ANSWER
KEY
Honors Biology
Photosynthesis Review
1. What is the formula for photosynthesis?
a. In the formula, draw a square around the reactants and products of the light-dependent
reactions.
b. In the formula, draw a circle around the reactants and products of the calvin cycle.
2. Which compound(s) provide the carbon for the production of sugar?
 sunlight
 water
 oxygen
 ATP
 carbon dioxide
3. Why are leaves green? ______they contain chloroplyll, a pigment which reflects green light.__
_____________________________________________________________________________
4. Why do leaves change color in the fall? __the chlorophyll breaks down causing the green color
to disappear. The accessory pigments, which are yellow, red and organge, become visible.
5. The primary energy storing compound made by photosynthesis and used by all living things for
energy is ____glucose________.
6. Explain how ATP stores and releases energy. __Energy is stored in the chemical bonds of ATP,
specifically between the phosphate groups. When a bond between the phosphate groups is
broken then energy is released. This process converts ATP into ADP. To store energy, a
phosphate group is added to ADP to create ATP.____________________________________
7. Which of the following will affect the rates of photosynthesis? check all that apply.
 oxygen levels
 temperature
 light intensity
 carbon dioxide levels
 water levels
 color of light
8. Match the chemical pathway to its location
__B___ Photosynthesis
__C___ Light-dependent reactions
__A___ Calvin cycle
a) Stroma
b) chlroplast
c) thylakoid
9. What are energy carriers?
 compounds that store energy for long periods of time such as glucose.
 high energy electrons
 enzymes involved in the calvin cycle
 compounds that carry energy from one set of reactions to others, such as ATP.
10. Which of the following analogies best describes the relationship between the calvin cycle and
the light-dependent reactions?
a. the light dependent reactions are the power generator while the calvin cycle is a factory.
b. the light dependent reactions are a brick while the calvin cycle is a brick wall.
c. the light dependent reactions are the principal while the calvin cycle is the school.
d. a. the light dependent reactions an engine while the calvin cycle is the gasoline.
11. The immediate purpose of the light dependent reactions is to
 Produce high-energy sugars
 Produce oxygen
 Produce ATP for the Calvin Cycle
 Release energy stored in food
12. Which enzyme converts ADP into ATP?
 NADPH dehydrogenase
 Proton pump
 Photosystem 1
 ATP Synthase
 chlorophyll
13. Which of the following shows the correct path of the electron as it moves through the light
dependent reactions.
 Carbon dioxide  proton pump  inner thylakoid  ATP Synthase  ATP
 Water  photosystem II  ETC  photosystem I  NADPH
 Sunlight  photosystem I  ETC  photosystem II  ATP
 Water  photosystem I  ETC  photosystem II  NADPH
14. What is the purpose of the proton gradient within the thylakoid?
 To cause ATP Synthase to spin which converts ADP + P  ATP
 To become part of NADPH
 To create an electrical charge
 To store the energy from the sun in high-energy electrons
15. As the electron travels through the ETC . . .
 The proton pumps move it between photosystems but do not change it in any way
 The proton pumps take energy away from it
 The proton pumps add more energy to it
 The proton pump converts the electrons into protons
16. What is carbon fixation?
 the process in which light energy is captured in the chloroplast
 the conversion of inorganic carbon to organic carbon
 the release of energy as carbon atoms break down into free electrons, protons and
neutrons
 the process in which plants use carbon atoms as energy carriers.
17. The immediate purpose of the Calvin Cycle is
 Produce high-energy sugars
 Produce ATP for the Calvin Cycle
 Produce oxygen
 Release energy stored in food
18. Which enzyme adds one molecules of CO2 to the compound RuBP?
 ATP Synthase
 Photosystem II
 Sodium Potassium Pump
 Rubisco
19. If a plant was deprived of sunlight for several days, how would this affect the Calvin Cycle
 the calvin cycle would immediately stop since it requires energy from the sun
 the calvin cycle would still continue, until it ran out of ATP.
 the calvin cycle will occur more slowly since it no longer has any carbon
20. Why are the rates of photosynthesis affected by temperature? ______________________
photosynthesis is controlled by many enzymes. Enzymes are affected by temperature._____
__________________________________________________________________________
21. Create a key for the following picture
A. ____sunlight___________________
G. ___Calvin Cycle_______________
B. _____H2O______________________
H. __________NADPH______________
C. ____CO2_________________________
I. _______ATP_____________________
D. ___NADP+______________________
J. ____Chloroplast________________
E. ____ADP________________________
K. _____O2________________________
F. _Light Dependent Reactions_
L. ___C6H12O6____________________
Rates of photosynthesis -- Analyzing Data
The rate at which a plant carries out photosynthesis depends in part on its environment. Plants that
grow in shade, for example, carry out photosynthesis at low levels of light. Plants that grow in the
sun, such as desert plants, typically carry out photosynthesis at much higher levels of light.
The graph compares the rate of photosynthesis between plants that grow in the shade and plants that
grow in the sun.
20
15
shade plants
10
sun plants
This graph shows how
the rate of
photosynthesis changes
with the number of
micromoles of photons
per square meter per
second (µmol
photons/m2/s), a
standard unit of light
intensity.
1000
800
600
400
0
200
5
0
Rate of Photosynthesis
(umol CO2
consumed/m2/s)
Rates of Photosynthesis
Light Intensity (umol
photons/m2/s)
22. Interpreting Graphics: When light intensity is below 200 µmol photons/m2/s, do sun plants or
shade plants have a higher rate of photosynthesis?
shade plants
23. Interpreting Graphics: When light intensity is above 400 µmol photons/m2/s, do sun plants or
shade plants have a higher rate of photosynthesis?
sun plants
24. Drawing Conclusions: Why do you think your answers for questions 1 and 2 are different?
What does it tell you about shade versus sun plants?
shade plants are better at performing photosynthesis in less sunlight.
25. Inferring: The average light intensity in the Sonoran Desert is about 400 µmol photons/m2/s.
According to the graph, what would be the approximate rate of photosynthesis for sun plants
that grow in this environment?
12 um/CO2
26. Going further: Suppose you transplant a sun plant to a shaded forest that receives about 100
µmol photons/m2/s. Do you think this plant will grow and thrive? Why or why not? How does
the graph help you answer the question?
No, according to the graph the plant would be producing aproximately 2 um/CO2. It would be
unable to perform enough photosynthesis to grow and thrive.