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Photosynthesis & Cellular Respiration Worksheet

Photosynthesis & Cellular Respiration Review


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


__B__5.Light energy is converted into __________

E. Chlorophyll

energy during photosynthesis

F. Photosystem

__C__6. Process requires oxygen

G. Oxygen

__J__7.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

J. Carbon Dioxide

and forming two molecules of pyruvic acid

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

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 Krebs 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 Krebs cycle, the pyruvic acid created in glycolysis enters into the Krebs 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 ATPs does each process produce, and what is the total ATP produced from one glucose molecule?

3 Processes of Cellular Respiration:

# ATP produced:


Net gain of 2 ATP

Krebs Cycle


Electron Transport Chain

32 ATP

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.

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

6 O2 + C6H12O6

Carbon dioxide + water + sunlight

oxygen + glucose

11. Describe in your own words what photosynthesis is and why it is important.

Photosynthesis is the process of capturing the suns 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.


Starting Molecule(s)


Photo or Light Reactions

Light and water

ATP/ NADPH/ Oxygen gas

Calvin Cycle/Light-independent/Synthesis reactions

Carbon dioxide

1 G3P (for every 3 CO2) or 1 glucose (for every 6 CO2)

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.

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.

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.


Cell Respiration

Organelle for process


1. light (energy)

2. water

3. carbon dioxide






1.carbon dioxide


3.ATP (energy)

Steps of the process

1.light/photo reaction

2.Calvin cycle/synthesis or light independent or dark reaction


2.Krebs Cycle

3.Electron Transport Chain

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.

A palisade cell (mesophyll)B upper epidermis

23. Label the leaf cross section belowC cuticle

Total ATP per 1 glucose =___36____

G guard cell

H phloem

I xylem

D chloroplast

E air space

J spongy cell (mesophyll)

F stoma




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