ENERGY & Entropy

1. ENERGY & Entropy BIO 391 Sections 2.2 – 2.5

2. ENERGY • The capacity to do work (move/distance) or cause change • can transfer from form to form • heat, electricity, chemical, mechanical, nuclear, electromagnetic radiation (light) “Free Energy” - Usable energy; available • Classification • Kinetic: matter’s mass & velocity, energy of motion • Potential: stored energy, energy of position

3. What is Chemical Energy? • Energy stored in the organic molecules that make up the organism • Specifically energy stored in bonds

4. Chemical Changes

5. THE LAWS OF THERMODYNAMICS Explain how energy can be transformed 1st Law 2nd Law • ENERGY IS CONSTANT • Energy is neither created nor destroyed but may be converted from one form to another. • Organisms must obtain their energy from something else • ENERGY CAN BE “LOST” • In any energy conversion, you will end up with less usable energy than you started with. • Increase entropy • Not all chemical energy from food is directly used by the animal. Some is lost as heat

6. What is Entropy? • A measure of disorder • As entropy increases, disorder increases

7. Energy & Entropy • Materials that are less ordered, contain less free energy. • Free energy and entropy have a reciprocal relationship. • As one increases the other decreases. • E S

8. How does this pertain to life? • The Laws of Thermodynamics • Living systems can neither create nor destroy energy, but only change its form. (1) • Living systems avoid the trend toward entropy or disorder by a constant input of energy from the environment and constant output of entropy to the environment (2)

9. Measuring Energy • A calorie is a measurement of the amount of heat (energy) needed to raise the temperature of 1 gram of water 1 degree Celsius • Unit of energy that food energy is measured in is the Calorie (or kilocalorie) • The SI unit is the Joule • One kilocalorie = 4.18 kilojoules (kj)

10. Autotrophs & Heterotrophs BOTH AUTOTROPHS AND HETEROTROPHS CARRY OUT CHEMICAL REACTIONS THAT RELEASE ENERGY FOUND IN BONDS OF ORGANIC COMPOUNDS AUTOTROPHS PHOTOSYNTHESIS CHEMOSYNTHESIS HETEROTROPHS CELLULAR RESPIRATION

11. Heat Heat Heat Tertiary consumers (human) Decomposers 10 Secondary consumers (perch) Heat 100 Primary consumers (zooplankton) 1,000 Heat 10,000 Usable energy Available at Each tropic level (in kilocalories) Producers (phytoplankton) Pyramid of Energy Flow - Pyramid of Biomass

12. How do organisms remain highly organized in spite of the universal tendency toward entropy? • By constantly taking in energy from their surroundings. • Eating!

13. Exit “Quiz” Brian eats a lunch of an apple and string cheese. Brie eats a lunch of a philly cheese steak with extra cheese. • What kind of energy are they ingesting? • Is it potential or kinetic? • Where is the energy located? • What process is happening to begin the accessing of that energy? • Is entropy increasing or decreasing in relation to the original food eaten during this process? • Whose food would contain more Calories? So therefore, whose food would have more potential energy?