1. Biogeochemical Cycles Chapter 3 Lesson 4

2. Introduction 1. Every organism needs nutrients to build tissues and carry out life functions. 2. Like water, nutrients pass through organisms and the environment. 3. 3 nutrient pathways: move carbon, nitrogen, and phosphorus through the environment. 4. Oxygen plays an important role in all 3 Nutrient Cycles.

3. Carbon Cycle Carbon is a major component of all organic compounds, including carbohydrates, lipids (fats), proteins, and DNA. 1.During Photosynthesis, plants use the carbon to build carbohydrates. 2.Organisms die, decomposers break down the bodies, releasing carbon to the environment. 3.Geologic forces can turn accumulated carbon into carbon-containing rocks or fossil fuels. 4.When animals break down “food”, carbon dioxide is released into the environment as a by- product.

4. The Carbon Cycle Photosynthesis and Cellular Respiration form the basis of the carbon cycle.

5. Photosynthesis 1.Performed only by plants and plant-like organisms (algae) 2.Process where CO 2, H 2 O, and sunlight are converted into O 2 and glucose (carbohydrate) 3.Chemical Formula: CO 2 + H 2 O → O 2 + C 6 H 12 O 6 Photosynthesis takes place in the leaf.

6. Cellular Respiration 1.Opposite of photosynthesis 2.Defined as the breakdown of glucose by cells to create energy 3.Glucose & O 2 are broken down into H 2 O, CO 2, and energy 4.Done by ALL living things 5.Chemical Formula: C 6 H 12 O 6 + O 2 → CO 2 + H 2 O

7. So…What’s the Problem? 1. If it were just photosynthesis and cellular respiration, the cycle would be balanced. 2. Humans have disrupted the carbon cycle through combustion- burning of fossil fuels. 3. Excess CO 2 has caused global climate change which has caused the melting of polar ice caps, severe storms, and floods.