Warm Up Monday November 19th List 5 common household items that you use everyday that come from plants. PHOTOSYNTHESIS The Sun the ultimate source of all energy for all life on Earth Autotrophs Vs. Heterotrophs An autotroph is an organism that feeds itself! (produces its own food!) A heterotroph is an organism that feeds on another organism (cannot produce own food!) Can you think of an example of each? Poison Sumac Lions (and Zebras for that matter!) Autotroph or Heterotroph? Autotroph or Heterotroph? Autotroph or Heterotroph? Autotroph or Heterotroph? Autotroph or Heterotroph? Photoautotrophs Photo = Light Auto = Self Troph = Feed Plants are “photoautotrophs” because they feed themselves with light. PHOTOSYNTHESIS …is the conversion of light energy into chemical energy by living organisms Prickly Pear Cactus Cedar Tree Why should I care about photosynthesis? More than 200 years ago, Priestly stumbled upon the answer! Who? Me? NO! ME!!! Joseph Priestly 1733-1804 Photosynthesis overview What Light is Available for Plants to use? Light acts as both a particle (photon) and a wave! The different lengths of light waves create the spectrum of colors we can see! Red = LONG waves Violet = SHORT waves How do plants absorb light? Pigments in the chloroplast absorb a variety of light energy wavelengths. Examples: Chlorophyll A & B Xanthophyll Carotenoids Chlorophyll a Found in all plants, algae and cyanobacteria. Makes photosynthesis possible. Participates directly in light reactions Can accept energy from chlorophyll b Chlorophyll b Is an accessory pigment Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a Plant Pigments Seen w/ Paper Chromatography Absorption Spectrum Plants only absorb violet and red light, and reflect green light, which is why plants appear green! Where does Photosynthesis happen? In Chloroplasts! What’s in a Chloroplast? Photosynthesis takes place within the thylakoid membranes! Light Reactions Light Reactions First step in photosynthesis where light energy is converted to chemical energy. Light energy is used to break apart H2O into H2 & O2. Light Reactions The H+ ions and the free electrons that result from breaking apart water make high energy molecules! ATP & NADPH The Calvin Cycle A set of reactions that turn CO2 into Carbon assembled into glucose. CO2 Sugars The Calvin Cycle requires energy from ATP & NADPH made by Light Reactions! aka “Dark Reactions” b/c doesn’t need light Dark Reactions (calvin cycle) Chemical reactions that convert CO2 and other compounds into Glucose! Doesn’t require light energy. Takes place in the space outside the thylakoid membrane. Photosynthesis