Spring.wmf (18300 bytes) Plant Physiology (Biology 327)  - Dr. Stephen G. Saupe;  College of St. Benedict/ St. John's University;  Biology Department; Collegeville, MN  56321; (320) 363 - 2782; (320) 363 - 3202, fax;    ssaupe@csbsju.edu

Photosynthesis Quiz: Carbon Fixation

True/False QuestionAnswer the following questions True (T) or False (F)

  1. _____ Rubisco is the enzyme that fixes carbon dioxide in the Calvin cycle.

  2. _____ The Calvin cycle must turn six times and fix six carbon dioxide molecules to yield one net glucose

  3. _____ The Calvin cycle occurs in the light.

  4. _____ The Calvin cycle occurs in the dark

  5. _____ The Calvin cycle requires ATP and NADPH that are supplied from the Z-scheme.

  6. _____ There is one reduction reaction in the Calvin cycle

  7. _____ ATP is required in one step in the Calvin Cycle

  8. _____ During the Calvin cycle glyceraldehydes--phosphate is reduced to phosphoglyeric acid

  9. _____ Carbon is fixed in the Calvin cycle

  10. _____ The first stable product of carbon fixation is a three-carbon compound (PGA)

  11. _____ Rubisco attaches carbon dioxide to a five carbon sugar (Ribulose bis phosphate)

  12. _____ Rubisco is a substrate specific enzyme

  13. _____ For every carbon fixed, it requires one ATP and one NADPH

  14. _____ The product of carbon fixation in C3 plants is phosphoglyceric acid

Calvin Cycle Question:  The symbols below represent intermediates (molecules)
in the Calvin cycle.  For example, C5 refers to a molecule that has five carbon atoms.  Given the following reactions, which does NOT represent a rearrangement of carbon skeletons during the Calvin Cycle? 

  1. C5 + C1 → 2 C3

  2. C3 + C3 → C6

  3. C3 + C4 → C7

  4. C7 + C3 → 2 C5

  5. C6 + C3 → C4 + C5

  6. C4 + C2 → C6

Classic Experimental Analysis:  The three graphs below represent the results from some classic experiments in elucidating the mechanism of the carbon fixation.  Provide an explain for each:

  1. Figure 1.

  2. Figure 2. 

  3. Figure 3. 




Comparison Matching Question Match each of the following with the appropriate response

a.  C3 plant c.  CAM plant  e.  C3 & CAM plants g.  all (C3, C4, CAM)
b.  C4 plant  d.  C3 & C4 plants  f.  C4 & CAM plants h.  none (C3, C4, CAM)
  1. _____ tobacco is an example
  2. _____ maize is an example
  3. _____ Cacti and bromeliad are examples
  4. _____ evolved in hot, dry environments
  5. _____ have the enzyme rubisco
  6. _____ have the enzyme PEP carboxylase
  7. _____ have a well developed bundle sheath
  8. _____ produce PGA
  9. _____ PGA is the first product of carbon fixation
  10. _____ malate is the first product of carbon fixation
  11. _____ readily detectable photorespiration
  12. _____ has one major chloroplast-containing cell
  13. _____ highest CO2 compensation point
  14. _____ highest transpiration rate
  15. _____ fixes carbon dioxide during the daytime
  16. _____ fixes carbon dioxide at night
  17. _____ highest yields
  18. _____ requires more energy per carbon dioxide fixed
  19. _____ leaves exhibit Kranz anatomy
  20. _____ has the lowest temperature optimum for photosynthesis
  21. _____ open stomata during the day
  22. _____ chloroplasts of two types (one typical, one with little stroma)
  23. _____ temporal separation of carbon fixation and the Calvin cycle
  24. _____ spatial separation of carbon fixation and the Calvin cycle
  25. _____ oxygen inhibits
  26. _____ least efficient water utilization (g H20/g dry weight)
  27. _____ produce glucose during the Calvin cycle
  28. _____ make starch in the chloroplasts
  29. _____ make sucrose in the chloroplasts

30. In what way are the photosynthetic adaptations of C4 and CAM plants similar?

a . neither C4 or CAM utilize thylakoids
b.  both CAM and C4 make their sugar in the dark
c.  both C4 and CAM plants make their sugar without using the Calvin Cycle
d.  in both C4 and CAM plants, they obtain their gases at night
e.  in both C4 and CAM, an enzyme other than rubisco carries out initial carbon fixation, then
            the Calvin cycle is utilized later

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Last updated:  01/07/2009     Copyright  by SG Saupe