Biolgoy Sect 1

Section 51-1 VOCABULARY REVIEW 1. Target cells are the specific cells that are affected by a hormone. 2. A second messenger is an intracellular molecule that amplifies the signal of a first messenger. 3. A prostaglandin is a lipid that regulates the activity of cells that are in close proximity to its site of production. 4. Hormones are molecules that are secreted in small amounts, circulate in the bloodstream, and affect distant target cells. MULTIPLE CHOICE 1. d 2. c 3. a 4. c 5. c SHORT ANSWER 1. A first messenger binds to cell surface receptors and stimulates production of a second messenger hat is located within the target cell. 2. Hormones are transported in the bloodstream. 3. No; they have ducts and secrete sweat, not hormones. 4. It depends on the enzymes and other proteins that c-AMP activates to change the function of the cell. STRUCTURES AND FUNCTIONS 1. Anti-C antibody prevents the hormone’s action. 2. No; the fact that three of the antibodies do not alter the hormone’s action is evidence that it is not simply the binding of an antibody that disrupts the action of the hormone. 3. Segment C is probably the receptor binding portion of the hormone. Section 51-2 VOCABULARY REVIEW . Hypothyroidism results from a thyroid-hormone deficiency, but hypoglycemia results from excessive insulin. 2. Epinephrine and norepinephrine are both secreted from the medulla of the adrenal glands. 3. Releasing hormones are produced by the hypothalamus and control the secretion of luteinizing hormone. 4. Neurosecretory cells of the hypothalamus produce oxytocin and antidiuretic hormone. 5. Estrogen, progesterone, and testosterone are all steroid sex hormones secreted by the gonads. MULTIPLE CHOICE 1. d 2. a 3. c 4. d 5. b SHORT ANSWER 1. No; the hypothalamus is a structure of the nervous ystem that regulates the pituitary gland. 2. The thyroid glands secrete calcitonin, which lowers blood levels of calcium, and the parathyroid glands secrete parathyroid hormone, which raises blood levels of calcium. 3. The thymus gland aids the immune system by contributing to the development of T cells. 4. Oxytocin and antidiuretic hormone (ADH), are produced in the hypothalamus by neurosecretory cells. Oxytocin stimulates uterine contractions during childbirth, and ADH stimulates water reabsorption in the kidneys. 5. Insulin hormone deficiency causes Type I diabetes mellitus.

