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PHOTOSYNTHESIS • Solar energy – Very available – Hard to store • Collected by plants • Converted to chemical energy – Easier to store • Requires chlorophyll ( chloroplast ) • Energy now stored as carbohydrates * Plants store energy AND plants spend energy* Properties of Light • ROYGBIV – White light contains all the colors (wavelenghts) • Reflected – You only see what’s not absorbed • Light is both energy and particle (photon) • Wavelength = energy l • Pigments = chemical compounds that reflect color. • Chlorophyll is pigment/chemical in chloroplast Plant Structures • Roots – Often underground – Collect water – Rarely green – need sugar supply !? • Stems – – – – Usually above ground Lots of cellulose ( herbaceous vs. wood) Support … hold up to sun. May be green • Leaves – GREEN!! Contain chlorophyll, in their chloroplasts – Collect sunlight and collect CO2, also release O2 – Do photosynthesis…. Make organic compounds like sugar • Flowers – Reproductive structures that contain eggs and pollen – Will eventually becomes seeds and/or a fruit with seeds. – May be colored but pigments are not usually chlorophyll Leaf structure Review of chemical molecules • • • • • Leaf vocabulary Cuticle: thin layer of clear, waxy cells on top, waterproof, Mesophyll: rectangular cells where photosynthesis occurs Palisade mesophyll: arranged in columns, lots of photo, very green Spongy mesophyll: scattered, air pockets, lighter green Chloroplast: organelle that performs photosynthesis – Thylakoid membrane – inner membranes, packets, have chlorophyll – Stroma – liquid inside chloroplast • Water vacuole: holds water, chloroplasts surround this • Stoma/ stomata: opening on underside of leaf, O2 out and CO2 in, open and close in response to the weather • Vascular tissue – carries fluids, just like our vascular tissue (veins) – Xylem : carries water and water soluble substances, from root to leaves – Phloem: carries “food”, sugars and organic compounds, from leaves to storage ( root or fruit) • • • • Water in the roots, up xylem Water split Requires solar energy Some energy now stored as chemicals called NADPH and ATP • Oxygen is released, hydrogen is used in chemicals • CO2 comes in through stomata as a supply • NADPH and ATP energy used to link C-C This creates organic compounds like glucose History and Discovery • Jan von Helmont – Mass of seedling, soil and water didn’t equal mass of tree …. What is rest of mass ? • Joseph Priestley – Discoverer of oxygen, mint plus candle in a bell jar would stay lit • Jan Ingenhousz – Priestley’s mint experiment only worked in the sunlight • Melvin Calvin – Used radioactive carbon to trace the dark reactions in photosynthesis… now called the Calvin Cycle Light reactions • IN – – • OUT – – • Water is split, electrons are moved, H is bonded Electrons are moved along Electron Transport Chain (ETC) Location – – • NADPH and ATP Oxygen Reactions – – • Water Light Photocenters on thylakoid membrane of chloroplast Requires chlorophyll Result – – – – Water is split H is bonded Oxygen is released (solar) ENERGY IS STORED (as a chemical bond) Dark reactions – Calvin Cycle • In – NADPH and ATP from light reactions – CO2 • Out – Carbohydrates (sugar) and organic compounds • Reactions – CO2 is added to organic acids to create compounds – Costs NADPH and ATP – C to C bonds are being formed • Location – Stroma (fluid) in the chloroplast • Result – Plants are producers …. Of organic compounds like carbohydrates – Organic acids are regenerated as part of the cycle. ** YOU MUST KNOW THIS ** Sunlight 6 CO2 + 6 H2O C6H12O6 + 6 O2 chlorophyll reactants, products, coefficients and subscripts Plants (Autotrophs) are able to make lots of compounds. Organic compounds with rings and chains of carbon. They include GLUCOSE, but also amino acids, proteins, fatty acids, lipids, other carbohydrates and the nucleic acis. sunlight 6CO2 + 6H2O C6H12O6 + 6O2 chlorophyll roots leaves stomata Reactants “react” phloem stomata and Products are “produced” Glucose and “sugars” Other Carbohydrates Cellulose and lignin