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Photosystem II



The photosystem that absorbs light for use to drive the oxidation of water and the reduction of plastoquinone, and whose reaction center chlorophyll is P680.


Photosystem II is named as such since it is discovered after photosystem I. Their names do not represent the electron flow as it begins in photosystem II I (i.e. when both of them are present in the organism, e.g plants and algae). When photosystem II releases an excited electron, it returns to its ground state by accepting an electron from the oxidation of water molecule whereas photosystem I receives its electron from the electron transport chain, which in turn received an electron from photosystem II.

Abbreviation: PS II

Compare: photosystem I

See also: P680

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I just taught that course (gr 12 photosynthesis): It appears that it is probably extremely unclear. I think it uses 4 photons per photosystem for each H2O broken. But since you need a mix of cyclic and non cyclic light reactions to produce anough ATP and NADPH, and that the cyclic reactions ...

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by canalon
Sat Apr 14, 2012 6:23 pm
Forum: Physiology
Topic: Photosynthesis
Replies: 2
Views: 3503


Is this statement true? Photosystem II is at highe energy level than Photosystem I.

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by chiayen
Sun Jan 15, 2012 4:43 am
Forum: General Discussion
Topic: photosystems
Replies: 1
Views: 936

reverse photosynthesis and get respiration

... respiration (as mith said) think how mitochondrias work ( the thylakloid membranes and ETC's and then the chemeoosmosis) and compare that with photosystem... an abvious answer it is a big NO... and the reasons you can get even by thinking a little good luck thinking ;) thhough if you still ...

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by jwalin
Sun Apr 11, 2010 11:55 am
Forum: Cell Biology
Topic: reverse photosynthesis and get respiration
Replies: 8
Views: 4541

Re: Why do intact chloroplasts fluoresce?

... acceptor. So at what point is energy released as light? Thanks for your reply. Don't they drop back down to near the ground state when going from Photosystem II to Photosystem I? Would that cause the fluorescence in intact photosystems?

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by mamoru
Tue Mar 09, 2010 12:32 am
Forum: Botany Discussion
Topic: Why do intact chloroplasts fluoresce?
Replies: 10
Views: 7308

Biology IQ test: How smart are you = look

... electron sink in respiration. 15) RUBISCO is optimally evolved to work in an oxygen atmosphere. 16) The chlorophyll A molecules of the two photosystems are chemically different which causes their difference in absorbance spectra. 17) The large +G of life (all life collectively) is ultimately ...

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by DemiMike
Sat Nov 28, 2009 6:21 am
Forum: General Discussion
Topic: Biology IQ test: How smart are you = look
Replies: 3
Views: 12211
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