Question 1

RU-486 is an effective abortifacient.It acts by which mechanism?&#10;A) Blocking oogenesis&#10;B) Causing menstruation&#10;C) Blocking ovulation&#10;D) Causing polyspermy&#10;E) Blocking capacitation

Accepted Answer

RU-486, also known as mifepristone, acts as an effective abortifacient by blocking the action of progesterone, leading to changes in the uterine lining and causing menstruation, which results in the termination of pregnancy.

Question 2

Increase in the levels of which hormone prevents menstruation during a cycle in which fertilization occurs?&#10;A) LH&#10;B) FSH&#10;C) GnRH&#10;D) hCG&#10;E) Estrogen

Accepted Answer

When fertilization occurs, the developing embryo produces human chorionic gonadotropin (hCG) which signals the corpus luteum to continue producing progesterone and estrogen, preventing menstruation and maintaining the uterine lining to support the developing embryo.

Question 3

The birth control pill acts by blocking which process?&#10;A) Fertilization&#10;B) Ovulation&#10;C) Cleavage&#10;D) Capacitation&#10;E) Implantation

Accepted Answer

The birth control pill primarily works by suppressing ovulation, which means that it inhibits the release of an egg from the ovary. Without ovulation, fertilization cannot occur, and therefore the pill also indirectly blocks fertilization. However, it does not have a direct effect on other processes such as cleavage, capacitation, or implantation.

Question 4

A baby is diagnosed with Down syndrome shortly after birth.Which of the following events occurred abnormally during prenatal development?&#10;A) Anaphase of mitosis&#10;B) Metaphase of mitosis&#10;C) Telophase of mitosis&#10;D) Anaphase of meiosis&#10;E) Metaphase of spermatogenesis

Accepted Answer

Down syndrome is caused by the presence of an extra copy of chromosome 21, which is the result of nondisjunction during meiosis. Nondisjunction occurs during anaphase of meiosis when homologous chromosomes fail to separate properly, resulting in one cell receiving an extra copy of a chromosome and another cell receiving none.

Question 5

A newborn girl is suspected of having Turner syndrome.Which diagnostic procedure would be used to determine if this is indeed the case?&#10;A) Karotyping&#10;B) Spectral karotyping (SKY)&#10;C) Comparative genomic hybridization (CGH)&#10;D) Fluorescent in situ hybridization (FISH)

Accepted Answer

Karyotyping involves examining the chromosomes of an individual to determine if there are any abnormalities. In the case of Turner syndrome, a karyotype would show that the individual only has one X chromosome instead of two. Spectral karyotyping, comparative genomic hybridization, and fluorescent in situ hybridization are all more specialized techniques that can be used to detect specific types of genetic abnormalities, but karyotyping is the standard diagnostic test for Turner syndrome.

Question 6

Formation of haploid spermatozoa occurs during which developmental event?&#10;A) Spermiation&#10;B) Capacitation&#10;C) Spermatogenesis&#10;D) Spermiogenesis&#10;E) Fertilization

Accepted Answer

Haploid spermatozoa are formed during spermatogenesis, which is the process of sperm cell development that includes both meiosis and extensive morphological changes to produce mature spermatozoa. Spermiation is the release of mature spermatozoa into the lumen of the seminiferous tubules. Capacitation is the process by which spermatozoa become capable of fertilizing the oocyte. Spermiogenesis is the final stage of spermatogenesis during which the round spermatids differentiate into functional spermatozoa. Fertilization is the fusion of gametes to form a zygote.

Question 7

A researcher establishes mouse spermatozoa lacking one of the following two sperm-specific proteins: Izumo and CD9.Which developmental events will be perturbed in the absence of either of these proteins?

A) Spermatogenesis
B) Capacitation
C) Binding of spermatozoa to the zona pellucida
D) Fusion of the egg and spermatozoa membranes
E) Spermiogenesis

Accepted Answer

The answer of A researcher establishes mouse spermatozoa lacking one...

Question 8

A researcher knocks out expression of the POU domain transcription factor Oct4 in the early epiblast of a mouse embryo.Which cell type would you expect to be affected?&#10;A) Neural crest cells&#10;B) Neural plate cells&#10;C) Mesodermal cells&#10;D) Primordial germ cells&#10;E) Endodermal cells

Accepted Answer

Oct4 is required for the formation of the inner cell mass and subsequent formation of the germ cell lineage in mice. Therefore, knocking out its expression in the early epiblast would likely affect the development of primordial germ cells.

Question 9

A child with a large sacrococcygeal teratoma is delivered by cesarean section.The teratoma likely arose from which type of cells?&#10;A) Neuroectodermal stem cells&#10;B) Neural crest cells&#10;C) Primitive streak cells&#10;D) Primordial germ cells&#10;E) Secondary oocyte cells

Accepted Answer

The answer of A child with a large sacrococcygeal teratoma...

Question 10

A 36-year-old woman is unable to conceive a child because both her oviducts were severely scarred by pelvic inflammatory disease resulting from gonorrhea.Which type of assisted reproductive technology could be used to help her conceive?

A) Gamete intrafallopian transfer (GIFT)
B) Zygote intrafallopian transfer (ZIFT)
C) In vitro fertilization (IVF) and embryo transfer

Accepted Answer

IVF and embryo transfer would be the best choice for this woman as her oviducts are severely scarred and therefore cannot transport eggs to the uterus. IVF involves fertilizing eggs with sperm in a laboratory and then transferring the resulting embryos directly into the uterus. This bypasses the need for functional oviducts and increases the chances of pregnancy. GIFT and ZIFT both require at least one functioning oviduct, which this woman lacks.

Deck 2: Gametogenesis, Fertilization, and First Week