photosynthesis Flashcards
Jon Baptista Van Helmont
designed first scientific study to measure if plants get mass from soil, found that as plant mass increased, soil mass did not decrease, proving plants come from air
co2 distribution
evenly distributed through the atmosphere at 0.04%
water and light distribution
unevenly distributed over space and time
light
visible portion of electromagnetic spectrum 400-700nm, less than 1% of solar energy is used for photosynthesis
chlorophyll a
primary pigment used in photosynthesis, electron excited by visible light initiates the electron transport chain, found in all photosynthetic organisms that use water
accessory pigments
absorb other wavelengths of light and pass the energy to chlorophyll a
chlorophyll b
found in all plants and green algae, absorbs blue and green light
carotenoids
carotene and xanthophyll, absorb blue and green pigments, found in all photosynthetic organisms
palisade mesophyll cells
tightly packed under the epidermis of the leaf to channel light into the interior where light bounces around increasing the chances of it hitting chlorophyll
photosynthesis equation
3CO2 +6H2O + light —chlorophyll, enzymes—> C3H6O3 +3H2O
light reactions
occur first using photosystems two and one, water is split and oxygen is released, NADPH and ATP are produced, takes place in the thylakoid membrane
photosystem II
associated with splitting water and generating oxygen, hydrogen donates an electron to chlorophyll a to regenerate it, generates ATP in the presence of PS 1
photosystem I
retrieves an electron from PS 2, gets excited by light triggering another ETC producing NADPH
cyclic phosphorylation
photosystem I working without PS 2 produces ATP
calvin cycle
uses ATP and NADPH from light reactions to fix CO2 into C3H6O3 in the stroma of the chloroplasts
rubisco
enzyme essential to the calvin cycle used in the first carbon fixation
possible routes for the G3P product
converted to sucrose to be used or stored as starch, lipids, or cellulose
photorespiration
in the absence of CO2 rubisco binds to O2 making a toxic product that must be broken down to recover the CO2 costing ATP
C4 plants
PEP carboxylase fixes carbon in mesophyll cells which is transported to bundle sheath cells for the calvin cycle, light reactions are done in mesophyll cells so that the calvin cycle can occur in the absence of oxygen
Kranz anatomy
bundle sheath cells are enlarged in C4 plants to allow for the calvin cycle
CAM plants
uses PEP carboxylase to form a 4 carbon compound, CO2 is collected overnight and converted to malic acid to store, during the day malic acid is converted to be used for photosynthesis, requires the most ATP
