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Photosynthesis
Produces organic substances
Uses light Energy, Simple inorganic substances
Light Energy to Chemical Energy
Absorption of Light
Sunlight = White light, but made up of wavelengths like red, green, blue
Pigments absorb lights Red, Blue > Green Green light cannot be reflected
Absorption of Energy
Some used to produce ATP. Some split water molecules – Photolysis
of Water This forms Oxygen and Hydrogen.
CO₂ is absorbed to make organic substances. Carbon in a gas to carbon in solid compounds –
Carbon Fixation This involves use of Hydrogen from photolysis
and Energy from ATP.
Measuring Rates of Photosynthesis
Production of O₂ : Aquatic plants release bubbles of O₂
Uptake of CO₂ :If CO₂ is absorbed from water, the pH of water rises
Increases in biomass : the rate of increase in biomass means more photosynthesis.
Limiting Factors
Each factors can limit the rate when below optimal level.
Combination of factors – only one factor furthest from its optimum limits
When 2 of the factors are equally close to optimum, increasing them rises the rate.
Action and Absorption Spectra
Action Spectra: % use of wavelengths of light in photosynthesis
Absorption Spectra: % use of the wavelengths of visible light that are absorbed
Photoactivation
Chlorophyll & accessory pigments -Photosystem
Chlorophyll molecules in photosystem absorb light energy and pass it to 2 special chlorophyll molecules in the reaction centre.
Electron within the molecules become excited and photoactivated.
Photophosphorylation
Photophosphorylation: the production of ATP, using E from light which is carried out by thylakoids
Thylakoids: regular “stack” of membranes that contain Photosystem I & , ATP Ⅱsynthase, a chain of electron carriers
Chemiosmosis
1. Protons pass across membrane and release E which is used by ATP synthase to produce ATP.
2. The coupling of ATP synthesis to electron transport via a concentration gradient of protons → CHEMIOSMOSIS
Chloroplasts structure
Chloroplast envelop Thylakoids Small fluid filled spaces inside Thylakoids Mostly have stacks of thylakoids called grana Colorless fluid around Thylakoids = stroma
Bibliography Course Companion p95-108 Study Guide p21, p75,p76-81 Pearson: p 74-78, p227-236 http://biotransitioneng.wordpress.com/2009/05/10/fossils-fuels-%E2%80%93-a-great-problem/ http://botit.botany.wisc.edu/images/130/Chlorophyta/Eremosphaera_Images/Chloroplasts_MC.html Pearson Education, Inc., publishing as Benjamin Cummings http://www.cbu.edu/~seisen/Photosynthesis.htm http://helpmyphysics.co.uk/wordpress/?m=200902 http://botit.botany.wisc.edu/images/130/Chlorophyta/Eremosphaera_Images/Chloroplasts_MC.html http://generalhorticulture.tamu.edu/lectsupl/physiol/physiol.html http://fhs-bio-wiki.pbworks.com/Factors-effecting-the-rate-of-photosynthesis http://reefbuilders.com/2010/08/23/chlorophyll-f-a-newly-discovered-photosynthetic-pigment-uses-infrared-light/ www.theoremeinnovation.com/revolution-en.html www.firstrays.com/plants_and_light.htm http://image.absoluteastronomy.com/images/encyclopediaimages/c/ch/chemiosmosis1.png www.cbs.dtu.dk/staff/dave/roanoke/bio101ch07.htm micro.magnet.fsu.edu/.../chloroplasts.html
Vocabulary
Photosynthesis: The process used by plants and other organisms to produce all their own organic substances (food), using only light energy and simple inorganic substances.
Photolysis of water: Splitting of water by energy absorbed by chlorophyll. Carbon Fixation: The conversion of carbon in a gas to carbon in solid compounds. Photosystem: protein complexes involved in photosynthesis Photoactivation: The initial stage of photosynthesis in chlorophyll Molecules where
the presence of light Energy raises the energy. Chemiosmosis: The coupling of ATP synthesis to electron transport via a
concentration gradient of protons Photophosphorylation: the production of ATP, using E from light which is carried out
by thylakoids Thylakoids: regular “stack” of membranes with very small fluid-filled spaces inside
that contain Photosystem I & , ATP synthase, a chain of electron carriersⅡ Grana: stacks of thylakoids Stroma: a colorless fluid around the thylakoids that contains many different enzymes
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