Photosynthesis & Cellular Respiration Review
Name:____________KEY___________________________Period:_______
Vocabulary: Match the phrases on the left with the term that best fits. Use answers only one
time.
__K__1. Organisms that make their own food
A. Chloroplasts
__A__2. Site of photosynthesis
B. Chemical
__L__3.
Process occurs in a mitochondrion
C. Aerobic
__E__4.
Light absorbing molecule in the chloroplast
D. ATP
__B__5.Light energy is converted into __________
energy during photosynthesis
E. Chlorophyll
F. Photosystem
__C__6. Process requires oxygen
G. Oxygen
__J__7.
reactions.
Gas used by plants in the light-independent
H. Glycolysis
__D__8.
Energy storing molecule of the cell
I. Heterotrophs
__H__9. The anaerobic process of splitting glucose
and forming two molecules of pyruvic acid
J. Carbon Dioxide
K. Autotrophs
__I__10. Organisms that do not make their own food
L. cell respiration
__G__11. Gas used by organisms for aerobic respiration
__F__12. Arrangement of light-catching pigments within
the chloroplast.
Directions: Answer each of the following questions in a clear and concise manner.
1. Describe in your own words what cell respiration is and why it is needed.
Cellular respiration is the process by which chemical energy stored in glucose is released and captured as
ATP. Cellular respiration is needed since ATP is a useable form of energy storage.
2. Write the equation for cell respiration in word form and molecular formula.
C6H12O6 + 6O2
6H2O + 6CO2 + energy (ATP)
Glucose + oxygen gas
water + carbon dioxide + ATP
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3. In what step of cell respiration does glucose get broken down? What does it get broken down into and
why is that important?
 Glycolysis will produce 2 NADH, 2 ATP (net gain) and 2 pyruvic acid
 Glycolysis is needed to produce the pyruvic acid to enter the Kreb’s cycle if oxygen is present or
undergo fermentation is oxygen is not present. This step is able to produce energy for the
organism in either situation.
4. Explain what happens during the Krebs Cycle.
During the Kreb’s cycle, the pyruvic acid created in glycolysis enters into the Kreb’s cycle and produces a
total of 4 NADH, 2 FADH2 (which are high energy electron carriers used later on in the electron transport
chain) and 2 ATP per glucose molecule.
5. Explain how the electron transport chain is able to produce ATP from ADP. Discuss the similarities
differences of this process in cellular respiration and photosynthesis.
Since both the mitochondria and the chloroplast are double membrane organelles, both are able to create a
H+ concentration gradient. As the H+ ions move down the concentration gradient, they pass through ATP
synthase to create ATP.
The differences are that the amount of ATP produced in the chloroplast is not as great as in the
mitochondria. Also, the energy to fuel the protein pumps in the chloroplast is fueled by the high energy
electron which is excited by a photon of light and in the mitochondria the ETC is fueled by high energy
electron carriers, NADH and FADH2
6. What is the difference in an aerobic process and anaerobic process?
Aerobic means oxygen is present (more ATP produced during cellular respiration)
Anaerobic means oxygen is not present (less ATP produced during cellular respiration)
7. Name the three processes of aerobic cellular respiration. How many ATP’s does each process produce,
and what is the total ATP produced from one glucose molecule?
3 Processes of Cellular
Respiration:
# ATP produced:
glycolysis
Net gain of 2 ATP
Kreb’s Cycle
2 ATP
Electron Transport Chain
32 ATP
Total ATP per 1 glucose =___36____
8. What is fermentation and why is it used?
Fermentation is the process by which an organism will produce a small amount of ATP when oxygen is
not present.
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9. Our bodies use fermentation when our muscles lack oxygen. What is the type of fermentation used by
us? Bacteria and yeast also use fermentation in the process of making bread, cheese and yogurt. What
type of fermentation do they use?
Animal= lactic acid fermentation
Yeast= alcohol fermentation
10. What is the general chemical equation of photosynthesis in word and molecular formula form.
6CO2 + 6H20 + Sunlight
Carbon dioxide + water + sunlight
6 O2 + C6H12O6
oxygen + glucose
11. Describe in your own words what photosynthesis is and why it is important.
Photosynthesis is the process of capturing the sun’s energy and converting it into chemical energy
(glucose). This is important since it is how energy needed for living organisms to survive is captured and
able to be converted into a more useable form.
12. Name the two stages of photosynthesis and list the starting molecule(s) or reactants and ending
molecule(s) or products of each.
Stages
Starting Molecule(s)
Light and water
Product(s)
ATP/ NADPH/ Oxygen gas
Carbon dioxide
1 G3P (for every 3 CO2) or 1
glucose (for every 6 CO2)
“Photo” or Light
Reactions
Calvin Cycle/Lightindependent/”Synthesis”
reactions
13. Explain how temperature and light intensity affect photosynthesis?
 Temperature can denature enzymes used in the chemical processes if the temperature is too high
or too low
 Light intensity will either increase the rate or decrease the rate if the amount of light is increased
or decreased
14. Explain how the equations for photosynthesis and respiration are related.
The equations are opposites of each other. The products of one are the reactants of the other.
