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Example Questions
Example Question #1 : Light Reaction Energetics
In photosynthesis, what is the purpose of absorbing light into chloroplasts?
The energy from the absorbed light generates NADPH from the electrons of water molecules, ultimately leading to the creation of carbon dioxide
The energy from the absorbed light generates NADPH from the electrons of water molecules, ultimately setting up a proton gradient
The energy from the absorbed light causes all of the electrons in the chloroplast to jump to higher energy levels
The energy from the absorbed light moves the electrons from NADPH to water molecules, ultimately setting up a proton gradient
The energy from the absorbed light causes the generation of NADH from the electron of water molecules, ultimately setting up a proton gradient
The energy from the absorbed light generates NADPH from the electrons of water molecules, ultimately setting up a proton gradient
In photosynthesis, light is absorbed in order to move electrons from water molecules to NADPH. The reduction of to NADPH is accompanied by the movement of protons across a membrane which sets up a gradient similar to that of oxidative phosphorylation. The protons eventually run through ATP synthase and ATP is formed.
Example Question #1 : Light Reactions
Photosynthesis consists of a light phase and a dark phase. The light phase precedes the dark phase and supplies it with __________.
During photosynthesis, the light phase is responsible for creating which the dark phase then consumes as a part of its process. In addition to is used in the dark phase as a high energy substrate to work properly.
Example Question #1 : Other Light Reaction Concepts
In photosynthesis, if photosystem II absorbs 12 photons, how many molecules of would be produced?
Absorbing four photons by photosystem II creates one oxygen molecule, so absorbing 12 would produce 3 molecules of .
Example Question #2 : Light Reactions
During photosynthesis there is both a light phase and a dark phase. If the light phase were to continue unabated, but the dark phase came to a halt, which of the following is most likely to occur?
A proportional decrease in
Decrease in the level of
An increase in the production of carbohydrates
Decreased sensitivity of the chloroplast to incoming light
Increased sensitivity of the chloroplast to incoming light
Decrease in the level of
During photosynthesis, the dark phase follows the light phase. The light phase produces which, along with , is fed into the dark phase where it is consumed (becomes and ). If the light phase continues working, but the dark phase does not, the and created during the light phase will not be consumed. Thus, there will be a decrease in the level of and (the correct answer). The relative proportion of will actually increase.
Carbohydrate production is a result of the dark phase working properly, so their levels would decrease in this instance. The sensitivity of the chloroplast to light would not change.
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