Biology I Honors Focus on Photosynthesis
I.
Name_______________________________
Overall:
1. State the equation that represents photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
2. All oxygen in the atmosphere can ultimately be traced back to what molecule?
H2O
3. All carbon in organic molecules can ultimately be traced back to what molecule?
CO2
4. Name four factors that can affect the rate of photosynthesis:
a. Light intensity
b. Temperature
c. Availability of carbon dioxide
d. Availability of water
5. What do autotrophs need to carry out photosynthesis?
Water, light, carbon dioxide, appropriate temperature
5. How do heterotrophs get energy from the sun?
By eating autotrophs or by eating other organisms who ate autotrophs
II. Light Dependent Reactions
6. Location?
Thylakoid membrane
7. Reactants?
H2O, ADP, NADP+
8. Products?
O2, ATP, NADPH
9. What is chlorophyll and why does it appear green to us?
Main light absorbing pigment during photosynthesis; reflects green wavelengths of
light
10.What happens when chlorophyll molecules absorb light?
Water molecules are split; 2 electrons are released from photosystem
12. What happens to the electrons once they are “excited” and leave chlorophyll
(where do they go?)? They enter an electron transport chain.
13. Energy to produce ATP molecules is provided by a proton gradient in the
thylakoid membrane (the picture you colored!)
14. Why does the inside of the thylakoid membrane become positively charged during
these reactions? Protons released from the splitting of water are pumped there
from outside the membrane.
15. What would happen to electron flow if the thylakoid’s interior were connected to
the stroma? There would be no electron flow and no ability to pump protons,
either.
16. Chemiosmosis requires the establishment of a proton gradient.
III. Light Independent Reactions
17. Another name for these? The Calvin Cycle
18. Location? The stroma
19. Reactants? CO2, ATP, NADPH
20. Which reactants were products from the light dependent reactions?
ATP, NADPH
21. Products? C6H12O6, ADP, NADP+
22. How do the light dependent and light independent reactions work together to
create a continuous cycle? Each set of reactions creates materials required by the
other set of reactions.
23. Why can CAM plants keep their stomata closed during daytime hours? What
does CAM stand for? CAM plants bring in CO2 at night; Crassulacean Acid
Metabolism
IV. Energy in general:
24. Ultimate source of energy for life on Earth? The sun
25. What makes up an ATP molecule? (three parts) a ribose sugar, a nitrogen base
(adenine), and three phosphates
26. What makes up an ADP molecule?
a ribose sugar, a nitrogen base (adenine), and two phosphates
27. What happens when a phosphate group is removed from an ATP molecule?
ADP is formed; energy is released
28. Why are hydrogen ions important in converting ADP into ATP?
They form a proton gradient that provides energy to power ATP synthase