1. Photosynthesis & Cell Respiration Study Guide Answers
AP BIO
Photosynthesis & Cell Respiration Study Guide Answers

2. #1
C6H12O O CO H20
+ ENERGY

3. #2
1.) Glycolysis
2.) Krebs Cycle
3.) ETC

4. #3
Glycolysis

5. #4
In the cytoplasm (cytosol) of the cell

6. #5
Glucose Pyruvate
2NAD+ 2NADH ADP ATP
2 ATP
2 ADP

7. #6
2 NADH
2 Pyruvate
2 ATP (net)

8. #7
They carry high energy e- to the electron transport chain.

9. #8
Molecule B has been reduced.
Molecule A has been oxidized.

10. #9
Krebs cycle
AKA:
The Citric Acid Cycle
TCA cycle

11. #10
In the mitochondrial matrix

12. #11 Pyruvate must combine with Coenzyme A
(Co-A) (changing pyruvate to Acetyl Co-A) before entering the Krebs cycle.

13. #12
Per turn of the cycle you get:
+ 1 ATP
+ 3 NADH
+ 1 FADH2
+ 2 CO2

14. #13
2 turns (1 for each pyruvate molecule)

15. #14
2 total ATP are produced

16. #15
The Electron Transport Chain (E.T.C.)

17. #16
In the inner membranes of the mitochondria.

18. #17
They bring high energy electrons from the first two steps in cell respiration to the E.T.C.
The E.T.C. cannot run without these electrons.

19. #18
The purpose of the E.T.C. is to pump hydrogens (protons) from the matrix into the Intermembrane space in order to create a gradient for chemiosmosis so that the oxidative phosphorylation of ADP into ATP can occur.

20. #19
It is the force generated by the chemiosmotic movement of protons down a concentration gradient.
This force is used to drive the ATP synthase “motor”.

21. #20
H+ are pumped into the intermembrane space by protein pumps in the E.T.C.
Then, via chemiosmosis, the H+ travel back into the matrix through a tunnel in the ATP synthase molecule.
The force of the H+ traveling through the ATP synthase (the proton motive force) drives the “machinery” that creates ATP via oxidative phosphorylation.

22. #21
Oxygen

23. #22
ATP
Water
NAD+
FAD+

24. #23

25. #24
Fermentation is necessary if there is not enough oxygen present to run the E.T.C.
Why ?
Without O2, NADH will accumulate.
Once all the NAD+ has been converted to NADH, the Krebs cycle and glycolysis both stop. (both need NAD+ to accept e-)
End result: no ATP is produced and the cell dies.

26. #25 Alcoholic fermentation produces ethanol.
Lactic acid fermentation produces lactic acid.

27. #25 continued… Alcoholic fermentation occurs in 2 steps:
2Pyruvate Acetaldehyde CO2
2 Acetaldehyde ethanol
2NADH NAD+

28. #25 continued Lactic Acid fermentation occurs in one step:
2 Pyruvate lactate (lactic acid)
2NADH NAD+
In humans and other mammals, most lactate is transported to the liver where it is converted back into glucose when there is enough ATP

29. #26
Yeast (a fungus), plants and bacteria

30. #27
When you exercise, need more ATP. Therefore, you increase your need for oxygen.
If you exercise too hard too fast, you enter a state of oxygen “debt” – creating an anaerobic state where there is not enough O2 to run the E.T.C.
So, you begin lactic acid fermentation in order to release some NAD+.
Problem: lactic acid can be toxic to cells, which some researchers link to the pain you get during exercise.

31. #28
6 CO2 + 6 H20 + Light  glucose + 6O2

32. #29
1.) Light reactions
2.) Calvin cycle

33. #30 P680  1o e- acceptor 1st E.T.C.  P700
A 2nd 1o e- acceptor  2nd E.T.C.
 NADPH reductase  NADPH

34. #31 Cyclic only produces ATP
Non-cyclic (Linear) produces both ATP and NADPH.

35. #32 Carboxylation: Reduction: Regeneration: 6 CO2 + 6 RuBP  12 PGA
12 PGA + 12 ATP + 12 NADPH  12 G3P
Regeneration:
10 G3P + 6 ATP  6 RuBP

36. #33
2 reasons:
1.) if rubisco is fixing O2, it thereby reduces the amount of CO2 that can be fixed.
2.) RuBP + O2  destruction of RuBP via oxidation

37. #34
Through the stomata

38. #35
In hot environments, like the tropics (high daytime temps and intense sunlight), plants often have to close their stomata in order to conserve water. By closing the stomata, there is a build up of waste O2, which is then fixed by rubisco into a useless product.
To combat this, C4 plants separate their C3 and C4 pathways into separate into different parts of the leaf. CO2 is incorporated into PEP to create OAA. The OAA is converted to malate which is shuttled into the bundle sheath cells. This results in a higher rate of photosynthesis.

39. #35 continued
Because there is a higher rate of photosynthesis, the C4 plants can reduce the time that the stomata are open, thereby reducing water loss.
Example plants: sugarcane, crab grass, corn, sorghum

40. #36
Bundle sheath cells

41. #37
By storing CO2 in malic acid during the night, the CAM plants are able to run photosynthesis during the daytime with the stomata closed, greatly reducing water loss.
Example plants: cacti, pineapple, other epiphytes.

42. #38
Both take more ATP than normal C3 photosynthesis.

43. #39
It is spatially segregated because the overall effect is to move CO2 from the mesophyll cells to the bundle sheath cells.

44. #40
It is temporally segregated because the overall effect is to store CO2 so that it is only used during the day.

45. #41
At night

46. Possible essays
1.) Explain, at the molecular level, why many organisms need oxygen to survive. Also, explain how many organisms are able to survive without oxygen.
2.) Explain how ATP is produced via oxidative phosphorylation and substrate level phosphorylation. Be sure to describe locations, processes, reactants and products associated with both types.
3.) Describe the biochemical pathways of the light and dark reactions in C3 photosynthesis. Begin with a molecule of H20 and CO2 and end with a molecule of glucose.
4.) Discuss how C4 and CAM photosynthesis improves upon C3 photosynthesis. Include both advantages and disadvantages of these processes. Be sure to describe appropriate leaf anatomy in your discussion.