photosynthesis 3.5 Flashcards
what are the two stages of photosynthesis
light dependent reaction
light independent reaction
what key products are produced in the LDR
ADP
NADPH
where does the light dependent reaction take place
thylakoids
where does the light independent reaction take place
stroma
what are the two groups of pigments
carotenoids
chlorophylls
what are the main primary pigments
chlorophylls
what are the main accessory pigments
carotenoids
what is the absorption peak of PSII
P680nm
what is the absorption peak of PSI
P700nm
RF value =
distance by pigment divided by distance by solvent
what are the 2 ways that ATP can be synthesised
1 non cyclic photophosphorylation
2 cyclic photophosphorylation
what is the flow of electrons called
Z scheme
stages of photophosphorylation in the LDR
1 photosystem 2 absorbs light
2 electrons raised to a higher energy level and leave chlorophyll molecule
3 electrons accepted by electron carrier
4 splitting of water/photolysis replaces electron
5 replacement e- accepted by chlorophyll molecule
6 electrons passed along electron carriers via redox reactions
7 causes pumping of protons into the thylakoid lumen
8 protons used to produce ATP by chemiosmosis
9 electrons enter PS1 and raised to a higher energy level
10 enter final electron carrier
11 electrons and protons reduce NADP which passes to calvin cycle with ATP
what is the chemiosmostic theory
production of ATP involves electron transfer and the passage of protons across chloroplast membranes
stages of chemiosmosis
1 electron flow provides energy to pump protons from stroma into thylakoid lumen.
2 creates a high conc of protons in thylakoid lumen and low in stroma
3 thylakoid membrane can maintain electrochemical gradient as it is impermeable to protons
4 protons move back into stroma via ATP synthase channel proteins
5 flow of protons leads to ATP formation (from ADP and Pi)
stages of the Calvin cycle
1 fixation- RuBp reacts with CO2 catalysed by RUBISCO
2 produces 2 molecules of GP
3 GP reduced to form TP using ATP and NADPH from LDR
4 some TP removed to form hexose sugars lipids, and amino acids
5 regeneration- RuBp regenerated using ATP
effect of decreased light intensity
TP - less
GP - more
RuBp - less
effect of increased CO2
TP - more
GP - more
RuBp - less
effect of increased temperature
TP - more (until RUBISCO denatures)
GP - more (until RUBISCO denatures)
RuBp - less
how is nitrogen absorbed
through roots as nitrates
how is nitrogen transported
as nitrate in xylem
amino acids in phloem
what is the appearance of a plant with nitrogen deficiency
chlorosis (yellowing of leaves)
what is the role of magnesium
forms part of the chlorophyll molecule
what is the appearance of a plant with magnesium deficiency
chlorosis (yellowing of leaves)
what is the law of limiting factors
when a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply.
what factors will limit the rate of photosynthesis
CO2 concentration, light intensity, water, availability of chlorophyll
what is the compensation point
where the rate of photosynthesis = the rate of respiration
