unit 8 Flashcards
autotrophs
- self feeders who can sustain themselves without eating anything derived from other living beings
- producers of biosphere bc large source of orgo comp. for non-autotrophic organisms
photoautotrophs
- type of autotroph
- use light as source of E to make orgo substances
heterotrophs
- unable to make their own food
- consumers of the biosphere that eat organisms or compounds produced by them
parts of a plant + chloroplast
- stomata: mouth openings on plant surface
- mesophyll: tissue cells that contain chloroplast that contain chlorophyll molecules
- chloroplast has inner and outer membrane
- stroma: sugary fluid in chloroplasts(where Calvin cycle happens)
- thylakoids: stacks of them found in chloroplast(where light rxns happen)
equation of photosynthesis
6CO2+ 6H2O -> C6H12O6 + 6O2
- CO2 reduced
- H2O oxidized
explain experiment that revealed source of oxygen produced during photosynthesis
Van Niel’s experiemtn.
- experiment used hydrogen sulfide (H2S) as a hydrogen donor instead of water inside photosynthetic bacteria
- bacteria produced sulfur instead of oxygen; showing O2 that is released comes from water, not CO2
reactants and products of light reactions
- reactants: Light, H20, NADP+, ADP+P
- products: O2, ATP, NADPH
reactants and products of Calvin cycle
- reactants: ATP, NADPH, CO2
- products: sugar(CH2O), NADP+, ADP+P
conclusions of Englemann’s experiments
pigments involved in photosynthesis
- highest rate of photosynthesis occurs when algae in red or blue light(bc most dense bacteria)
- chlorophyll(pigment in photosynthesis) absorbs red and blue wavelengths, so that most oxygen is produced
how a plant absorbs light energy using pigments
in chloroplast, pigment molecules(like chlorophyll) capture photons and transfer absorbed energy to start photosynthesis
pigment molecules arranged in antenna complex so light energy passed around to reaction center
- when less sunlight, trees break down chlorophyll to reuse in the spring which shows other pigments with other colors reflected like carotenoids
Light reaction process
- water broken down which produces O2 that diffuses out and protons that go into thylakoid space
- electrons from H20 enter photosystem 2, where they are excited by photons and then have the energy to to through the electron transport chain
- energy expended during transport chain used to pump protons through proteins from the stroma to the thylakoid space
- electrons arrive at photosystem 1, with low energy
- electrons once again excited by light and then captured by reductase, whichever reduces NADP+ to NADPH
- protons in thylakoid space go through ATP synthase so that ADP+P Is aded to H+ to make ATP
compare and contrast chemiosmosis in chloroplasts and mitochondria
- chemiosmosis: protons across membrane to generate ATP
- Chloroplasts: source of E driving protein gradient is the sun and protons pumped from stroma to thylakoid
- mitochondria: source of E driving protein gradient is glucose and protons pumped from mitochondrial matrix to inter-membrane space
3 phases of Calvin cycle
- carbon fixation: carbon from CO2 added to RuBP by Rubisco(enzyme) to make C-P chain
- reduction: high E e- from light rnx to make G3P(simple sugar carbon chain)
- regeneration if RuBP by ATP which is used for another calvin cycle
problems of plants in hot,dry environments
- open stomata creates dehydration
- when stomato only closes: oxygen builds up and there is not enough CO2
- this causes photorespiration: calvin cycle malfunction where ATP used and no sugar forms)
CAM plants
- open stomata only at night to store CO2 in orgo acids
- during day, H2O conserved and orgo acid broken to CO2 to be used in Calvin cycle
- ex: pineapple, aloe, cacti
