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

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 ^

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

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 |：

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

56. In what symptoms may be resulted by damage to the corpus callosum? (A) loss of short-term memory (B) inability to integrate information from the two sides of the body (C) inability to form long-term memory (D) sleeplessness (E) loss of fine motor control

57. What does the Hardy-Weinberg expression 2pq represent? (A) the gene frequency of the dominant allele (B) the gene frequency of the recessive allele (C) the frequency of the dominant phenotype (D) the frequency of the recessive phenotype (E) the frequency of heterozygotes