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Name: __________________________________ Per.:______
Date: __________
Ch. 7 Photosynthesis Self Check
7.7: Light Reaction: Photosystems
1. What does it mean for an electron to be “excited”?
2. What causes electrons to be “excited” in photosynthesis?
3. When electrons “fall” from an excited to “ground” (normal) state, what happens in terms of energy?
4. Photosystems consist of _________________________ molecules (like chlorophyll a, b, and
carotenoids) that are bound to membrane proteins. These molecules absorb photons of light and pass
energy from molecule to molecule.
5. Inside each photosystem are molecules that act as electron – acceptors. When they accept electrons they
become (oxidized/reduced).
6. There are two photosystems that work together in the light reaction: Photosystem II and Photosystem I.
Photosystem II is absorbs wavelengths of light that are ___________ nm and Photosystem I absorb
wavelengths of light that are ______________ nm. Both photosystems have a preference for
_________________ (color) light.
7. Where are these photosystems located? (specifically)
7.7: Photosystems generate ATP and NADPH
1. When P680 absorbs photons of light, it’s excited electrons are passed to the
__________________________. What replaces the electrons left P680?
2. The excited electrons pass from photosystem II to photosystem I via a system of membrane proteins
called the _____________________________. As excited electrons move from one protein to next, energy
is (absorbed/released). This process is (endergonic/exergonic). The energy released is used to make
_________.
3. When photons excite pigment molecules in photosystem I, the excited electrons of P700 are donated to
its primary acceptor. What replaces the electrons from P700? (Where do those electrons come from?)
4. The excited electrons from the primary acceptor in Photosystem I are passed to proteins and are finally
accepted by _____________ which is reduced to become ______________ (The final electron acceptor).
7.9: Making ATP during the Light Reaction
1. The energy released by “falling” electrons moving through the electron transport
chain (ETC) is used to pump ________ ions into the thylakoid.
2. Where is the [H+] the greatest?
3. Discuss the movement of H+ in terms of concentration gradient.
4. What type of transport is this?
5. The H+ ions then move through a transport protein that also acts as an enzyme that
phosphorylates ADP. This protein is called ______________________.
6. What type of transport is occurring when H+ ions move through ATP synthase?
Discuss in terms of concentration gradients and energy.
7. ATP synthase facilitates the following reaction: ADP + Pi  ATP. This reaction
involves (dehydration synthesis/ hydrolysis)
8. How do the ETC and ATP synthase work together?
9. Chemiosmosis is the production of ATP using [H+] gradients across a
membrane. Explain how it works.
10. In photosynthesis, the chemiosmotic production of ATP is called,
________________________________ because the initial energy input is light
energy.
7.10
Calvin Cycle (Light Independent)
1. Inputs for Calvin Cycle are: ____________, ____________, and ____________
2. Takes place in the _____________________ .
3. Adds the carbon from CO2 to a sugar called RuBP. How many carbons does
RuBP have? _______________
4. When a carbon is added to RuBP it forms a 6-Carbon compound that is unstable
and breaks apart into a ______ - carbon compound called 3-PGA.
5. ATP is (made/used), to modify 3-PGA into a sugar.
6. How is NADPH involved in the Calvin cycle?
7. The output of the Calvin cycle is a 3-carbon sugar called ____________. Some
of these molecules will be assembled into sugars and starches and some will be
recycled back into _______________ molecules so that they cycle can continue.
8. The sugar made in photosynthesis is “highly reduced”. Explain.
7.11: Review of two stages of Photosynthesis
Sugars used in Respiration;
Make Cellulose; Starch; Other
Organic Compounds
1. What happens to the sugar made in photosynthesis?
Ch. 7.12: Adaptations to save water in hot, dry climates
C3 plants – are plants that start the Calvin cycle by making a 3-carbon compound, 3PGA.
2. What do C3 plants do in response to hot, dry weather by …
3. How does this help conserve water?
4. What gas builds up inside the plant during these conditions?
5. When oxygen is added to RuBP, instead of carbon (from carbon dioxide), can
sugar be made?
6. Enzyme that adds carbon or oxygen to RuBP (rubisco) binds with oxygen more
favorably than CO2. Oxygen and carbon dioxide can both fit in rubisco’s active
site. This is an example of _____________________________ in enzyme
activity.
C4 Plants
7. C4 plants adapt to hot, dry weather by (opening/closing) stomates.
8. C4 plants have different enzymes that allow them to add carbon (from carbon
dioxide) to 4-Carbon compound. They use different enzymes that are not binding
with oxygen (that is building up). Sugar (can/cannot) be made when stomates
are closed in C4 plants.
9. Examples of C4 plants are: ______________________________.
CAM Plants
10. CAM plants adapt to hot, dry weather by closing stomates during the (day/night)
to conserve water and open stomates during the (day/night). The carbon dioxide
admitted at (day/night) is used during the day in the calvin cycle to make sugar.
11. Examples of CAM plants include: ______________________________