C1.3 HL Flashcards
Describe the arrangement of pigments into photosystems in membranes.
Chloroplast - Granum - Thylakoid - Thylakoid membrane - Photosystem with chlorophyll pigment (capture light electrons excited)
Outline the advantage of pigments being arranged in photosystems as opposed to being dispersed.
causes the excitation and the release of e- that will provide energy for the rest of the light-dependent phase of photosynthesis.
Outline each photosystems: include where the replace lost electrons, peak absorbance of the reaction center of chlorophyll molecules, what they produce/function
PSII —> ATP
-P680 (best wavelength for absorbing)
- electron from photolysis
PSI —> reduced NADP
-P700
-electron from PSII
Photosystems as arrays of _____ molecules that can generate and emit excited ______.
pigment, electrons
Outline advantages of different types of pigment molecules being arranged within a photosystem.
- more pigment = more photons of light absorbed
- increases range of wavelengths
- efficient energy transfer to the reaction center
Describe the role of photosystem II in photolysis.
- pigment chlorophyll absorb light
-excited electron moves down ETC - water splits and gives 2 electrons to PSII to replace lost electrons (happens twice to make oxygen gas)
Photolysis of water at photosystem II contributes to the _________ in the thylakoid lumen.
proton gradient (inc. of H+)
Outline the role of photosynthesis of the “Great Oxygenation Event” on early Earth.
-oxygenation of atmosphere
-increase in biodiversity after early life formed
Outline the evidence for the “Great Oxygenation Event” provided by banded iron formations.
The increase in oxygen allowed it to react with iron to form several layers of iron oxide sediments.
Sketch a cross section of the thylakoid membrane, inclusive of photosystem II, ATP synthase, an electron transport chain (with Pq) and photosystem II.
(view diagram/interactive)
Define chemiosmosis and photophosphorylation.
Chemiosmosis - ATP synthase pump H+ (high to low- facilitate diffusion)
Phosphorylation - Kinetic energy allows ADP + Pi to convert to ATP
electrons generated by photosystem II pass from ________ through a chain of electron carrier molecules.
plastoquinone (Pq)
The energy _____ by the movement of electrons is used to __________ across the thylakoid membrane, from the ____ into the thylakoid lumen.
released, pump protons (H+), stroma
The result of the electron transport chain is a ______, with a high concentration of protons in the _______.
proton gradient, thylakoid lumen
Compare the flow of electrons in cyclic vs noncyclic photophosphorylation.
(ONLY PS1)Cyclic photophosphorylation- electrons get expelled by photosystem I and they return to the system.
- (BOTH PHOTOSYSTEMS) non-cyclic photophosphorylation, the electrons that are expelled by the photosystems do not return.
the photoactivation of the reaction center _______ in photosystem I _____ electrons which pass through a different electron transport chain.
chlorophyll, excites
Outline the flow and function of electrons from photosystem I in cyclic photophosphorylation.
-as excited electron travels ETC it uses energy to pump protons into thylakoid lumen
- ATP synthase uses facilitated diffusion to transfer protons into the stroma
-Kinetic energy: ADP +Pi –> ATP molecules are produced.
Outline the flow and function of electrons from photosystem I in non-cyclic photophosphorylation.
-excited electron leaves PSII (P680)
-electron leaves PSI (P700)and enters NADP reductase enzyme embedded within the membrane
-Both NADPH and ATP molecules are produced.
In noncyclic photophosphorylation, the electrons of ________ are used to reduce _____ to form NADPH.
photosystem I, NADP+
State the function of the enzyme NADP reductase.
use electrons to reduce NADP+ to form NADPH for Calvin cycle
The light dependent reactions convert ________ into chemical energy in the form of ___ and ________.
light energy, ATP, reduced NADP (=NADPH)
In cyclic phosphorylation, water is ______ and NADPH is _______. The main action of this is _______. Product: _____
not required, not synthesized, hydrogen ions being pumped into lumen and stroma, ATP
______ is an electron carrier in Photosynthesis
NADP
Describe the structure of the thylakoid grana and stroma lamellae.
thylakoid grana - stack of pancakes
stroma lamellae - connect thylakoids of two different grana. increase the efficiency of photosynthesis - keep distance so that thylakoids do not clutter together.
