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Photosynthesis is a crucial process for autotrophs that enables them to convert sunlight into energy and produce oxygen. This article explores the significance of plants in food production, oxygen supply, and ecosystem balance, detailing the light-dependent and light-independent reactions involved in photosynthesis.
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Photosynthesis autotrophs – make their own food from the sun’s energy **ALL LIFE DEPENDS ON AUTOTROPHS** Importance of plants: food shelter drugs O2 soil fertility clean H2O fossil fuel wood prevent soil erosion
heterotrophs – cannot make their own food from the sun’s energy, they rely on autotrophs
Cells need Energy ATP = Adenosine Triphosphate low energy bond A—P—P—P high energy bonds When a cell needs energy, high energy bonds are broken by an enzyme. + P A—P—P—P A—P—P (ATP) (ADP) energy
Jan Van Helmont Planted a seed in a pot of soil (mass = 2g) 5 years later the mass of the tree was 75,000g Where did the increase in mass come from? His conclusion was from the H2O = hydrate That’s only partly correct. Most of the mass comes from CO2
Joseph Priestley Discovered that plants released oxygen (O2)
Photosynthesis Reaction Photosynthesis -- plants convert sunlight (chemical energy) into sugar (carbohydrates) photo = light synthesis = to make
Light 6 CO2 6 H2O C6H12O6 + 6 O2 + The Balanced Photosynthesis Equation
Visible Light Spectrum The suns energy travels in waves The distance between waves = wavelength Different wavelengths of light are visible as different colors
ROY G BIV Longest wavelength = Least amount of energy Shortest wavelength = larger amount of energy
Chloroplasts Have chlorophyll and accessory pigments that trap different wavelengths of light Chlorophyll – reflects Green light Accessory pigments -- Carotenoids (Kuh-RAHT-uhn-OYDZ) reflect Yellow, Orange, & Red light Elodea leaf
8-1 Why do plants lookGreen? There is much more chlorophyll than the other pigments (the other colors are masked). In the Fall, chlorophyll is broken down and the accessory pigment colors are shown. Why do trees lose leaves in the winter? It’s difficult to absorb H2O from frozen ground so leaves drop off to save water.
As the chlorophyll in leaves decays in the Fall, the green color fades and is replaced by the oranges and reds of carotenoids
Photosynthesis There are two reactions to photosynthesis 1. Light-Dependent reaction “LIGHT” * only occurs in light * occurs in the thylakoid membrane chloroplast * photosystem II * photosystem I * H2O&sunlight make (ATP) & release (O2)
2. Light-Independent reaction(Calvin Cycle) “DARK Reaction” * can occur in the light or dark * occurs in the stroma of the chloroplasts * Reactant CO2 * Energy ATP (from the light-dependent reaction) * Product C6H12O6 (glucose)
Factors Affecting Photosynthesis • Water • Temperature • Light intensity
Use the following words to fill in the drawing: C6H12O6 -(5) Sunlight - (4) CO2 - (4) H20 - (5) O2 - (4)
Photosynthesis Summary Light reaction (Location: thylakoid) ReactantsProcessesProducts 1. 1. 2. 2. • 1. • 2.
Photosynthesis Summary Light reaction (Location: thylakoid) ReactantsProcessesProducts 1. light 1. O2 2. H2O 2. energy (ATP) • 1. Photosystem II • 2. Photosystem I