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Photosynthesis

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Why can the rate of photosynthesis be estimated by measuring the rate of oxygen production in chloroplasts?
a. Oxygen is produced by "splitting" water in the PS I complex.
b. Oxygen is produced by "splitting" water in the PS II complex.
c. The Calvin cycle produces oxygen.
d. Oxygen is produced by splitting CO2 in the PS II complex
b. Oxygen is produced by "splitting" water in the PS II complex.
The most abundant enzyme on Earth, which catalyzes the fixation of carbon dioxide in photosynthesis, is _____.
Rubisco
Why have biologists stopped using the once-common phrase "light-independent reactions" to describe the Calvin cycle?
a. Calvin cycle enzymes are found in the same cellular location as photosystems I and II.
b. Biologists have discovered that its reactions are triggered directly by light.
c. The Calvin cycle occurs only when stomata are open, which is triggered by light.
d. Although its reactions are not triggered directly by light, they depend on the products of light-capturing reactions.
d. Although its reactions are not triggered directly by light, they depend on the products of light-capturing reactions.
Both photosystem I and photosystem II employ the use of a(n) _____, which drives the formation of ATP and NADPH.
a. citric acid cycle
b. ferredoxin shuttling chain
c. electron transport chain
d. calvin cycle
c. electron transport chain
Plant leaves contain openings called _____, which allow the diffusion of carbon dioxide into the leaf tissue.
Stomata
During the Calvin cycle, carbon dioxide is _____, in order to drive the formation of sugars.
Reduced
What would happen in a chloroplast containing an unusual form of rubisco that did not bind oxygen?

a. Both photosynthesis and photorespiration would occur.
b. Photorespiration would occur but photosynthesis would not.
c. Neither photosynthesis nor photorespiration would occur.
d. Photosynthesis would occur but photorespiration would not.
d. Photosynthesis would occur but photorespiration would not.

Photosynthesis depends on binding of CO2, whereas photorespiration depends on binding of O2 to rubisco.
According to the Z scheme, what is the path of electrons through photosystem I (PS I) and photosystem II (PS II)?
PS II → pheophytin → plastoquinone → cytochrome complex → plastocyanin → PS I → ferredoxin
During photosynthesis, the light energy from the Sun is captured and stored in the bonds of _____.
glucose
What important molecule that is needed for cellular respiration is released when water is split in the light reactions of photosynthesis?
oxygen
How many photosystems are used in photosynthesis?
2
Which system absorbs at the spectrum known as P680? P700?
P680 --> Photosystem II
P700--> Photosystem I
What is the end product of Photosystem II? Photosystem I?
Photosystem II --> ATP
Photosystem I --> NADPH
What is carbon fixation?
The attachment of CO2 to an organic compound (ribulose bisphosphate or RuBP) which produces two 3-phosphoglycerate molecules
What are the three phases of the Calvin Cycle?
1. Fixation: CO2 reacts with RuBP producing two 3-phosphoglycerate molecules
2. Reduction: The 3-phosphoglycerate moleules are phosphorylated by ATP and reduced by NADPH to produce G3P.
3. Regeration: The remaining G3P is used in reactions that regenerage RuBP
Why is water important for photosynthesis in plants?
1.Provides electrons to replace those electrons removed from the chlorophyll in Photosystem II.
2.Provides H+ to reduce NADP to NADPH which is needed in the Calvin Cycle.
3. Produces oxygen
Why is photorespiration disadvantageous?
Photorespiration "undoes" photosynthesis because it consumes energy and releases fixed CO2.
When photorespiration occurs, the rate of photosynthesis declines.
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