50. The high osmolarity of the renal medulla is maintained by all of the following except ________.
(A) diffusion of salt from the ascending limb of the loop of Henle
(B) active transport of salt from the upper region of the ascending limb
(C) the spatial arrangement of juxtamedullary nephrons
(D) diffusion of urea from the collecting duct
(E) diffusion of salt from the descending limb of the loop of Henle .

46. A founder event favors microevolution in the founding population mainly because ________. (A) mutations are more common in a new environment (B) a small founding population is subject to extensive sampling error in the composition of its gene pool (C) the new environment is likely to be patchy, favoring diversifying selection (D) gene flow increases (E) members of a small population tend to migrate

47. Which of the following descriptions are correct? 1. Green algae — closest relative of green plants 2. Brown algae — includes the largest seaweeds 3. Diatoms — examples of stramenopiles 4. Dinoflagellates — glass, two-part shells 5. Red algae — has no flagellated stages in life cycle (A) 1234 (B) 2345 (C) 1245 (D) 1235 (E) 2345

48. Which of the following is an example of an opportunistic pathogen that can cause a mycosis? (A) Claviceps pururea, which produces ergots on rye that can cause serious symptoms in humans if milled into flour (B) Ophiostoma ulmi, which causes Dutch elin disease (C) the ascomycetes that causes ringworm (D) Candida albicans, which causes vaginal yeast infections (E) the mold Penicillium, an ascomycete that is now grown in liquid culture to produce antibiotics

49. Which of the following hormones is produced by adipose cells that helps to control appetite? (A) Insulin (B) Neuropeptide Y (C) Glucagon (D) Leptin (E) Ghrelin

51. When light strikes the pigment rhodopsin in a rod cell, retinal dissociates from opsin, initiating a signal-transduction pathway that ________. (A) depolarizes the neighboring bipolar cells and initiates an action potential in a ganglion cell (B) depolarizes the rod cell, causing it to release the neurotransmitter glutamate, which excites bipolar cells (C) hyperpolarizes the rod cell, reducing its release of glutamate, which excites some bipolarcells and inhibits others (D) hyperpolarizes the rod cell, reducing its release of glutamate, which excites amacrine cells but inhibits horizontal cells (E) converts cGMP to GMP, opening sodium channels and hyperpolarizing the membrane, causing the rhodopsin to become bleached

52. The transduction of sound waves to action potentials takes place ________. (A) within the tectorial membrane as it is stimulated by the hair cells (B) when hair cells are bent against the tectorial membrane, causing them to depolarized and release neurotransmitter molecules that stimulate sensory neurons (C) as the basilar membrane becomes more and depolarizes, initiating an action potential in a sensory neuron (D) as the basilar membrane vibrates at different frequencies in response to the varying volume of sounds (E) within the middle ear as the vibrations are amplified by the malleus, incus, and stapes

53. Which one of the following hormones could raise the level of basal metabolic rate (BMR)? (A) Calcitonin (B) Thyrocalcitonin (C) Triiodothyronine (D) Dexamethasone (E) Parathyroid hormone

【已刪除】54. Which of the following amino acid and the derivative is not proved to be a neurotransmitter? (A) Glycine (B) Glutamic acid (C) Aspartic acid (D) Gamma-aminobutyric acid (E) Histamine

55. Which of the following chemicals from plants has been using as an indicator to measure the glomerular filtration rate (GFR) in clinical, because it cannot be re-absorbed and secreted in nephron tubules. (A) Creatinin (B) Inulin (C) Digitalis (D) Colchicine (E) Alkaloids

56. Which of the following statements is true? (A) In Crassulacean acid metabolism (CAM) plants, carbon fixation and the Calvin cycle occur in the same cells at different times. The Calvin cycle of CAM plants occurs during the night, so that the Calvin cycle is also named the dark reaction. (B) Pineapples are CAM plants. (C) For C4 plants, the Calvin cycle is mainly carried out in the mesophyll cells. (D) C3 plants are more resistant to drought than C4 plants. (E) Photorespiration occurs when stomata of C3 plants are fully open during the day.