STUDY GUIDE
Ch 8 PHOTOSYNTHESIS
1. How are autotrophs and heterotrophs alike? How are they different?
They both need to break food down into energy.
Autotrophs can make their own food through photosynthesis.
Heterotrophs cannot make their own food and physically have to obtain and consume it.
2. Define ATP, what are the parts that make it up and draw a picture of the structure with labels.
Adenosine triphosphate. It provides energy for the cell
Made of adenine, ribose, and three phosphates.
ATP releases energy when the bond between the second and third phosphate groups is
broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.
3. What do ATP, ADP and AMP stand for?
ATP = Adenosine triphosphate
ADP = Adenosine diphosphate
AMP = Adenosine monophosphate
4. Describe Helmont, Priestley and Ingenhousz’s work/contributions to photosynthesis.
MAKE SURE YOU EXPLAIN THE EXPERIMENTAL SETUP
Van Helmont’s Experiment – wanted to know if plants grow from taking material out of the soil.
Concluded that trees gain most of their mass from water.
Priestley’s Experiment – finds that plants release a substance that keeps a candle burning – oxygen
Ingenhousz’s Experiment– concludes that plants need sunlight to produce oxygen.
5. Write the overall chemical equation of photosynthesis (not words).
6 CO2
+
6 H2 O
+
sunlight
----> C6H12O6
+
o What are the reactants and products of the equation?
Carbon dioxide, water and sunlight = reactants
Sugar and oxygen
6. What happens when bonds are made?
Bonds are made = energy is stored by adding a phosphate
6 O2
7. What happens when bonds are broken?
Bonds are broken = energy is released by removing a phosphate
8. Define a pigment and provide two examples.
A light absorbing molecule.
Chlorophyll and Carotene
o Explain how they play a role in the color you see.
The colors that cannot be absorbed will be reflected and those will the colors that will be seen. Colors
that are absorbed are not seen.
9. Draw the structure of a chloroplast and identify/label its many parts.
10. Define and explain how each of the following have a role in photosynthesis:
Light – Is absorbed by the photosystems on the thylakoid membrane. It also splits water during the
light dependent reactions.
Water – Is absorbed during the light dependent reactions, is split by sunlight into protons, electrons
and oxygen gas. Supplies the light dependent reactions with electrons.
Thylakoid – Photosynthetic disc-like structures that are found inside the chloroplast, contain
chlorophyll, are part of the light dependent reactions.
granum (grana) – Stacks of thylakoids inside the chloroplast.
stroma – The space surrounding thylakoids inside the chloroplast.
thylakoid membrane – Specifically where the light dependent reactions take place.
photosystems – contain the chlorophyll pigments, are responsible for absorbing light during the light
dependent reactions, found on the thylakoid membrane.
ETS – Electron Transport System, found on the thylakoid membrane, part of the light dependent
reactions, responsible for transporting high energy electrons to NADP+
ADP/ATP – A form of energy. ATP = a fully charged battery. ADP= a partially charged battery.
ATP synthase – An enzyme found inside the thylakoid membrane, responsible for moving hydrogen
ions across the thylakoid membrane to the stroma. Makes ATP, which will be used in the calvin cycle.
NADP+/NADPH – Electron carries. NADP+ accepts the electrons in the light dependent reactions
and converts into NADPH will be used in the calvin cycle.
CO2 – Needed for the calvin cycle, gets broken down into sugars which will be made.
Sugars – A useful product created from the calvin cycle.
11. What is the difference between NADP+ and NADPH? How are they related to one another?
They are both electron carries. NADP+ (does not have electrons) accepts the electrons in the light
dependent reactions and converts into NADPH (which has the electrons) will be used in the calvin cycle
12. What are products and reactants of the light dependent reactions?
Reactants = light, water ADP and NADP+
Products = oxygen (waste), ATP and NADPH
13. List the steps and explain the steps of the light dependent reactions.
Refer to your chemiosmosis packet and large light dependent worksheet from class.
14. Why does the inside of the thylakoid membrane become positively charged during the light-dependent
reactions?
From the accumulation of hydrogen ions from the splitting of water.
15. What are two other names for the Calvin Cycle and where does it take place inside the chloroplast?
Light independent reactions
Dark reactions
Inside the stroma
o What three substances are involved and how is each one important during the light independent
reactions?
Carbon dioxide is needed to convert into sugar
ATP and NADPH are used to power the cycle – releasing ADP and NADP+ back into the light
dependent reactions.
o What are the products and reactants of the light independent reactions?
Sugars are a useful product.
ADP and NADP+ are recycled back into the light dependent reactions.
o Explain the steps of the light dependent reactions (draw a picture to help you if needed).
Refer to diagrams from notes and back side of light dependent reaction handout from class.
16. Describe the relationship between the light-dependent and the light-independent reactions.
They both need each other in order to work. ATP and NADPH are used to power the calvin cycle. The
calvin cycle releases AP and NADP+ back into the light dependent reactions.
17. How does water, CO2, light and temperature affect the rate of photosynthesis?
Water – can slow or stop
Temperature – enzymes work best at 0 to 35.0 C, slow or stop
Light intensity – reaches a plateau but varies with the plant
CO2 – reaches a plateau but again varies with the plant