p2: photosynthesis Flashcards
NADP
- Hydrogen acceptor
- NADPH reducing agent, donates H to other molecules in REDOX
photoionisation
- loss of an electron in chlorphyll due to light
photolysis
- splitting water with light
photophosphorylation
- adding an inorganic phosphate group to ADP using light to form ATP
where does the LDR take placE?
- specifically in grana
- forms NADPH and ATP
describe the light dependent reaction (LDR)
- chlorophyll absorbs light energy via photoionisation
- excites electrons (raised to a higher energy level) and removed
- electrons move along electron transport chain releasing energy via series of REDOX reactions
- energy released used to form proton gradient
- H+ ions diffuse through ATP synthase
- provides energy to join ADP and Pi to form ATP
- photolysis of water produces 2 protons, 2 electrons and half oxygen
- NADP reduced by electrons (forms NADPH)
- electrons left the chlorophyll replaced by electrons from water molecules
chemiosmotic theory
- photoexcited electrons from chlorophyll transferred along the ETC
- electrons provide energy to pump protons, forming a proton gradient
- protons diffuse through transmembrane protein called ATP synthase down an electrochemical gradient
- movement provides energy to join ADP and Pi to form ATP
- electrons reduce NADP
why is LDR not active transport
- H+ ions pumped into thylakoid spaces use energy released from electrons, not ATP
where does photolysis of water occur?
thylakoid space
name the two products of the LDR that are required for the LIR
- ATP
- NADPH
in plants, ATP produced in the LDR. suggest why this is not a plants only source of ATP
- plants dont PS in dark
- not all parts of plant PS
- plants requre more ATP than produced in LDR
- ATP used in active transport
describe the effect of using a herbicide on the ETC
- reduced proton gradient across thylakoid membrane
- so less ATP produces
- so less NADPH produced
- so LDR slows
light independent reaction (LIR)
- CO2 combines/ is fixed with RuBP via Rubisco enzyme
- produces 2 GP molecules
- 2GP reduced to triose phosphate
- using reduced NADP
- using energy from ATP
- triose phosphate converted to glucose/AA/pyruvate/DNA/cellulose or regenerated to RuBP
how is the chloroplast adapted to maximise the rate of PS in the stroma?
- large SA:V
- large number of grana and thylakoids
- aqueous
where does the LIR take place?
stroma
- requires ATP and NADPH from LDR
factors affecting rate of photosynthesis
- temperature
- CO2 concentration
- light intensity
the concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. use your knowledge of PS to describe and explain these changes and why they occur.
- high conc of CO2 linked with night
- no PS in dark
- in dark, plants respire
- in light, rate of PS greater than rate of RP
- decrease in CO2 conc with height
- ground level has fewer leaves/less light
explain why scentists measure rate of production of O2 in this investigation?
- O2 produced in LDR
- faster O2 produced, faster LDR
GLASSHOUSES
- artificial lights increase light intensity to optimum level
- increaes productivity
- increases yields
- grown all year around
- increases CO2 levels (burn fossil fuels)
- heaters raise temp
explain why plants with more chlorophyll will grow faster than plants without chlorophyll
- have faster production of ATP and NADPH
- more LDR
- so produces more sugars used in RP
- so more energy for growth
- faster synthesis of new organic materials
describes what happens in the photoionisation in LDR
- chlorophyll absorbs light
- electrons lost
when producing a chromatogram explain why origin marked marked using pencil not pen
- ink and leaf pigments mix
- line still visible
while making a chromatogram, describe the method used to separate the pigments after the solution of pigments had been applied to origin
- level of solvent below line
- stop before solvent reaches end
suggest and explain the advantage to plants of having different coloured pigments in the plant
- absorbs different wavelengths of light for PS
explain the relationship between stomatal opening and pS
- stomata allow uptake of CO2
- CO2 used in PS
