Chapter 10 - Photosynthesis Flashcards
What is photosynthesis?
The process that converts solar energy into chemical energy within chloroplasts
autotrophs are:
“self-feeders” that sustain themselves
heterotrophs are:
they obtain organic material from OTHER organisms; the CONSUMERS of the biosphere
Photosynthesis equation:
6 CO2 (carbon dioxide) + 12 H2O (water) + Light energy → C6H12O6 (glucose) + 6 O2 (oxygen) + 6 H2O (less water)
Photosynthesis is redox process in which _ is oxidized + it is a (_) reaction
H2O is oxidized;
Photosynthesis is an endergonic process
Light reactions (stage 1)
They convert solar energy to the chemical energy of ATP and NADPH; (light is electromagnetic energy)
A wavelength is:
a measure of distance between the crests of the waves
Pigments are…
substances that absorb visible light;
wavelengths of this light that are not absorbed are reflected (chloroplasts are green from reflected light)
The action spectrum…
For photosynthesis, is a profile of the relative effectiveness of different wavelengths/colors of lights on photosynthesis
Chlorophyll a and b are different because…
CH3 in chlorophyll A;
CHO in chlorophyll B
In isolation, an excited isolated chlorophyll will…
After absorbing light-> gets to excited state-> falls back to ground state, releasing excess energy->causing FLUORESCENCE
A photosystem is…
consisting of a reaction-center complex surrounded by light-harvesting complexes
The reaction-center complex is…
an association of proteins holding a special pair of chlorophyll a molecules + primary electron acceptor
The light-harvesting complex…
group of pigment molecules bound to proteins; they transfer energy of photons to the c.A molecules in reaction-center
The thylakoid membrane holds 2 photosystems…
Photosystem I:
-cyclic electron flow, produces ATP
Photosystem II:
-can take electrons from water
linear electron flow:
inbetween systems 2 & 1, is the flow of electrons through the photosystems and other molecule components
In mitochondria, protons are pumped…
to the INTERMEMBRANE SPACE and drive ATP synthesis as they diffuse back into the mitochondrial matrix
In chloroplasts, protons are pumped…
into the THYLAKOID space and drive ATP synthesis on the stroma side of the membrane as they diffuse back into the stoma
Photophosphorylation v.s. Oxidative Phosphorylation
-mitochondria extracts electrons from organic molecules, transfers chemical energy from food to ATP
-chloroplasts, high energy electrons drop down the transport chain from water; transforms light energy into chemical energy of ATP
The Calvin Cycle (stage 2)
-anabolic, builds sugar from smaller molecules by using ATP
-3 CO2 goes in->is FIXATED to 6x3C->REDUCED and outputs glucose->REGENERATES 5x3C-> repeat process (3 CO2 keeps process going)
Photorespiration is…
COSTLY :(
rubisco binds with O2 instead of CO2 ->producing a 2-carbon compound
C4 plants…
-most plants are C3, but C4 plants minimize the cost of photorespiration;
-in hot weather, close stomata to conserve water
Photosynthesis begins in mesophyll cells, but is completed in…
Bundle-sheath cells: cells arranged in tightly packed sheaths around the leaf veins
CAM Plants…
Crassulacen acid metabolism (succulents), open stomata at night, incorporate CO2 into organic acids; during day, CO2 is released and used in Calvin Cycle
C4 vs CAM
-similar steps: organic acid-> Calvin cycle
-differ in times (CAM plants using night/day)
the rubisco is…
the base 3-6 carbonds that get changed throughout the Calvin cycle
in a plant, what reactions produces molecular oxygen ?
the light reactions
