Ch 4, Sec 1 Photosynthesis

1. Target: I will understand how the sun supplies livings with the energy they need, and what happens during the process of photosynthesis. The sun is the source of energy for most living things!!! - plants use energy from sun to make their own food - some animals obtain energy by eating plants, other animals obtain their energy by eating other animals Ch 4, Sec 1 Photosynthesis

2. Photosynthesis - process by which a cell captures energy in sunlight and uses it to make food - greek word - photo: light - synthesis: putting together *Nearly all living things obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis Autotroph - an organism that makes its own food - plants make their own food through this photosynthesis - grass, plants, trees

3. Heterotroph - an organism that cannot make its own food, including animals - mushrooms are heterotrophs, get their food from other organisms Photosynthesis has 2 steps Stage 1 - Capturing sun’s energy - happens mostly in the leaves, via chloroplasts (green in color) - Pigments - colored chemical compounds that absorb light - Chlorophyll - main photosynthetic pigment in chloroplasts - like solar cells, captures light energy, then that powers the 2nd stage of photosynthesis

4. Stage 2 - cell uses captured energy to make sugars - H2O & CO2 are the reactants (raw materials {ingredients}) - plants draw H2O from roots in soil, then to stem & leaves - CO2enters the underneath of leaves in the stomata - the H2O & CO2then move into the chloroplasts

5. - inside the chloroplasts, the H2O & CO2 undergo chemical reactions - these chemical reactions are powered from the energy obtained in Stage 1 - the reactions produce C6H12O6 & O2 which are the products - the C6H12O6 is used by the cells for energy and O2 is released through the stomata of the leaf

6. Photosynthesis Equation Reactant sideProduct side light energy 6 CO2 + 6H2O C6H12O6+ O2 Carbon dioxide water a sugar oxygen How the plant uses the sugar molecules: - some broken down for plant to use for energy • - some converted into cellulose (main component of plant cell walls) • - some stored for later use When you eat your autotrophs, you’re eating the stored energy