15. Discuss the function of water splitting in photosynthesis.
Water is split during photosynthesis in order to donate a low energy electron to the chlorophyll A
molecule. The H+ ions produced during water splitting contribute to the concentration gradient which
produce ATP during the electron transport chain and oxygen gas is given off as a by product.
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16. Summarize the events of the “photo” reaction. Be sure to include all inputs and outputs.
Water splitting photosystem- energy captured from a photon of light and as excited electron in the
chlorophyll molecules fall back to the resting state, energy is released and funneled to a nearby molecule.
Eventually an electron from the specialized chlorophyll A molecule is excited and captured by the
primary electron acceptor. The lost electron in the chlorophyll A molecule is replaced by the splitting of
water and oxygen gas and H+ are produced in the process. The high energy electron is passed to the first
electron transport chain which supplies energy to the proton pumps. The proton pumps pump H+ from an
area of low concentration to an area of high concentration. As a concentration gradient is formed H+
diffuse through the ATP synthase molecule and produce ATP. The once high energy molecule has now
lost the energy it transferred to fuel the pumps and is now low energy. This low energy electron is used in
the NADPH producing photosystem to replace the electron lost in the Chlorophyll A molecule when an
electron is excited and donated to the primary electron acceptor. The high energy electron that is donated
is passed to the second electron transport chain and the same process used before happens again but this
time rather than ATP being produced, NADPH is produced. Both the ATP and NADPH are sent to the
Calvin cycle as high energy molecules used to fuel the reactions to synthesize glucose.
17. Summarize the events of the “synthesis” reaction. Be sure to include all inputs and outputs.
In the Calvin cycle, carbon dioxide from the atmosphere enters the chloroplast. The carbon atom from the
carbon dioxide is fixed to the 5 carbon organic molecule present in the Calvin cycle with the help of the
enzyme rubisco. Once the carbon atom is fixed to the 5 carbon molecule a 6 carbon molecule is formed.
Through a series of reactions fueled by the ATP and NADPH produced during the light reaction, the 6
carbon molecule splits and produced two 3-carbon molecules or G3P molecules. One G3P molecules is
reserved for glucose production and the other is used to regenerate the 5- carbon organic molecule needed
for carbon fixation. After six turns of the calving cycle with 1 carbon dioxide entering each time, there is
an end result of 2 reserved G3P which combine to make glucose and the remaining 10 G3P are used to
regenerate the 5-carbon organic molecule (6 in total).
18. Discuss why leaves appear green in the spring and reddish-orange in the fall.
In the spring the amount of chlorophyll a & b is in a higher amount than carotenoids. Since chlorophyll a
& b reflect the blue-green spectrum, the green color will mask the orange-red spectrum reflected by the
carotenoids. In the fall, as the trees prepare for winter, the production of chlorophyll a & b is decreased
but the carotenoids levels stay the same and will be greater than chlorophyll a & b. The carotenoids will
now mask the green color reflected by chlorophyll and the leaves appear orange-red.
19. Discuss the difference between stoma and stroma.
Stoma- pore located on the underside of a leaf that allows for gas exchange
Stroma- the space between the thylakoids of a chloroplast that is the location of the “synthesis”
reaction/Calvin cycle.
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20. Discuss how the leaf structure is efficient for photosynthesis. Be sure to discuss the function of all
key structures.
The structure of a leaf is efficient for photosynthesis. The high concentration of chloroplasts located in
the palisade cells, which are located just under the upper epidermis allow for the absorption of sunlight
energy. Since the cells are densely packed, all possible space is utilized to ensure the greatest amount of
absorption. The need for water, is supplied either through the xylem cells located in the vein which can
carry water from the roots, or water vapor can enter through the stoma located on the underside of the
leaf. The stoma will also take in the needed carbon dioxide which is a reactant for the Calvin cycle and
large air spaces are present for the large amount of gas exchange. The oxygen gas that is produced as a
by-product during the light reaction is released to the atmosphere through the stoma. Once the glucose is
produced during the Calvin cycle, the phloem cells will translocate the material for other parts of the
plant.
21. Fill in the chart comparing and contrasting cell respiration and photosynthesis.
Photosynthesis
Organelle for process
Reactants
Products
Steps of the process
1. light (energy)
2. water
3. carbon dioxide
1.glucose
2.oxygen
Cell Respiration
1.glucose
2.oxygen
1.carbon dioxide
2.water
3.ATP (energy)
1.light/”photo” reaction
1.glycolysis
2.Calvin cycle/”synthesis or light 2.Kreb’s Cycle
independent or dark” reaction
3.Electron Transport Chain
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22. Animals do not perform photosynthesis; however, it is essential to our survival. Explain this.
4&5 – As the sun rises the rate of
photosynthesis increases with the increase of
light. Therefore carbon dioxide is “fixed”
during the Calvin cycle and utilized for the production of glucose, the levels of carbon dioxide decrease
during the day. When the sun goes down, animals are still undergoing cellular respiration and carbon
dioxide is still being produced but since photosynthesis has decreased due to less light not as much carbon
dioxide is used for carbon fixation. This is why we see an increase of CO2 levels during the evening
hours and a decrease during the daytime hours.
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A palisade cell (mesophyll) B upper epidermis
23. Label the leaf cross section below
C cuticle
I xylem
D chloroplast
H phloem
E air space
J spongy cell
(mesophyll)
G guard
cell
F stoma
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