Name
Date
Per.
CHAPTER 10 STUDY ?’s, part 3 (10.3 – 10.4): The Calvin Cycle / Mechanisms of C-Fixation
**NOTE: Read ALL of the figure captions!!!
1) REVIEW: Which 2 products of the light reactions are necessary for the running of the Calvin cycle? On
which side of the thylakoid membrane are these 2 substances produced?
2) Complete this passage by filling in the blanks: “Carbon enters the Calvin cycle in the form of
and leaves in the form of
. The cycle spends
as an energy source and consumes
as reducing power for adding high-energy electrons to make the sugar.”
3) What carbohydrate is produced directly from the Calvin cycle? How many times must the cycle take
place to synthesize one molecule of this sugar?
4) What is RUBISCO? What is its function?
5) Create a chart in which you summarize the 3 phases of the Calvin cycle with respect to the “inputs” and
“outputs”, including any energy molecules consumed.
6) Compare the use of ATP during the Calvin cycle with the use of NADPH (in terms of # of each). How is
this difference related to the light reactions?
7) What happens to the G3P produced by the Calvin cycle?
8) WHAT IF? Explain why a poison that inhibits an enzyme of the Calvin cycle will also inhibit the light
reactions.
10.4 - Alternative Mechanisms of Carbon Fixation
9a) What is meant by TRANSPIRATION?
9b) What do most plants do on hot, dry days? Why? What is the “tradeoff” of doing this?
10a) Describe the process of PHOTORESPIRATION. Compare photorespiration to normal cellular
respiration and to photosynthesis.
10b) Explain the hypothesis that photorespiration is a “leftover” of evolution.
11a) Explain the significance of the name: C4 plants.
11b) Explain the role of bundle-sheath cells and mesophyll cells in C4 photosynthesis. Include in your
explanation the location or arrangement of these cells in a leaf.
11c) How is the enzyme PEP carboxylase better suited to hot, dry climates than the enzyme rubisco?
12) How are CAM plants adapted to performing photosynthesis in hot climates?
13) Describe how C4 and CAM plants are similar and how they are different.
14) How much carbohydrate is estimated to be produced each year by photosynthesis?