Ch. 28 Development & Inheritance Flashcards
Sperm and ova are similar in terms of (BLANK).
A) Size.
B) Quantity produced per year.
C) Chromosome number.
D) Flagellar motility.
C) Chromosome number.
Explanation: Both sperm and ova are haploid, containing 23 chromosomes. When they fuse, the zygote becomes diploid with 46 chromosomes.
Incorrect Answers:
A) Size: The ovum is much larger than the sperm.
B) Quantity produced per year: Sperm are produced in the millions daily; only one ovum is typically ovulated per cycle.
D) Flagellar motility: Only sperm have flagella and motility; ova do not.
Although the male ejaculate contains hundreds of millions of sperm, (BLANK).
A) Most do not reach the oocyte.
B) Most are destroyed by the alkaline environment of the uterus.
C) It takes millions to penetrate the outer layers of the oocyte.
D) Most are destroyed by capacitation.
A) Most do not reach the oocyte.
Explanation: Many sperm are lost in the journey through the female reproductive tract due to acidic pH, immune response, or getting trapped in mucus.
Incorrect Answers:
B) Most are destroyed by the alkaline environment of the uterus: The uterus is supportive; it’s the acidic vaginal environment that poses more danger.
C) It takes millions to penetrate the outer layers of the oocyte: Only one sperm actually fertilizes the oocyte; others assist but don’t penetrate.
D) Most are destroyed by capacitation: Capacitation prepares sperm, but doesn’t destroy them.
As sperm first reach the oocyte, they will contact the (BLANK).
A) Acrosome.
B) Corona radiata.
C) Sperm-binding receptors.
D) Zona pellucida.
B) Corona radiata.
Explanation: This is the outermost layer of granulosa cells surrounding the oocyte and the first barrier sperm encounter.
Incorrect Answers:
A) Acrosome: This is part of the sperm, not the oocyte.
C) Sperm-binding receptors: These are in the zona pellucida and not encountered first.
D) Zona pellucida: Reached only after passing through the corona radiata.
Fusion of pronuclei occurs during (BLANK).
A) Spermatogenesis.
B) Ovulation.
C) Fertilization.
D) Capacitation.
C) Fertilization.
Explanation: Pronuclear fusion (male and female) completes fertilization by forming a diploid zygote.
Incorrect Answers:
A) Spermatogenesis: This is sperm production in the testes.
B) Ovulation: Refers to oocyte release from the ovary.
D) Capacitation: A process that prepares sperm but does not involve pronuclei.
Sperm must first complete (BLANK) to enable the fertilization of an oocyte.
A) Capacitation.
B) The acrosomal reaction.
C) The cortical reaction.
D) The fast block.
A) Capacitation.
Explanation: Capacitation is a necessary maturation step that makes sperm capable of the acrosomal reaction. Sperm capacitation is the process that spermatozoa undergo to gain the ability to penetrate and fertilize an egg.
Incorrect Answers:
B) The acrosomal reaction: Happens after capacitation.
C) The cortical reaction: Happens in the oocyte after sperm entry to prevent polyspermy.
D) The fast block: Also prevents polyspermy, not related to sperm preparation.
Cleavage produces daughter cells called (BLANK).
A) Trophoblasts.
B) Blastocysts.
C) Morulae.
D) Blastomeres.
D) Blastomeres.
Explanation: Cleavage divides the zygote into smaller cells called blastomeres without increasing overall size.
Incorrect Answers:
A) Trophoblasts: Develop later from the blastocyst.
B) Blastocysts: A structure that forms after cleavage.
C) Morulae: A solid mass of blastomeres, not the individual cells.
The conceptus, upon reaching the uterus, first (BLANK).
A) Implants.
B) Divides.
C) Disintegrates.
D) Hatches.
B) Divides.
Explanation: As the conceptus travels down the uterine tube, it undergoes mitotic divisions (cleavage). Upon entering the uterus, division continues forming a morula and then a blastocyst.
Incorrect Answers:
A) Implants: Happens a few days later after hatching.
C) Disintegrates: Not part of typical development.
D) Hatches: Occurs just before implantation.
The inner cell mass of the blastocyst is destined to become the (BLANK).
A) Embryo.
B) Trophoblast.
C) Chorionic villi.
D) Placenta.
A) Embryo.
Explanation: The inner cell mass gives rise to the embryo proper.
Incorrect Answers:
B) Trophoblast: Becomes part of the placenta.
C) Chorionic villi: Arise from trophoblast tissue.
D) Placenta: Mainly forms from trophoblast and maternal endometrium.
