Photosynthesis Flashcards
How many cell membranes does a chloroplast have? names?
3, outer membrane, inner membrane, thylakoid membrane
What is photosynthesis?
The synthesis of organic compounds from inorganic as a result of the fixation & reduction of carbon dioxide using light energy
What type of nutrition is photosynthesis?
Autotrophic nutrition
What does photosynthesis occur in?
All plants, many protoctists, some prokaryotes (bacteria)
Where do light dependent reactions take place?
Thylakoid Membrane
Where do light independent reactions take place?
Stroma
Why is the upper epidermis transparent?
for maximum light absorption
why are the long sides of palisade cells exposed to intercellular spaces?
for rapid uptake of carbon dioxide
why do palisade cells have thin cell walls?
so there is a short diffusion pathway
Why are palisade cells columnar shaped?
so the cross wall effect is reduced and therefore maximum light penetration is obtained
what does the cytoplasm of palisade cell contain lots of? and why?
Chloroplasts for maximum photosynthesis
What colour does chlorophyll show?
green
what colour does carotenes show?
reds
what colour does xanthophylls show?
yellows
what are the absorbance peaks of chlorophyll a?
420 & 660
what are the absorbance peaks of chlorophyll b?
435 & 643
what is the absorbance peaks of ß carotenes?
425 to 480
what is the function of pigments?
to absorb light energy
why are there so many pigment types?
to enable absorption of light energy from a wider range of wavelengths
what does an absorption spectrum show?
the wavelengths of light energy absorbed by pigments
what does an action spectrum show?
the rate of photosynthesis at different wavelengths
what is chromotography?
technique used to separate substances in a mixture, relies on molecular size and solubility in solvent, small molecules/more suluble move faster/further
what is the equation for r.f. values?
(distance moved by substance) / (distance moved by solvent front)
what do light dependent reactions produce?
ATP by cyclic & non-cyclic photophosphorylation, reduced NADP
What do light independent reactions form by reducing & fixing carbon dioxide?
carbohydrate
What does OIL RIG stand for?
Oxidation Is Loss of electrons Reduction Is Gain of electrons
What are the 2 types of pigments in Photosystems (PS) I and II?
Primary pigments and Accessory pigments
What are primary pigments?
2 types both specialised forms of chlorophyll a, P680 in PSII with absorbance peak at 680nm, and P700 in PSI with absorbance peak at 700nm
what are accessory pigments?
all other pigments, enable trapping of light energy from a wide range of wavelengths, energy from these is passed on to primary pigments
what does cyclic phosphorylation produce and which photosystem is used?
produces ATP, involves photosystem I only
what does non-cyclic photophosphorylation produce and involves which process/photosystems?
produces ATP, reduced NADP, and oxygen
involves photosystem I and photosystem II, and the photoslysis of water
What are 4 similarities between Photophosphorylation and Oxidative Phosphorylation?
Electrons are passed through membrane bound carriers in a series of redox reactions
energy released from the electrons moving causes proton pumps to pump H+ into the thylakoid lumen
this causes an increase in H+ concentration in the thylakoid lumen
H+ flow from the lumen into the stroma through facilitated protein channels associated with ATP synthetase
What are the 4 main stages of the Calvin Cycle?
Carboxylation (1st: C fixation)
Phosphorylation(using ATP + Reduction(using reduced NADP)
Glucose synthesis from triose phosphate
Regeneration of Ribulose biphosphate
What happens during carboxylation in calvin cycle?
ribulose biphosphate fixes Carbon dioxide into 2 x glycerate 3-phosphate
What is used during photophosphorylation and reduction in calvin cycle? what happens?
Photophosphorylation uses ATP and Reduction uses reduced NADP
Glycerate 3-phosphate coverted to triose phosphate
What happens during regeneration in calvin cycle?
Ribulose biphosphate regenerated from triose phosphate using ATP
What is Blackman’s law?
When the rate of a process is governed by a number of factors the overall rate will be limited by the factor with the lowest quantity
What are 5 environmental factors limiting the rate of photosynthesis?
Light Wavelength
Light Intensity
Carbon dioxide concentration
temperature
water availability
What is Gross Photosynthesis?
total amount of Carbon dioxide fixed into carbohydrate
what is the equation for net photosynthesis?
gross photosynthesis - respiration
what is compensation point?
when carbon dioxide fixed in photosynthesis = carbon dioxide released by respiration
