Biochemistry : Light Reaction Energetics

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #1 : Photosynthesis

In photosynthesis, what is the purpose of absorbing light into chloroplasts?

Possible Answers:

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 all of the electrons in the chloroplast to jump to higher energy levels

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 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 leading to the creation of carbon dioxide

Correct answer:

The energy from the absorbed light generates NADPH from the electrons of water molecules, ultimately setting up a proton gradient

Explanation:

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 #2 : Photosynthesis

Photosynthesis consists of a light phase and a dark phase. The light phase precedes the dark phase and supplies it with __________.

Possible Answers:

Correct answer:

Explanation:

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.

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