterine lining takes about
A) 4 weeks.
B) 1 week.
C) 3 weeks.
D) 2 weeks.

Accepted Answer

The answer of Implantation of the blastocyst on the uterine...

Question 6

The urinary bladder is derived from which embryonic layer?
A) mesoderm
B) ectoderm
C) neural crest
D) endoderm

Accepted Answer

The urinary bladder is derived from the endoderm layer of the embryo.

Question 7

A teratogen is
A) a specific sedative used in the 1950s in Europe.
B) a stage of development in the mid-fetal period.
C) a deformed baby.
D) a chemical agent, infectious agent or environmental factor that causes birth defects.

Accepted Answer

A teratogen is a chemical agent, infectious agent or environmental factor that causes birth defects in developing fetuses. Examples include drugs such as thalidomide and environmental factors such as radiation exposure.

Question 8

The primary germ layer that ultimately forms the serous membranes of the peritoneum is
A) ectoderm.
B) neural crest.
C) endoderm.
D) mesoderm.

Accepted Answer

The mesoderm is the primary germ layer that gives rise to the serous membranes of the peritoneum, as well as other serous membranes in the body. The peritoneum lines the abdominal cavity and covers the organs within it.

Question 9

The most common cause of mental retardation in the United States is
A) thalidomide.
B) spina bifida.
C) fetal alcohol syndrome.
D) anencephaly.

Accepted Answer

Fetal alcohol syndrome is the most common cause of mental retardation in the United States. It occurs when a mother consumes alcohol during pregnancy, which can result in developmental abnormalities in the brain and other organs, leading to cognitive impairment and other issues. Thalidomide, spina bifida, and anencephaly can also cause developmental abnormalities and impairments, but they are not as common as fetal alcohol syndrome as a cause of mental retardation in the US.

Question 10

Thalidomide, once used to alleviate morning sickness in pregnant women, resulted in
A) heart defects.
B) severe limb abnormalities.
C) multiple births.
D) mental retardation.

Accepted Answer

Thalidomide was responsible for severe limb abnormalities in babies whose mothers took the drug during pregnancy.

Question 11

Mesenchyme would refer to but not .
A) mesoderm; ectoderm
B) endoderm; ectoderm
C) ectoderm; mesoderm
D) ectoderm; endoderm

Accepted Answer

Mesenchyme refers specifically to the embryonic connective tissue derived from the mesoderm. It does not include tissue derived from the ectoderm or endoderm.

Question 12

The neural tube of the embryo develops into the
A) dorsal skin.
B) neural crest.
C) spinal cord.
D) sensory neurons.

Accepted Answer

The neural tube is the embryonic structure that develops into the spinal cord.

Question 13

The expression ʺbreaking waterʺ during birthing refers to the
A) allantois.
B) amnion.
C) chorion.
D) yolk sac.

Accepted Answer

Breaking water refers to the rupture of the amniotic sac, which is filled with amniotic fluid that surrounds and protects the developing fetus during pregnancy.

Question 14

Which of the following does not distinguish mesoderm from either endoderm or ectoderm?
A) It is a mesenchyme tissue.
B) Its cells can migrate widely within the embryo.
C) It is the last of the three germ layers to develop.
D) It is derived from the epiblast.

Accepted Answer

The answer of Which of the following does not distinguish...

Question 15

The term bilaminar disc refers to the embryonic and .
A) epiblast; hypoblast
B) epidermis; dermis
C) ectoderm; mesoderm
D) inner cell mass; trophoblast

Accepted Answer

The bilaminar disc refers to the two layers of cells that are present in the early embryonic stage, specifically the epiblast (upper layer) and the hypoblast (lower layer).

Question 16

In human embryos, the yolk sac is important because it
A) stores nitrogenous wastes.
B) allows for gas exchange through the placenta.
C) stores yolk.
D) gives rise to earliest blood cells and blood vessels.

Accepted Answer

The yolk sac in human embryos gives rise to the earliest blood cells and blood vessels, which are crucial for the development of the circulatory system. The yolk sac does not store nitrogenous wastes or yolk, and gas exchange typically occurs through the placenta rather than the yolk sac.

Question 17

The solid mass of cells that results from cleavage of the zygote is the
A) blastocyst.
B) morula.
C) gastrula.
D) trophoblast.

Accepted Answer

The solid mass of cells that results from cleavage of the zygote is called the morula.

Question 18

Fertilization is to zygote as
A) birth is to parturition.
B) oocyte is to ovary.
C) cleavage is to morula.
D) egg is to sperm.

Accepted Answer

The answer of Fertilization is to zygote as
A) birth is...

Question 19

Chemical, physical, or biological agents that can induce birth defects are called
A) mutagens.
B) carcinogens.
C) free radicals.
D) teratogens.

Accepted Answer

Teratogens are agents that can cause or increase the incidence of physical or functional abnormalities in a developing embryo or fetus. This can result in birth defects such as malformations or developmental delays. Mutagens are agents that can cause changes in the genetic material of an organism, but may not necessarily result in birth defects. Carcinogens are agents that can cause cancer, which is not directly related to birth defects. Free radicals are unstable molecules that can damage cells, but are not necessarily linked to birth defects.

Question 20

Which characteristic is not true of a blastocyst?
A) It has an inner cell mass and an outer trophoblast.
B) It implants into the uterus.
C) It develops 24-36 hours after conception.
D) It contains a fluid-filled cavity.

Accepted Answer

A blastocyst actually develops about 5-7 days after conception, not 24-36 hours. The other characteristics listed are true of a blastocyst.

Quiz 3: The Tissue Level of Organization

Most organ systems are fully formed and ready to function in the fetus by the sixth month. Which of the following systems is the exception to this generalization because it takes longer to finish development?

The bodyʹs axis of development is determined by the

The primary germ layer that ultimately produces the hair, fingernails, and toenails is

Male and female fetuses can first be distinguished by their genitalia at

Implantation of the blastocyst on the uterine lining takes about

The urinary bladder is derived from which embryonic layer?

A teratogen is

The primary germ layer that ultimately forms the serous membranes of the peritoneum is

The most common cause of mental retardation in the United States is

Thalidomide, once used to alleviate morning sickness in pregnant women, resulted in

Mesenchyme would refer to but not .

The neural tube of the embryo develops into the

The expression ʺbreaking waterʺ during birthing refers to the

Which of the following does not distinguish mesoderm from either endoderm or ectoderm?

The term bilaminar disc refers to the embryonic and .

In human embryos, the yolk sac is important because it

The solid mass of cells that results from cleavage of the zygote is the

Fertilization is to zygote as

Chemical, physical, or biological agents that can induce birth defects are called

Which characteristic is not true of a blastocyst?