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Reproductive System Concept Questions
1. It is important that only one sperm fertilize an egg. What would be the result if multiple spermfertilized a single egg? (If more than one sperm fertilized an egg, the zygote would have an extra set ofchromosomes (i.e.
, it would be polyploid).)2. Explain how each of the following could be described as an adaptation that helps to ensure fertilization:a) seminal fluid (Seminal fluid provides hormones and other components to protect sperm and helpthem move through the female reproductive tract.)b) production of millions of sperm (Producing millions of sperm increases the chance that one willreach the egg.)c) cilia lining the walls of the oviducts. (Cilia help to sweep the egg through the oviduct toward thesperm.)3. Before birth, the male testes descend from the abdominal cavity into the scrotum. Explain why testesthat fail to descend cannot produce sperm. (It is too warm in the body cavity for sperm to formcorrectly.)4. Why is the ejaculatory duct important to help increase the chance of fertilization? (Sperm and urineboth pass through the urethra. The duct prevents passage of both at the same time as urine in the vaginawould be toxic to sperm.)5. All humans start out as females but those with a y chromosome become males during early embryonicdevelopment. As we would expect, females and males have analogous structures that have slightlydifferent functions. Which female structure is analogous to the malea) testes? (Ovaries.)b) vas deferens? (Oviducts.)c) penis? (Clitoris.)6. Most ectopic pregnancies are tubal. Explain why they are dangerous. (The oviduct cannot expand toaccommodate the growing fetus like the uterus can so internal bleeding occurs. It can be fatal if notdetected.)7. The fetus is unable to breathe oxygen or eat in utero
. What important substances must pass through theplacenta? (Nutrients and oxygen pass from the mother to the fetus while wastes and carbon dioxidemust be removed. Some antibodies are also able to cross the placenta.)8. Sometimes physical trauma to the mother can affect the fetus. How would partial detachment of theplacenta from the endometrium affect the fetus? (The fetus would not get sufficient nutrition so lowerbirth weight could result.)9. Suppose a woman’s oviducts were blocked.
a) Would she produce ova? (Yes.)b) Could she become pregnant? (No, except by medical intervention.)10. a) When is the fertile period during the menstrual cycle? (The fertile period is 10-14 days after thefirst day of the last flow phase.)b) Why is the female only fertile during this period? (The egg is only present and viable for about 48hours after ovulation.)11. Why is estrogen at its highest just before ovulation and why is this important? (Estrogen is producedby the follicle throughout follicular phase so it is highest at the end of the phaser. It causes thickening ofthe endometrium and triggers the release of LH.)12. Explain how negative feedback regulates the level of FSH during the menstrual cycle. (FSH causesa follicle to develop, leading to ovulation. After ovulation the corpus luteum keeps the progesteroneconcentration high, suppressing FSH, so a second egg is not released. If fertilization does not occur thecorpus luteum disintegrates and progesterone falls, allowing FSH to accumulate again.)13. What hormone changes trigger the beginning of a new menstrual cycle? (Progesterone from the
corpus luteum inhibits the hypothalamus and pituitary. The resulting decline in LH causing the corpusluteum to disintegrate. Without the corpus luteum, there is a drop in progesterone which releases thepituitary and hypothalamus from inhibition so FSH is produced again. The surge in FSH triggers a new ovarian cycle. The lack of progesterone triggers contractions of the myometrium, starting flow phase.)14. What would happen if the corpus luteum disintegrated during pregnancy? (Progesterone would not beproduced so the uterine wall would be shed, terminating pregnancy.)15. Explain why it is important that the menstrual cycle is stopped during pregnancy and how hormoneinteractions achieve this. (The embryo releases hCG which maintains the corpus luteum so thatprogesterone production continues. Without progesterone, contractions of the myometrium would beginand the embryo would be shed with the endometrium.)16. a) How does the birth control pill prevent pregnancy? (The birth control pill contains estrogen andprogesterone which inhibit the hypothalamus and pituitary, inhibiting the release of FSH, therebypreventing ovulation.)b) Why would a woman not take birth control pills for the entire 28 days of the menstrual cycle? (Theconcentration of progesterone and estrogen must be allowed to decline to induce flow phase at the end ofthe cycle.)c) On which days of the menstrual cycle would the pill not be taken? (The sugar pills replace thehormone pills for the last 7 (or for some brands, 4) days of the cycle, allowing flow phase.)17. Why do you think doctors recommend that women avoid most medications and alcohol duringpregnancy? (During pregnancy, especially early development, the fetus is sensitive to potentiallyharmful molecules that can cross the placenta.)18. Can a woman who has reached menopause ever become pregnant? Explain. (Not naturally (althoughsome cases of pregnancy during the first few months of menopause have been reported) because ovulationstops.)19. If a woman is past her due date or complications are suspected, her obstetrician might induce labor.
How do you think this could be done? (Drugs which mimic oxytocin trigger the contractions which leadto childbirth.)
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