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Study Guide- Unit 4 Photosynthesis and Cellular Respiration

Essential Skills  essential skills (click to follow link)

1. Be able to name the reactants and products of Photosynthesis

Carbon Dioxide + Water > Using Light Produce > Glucose + Oxygen

2. Be able to name the reactants and products of Aerobic Respiration

Glucose + Oxygen > Are used to produce > Carbon Dioxide + Water + ATP Energy

3.Explain how the reactants and products of photosynthesis and respiration relate to each other.

They are involved in a cycle where the products of one reaction are the reactants of the other.

Photosynthesis (General)

1.  Write the overall chemical equation for photosynthesis (label the reactants & the products). 

2. What is the role of the following items in photosynthesis:


                        -thylakoid membrane:  Where light is captured for the light reaction

                        - stroma:  Where the calvin cycle takes place

                        -Pigments (chlorophyll a, chlorophyll b, cartenoids):

 Chlorophyll captures light energy to be used in the light reaction, the other pigments are called accessory pigments which means they "help" chlorophyll.

3.       Draw a picture of ATP and show how it gains and loses energy.

 (AT)-P-P~P  > gives away energy in its third bond to become > (AD)-P-P  +  P

re-bonds the third P to store the energy again.  (See Chemiosmosis for dart gun example)



4. Label the diagram on the right with the following terms:

-         Calvin Cycle(8)

-         ATP(5)

-         NADPH(6)

-         Photon of Light(1)

-         Light Dependent RXN(3)

-         Light Independent RXN (Calvin Cycle)(8)

-         H20(2)

-         CO2(4)

-         PGAL (Sugar)(9)




5.       Reaction




Light dependent RXN

 thylakoid membrane

 Water (uses light as energy) NADP & ADP

 Oxygen, ATP & NADPH

Calvin Cycle


 Carbon Dioxide (uses ATP & NADPH as energy)

 PGAL ("1/2 a sugar") NADP & ADP

6. What is PGAL? How does this relate to Glucose?

 PGAL is the product of the Calvin cycle.  2 PGAL molecules make up one glucose.


7.       Why is the light independent reaction described as a “Cycle”?  How many CO2’s are required to make 1 PGAL?

 The intermediate molecules in the Calvin Cycle are not consumed in the reaction.  There is an addition of Carbon Dioxide and a production of PGAL, but the molecules used in the reaction are not used up, but continue in the cycle to do it all over again.  It takes 3 Carbon Dioxide molecules to make one PGAL.

8. What is ATP synthase?

 "ATP Build Enzyme"  The enzyme that makes ATP from ADP

9. Define an autotroph:

 An organism that makes its own food (like a plant in photosynthesis)

10.. Define a heterotroph;

 An organism that must eat other organisms for food

11 ATP is an acronym for _____________________________.

 Adenosine Tri-Phosphate

12. What is the difference between ATP and ADP?

 ATP (A-P-P~P) has three Phosphates and is a "charged battery"  ADP (A-P-P) has only two Phosphates and thus is a "dead battery".

13. How does ATP store and release energy?

 The energy is stored in the "high energy bond" between the second and third Phosphate groups (A-P-P~P).

14. Know and understand the photosynthesis equation…what are the reactants, and where do they come from.

 The sunlight is used in the Light Reaction to break H2O into O2 & the CO2 is used in the Calvin Cycle to make Glucose.       H2O   +   CO2   (+  Light)   -->    O2   +   C6H12O6

15. What gas do plants take in? What gas do plants give off?

 Plants take in CO2 gas and release O2 gas.

16. Why do plants appear green?

 Plants do not use Green light, so they appear Green because the reflect it.  Plant actually use and absorb Red and Yellow light for use in Photosynthesis.

17. What is a pigment?

 A pigment is a compound that absorbs light.  In a plant the pigments Chlorophyll a, Chlorophyll b, and carotenoids are the main pigments which absorb light for use in the Light Reaction of Photosynthesis.

18. What is the purpose of the light-dependent reaction?

 To produce the energy storing compounds NADPH and ATP.

19. What are the products of the light reactions?

 Oxygen, NADPH & ATP are produced in the Light Reaction.

20. How does the Calvin cycle differ from the light-dependent reactions?

 The Calvin Cycle uses the NADPH & ATP energy to make PGAL.  The Light Reaction recharges the NADPH and ATP that are necessary for the Calvin Cycle.

21. Where does the oxygen come from in photosynthesis?

 The O2 comes from H2O which is split during the Light Reaction.

22. What is another name for the Calvin cycle?

 IT is also called the Light Independent Reaction (formerly known as the Dark reaction).

23. What is the electron transport chain, and what does it do?

 The electron transport chain is a series of protein molecules found in the Thylakoid membrane inside the chloroplast.  It serves to transport the electrons from the H2O to the NADPH.

24. What compound is the reactant for the Calvin cycle?

 Carbon Dioxide (CO2)

25. Where in the chloroplasts are photosystems I and II found?

 Thylakoid Membrane inside the chloroplast.  (part of the electron transport chain.)  Part of "The Light Dependent Reactions".

26. The stroma is  _________________..

Fluid filled-space inside the chloroplast where the Calvin Cycle takes place.

27. How are cellular respiration and photosynthesis almost opposite reactions?

The reactants of one are the products of the other.  They are pretty much the same reaction but backwards

See question # 2 on essential skills (click to follow link)