1. Chapter 19; Natural Systems and Interactions

2. B 9. B C
D A A
B C B
C D 20.C
D A A
C B C
D A 23.B
A A D

3. 25. A 33. Dissolved Oxygen, temp 26. C 34. What it eats determines 27
25. A 33. Dissolved Oxygen, temp 26. C 34. What it eats determines 27. C where it can live 28. A 35.Not enough water limits 29. D how many trees can grow 30. C 36.salt/Temp/sunlight - determine 31. D what food lives there 32. Biotic – living; fish, grass Abiotic – nonliving; rock, soil

4. 37. More resources available
40. Slower increase
41. same habitat = same food; survival of the fittest
42. B

5. 43. B 44. Mouse – grass, grain - water , shelter 45
43. B 44. Mouse – grass, grain - water , shelter 45. Both harm organism, one kills, one usually only harms 46. C 47. D 48. B 49. B 50. flooding