Biology 120 Worksheet: Chapter 3

1. Define: energy.

2. On the cellular level, what are some examples of work?

3. Name some types of energy.

4. How do autotrophic organisms get their food?

5. Plants make their food through what process?

6. Name the raw materials and the products of this process.

7. a) How do heterotrophic organisms get their food?

b) The energy generating process occurring in the cells of heterotrophs is called what?

8. a) Name the three phases of an energy system.

b) Where does the transformation phase occur?

9. a) Why do the authors state matter cycles between autotrophs and heterotrophs?

b) Does energy also cycle between them?

10. The branch of science called Thermodynamics studies what?

11. State the first law of thermodynamics.

12. Apply this law to the creation of sugar in a plant.

13. If energy seem to get "lost", what is happening to it?

14. State the second law of thermodynamics.

15. What does this law say about the efficiency of energy conversions?

16. Define: entropy.

17. Figure 3.4, p 76, shows three organisms creating or obtaining food. Describe the energy changes occurring in each organism. Refer to the role of entropy.

18. a) In an exergonic reaction, which chemicals have less energy, the reactants or products?

b) What is an example of this type of reaction?

19. What is the role of activation energy in exergonic reactions?

20. a) In an endergonic reaction, which chemicals have less energy, the reactants or products?

b) What is an example of this type of reaction?

21. Are microscopic particles ever at rest?

22. Adding heat to a material has what effect on the motion of its particles?

23. And, what effect does adding heat have on the rate of chemical reactions?

24. But, what happens if too much heat is added to particles?

25. Why are catalysts important to the health of cells?

26. What are enzymes?

27. a) Look at Figure 3.5, p 77. What landform does the diagram resemble?

b) What "construction work" is done by the catalyst?

c) And, is the reaction exer- or endergonic?

28. Define: substrate.

29. a) Which gets changed permanently during a reaction, the enzyme or the substrate?

b) Which undergoes a temporary change?

30. There are about how many types of reactions occurring in your body's cells?

31. How do enzymes increase the rate of reactions?

32. What is the important area of the enzyme?

33. How is the "induced fit" model of enzyme behavior different than the earlier "lock and key" model?

34. What is the role of coenzymes or cofactors?

35. Just how much work can an enzyme do in only 60 seconds?

36. Why do enzymes become less effective as the temperature rises above about 37⁰?

37. Also, why does the pH affect the efficiency of enzymes?

38. And, why does adding more and more substrate not cause the reaction rate to keep climbing?

39. What is the effect of competitive inhibitors?

40. What is a metabolic pathway?

41. How does feedback inhibition work?

42. The opposite of feedback inhibition is precursor activity. How does this process work?

43. Both of these processes are both examples of what type of reaction?

44. Read about the work of Dr. Penelope Codding

45. Recall: what energy changes occur during photosynthesis?

46. What plant structure absorbs the sun's energy?

47. What energy changes occur during cellular respiration?

48. In what organelle does cellular respiration occur?

49. What molecule captures the energy released during cellular respiration?

50. Where in an ATP molecule is the energy actually stored?

51. How is this energy released for use by the cell?

52. What process recreates ATP molecules?

53. What "system" controls the rate of energy release within the cell?

54. What actually moves through this system?

55. At each step in this system, what is released?

56. What two general types of chemical reactions occur within the electron transport system?

57. a) Look at Figure 3.19, p 87. What are the reactants and products of photosynthesis?

b) From where does each come?

c) Which ones are high energy? low energy?

58. Exactly where in the cell does photosynthesis occur?

59. a) Look at Figure 3.25, p 93. What are two types of anaerobic respiration?

b) In each type, what is the high energy reactant? the low energy products?

60. As you follow around the Krebs cycle, what happens to the carbon content of the carbon compounds at each step?

61. What gas is released from the Krebs cycle?

62. What liquid is taken up during the cycle?

63. Which releases more energy, anaerobic or aerobic respiration?

64. Now, go back to Figure 3.14, p 84. In what general way are photosynthesis and cellular respiration the opposite of each other?