photosynthesis

where are LDS and calvin cycle (LIS)

lds thylakoid membranes

calvin stroma

role of chlorophyll

absorbs light energy, exciting electrons to higher energy levels

role of photosystem II

absorbs loght and excites electrons: lost electrons are replaced by photolysis

role of PSI

re excites electrons using light energy so they can help reduce NADP

role of accessory pigments

absorb additional wavelengths and transfer energy to chlorophyll a

photolysis

splitting water through light

2H2O → 4H* + 4e- + O2

what happens in non cyclic photophosphorylation

electrons flow from water through PSII and PSI to ANDP ATP NADPH and O2 forms

what happens in cyclic photophosphorylation

electrons from PAI return to electron carriers; extra ATP forms only

how is atp made during photosynthesis

electron transport builds a proton gradient, h* flows through ATP synthase, makes ATP

how is NADPH formed and used

NADP gains electrons and H*

NADPH supplies reducing power in calvin cycle

what is carbon fixation

rubisco catalyses CO2 combining RuBP forms unstable 6c compound

what happens to the unstable 6C compound

splits into 2 molecules of glycerate 3 phosphate (GP)

how is GP converted into TP

ATP supplies energy (makes ADP and Pi)

NADPH supples electrons/H (makes NADP)

these are from the LDS

what happens to TP in calvin chcle

some makes orgnic molecules, most regenerates RuBpP using atp ?

absorption and action spectra

a: loght absorbed by pigments

as: photosynthesis rate at doff wavelengths

how does light intensity affect ptsts

increases then plateus when another factor becomes limiting

w/o light LD rection cant occur - atp and NADPH not made,

so GP cnt be reduced to TP

how does CO2 conc affect ptsts

rate increases until another factor limits

less Co2 mens less RuBP is converted to GP

why can high temps reduce ptsts

enzymes lose activity; stomata may clsoe, reduces Co2 entry

compare LIS and LDS

LIS: only PSI, no photolysis, NADPH not made

LDS: PSI PSII, photolysis, NADPH synthesised

light compensation poitns