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PHOTOSYNTHESIS Energy is used to make: -Proteins -Sugars -Fats -Nucleic acids All living things need energy. Energy comes from sun. PHOTOSYNTHESIS Energy is harnessed: Producers (plants) are able to convert this light energy (sunlight) into chemical energy (sugar). PHOTOSYNTHESIS EQUATION: 6 CO2 Carbon Dioxide + 12 H2O Sunlight Water chlorophyll C6H12O6 + 6 O2 + 6 H2O Sugar Oxygen Water CHLOROPLASTS All cells in leaves have thousands of green organelles called chloroplasts. CHLOROPLASTS Stroma:Stacks Thylakoid: Grana: Cytoplasm Flattened of thylakoids ofsacs; chloroplast; convert contains light NRG enzymes to for chemical making sugar NRG CHLOROPHYLL Molecule that absorbs sunlight energy. Photoreactive core SUNLIGHT What do Plants appear you think to bewould greenhappen because if chlorophyll you placed adoes plant not in absorb just green green light? wavelengths of light. Just blue light? HOW DOES A CHLOROPLAST WORK? A. Light reaction 1. Sunlight is absorbed by chlorophyll in thylakoid. 2. This energy is used to split water. 2 H2O O2 + 4 H+ + 4 electrons 3. Oxygen is produced. 4. Electrons are excited (contain super energy). 5. No carbon dioxide is used; no sugar is produced. HOW DOES A CHLOROPLAST WORK? Light reactions harness sunlight to split water, produce oxygen, and excite an electron. Occurs in thylakoids. HOW DOES A CHLOROPLAST WORK? B. Dark Reaction (Calvin Cycle) 1. Enzymes in stroma use the excited electron’s energy to build sugar from CO2 and H+. 2. DOES NOT REQUIRE DARKNESS, BUT CAN HAPPEN IN DARK BUT . . . Only if there are enough excited electrons. Once those run out – photosynthesis is done. Leaf Structure Cuticle – waxy layer on top of leaf Leaf Structure Epidermis – outermost layer of cells Leaf Structure Upper epidermis Lower epidermis PALISADES Leaf Structure Palisade layer – “tall” cells; primary site of photosynthesis in leaf (many chloroplasts) Leaf Structure Spongy layer – cells are not tightly packed; room for gas exchange; some chloroplasts Leaf Structure Guard cells – form openings to allow gases and water to enter/leave leaf; some chloroplasts Leaf Structure Stomata – openings formed by guard cells Leaf Structure Xylem – transport of water Leaf Structure Phloem – transport of sugar