Type I can be differentiated from Type II diabetes mellitus by an injection of insulin; the symptoms of Type I will be relieved, while the insulin injection will have no effect on the symptoms of Type II. STRUCTURES AND FUNCTIONS 1. D 2. A 3. E 4. F 5. B 6. C Section 51-3 VOCABULARY REVIEW 1. Antagonistic hormones are hormones that have opposite effects on the concentrations of substances that they regulate. 44 HRW material copyrighted under notice appearing earlier in this work. Modern Biology Study Guide Answer Key 2. A feedback mechanism is a series of events in which the last step controls the first step. . In negative feedback, the last step inhibits the first step. 4. In positive feedback, the last step stimulates the first step. MULTIPLE CHOICE 1. d 2. a 3. c 4. c 5. b SHORT ANSWER 1. Based on the information provided, the defective organ would be the testis because excessive LH was being secreted. The negative feedback mechanism was attempting to increase the low level of testosterone. Therefore, the LH concentration was above normal. 2. Hormone concentrations would increase steadily and without inhibition. 3. The TSH level should be above normal because the negative feedback mechanism would attempt o normalize the thyroid hormone levels by increasing stimulation. STRUCTURES AND FUNCTIONS 1. In Situation 1, the receptors of Cell M are defective. There is no Cell M secretion, indicating that hormone secreted by Cell D is required to stimulate Cell M. Cell D secretion increases due to its attempt to increase the level of Cell M secretion to normal. Both of these responses indicate that Cell D secretes the regulating hormone. 2. In Situation 2, the receptors of Cell D are defective. Cell D secretion is increased because it is unable to detect hormone secreted by Cell M. In response to he increased levels of Cell D hormones, Cell M secretions increase. Section 52-1 VOCABULARY REVIEW 1. Semen contains sperm and the secretions of three exocrine glands-the seminal vesicles, the bulbourethral glands, and the prostate gland. 2. The testes are the gamete-producing organs of the male reproductive system. 3. Ejaculation is the forceful expulsion of semen from the penis. 4. Seminiferous tubules are the specialized compartments of the testes in which sperm are produced. 5. Sperm complete development within each epididymis, which is closely attached to each testis. MULTIPLE CHOICE . c 2. c 3. c 4. c 5. d SHORT ANSWER 1. Sperm move from the seminiferous tubules to the epididymis, through the vas deferens and urethra, and out of the penis. 2. Semen is composed of sperm and secretions from three exocrine glands-the seminal vesicles, bulbourethral glands, and the prostate gland. 3. Seminiferous tubules are located in the testes- the vas deferens is not; there is more than one seminiferous tubule-there is only one vas deferens; seminiferous tubules have meiotic cells in their walls-the vas deferens does not; and the vas deferens has abundant smooth muscle cells in ts wall-seminiferous tubules do not. 4. The sperm’s flagellum enables it to swim to an egg, and its head contains digestive enzymes that help it penetrate the egg’s outer layers. 5. Yes; androgens, including testosterone, are required for the successful completion of spermatogenesis. Therefore, it is advantageous that the source of androgens be within the testes to ensure the success of spermatogenesis. STRUCTURES AND FUNCTIONS 1. a, vas deferens; b, seminiferous tubule; c, epididymis 2. a, mature; b, immature; c, immature Section 52-2 VOCABULARY REVIEW 1. Ovulation occurs when an ovum, or mature egg, is eleased from an ovary into the fallopian tube. 2. A woman stops menstruating when her follicles have either ruptured or degenerated. This is called menopause. 3. The uterus is the site of fetal development. During childbirth, the fetus passes through the cervix, which dilates, and then through the vagina. 4. The follicular phase is a stage of the menstrual cycle. 5. The luteal phase is the stage of the menstrual cycle during which the corpus luteum begins to secrete large amounts of progesterone and estrogen. MULTIPLE CHOICE 1. a 2. d 3. b 4. c 5. a SHORT ANSWER 1. Male and female gametes contribute equal numbers f chromosomes to the fertilized egg. Without the diploid number of chromosomes, the fertilized egg usually will not survive. 2. An egg is a round cell, a sperm is an elongated cell; a sperm has a flagellum, an egg does not have a flagellum; a sperm has a midpiece encircled by mitochondria, an egg does not have a midpiece; an egg has a normal amount of cytoplasm, a sperm has almost no cytoplasm; an egg is larger than sperm; and a sperm has a condensed elongated nucleus, an egg has a round nucleus. 3. At menopause, most of the follicles have either ruptured or degenerated. Students should be able o deduce that without follicles, there are no eggs. STRUCTURES AND FUNCTIONS 1. In figure a, FSH stimulates follicular cells within the ovary during the follicular phase of the menstrual cycle. In figure b, a corpus luteum within the ovary secretes progesterone during the luteal phase. In figure c, the uterine lining sloughs off during menstruation. In figure d, an egg is ovulated from an ovarian follicle during ovulation. In figure e, estrogen stimulates the reestablishment of the uterine lining during the follicular phase. Section 52-3 VOCABULARY REVIEW 1. Human chorionic gonadotropin is a hormone ecreted by the placenta that stimulates further hormone production in the corpus luteum. 2. Implantation is the beginning of pregnancy when the blastocyst embeds into the uterine lining. 3. Chorionic villi are the part of the placenta that extend into the uterine lining. 4. The umbilical cord consists of fetal arteries and veins that transport nutrients from the mother to the fetus and waste products from the fetus to the mother via the placenta. 5. The fluid-filled amniotic sac surrounds the embryo and cushions it from injury. MULTIPLE CHOICE 1. c 2. c 3. d 4. b 5. c SHORT ANSWER 1.

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Estrogen and progesterone inhibit the secretion of LH and FSH. A negative feedback mechanism exists between the female sex hormones and LH and FSH. Without FSH, new follicles do not develop and eggs are not prepared for ovulation. 2. All three structures are involved in the transfer of nutrients and waste products between the fetus and mother. Blood vessels originating from the allantois (one of the four embryonic membranes) extend into the chorionic villi. The combination of the chorionic villi and the portions of the uterine lining into which they extend is called the placenta. 3.

Estrogen maintains the uterine lining throughout development, ensuring the protection and nourishment of the fetus. 4. An egg must be fertilized, then the zygote must undergo a series of mitotic divisions (called cleavage) that produce a morula and finally a blastocyst. Buildup of the uterine lining must occur prior to implantation. 5. Human chorionic gonadotropin (HCG); HCG is only produced by the placenta. Consequently, HCG is a pregnancy-specific hormone. STRUCTURES AND FUNCTIONS 1. a, fallopian tube; b, ovary; c, vagina; d, uterus 2. blastocyst-d; zygote-a; corpus luteum- b; fertilization-a

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