Question 1

Which of these statements concerning the neural tube is NOT correct?

Accepted Answer

The cells of the neural tube are not called neural crest cells. Neural crest cells are a group of cells that form at the boundary between the neural tube and the ectoderm and migrate to form various structures in the body, such as the sensory ganglia and cranial nerves.

Question 2

All of these are factors that facilitate the fertilization process EXCEPT:

Accepted Answer

The oocyte does not typically reside in the uterus, but rather travels through the fallopian tube towards the uterus, where it may be fertilized by sperm. The other factors listed all play a role in facilitating the fertilization process.

Question 3

Chorionic villi protrude into blood-filled cavities called _____ formed within the maternal endometrium.

Accepted Answer

Lacunae are the blood-filled cavities within the maternal endometrium into which the chorionic villi protrude.

Question 4

The fluid-filled cavity in the blastocyst is called the

Accepted Answer

The fluid-filled cavity in the blastocyst is called the blastocele.

Question 5

The trophoblast

Accepted Answer

The trophoblast does form the embryonic part of the placenta and other membranes, its cells do digest uterine tissues to allow implantation, and it becomes the chorion. Additionally, the trophoblast is not just a single layer of cells around the blastocele, but rather is a differentiated layer of cells that also gives rise to other structures in the developing embryo.

Question 6

Fertilization,the union of the sperm cell and the oocyte,produces a

Accepted Answer

Fertilization involves the fusion of a haploid sperm cell and haploid oocyte, resulting in the formation of a diploid zygote with a complete set of chromosomes. Therefore, the correct answer is D) diploid zygote.

Question 7

Which of the following tissues most likely developed from the endoderm layer of the embryo?

Accepted Answer

The endoderm layer of the embryo gives rise to the lining of the digestive tract and associated organs such as the liver, pancreas, and thyroid gland. The thyroid gland is an endocrine gland that produces hormones involved in metabolic processes, and it is derived from the endoderm. The epidermis is derived from the ectoderm, muscle is derived from the mesoderm, gonads are derived from the mesoderm and germ cells, and bone is derived from the mesoderm.

Question 8

The face develops from

Accepted Answer

The face develops from five tissue masses: the frontonasal prominence, two maxillary prominences, and two mandibular prominences.

Question 9

Which of these is NOT a structure formed from neural crest cells?

Accepted Answer

The spinal cord is formed from the neural tube, not neural crest cells. The other structures listed are derived from neural crest cells.

Question 10

The chorion (later placenta)secretes

Accepted Answer

The chorion, which later forms the placenta, secretes human chorionic gonadotropin (HCG), which is important in maintaining the corpus luteum during the first trimester of pregnancy, thus ensuring sufficient levels of progesterone to support the developing embryo/fetus.

Question 11

Functions of the placenta include

Accepted Answer

The placenta performs all of the listed functions, including the production of HCG, diffusion of nutrients from the mother's blood to the embryo's blood, diffusion of waste products from the embryo's blood to the mother's blood, and production of estrogen and progesterone.

Question 12

Human chorionic gonadotropin (HCG)

Accepted Answer

HCG is a hormone produced during pregnancy by cells in the placenta. It can be detected in the blood or urine of a woman as early as 8 to 11 days after conception, making it a useful indicator of pregnancy for most pregnancy tests. HCG also plays a role in maintaining the function of the corpus luteum, which produces progesterone necessary for sustaining a pregnancy.

Question 13

The embryonic disk

Accepted Answer

The embryonic disk is composed of two layers of cells (the ectoderm and endoderm), is produced when the amniotic cavity forms, and develops a primitive streak. Therefore, all of the choices are correct.

Question 14

Which of the following tissues most likely developed from the ectoderm layer of the embryo?

Accepted Answer

The ectoderm layer of the embryo gives rise to the skin and its derivatives, including hair, nails, and glands such as sweat glands. Therefore, the epidermis of the skin would be the most likely tissue to develop from the ectoderm layer.

Question 15

Gastrulation:

Accepted Answer

Gastrulation is the process by which the blastula transforms into a gastrula with three germ layers- ectoderm, mesoderm, and endoderm. It involves cell migration, organization, and differentiation, and leads to the formation of the mesoderm among other structures.

Question 16

Implantation of the blastocyst in the uterine wall begins about _____ days after fertilization.

Accepted Answer

Implantation of the blastocyst in the uterine wall begins about 7 days after fertilization.

Question 17

The second meiotic division of the oocyte occurs

Accepted Answer

The second meiotic division of the oocyte is completed only after a sperm cell enters it, which typically occurs during fertilization.

Question 18

Which of the following tissues most likely developed from the mesoderm layer of the embryo?

Accepted Answer

The mesoderm layer of the embryo gives rise to the circulatory system, as well as muscle, bone, and other connective tissues. The epidermis of the skin comes from the ectoderm layer, while the parathyroid and thyroid glands come from the endoderm layer. The brain is derived from both the ectoderm and neural crest cells.

Question 19

The umbilical cord

Accepted Answer

The umbilical cord is a connecting stalk between the embryo and the placenta, and it has two umbilical arteries that carry blood from the embryo to the mother.

Question 20

The middle germ layer is the

Accepted Answer

The middle germ layer is called the mesoderm. It gives rise to the musculature, the circulatory system, and the connective tissues of the body. The ectoderm forms the outermost layer of the embryo and gives rise to the skin, hair, and nervous system. The endoderm forms the innermost layer and gives rise to the digestive and respiratory systems.

Quiz 20: Development, heredity, and Aging