The Rainbow Connection- Visible light (the rainbow): 380-740nm wavelengths- White light is all visible colors- The depth of the water filters out the lower/longer wavelengths like redGeneral Structure of EyeRods – black and whiteCones – colorRods and cones are at the end of the eye; light goes through other eye cells firstLight PerceptionLight is reflected off an object  enters cornea  pupil  lens  vitreous humor  arrives at retina  photoreceptors in retina (rods and cones) This process is similar to action potentials.Why does an object appear to be one color? The object absorbs all colors but reflects the one wavelength it appears. EX; light bulb with shirtColor allows for:- Environmental cues (flowers, trees)- Mating displays- Color warnings- CamouflageSome animals have more/less rods/cones in their retinas- Used for nocturnal animals- Tetrachromatic visionPerceiving LightsCan plants sense color? Yes!- Pigments in plants absorb color (light) to be used in photosynthesis- Plants grow towards light sourcesCO2/H20  photosynthesis (sunlight enters/heat energy leaves)  O2/glucose  cellular respiration  CO2/H20 and the process repeatsPhotosynthesis: synthesis of light - Solar energy converts to chemical energy- Photosynthesis is anabolic process (complex molecule goes to a simple molecule)- Respiration is catabolic (releases energy stored by photosynthesis as glucose)The actual conversion of CO2 and H20 to sugar is achieved by:- Light dependent reactions- Light independent reactionsChloroplasts: 2 membranes- Stoma - Pigment molecules embedded in thylakoidThe Sun: A mixture of wavelengths- Pigment – anything that absorbs light- Plants pigment – mainly chlorphyll a & b- Extra pigments in plants – carotenoids and phycobilinsThese increase range of light absorption/help increase photosynthesis efficiencyLDRH20  light reactions  O2Uses light, pigments, H2O, NADP+, ADP  ATP, NADH, O2LOWER ENERGY MOLECULES FORM HIGHER ENERGY MOLECULESLIRCO2  carbon reactions  glucoseUses ATP, NADPH, CO2, enzymes  glucose- Also called calvin cycle, carbon fixation reactionLight dependent stage- Thylakoid membrane inside chloroplasts- Involves excitation of pigments by light and energy released by oxidation (loss of electrons)Photosystems in LDRPhotosystems are protein complexes in the thylakoid membrane that capture and release energy- Photosystem 2: pair of chlorophyll A (P680) produces ATP in the reaction center- Photosystem 1: pair of chlorophyll A (P700) produces NADPH in the reaction centerElectron Transport Chain - Photosystems utilize light energy to feed in electrons- As these electrons move through the chain, ATP and NADPH are generated- Compounds are alternatively:o Oxidized – loses one or more electrons & releases energyo Reduced – gains one or more electrons & requires energyPhotosystem 2:Absorb light  P680 releases 2 electrons  H2O donors 2 electrons (O2 released here) electrons transferred through ETC  H+ proton gradient fueling  ATP syntahse  photosystem 1Photosystem 1:Electrons from photosystem 2 arrive  replace light excited electrons P700  another set of electrons lost  NADPH producedWhat happens when light strikes a pigment?- Light energy excite a pigment and it boosts to a higher electron orbit from its ground state- Herbicides act upon electron flow of LDR in photosynthesisLight independent stage(Calvin Cycle)- Reactions take place in chloroplast stoma- Uses the ATP and NADPH that was produced in the LDR- Atmospheric CO2 is also used- CO2 enters plant through stromata and joins a 3 Carbon molecule (PGAL) and then becomes a 6 Carbon molecule