Photosynthesis and Cell Respiration How do organisms obtain

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 Photosynthesis Cellular respiration Visual Summary 6. 1

Photosynthesis! • What happens during photosynthesis? – Plants (autotrophs) use energy from sunlight to convert water and carbon dioxide into carbohydrates (energy) and oxygen • 6 CO 2 + 6 H 2 O (light) → C 6 H 12 O 6 + 6 O 2 Reactants? Carbon dioxide (CO 2) and Water (H 2 O) Products? Glucose—Sugar (C 6 H 12 O 6) and Oxygen (O 2)

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 6 O 2 + C 6 H 12 O 6 6 CO 2 + Oxygen + glucose 6 H 2 O + Energy 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 • Occurs in the Mitochondria