25. When DNA is compacted by histones into 10 nm and 30 nm fibers, the DNA is unable to interact wit
27. Which of the following is a correct statement about nitrogen fixation in root nodules?(A) The pl
28. In animals, embryonic stem cells differ from adult stem cells in that(A) embryonic stem cells ar
29. Which of the following best describes siRNA?(A) a short double-stranded RNA, one of whose strand
30. Which of the following series best reflects what we know about how the flu virus moves between s
31. Biofuels are mainly produced by:(A) plants that convert hemicellulose into gasoline.(B) the brea
33. All of the following are responses of plants to cold stress except:(A) the production of a speci
34. Processing of filtrate in the proximal and distal tubules accomplishes what important function?(
35. Your bone cells, muscle cells and skin cells look different because(A) they contain different nu
37. Biologists have discovered how to put together a bacteriophage with the protein coat of phage T2
38. Which of the following hormones have antagonistic (opposing) effects?(A) growth hormone and epin
40. Which of these statements about gamma interferon is false?(A) It stimulates the immune system to
41. Which of these statements about intrinsic factor is false?(A) It helps prevent pernicious anemia
42. Which of the following would tend to reduce the concentration of lactic acid that accumulates in
43. Which of these statements about fat digestion and absorption is false?(A) Triglycerides are resy
44. Moment-to-moment changes in total peripheral resistance are normally due to changes in(A) the vi
45. The motor end plate is(A) the specialized region of an effector organ innervated by an autonomic
46. Which of the following is most likely to cause a decrease in the stroke volume of the left ventr
47. Lymphatic capillaries differ from blood capillaries in that(A) lymphatic capillaries are not con