Which primary germ layer gave rise to the cells that eventually became the central nervous system?
A) Endoderm.
B) Ectoderm.
C) Acrosome.
D) Mesoderm.
B) Ectoderm.
Explanation: The ectoderm gives rise to the epidermis and entire nervous system.
Incorrect Answers:
A) Endoderm: Forms internal organs like the digestive tract.
C) Acrosome: Not a germ layer; it’s part of the sperm.
D) Mesoderm: Gives rise to muscles, bones, circulatory system.
What would happen if the trophoblast did not secrete hCG upon implantation of the blastocyst?
A) The cells would not continue to divide.
B) The corpus luteum would continue to produce progesterone and estrogen.
C) Menses would flush the blastocyst out of the uterus.
D) The uterine mucosa would not envelop the blastocyst.
C) Menses would flush the blastocyst out of the uterus.
Explanation: hCG maintains the corpus luteum to keep progesterone levels high. Without it, progesterone drops and menstruation begins.
Incorrect Answers:
A) Cell division continues regardless of hCG.
B) The corpus luteum regresses without hCG.
D) Envelopment depends on progesterone, which drops without hCG.
During what process does the amnion envelop the embryo?
A) Embryonic folding.
B) Gastrulation.
C) Implantation.
D) Organogenesis.
A) Embryonic folding.
Explanation: During embryonic folding, the embryo becomes 3D and is surrounded by the amnion.
Incorrect Answers:
B) Gastrulation: Formation of germ layers.
C) Implantation: Occurs earlier as blastocyst embeds in uterus.
D) Organogenesis: Occurs after folding.
The placenta is formed from (BLANK).
A) The embryo’s mesenchymal cells.
B) The mother’s endometrium only.
C) The mother’s endometrium and the embryo’s chorionic membrane.
D) The mother’s endometrium and the embryo’s umbilical cord.
C) The mother’s endometrium and the embryo’s chorionic membrane.
Explanation: Chorion (from trophoblast) and maternal endometrium form the placenta.
Incorrect Answers:
A) Mesenchymal cells form connective tissues.
B) Endometrium alone is not sufficient.
D) Umbilical cord connects to but does not form the placenta.
A (BLANK) is a term for the conceptus at the developmental stage that consists of about 100 cells shaped into an inner cell mass that is fated to become the embryo and an outer trophoblast that is fated to become the associated fetal membranes and placenta.
A) Blastomere.
B) Blastocell.
C) Blastocoel.
D) Blastocyst.
D) Blastocyst.
Explanation: The blastocyst is the stage with an inner cell mass and trophoblast layer.
Incorrect Answers:
A) Blastomere: A single cell from early cleavage.
B) Blastocell: Not a valid term.
C) Blastocoel: Fluid-filled cavity within the blastocyst.
The foramen ovale causes the fetal circulatory system to bypass the (BLANK).
A) Liver.
B) Lungs.
C) Kidneys.
D) Gonads.
B) Lungs.
Explanation: The foramen ovale allows blood to flow from the right atrium to the left atrium, bypassing the non-functional fetal lungs.
Incorrect Answers:
A) Liver: Bypassed by the ductus venosus.
C) Kidneys: Not bypassed by a fetal shunt.
D) Gonads: Not part of the fetal shunting system.
What happens to the urine excreted by the fetus when the kidneys begin to function?
A) The umbilical cord carries it to the placenta for removal.
B) The endometrium absorbs it.
C) It adds to the amniotic fluid.
D) It is turned into meconium.
C) It adds to the amniotic fluid.
Explanation: Fetal urine contributes significantly to the volume of amniotic fluid in the second and third trimesters.
Incorrect Answers:
A) Umbilical cord…: Metabolic waste like urea is filtered by the placenta, but urine is released into the amniotic sac.
B) Endometrium absorbs it: The urine stays within the amniotic sac.
D) Meconium: Meconium is the fetus’s feces, not urine.
During weeks 9–12 of fetal development, (BLANK).
A) Bone marrow begins to assume erythrocyte production.
B) Meconium begins to accumulate in the intestines.
C) Surfactant production begins in the fetal lungs.
D) The spinal cord begins to be myelinated.
A) Bone marrow begins to assume erythrocyte production.
Explanation: Around weeks 9–12, red blood cell production shifts from the liver and spleen to the bone marrow.
Incorrect Answers:
B) Meconium accumulation: Occurs later, during the second trimester.
C) Surfactant production: Begins around week 24.
D) Spinal cord myelination: Begins in the third trimester.
Progesterone secreted by the placenta suppresses (BLANK) to prevent maturation of ovarian follicles.
