Chapter 8: Fossil Fuels Unit B: Understanding Common Energy Conversion Systems

7.1 Nature’s Energy Conversion  Cells of green plants have special parts that capture solar energy and convert it into energy for the plants (food)  These cells are called CHLOROPLASTS  Chloroplasts also contain chlorophyll.  Chlorophyll assists in converting carbon dioxide and water into glucose and oxygen.  This process is know as photosynthesis  Equation: Sunlight + CO 2 + H 2 0  Glucose and O 2

7.1 Nature’s Energy Conversion  Cellular respiration is how plants and animals obtain energy from food  Cellular respiration takes place in the mitochondria  Equation: Glucose + O 2  energy + H CO 2  Why is cellular respiration important?

7.1 Nature’s Energy Conversion  Two Energy Conversions  Input energy  converter  output energy  This equation shows the energy conversion in plants  Solar energy  chloroplasts in plant leaf  glucose  This equation shows the energy conversion in animals  Glucose  mitochondria  kinetic energy

7.1 Nature’s Energy Conversion  When any energy conversion happens, a certain amount of energy is lost.  Only about 10 percent of energy is passed from one level to the next

7.2 The Need for Energy  Homeostasis  No matter what is happening outside your body, your body will remain approximately 37 degrees Celsius.  How does your body remain around 37 degrees Celsius?  The rate at which your body uses energy is metabolism.  Someone who has a high metabolism has high energy needs

7.3 Sources of Energy  The main source of energy for humans are simple carbohydrates (glucose)  If we take in more glucose than necessary, it will be converted to glycogen  Glycogen is a starch-like substance that is stored in the liver and muscles  Carbohydrates are the most direct source of energy

7.3 Sources of Energy  Fats  2 types of fats: Saturated and Unsaturated  Saturated fats come from animal fats and some oils  Increased risk of heart disease  Unsaturated fats come from healthier oils  Decreased risk of heart disease

7.3 Sources of Energy  One gram of protein contains the same energy as one grain of carbohydrate.  The difference is that it is more difficult for the body to break it down  Only 10% of our daily intake should be protein  Examples of protien:  However proteins are still extremely important, protiens are the building blocks of our physical body

7.4 Human Energy Needs Change  4 things that affect our metabolism:  Age, time of day, exercise, level of fitness  Age: Younger people have higher metabolisms  Time of Day: Our metabolism peaks at 10:00am  Exercise: Activity raises metabolism  Level of fitness: Use a large amount of energy getting and keeping in shape