1. Photosynthesis and Cell Respiration

2. How do organisms obtain energy?
Autotrophs
Able to produce their own food
Ex. Plants use sunlight to produce energy
Photosynthesis
Heterotrophs
Unable to produce their own food, rely on other organisms as a source of energy
Ex. Animals need to eat to survive
Cellular Respiration

3. Organisms rely on PHOTOSYNTHESIS and CELLULAR RESPIRATION for their energy needs
Heat
Sunlight
Cellular
respiration
Photosynthesis
Visual Summary 6.1 3

4. Photosynthesis! What happens during photosynthesis?
Plants (autotrophs) use energy from sunlight to convert water and carbon dioxide into carbohydrates (energy) and oxygen
6CO2 + 6H2O (light) → C6H12O6 + 6O2
Reactants?
Carbon dioxide (CO2) and Water (H2O)
Products?
Glucose—Sugar (C6H12O6) and Oxygen (O2)

5. Photosynthesis: Light and Pigment
In addition to water and carbon dioxide, photosynthesis needs light and chlorophyll (a molecule in chloroplasts)
Light is converted into chemical energy
Occurs in chloroplasts
Chlorophyll absorbs the light (it makes plants green!)

6. The Two Parts of Photosynthesis
Light-dependent reactions
Need light to happen
Occurs in Chloroplast
Produces Oxygen
Light-independent reactions (Calvin Cycle)
Does not need light
Use energy molecules (NADPH) to produce sugars for the plant

8. Cellular Respiration
Heterotrophs need to consume other organisms in order to survive
Glucose (sugar) is a main source of this energy

9. Cellular Respiration
Cellular respiration… is the process that releases energy by breaking down food molecules (glucose) in the presence of oxygen
6O2 + C6H12O6  6CO H2O + Energy
Oxygen + glucose  carbon dioxide + water energy
Compare this to the equation for photosynthesis….what do you notice?

10. Cellular Respiration Occurs in three different steps:
Glycolysis: one molecule of glucose is split in half
Occurs in the cytoplasm
Krebs Cycle: the half-glucose molecules are broken down into carbon dioxide
Occurs in the Mitochondria
Electron Transport: high energy electrons are used to produce energy for the cell