1. AP BIO is
TOOOOOO HOT...

2. what if it is tooo
hot????

3. Alternatives to “C-3”
this is the “normal” way of photosynthesis.

4. Alternatives to C-3 fixation
gas exchange in stomata-- only occurs across a moist surface.
In hot dry conditions stomata close in order to conserve H2O:

5. Why would this be bad for photosynthesis??

6. Alternatives to C-3 fixation
CO2 intake decreases
O2 content increases.

8. Photosynthetic Yield
reduced

10. C-4 Photorespiration: Stomates close during the day to save water
In HOT / DRY climates
Stomates close during the day to save water
……………………low CO2

11. ex.

13. THAT IS DIFFERENT!! Isn’t it
C-4 Photorespiration:
These plants have different types of photosynthetic cells:
THAT IS DIFFERENT!! Isn’t it

14. Higher affinity for CO2 than RUBISCO

15. C-4 Photorespiration: C-C-C-C in mesophyll:
PEP (enzyme) has a higher affinity for CO2 than Rubisco.
1)PEP “fixes” C, & forms a 4-C compound as the 1st product “OX”.
C-C-C-C

16. C-C-C-C

17. Higher affinity for CO2 than RUBISCO

18. C-4 Photorespiration:
2)NADPH converts the 4-C to 2nd product (malate) and exports it to bundle sheath.

20. 3) 4-C releases CO2 to “the Calvin”
C-4 Photorespiration:
3) 4-C releases CO2 to “the Calvin”
the “Calvin”
occurs in bundle sheath.

21. C-4 Photorespiration: 4) CO2 combines with rubisco
5) the usual Calvin cycle begins.
**pyruvate returns to mesophyll cells.

23. CAM
plants

24. CAM Plants (Xeric conditions):
1)Open stomata at night (cooler) & close them during day--> reduces H2O loss during HOT DAY

25. CAM Plants (Xeric conditions):
1)Open stomata at night (cooler) & close them during day--> reduces H2O loss/ problem: cannot fix CO2 (b/c no night to run the light reaction)

27. CAM Plants (Xeric conditions):
1)Open stomata at night (cooler) & close them during day--> reduces H2O loss/cannot fix CO2 (no light)
2)Take in CO2 at night and “fixes” the CO2 into another molecule….

28. C-C-C-C

29. CAM Plants (Xeric conditions):
3)Then incorporates it into Malate (4-C).

30. CAM Plants:
4)Malate stored until morning.

31. CAM Plants:
5)CO2 released from the Malate.

32. CAM Plants:
6)The CO2 then moves to the Calvin Cycle.

35. C3 plants are those that “do the Calvin”…
Photorespiration C3 plants:
Rubisco accepts O2 in place of CO2.
2)O2 is added to the Calvin Cycle instead of CO2.
C3 plants are those that “do the Calvin”…

36. Photorespiration C-3:
3)2-C compound is made (w/ oxygen attached) and exported from the chloroplast.
4)mitochondria and peroxisomes break 2-C down into CO2
AND RELEASES IT!!! GASP.

37. It essentially, undoes the Calvin
Photorespiration C-3:
Photorespiration occurs in light and uses O2 but generates no ATP and produces no food.
It essentially, undoes the Calvin

38. Why have it