29. a
30. c
31. n/a

39. b         
40. a
41. a
42. a
43. d
44. a
45. d
46. b
47. a
48. a
49. c
50 in extreme environments
51. c
52. a
53. b
54. c
55. c
56. b
57. a
58. d
59. a
60. a
61. a
62. c
63. c
64. a
65. a
66. c
67. b
68. d
69. a
70. a
71. d
72. a

DNA is made up of nitrogen bases and looks like a ladder, a spiral staircase, or a zipper
adenine-thymine
cytosine-guanine
Genetic disorders are caused by mutations
mutations can be insignificant unless they affect an organisms ability to survive