1. Sources of Energy All living things need energy All cells need energy to carry out their functions

2. Photosynthesis Photo (light) + synthesis (putting together) Process by which a cell captures energy in sunlight to make food Living things can obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis

3. Organisms autotroph Organism that makes its own food (uses sunlight directly) Plants, some bacteria heterotroph Organism that cannot make its own food (uses sunlight indirectly) Animals that eat plants or other animals

4. Photosynthesis is a complex process that takes two stages: Stage 1: Capturing the Sun’s energy Stage 2: Producing sugars

5. Stage 1 Chloroplasts in the leaves capture energy from sunlight The main pigment in chloroplasts is chlorophyll (a colored chemical compound that absorbs light)

6. Stage 2 Need water (H 2 O) and carbon dioxide (CO 2 ) water soil roots stem leaves carbon dioxide (gas in the air) enters from stomata (small openings on back side of leaf)

7. Inside the chloroplasts, the H 2 O and CO 2 undergo a complex series of chemical reactions: PRODUCTS: sugar with 6 carbon atoms (C 6 H 12 O 6 ), a type of carbohydrate which fuels cells oxygen (O 2 ) which exits the leaf through the stomata *Almost all the oxygen in Earth’s atmosphere was produced by living things through photosynthesis

8. Photosynthesis Equation: 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 raw materials products = “yields” (or gives) Light energy

9. Uses for sugar? Some is used for food Can be converted into other compounds (such as cellulose) Some stored in plant for later use…