A) LH and estrogen.
B) hCG and FSH.
C) FSH and LH.
D) Estrogen and hCG.
C) FSH and LH.
Explanation: FSH and LH stimulate follicle development and ovulation, which must be suppressed during pregnancy.
Incorrect Answers:
A) LH and estrogen: Estrogen is produced during pregnancy and is not suppressed.
B) hCG and FSH: hCG supports the pregnancy and is not suppressed.
D) Estrogen and hCG: Both are active and necessary during pregnancy.
Which of the following is a possible culprit of “morning sickness”?
A) Increased minute respiration.
B) Decreased intestinal peristalsis.
C) Decreased aldosterone secretion.
D) Increased blood volume.
B) Decreased intestinal peristalsis.
Explanation: Progesterone slows down GI motility, leading to nausea and vomiting.
Incorrect Answers:
A) Increased minute respiration: Helps with oxygen exchange; unrelated to GI issues.
C) Decreased aldosterone secretion: Aldosterone increases during pregnancy.
D) Increased blood volume: Not directly linked to nausea.
How does the decrease in progesterone at the last weeks of pregnancy help to bring on labor?
A) Stimulating FSH production.
B) Decreasing the levels of estrogens.
C) Dilating the cervix.
D) Decreasing the inhibition of uterine contractility.
D) Decreasing the inhibition of uterine contractility.
Explanation: Progesterone suppresses contractions; its decline permits the uterus to contract and initiate labor.
Incorrect Answers:
A) Stimulating FSH: FSH relates to follicle development, not labor.
B) Decreasing estrogens: Estrogen increases at term and helps prepare for labor.
C) Dilating the cervix: Happens during labor, not caused by progesterone drop.
Which of these fetal presentations is the easiest for vaginal birth?
A) Complete breech.
B) Vertex occiput anterior.
C) Frank breech.
D) Vertex occiput posterior.
B) Vertex occiput anterior.
Explanation: This head-down, face-toward-spine position is optimal for vaginal delivery.
Incorrect Answers:
A) Complete breech: Buttocks and feet come first—less ideal.
C) Frank breech: Feet up, buttocks down—often requires C-section.
D) Vertex occiput posterior: Head-first but facing up—can lead to longer labor.
Which of these shunts exists between the right and left atria?
A) Foramen ovale.
B) Ductus venosus.
C) Ductus arteriosus.
D) Foramen venosus.
A) Foramen ovale.
Explanation: The foramen ovale allows blood to bypass the fetal lungs by flowing directly from the right atrium to the left atrium.
Incorrect Answers:
B) Ductus venosus: Connects the umbilical vein to the inferior vena cava to bypass the liver.
C) Ductus arteriosus: Connects the pulmonary artery to the aorta.
D) Foramen venosus: Not a real anatomical structure.
Why is brown fat important?
A) It is the newborn’s primary source of insulation.
B) It can be broken down to generate heat for thermoregulation.
C) It can be broken down for energy between feedings.
D) It can be converted to white fat.
B) It can be broken down to generate heat for thermoregulation.
Explanation: Brown fat is metabolically active and helps newborns regulate body temperature by producing heat without shivering.
Incorrect Answers:
A) Primary insulation: Subcutaneous white fat is the main insulator.
C) Energy between feedings: Brown fat specializes in heat, not energy storage.
D) Converted to white fat: This is not a typical physiological process.
Constriction of umbilical blood vessels during vaginal birth (BLANK).
A) Causes respiratory alkalosis.
B) Inhibits the respiratory center in the brain.
C) Elevates carbon dioxide levels in the blood.
D) Both A and B.
C) Elevates carbon dioxide levels in the blood.
Explanation: CO₂ buildup stimulates the newborn’s respiratory center to initiate the first breath.
Incorrect Answers:
A) Causes respiratory alkalosis: Actually, CO₂ buildup leads to acidosis.
B) Inhibits the respiratory center: It activates the center, not inhibits it.
D) Both A and B: Both are incorrect.
Alveoli are connected to the lactiferous sinuses by (BLANK).
A) Lactocytes.
B) Lactiferous ducts.
C) Nipple pores.
D) Lobules.
B) Lactiferous ducts.
Explanation: These ducts carry milk from alveoli to the lactiferous sinuses and eventually to the nipple.
Incorrect Answers:
A) Lactocytes: These are the milk-producing cells, not ducts.
C) Nipple pores: These are the final openings of the ducts on the nipple surface.
D) Lobules: Clusters of alveoli, not conduits for milk transport.
