Alberta Biology 30: Reproduction & Development Questions and Answers Graded A

Alberta Biology 30: Reproduction & Development Questions and Answers Graded A What is the difference between primary and secondary sex characteristics? primary = direct role in reproduction (gonads) secondary = features that distinguish the two sexes; develop at puberty What is the process of creating a zygote called? How many chromosomes does it have? fertilization; 46 chromosomes What kinds of sex chromosomes can a sperm contribute? An egg? sperm = X or Y egg = only X What is the function of the scrotum? highly elastic skin; holds testes outside of body for optimal sperm production What is the function of the seminiferous tubules? Where are they found? produce sperm in response to FSH; found in testes What is the function of the interstitial cells? Where are they found? produce testosterone in response to LH; found in testes (between sem. tubules) What is the function of the epididymis? site of sperm maturation and storage What is the function of the vas deferens? tubes; carry sperm from epididymis to urethra; cut and tied during a vasectomy What is the function of the Seminal vesicles? produce Sugar which nourishes sperm & increases motility; produces prostaglandins which stimulate uterine contractions (aids the movement of sperm cells) What is the function of the ejactulatory duct? regulates release of sperm into urethra What is the function of the prostate gland? produces basic mucus to protect sperm from acidity of vagina What is the function of the Cowper's gland? produces basic mucus that Cleans the urethra of acidic urine What is the composition of semen? sperm, sugar (fructose), basic mucus, prostaglandins Name the glands that contribute to the composition of semen. testes, seminal vesicles, prostate gland, Cowper's gland Which gland contributes a cellular component of semen? only the testes What is spermatogenesis? What are the products? production of sperm in response to FSH; meiosis that occurs in the sem. tubules; produces four equal sized daughter cells What is the function of the Sertoli cells? nourish/protect the sperm; have FSH receptors; make inhibin (prevents spermatogenesis during childhood) *not curricular* Name the three parts of sperm and their functions. head = contains acrosome with digestive enzymes to help penetrate the egg & 23 chromosomes midpiece = contain mitochondria to power the flagellum tail = aka flagellum; moves sperm What is the function of the ovaries? produces an egg within the follicles in response to FSH; site of ovulation in response to LH What is the function of the fallopian tubes? carry ovum towards uterus; normal site of fertilization; cut & tied during tubal ligation What is the function of the uterus? implantation of zygote in the endometrium What is the function of the cervix? muscular ring; hold developing fetus in uterus; dilates during birth What is the function of the vagina? muscular, elastic canal; used for intercourse, birth and menstruation What is oogenesis? What are the products? production of eggs in response to FSH; asymmetrical form of meiosis; starts within follicles; produces 4 unequal daughter cells (1 useable gamete and 3 polar bodies) What is ovulation? release of egg from follicles in response to LH on approx. day 14 of menstrual cycle What are the 4 phases of the menstrual cycle? Flow, follicular, ovulatory, luteal Describe the flow phase of the menstrual cycle. if pregnancy did not occur, corpus luteum degenerates; secretions of estrogen & progesterone decrease; causes uterine contractions and shedding of endometrium Describe the follicular phase of the menstrual cycle. follicles within ovary develop in response to FSH; secretes estrogen which initiates development of endometrium. Describe the ovulatory phase of the menstrual cycle. DAY 14: the egg ruptures from follicle into fallopian tube in response to LH; remaining follicular cells develop into corpus luteum Describe the luteal phase of the menstrual cycle. corpus luteum produces estrogen (thickens endometrium) and progesterone (prevents contractions) What kind of feedback does estrogen have on FSH? negative; inhibits production What kind of feedback does estrogen have on LH? positive; increases production What kind of feedback does progesterone have on LH? negative; inhibits production What two hormones are typically found in a birth control pill? estrogen and progesterone What kinds of twins are produced from the release and fertilization of two separate eggs? fraternal (dizygotic) twins What kinds of twins are produced from the release and fertilization of one egg that splits into two cell masses? identical (monozygotic) twins What happens to the zygote shortly after fertilization? cleavage; a series of cell divisions without growth What is a blastocyst? zygote forms a hollow ball; inner cells form embryo; outer cells form extra embryonic membranes What is the term for the period from implantation to parturition? gestation What is gastrulation? blastocyst develops into a three layered disc called a gastrula Name the three layers of the gastrula. outer layer = ectoderm = skin, nervous system middle layer = mesoderm = skeleton, muscles, reproductive structures inner layer = endoderm = linings of digestive and respiratory tracts, endocrine glands What is the function of the chorion? embryonic portion of the placenta; secretes hCG; maintains corpus luteum What is the function of the amnion? filled with amniotic fluid; prevents shock to embryo; regulates body temperature, prevents infection, allows movement What is the function of the yolk sac? no nutritive purpose in humans; site of early RBC formation What is the function of the placenta? site of gas, nutrient, mineral, hormone, antibody, waste exchange; produces hormones (estrogen, progesterone, hCG and relaxin); acts as barrier to most except teratogenic agents Describe what happens to levels of hormones during parturition. estrogen/progesterone levels decrease; levels of prostaglandins/relaxin/oxytocin increase What produces relaxin? What is it's purpose? produced by placenta; causes relaxation of pelvic ligaments & widening of birth canal What is the function of prostaglandins and oxytocin during parturition? cause uterine contractions What are the two hormones that participate in lactation? prolactin = produces milk oxytocin = releases milk