Photosynthesis (easy) Flashcards
Compare absorption spectrum of chl a & chl b [2]
D: compare peaks; give (x: wavelength, y: % light absorption)
S1: Higher absorption of blue light and red light
S2: Peaks in blue light higher than red light
S3: Least absorption of green light
Explain the shape of the action spectrum [2]
- Peaks correspond to peaks of absorption spectra
» higher rate of photosynthesis in red and blue light - Region (500-600 nm) not an exact match between absorption and action spectra
» due to accessory pigments that pass the energy via resonance to reaction centre
» FUNCTION: widen action spectrum - absorb LE of different wavelengths
Explain how an electron carrier inhibitor acts as an effective herbicide [3]
- Electrons cannot be passed down ETC
- No NADPH produced
- No pumping of protons across thylakoid membrane from stroma to thylakoid lumen
» no proton gradient»_space; no chemiosmosis»_space; no ATP produced - No CC»_space; no GP»_space; G3P produced for respiration
Explain role of thylakoid membrane [3]
CHEMIOSMOSIS:
- Hydrophobic core»_space; impermeable to H+»_space; establish H+ gradient
- Sequential order of electron carriers»_space; energy released to pump H+»_space; establish H+ gradient
- Large SA»_space; many ATP synthases»_space; ATP synthesis
CC:
- Large SA»_space; many NADP reductase»_space; reduce NADP
Explain how LDR is linked to LIR
- NADPH - reduce GP to G3P
- ATP - energy for reduction stage
- ATP - regeneration of RuBP»_space; continue CC
Explain role of water [2]
Photolysis…
- H+ - establish H+ gradient
- Electrons - replace electrons lost by chl a in PS II
Compare cyclic vs. non-cyclic photophosphorylation [3]
- End-product
» only ATP vs. ATP, NADPH, O2 - PS involved
» PS I only vs. PS I and II - Source of electrons / electron donor
» P700 vs. water, direct electron donor is P680 - Pathway of electrons
» cyclical (PS I > 1st ETC > PS I) vs. 1 direction (PS II > 1st ETC > PS I > 2nd ETC) - Final electron acceptor
» P700 vs. NADP+
Explain how O2 consumption and succinic acid oxidation are linked [2]
- FAD reduced to FADH2 (ELECTRONS DONATED) in breakdown of succinate
- O2 as final electron acceptor
» maintains flow of electrons down ETC - FADH2 can donate electrons to ETC
» regenerate FAD+
Compare SLP and OP
- Role of coenzyme
SLP - NAD+ needed for oxidation of G3P
OP - NADH and FADH2 pass electrons to ETC - Enzyme
» kinase vs. ATP synthase - ATP synthesis
SLP - enzymatic transfer of phosphate from substrate to ADP via a kinase
OP - due to diffusion of H+ down H+ gradient from IMS to MM via ATP synthase - Source of phosphate
» organic molecule vs. inorganic phosphate - (transfer of electrons down) ETC and (generation of) H+ gradient
- ATP yield / glucose (2 vs. 32/34)
Explain why rate of O2 uptake can be used as an indicator of rate of respiration [2]
Final electron acceptor in OP
Explain why glucose has no effect on rate of O2 uptake by ISOLATED MITOCHONDRIA [2]
- No enzymes for glycolysis
- Glucose not oxidised to pyruvate
» no acetyl CoA produced for KC
» no NADH/FADH2 produced to donate electrons to ETC for OP - Thus O2 not reduced to produce water
Explain the different yields of ATP from glycogen and palmitic acid [2]
- Palmitic acid yields higher energy
- Palmitic acid has more C-H per mole
- More H+ released for chemiosmosis in OP
» produce more ATP
Explain ATP’s “universal role as the energy currency” [4]
- Immediate source of energy in most cells
» easily hydrolysed to ADP + Pi + energy
» used in metabolic reactions - link catabolic + anabolic reactions
» reversible reaction»_space; high turnover - Small, water soluble»_space; diffusible around cell
