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AP Biology 2014 > Photosynthesis > Flashcards

Flashcards in Photosynthesis Deck (10):

Reactants and Products of Photosynthesis

Reactants: 6 CO2 and 12 H2O

(Carbon Dioxide and Water)


Products: 6 H2O, 6 O2, and C6 H12 O6

(Water, Oxygen, and Glucose)

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Chloroplast function and major components

Chloroplast: found in the interior tissue of the leaf (Mesophyll)

Thylakoids: membranes that contain the chlorophyll and stacked in columns called grana

Stroma: dense fluid

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Light Reactions

Light reactions are endergonic reactions that occur in the thylakoids and capture light energy to reduce NADP+ and convert ADP to ATP. Electrons are provided through water.


The Calvin Cycle

The CC occurs in the stroma at night and uses ATP and NADPH to build carbohydrates (glucose).

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Photosystem II

The first photosystem to function in the light reactions by absorbing light with a wavelength of approximately 680nm (red/orange light)


Photosystem I

Occurs after Photosystem 2 and has a reaction center called P700. Makes NADPH. 



Pigments: Absorb certain wavelengths but reflect others Chlorophyll a is the main photosynthetic pigment 

Accessory pigments: widen the spectrum used for photosynthesis (chlorophyll b)

Carotenoids: red and yellow pigments that prevent damage to the plant by reflecting excessive light


Linear Electron Flow

The primary pathway that involves both the photosystems and produces ATP and NADPH with light energy. Electrons move down the electron transport chain and pump protons and lose energy. The proton gradient is used to build ATP. 

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In photophosphorylation, light energy is used to create a high-energy electron donor and a lower-energy electron acceptor. Electrons then move randomly from donor to acceptor through the electron transport chain.


Cyclic Electron Flow 

Only used in Photosystem I to only produce ATP. Excited electrons reach the second electron acceptor and are sent back to the electron transport chain to continue to drive the proton gradient. This makes more ATP.