49. A peak in_triggers ovulation on about the_day of the monthly cycle. [
(A) progesterone ... fourteenth
(B) LH ... seventh
(C) FSH ... second
(D) LH .. .fourteenth |
(E) estrogen ... twentieth

45. Fermentation is essentially glycolysis plus an extra step in which pyruvic acid is reduced to form lactic acid or alcohol ; and carbon dioxide. This last step 養 (A) removes poisonous oxygen from the environment (B) extracts a bit more energy from glucose [ (C) enables the cell to recycle NAD+ (D) inactivates toxic pyruvic acid (E) enables the cell to make pyruvic acid 奪 into substances it can use [

46. A biologist isolated a gene from a human cell, attached it to a plasmid, and inserted the plasmid into a bacterium. The I； bacterium made a new protein, but it was nothing like the protein normally produced in a human cell. Why? ; (A) the bacterium had undergone transformation (B) the gene did not have sticky ends 誓 (C) the gene contained introns (D) the gene did not come from a genomic library ; (E) the biologist should have cloned the gene first ^

47. During kidney dialysis, blood and a dialyzing solution are separated by a semipermeable membrane. For kidney dialysis to work properly, the dialyzing solution should contain  (A) a lower solute concentration than blood (B) a higher concentration of urea than blood  (C) a lower glucose concentration than blood (D) a lower concentration of urea than blood  (E) a much smaller volume of fluid than the blood passing through it 

48. It takes much longer for sex hormones and other steroids to produce their effects than it takes for nonsteroid hormones. ; Why? | (A) steroids are bigger, slower molecules (B) steroids usually must be carried longer distances by the blood ^ (C) steroids cause target cells to make new proteins, which takes time (D) steroids must relay their message via a ; second messenger (E) it takes longer for endocrine cells to make and secrete steroids ^

50. Mitosis and cytokinesis result in the formation of_, meiosis and cytokinesis result in the formation of_. (A) 4 diploid cells ... 4 haploid cells (B) 2 diploid cells …2 hap]oid cells (C) 2 diploid cells ... 4 haploid cells | (D) 2 diploid cells ...2 diploid cells (E) 4 haploid cells ...2 diploid cells |：

51. During the early development of a human embryo the_________eventually forms_________. (A) blastocoel ... arch enter on (B) epiblast...ectodermal, mesodermal, and endodermal tissues (C) epiblast... placenta (D) trophoblast... embryo proper (E) hypoblast ... amniotic cavity

52. You would expect a cell with an extensive Golgi apparatus to (A) make a lot of ATP (B) secrete a lot of material (C) move actively (D) perform photosynthesis (E) store large quantities of food

53. In a laboratory, a scientist feeds yeast cells sugar made with radioactive carbon and keeps oxygen gas out of the container. In which substance will the radioactive carbon appear first? (A) water (B) phospholipids (C) pyruvate (D) carbon dioxide (E) electron transport molecules

54. Which of the following people would probably be making the most antidiuretic hormone?   (A) a person drinking beer (B) a person swimming in a cold lake (C) a person eating salty potato chips (D) a person drinking acidic lemonade (E) none of the above - the production of anti diuretic hormone is constant 

55. The brain perceives the brightness of light by sensing (A) the voltage of action potentials in the optic nerve (B) the frequency of action potentials in the optic nerve (C) which specific rod cells are stimulated (D) how many hair cells are stimulated (E) action potentials from brightness-sensing neurons