Photosynthesis Process

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Questions and Answers

What is the location where photosynthesis takes place in plant cells?

Cell wall

Chloroplasts (correct)

Nucleus

Mitochondria

What is the purpose of the reaction-center chlorophyll in the light-dependent reactions?

To concentrate solar energy (correct)

To synthesize glucose

To release oxygen

To produce ATP and NADPH

What is the outcome of the cyclic electron pathway in photosynthesis?

Synthesis of glucose

Production of ATP and NADPH

Production of ATP only (correct)

Release of oxygen

What is the role of the electron transport chain (ETC) in the light-dependent reactions?

To produce NADPH Signup and view all the answers

What is the name of the fluid-filled space surrounding the grana within the chloroplast?

Stroma Signup and view all the answers

What is the pigment responsible for photosynthesis found in the thylakoid membranes?

Chlorophyll a Signup and view all the answers

What is the result of the energy provided by the flow of hydrogen ions down the electrochemical gradient?

Production of ATP Signup and view all the answers

What is the location of the ATP synthase complex?

Thylakoid membrane Signup and view all the answers

What is the enzyme that combines RuBP with carbon dioxide during carbon fixation in the Calvin cycle?

Rubisco Signup and view all the answers

What is the molecule that represents the end product of the Calvin cycle?

G3P Signup and view all the answers

What is the energy-rich organic compound produced as a result of the Calvin cycle?

Glucose Signup and view all the answers

What are the two molecules required for reduction in the Calvin cycle?

ATP and NADPH Signup and view all the answers

What is the primary function of the light-dependent reactions?

To generate ATP and NADPH Signup and view all the answers

What is the role of the electron transport chain in the light-dependent reactions?

To create a proton gradient across the thylakoid membrane Signup and view all the answers

What is the wavelength of light absorbed by Photosystem I?

700 nm Signup and view all the answers

What is the location of Photosystem II in the thylakoid membrane?

Stacked regions Signup and view all the answers

What is the energy source used to drive ATP synthesis in the light-dependent reactions?

Proton gradient Signup and view all the answers

What is the product of ATP synthesis in the light-dependent reactions?

ATP Signup and view all the answers

Study Notes

Photosynthesis

Photosynthesis is the ability of plants, algae, and some bacteria to produce their own food in the presence of sunlight.
All heterotrophs (consumers) are dependent on autotrophs (producers) for their food.

Structures Involved in Photosynthesis

Chloroplasts are the organelles within plant cells where photosynthesis occurs.
Thylakoids are membranous compartments within chloroplasts that contain chlorophyll.
Grana are stacks of thylakoids within chloroplasts.
Stroma is the fluid-filled space surrounding the grana within the chloroplast.

Light-Dependent Reactions

Light-dependent reactions occur in the thylakoid membranes of chloroplasts.
Light energy is absorbed by reaction-center chlorophyll, typically chlorophyll a.
Electrons become excited and escape, moving to a nearby electron-acceptor molecule.
There are two electron pathways: cyclic and noncyclic.

Cyclic Electron Pathway

Electrons flow in a circle within Photosystem I.
Only produces ATP.
No oxygen is released.

Noncyclic Electron Pathway

Electrons flow in a straight line from water to NADP+ via both Photosystem II and Photosystem I.
Produces both ATP and NADPH.
Oxygen is released when water splits.

ATP Synthesis

The flow of hydrogen ions down the electrochemical gradient through a channel in the thylakoid membrane provides the energy for ATP production.
ATP synthase complex facilitates the synthesis of ATP.
ATP is produced in the stroma of the chloroplast.

Light-Independent Reactions (Calvin Cycle)

Carbon dioxide is reduced to form a carbohydrate.
The reduction of carbon dioxide occurs in the stroma.
RuBP carboxylase (Rubisco) combines RuBP with carbon dioxide during carbon fixation.
5 carbons are in RuBP.
3-PGA is the first detectable molecule in the Calvin cycle after carbon dioxide fixation.
PGA, BPGA, and G3P are intermediate molecules in the Calvin cycle.
Five molecules of G3P are used to re-form 3 molecules of RuBP.
G3P represents the end product of the Calvin cycle.
ATP and NADPH are converted to ADP + Pi and NADP+ during the light-independent reaction.
Glucose is the energy-rich organic compound produced as a result of the Calvin cycle.

Electron Transport Chain

A series of protein complexes that generate a proton gradient across the thylakoid membrane.
Energy from light is used to pump protons across the membrane, creating a proton gradient.
The proton gradient is used to drive ATP synthesis.
Involves the transfer of electrons from high-energy molecules to lower-energy molecules.

Photosystem I

Absorbs light energy at a wavelength of 700 nm (P700).
Generates a high-energy electron that is used to reduce NADP+ to NADPH.
Produces a proton gradient that drives ATP synthesis.
Located in the unstacked regions of the thylakoid membrane.

Photosystem II

Absorbs light energy at a wavelength of 680 nm (P680).
Generates a high-energy electron that is used to reduce plastocyanin.
Produces a proton gradient that drives ATP synthesis.
Located in the stacked regions of the thylakoid membrane (grana).

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Description

Test your knowledge about photosynthesis, the process by which plants and some organisms produce their own food in the presence of sunlight. Learn about the role of chloroplasts, thylakoids, and chlorophyll.