Photosynthesis and Cell Respiration

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

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

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)

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!)

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

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

Cellular Respiration Cellular respiration… is the process that releases energy by breaking down food molecules (glucose) in the presence of oxygen 6O2 + C6H12O6  6CO2 + 6 H2O + Energy Oxygen + glucose  carbon dioxide + water + energy Compare this to the equation for photosynthesis….what do you notice?

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