p2: photosynthesis Flashcards
1
Q
NADP
A
- Hydrogen acceptor
- NADPH reducing agent, donates H to other molecules in REDOX
2
Q
photoionisation
A
- loss of an electron in chlorphyll due to light
3
Q
photolysis
A
- splitting water with light
4
Q
photophosphorylation
A
- adding an inorganic phosphate group to ADP using light to form ATP
5
Q
where does the LDR take placE?
A
- specifically in grana
- forms NADPH and ATP
6
Q
describe the light dependent reaction (LDR)
A
- 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
7
Q
chemiosmotic theory
A
- 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
8
Q
why is LDR not active transport
A
- H+ ions pumped into thylakoid spaces use energy released from electrons, not ATP
9
Q
where does photolysis of water occur?
A
thylakoid space
10
Q
name the two products of the LDR that are required for the LIR
A
- ATP
- NADPH
11
Q
in plants, ATP produced in the LDR. suggest why this is not a plants only source of ATP
A
- plants dont PS in dark
- not all parts of plant PS
- plants requre more ATP than produced in LDR
- ATP used in active transport
12
Q
describe the effect of using a herbicide on the ETC
A
- reduced proton gradient across thylakoid membrane
- so less ATP produces
- so less NADPH produced
- so LDR slows
13
Q
light independent reaction (LIR)
A
- 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
14
Q
how is the chloroplast adapted to maximise the rate of PS in the stroma?
A
- large SA:V
- large number of grana and thylakoids
- aqueous
15
Q
where does the LIR take place?
A
stroma
- requires ATP and NADPH from LDR
