Biol 131
Question Bank
Photosynthesis
1. Place a check in the boxes to indicate where each process occurs. A question like this is will be on
the exam, so do not simply guess – review your notes, diagrams of the processes, and pertinent
sections of the textbook.
These processes
CO2 Produced
CO2 Used
O2 Produced
O2 Used
ATP Produced
ATP Used
NADH Produced
NADH Used
NADPH Produced
NADPH Used
H2O Produced
H2O Used
2
Krebs
Cycle
Occur during which of these reactions
Mitochondrial
PS-I
PS- II
Calvin
e- transport
Cycle
A. The pH of the interior of the thylakoid disks become acidic in the presence of light. Why?
B. A scientist hoping to develop a new herbicide decided to test a chemical known to make the inner
membrane of mitochondria permeable to ions. In mitochondria, this chemical inhibits ATP
synthesis. When tested on chloroplasts, it also made the inner membrane more permeable but
had little effect on ATP synthesis. How would you explain the difference in effect of this
chemical in mitochondria and chloroplasts?
3. Suppose that you are shining a light on a leaf that is actively carrying out photosynthesis.
A. If you turned off the light (so that the leaf was now in the dark). During the next 60 seconds
what would happen to the level of:
a. ATP?
____________________________
b. NADPH? __________________________
c. RUBP? ____________________________
B. Based upon the above answers, what must happen to the rate of CO2 fixation in a leaf placed
in the dark?
Biol 131`
Question Bank
Photosynthesis
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4. Suppose that you found a plant that contains large quantities of
malate in its leaves. Could you tell whether it was performing C4 or
CAM photosynthesis? Why or why not? In order to determine
which type of photosynthesis is occurring you make some other
observations.
A. In the space to the rights draw the arrangement of cells in the
leaves of a C4 plant?
B. If this is a C4 plant, will the levels of malate increase or decrease
(circle) during the day? Explain:
C. If it is a CAM plant, will the levels of malate increase or decrease (circle) during the day?
Explain:
D. If this is a C4 plant, will the stomates be open or closed (circle) during the day? If it is a CAM
plant will the stomates be open or closed (circle) during the day?
E. What happens to CO2 absorbed by the plant in the mesophyll cells of C4 plants?
What then happens in the bundle sheath cells?
5. The enzyme ribulose bisphosphate carboxylase (Rubisco) normally adds CO2 to RUBP. However, it
will also catalyze a competing reaction in which O2 is added to RUBP to form the three-carbon
molecule 3-phosphoglycerate and the two-carbon molecule phosphoglycolate.
A. What is the name of this process? ______________________
B. Does the reaction of O2 with Rubisco lead to a net gain or loss (circle) of energy for the cell?
C. Plants that carry out _____ type photosynthesis reduce the level of this process in
photosynthetic cells. It does so by increasing the concentration of the molecule ______ in
__________________________ type cells.
Biol 131`
Question Bank
Photosynthesis
Page 2
6. Plants contain chloroplasts and mitochondria, organelles that are both involved in energy
interconversions and which have similar structures and processes.
A. In terms of similar functions, which part of the mitochondria is similar to the:
1. thylakoid membrane? ___________________ Why?
2. thylakoid lumen? ____________________ Why?
3. stroma? ___________________ Why?
B. ATP cannot be exported from chloroplasts. How then do plant cells generate the ATP that
they require for cellular metabolism?
7. A. Using the diagram to the right, label these
structures and compartments of the chloroplast:

stroma

inner membrane

outer membrane

thylakoid membranes

grana
B. In which compartment does the light-independent reactions occur? ____________________
C. On which membranes do the light-dependent reactions occur? ____________________
8. The figure to the right shows the appearance
of a Spirogyra filament as observed in the
classic experiments by T.W. Engelmann in
1882.
A. What are the small cells clustered
around the algal filament?
___________________
B. Why are they located in the positions in which they are observed?
C. What did this experiment reveal about photosynthesis?
Biol 131`
Question Bank
Photosynthesis
Page 3
9. Assume that this diagram shows part of the light-dependent reactions in the thylakoid membrane.
A. Label the stromal and thylakoid lumen sides of the membrane.
B. Label the components of the
pathway included in this diagram.
C. Which major component is
missing? Add the missing
components of the diagram and
complete the flow of electrons.
D. Label the sites of H2O splitting and
ATP synthesis.
10. The diagram to the right shows the structure of the chlorophyll
molecule.
A. Label as ‘A’ the part of the molecule involved in absorption of
energy from light?
B. The part of the molecule highlighted in grey is very hydrophobic
in nature. Explain why?
C. Light of which colors are principally absorbed by chlorophyll?
________________________________________
D. An “action spectrum” of photosynthesis would reveal that
photosynthesis occurs at other wavelengths of light as well.
How is this possible?
E. Why do leaves appear green?
11. Which one of the following statements is true of both cellular respiration and photosynthesis?
A. the transfer of electrons to CO2
B. the chemiosmotic formation of ATP
C. oxygen is one of the byproducts
D. mitochondria are essential organelles
E. CO2 is released.
Biol 131`
Question Bank
Photosynthesis
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12. Name the molecules
A - F in this diagram.
13. Complete the following questions referring to the diagram below.
A. Explain why, in an intact leaf, the light-dependent reactions of photosynthesis only occur in the
presence of light (if you cannot answer this question correctly you do not understand some of
the most fundamental principles of photosynthesis):
B. Which part of the Calvin cycle (1 – 3) highlighted in black represents the stage in which
___ RUBP is regenerated
___ metabolites are reduced
___ CO2 fixation occurs
C. Label the metabolites indicated with the lines, and in the parentheses indicate the number of
carbon atoms in that metabolite.
D. Indicate where in the diagram ATP is hydrolyzed to ADP (there are two places) and where
NADPH is converted to NADP.
E. For each CO2 that is fixed, ___ ATP and ___ NADPH are used during the cycle.
Biol 131`
Question Bank
Photosynthesis
Page 5
Rate of photosynthesis
14. The graph to the right shows the results of an experiment similar to the one that you performed in
Biol 106 where the rate of photosynthesis was measured for leaves exposed to different levels of
illumination. In this case, the experiment was also performed with the leaves held at two different
CO2 concentrations.
A. Under conditions to the left of the dashed line,
does the amount of light or the concentration of
CO2 limit the rate of photosynthesis?
high carbon dioxide
_____________________
normal carbon dioxide
B. In each experiment as illumination is increased,
the rate of photosynthesis eventually ‘saturates’.
What does this expression mean?
C. Under conditions to the right of the dashed line,
does the amount of light or the concentration of
CO2 limit the rate of photosynthesis?
_____________________
irradiance level
D. For a plant growing in bright sunlight, which
factor is most likely to be limiting the rate of
photosynthesis?
50
Plant 1
Rate of Ps
15. This graph shows the rate of carbon fixation for two
plants over a range of oxygen concentrations with
normal carbon dioxide concentrations. Which plant
appears to be using C4 photosynthesis? Explain the
reason for your conclusion.
Plant 2
40
30
20
10
0
0
Biol 131`
Question Bank
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20
30
% oxygen
40
50
Photosynthesis
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