1. TOPIC 1 LESSON 5 The Laws of Thermodynamics (Energy Transfer and Efficiency) Syllabus Link 1.1.4 - Describe how the first and second laws of thermodynamics are relevant to environmental systems.

2. ENERGY and MATTER FLOWS through an ECOSYSTEM ProducersConsumers decomposersInorganic nutrient pool Sun Heat http://www.wisegeek.org/what-are-inorganic-nutrients.htm

3. The energy in all ecosystems is subject to the FIRST and SECOND LAWS of THERMODYNAMICS

4. 1 st LAW – “CONSERVATION OF ENERGY” ENERGY IS NEITHER CREATED NOR DESTROYED Energy can be converted from one form into another, but not consumed. Ecosystems are characterised by constant flows and transformations of energy: Electromagnetic energy (light) transformed into chemical energy (sugar) by photosynthesis. Chemical energy transformed into heat. Chemical energy transformed into electrical energy. Read the hand-out on Photosynthesis.

5. An example would be a simple food chain. Draw a simple food chain with 5 components.

6. Where does the sun’s energy (that reaches Earth’s surface) go?

7. 2 nd LAW – “The ENTROPY OF AN ISOLATED SYSTEM NOT IN EQUILIBRIUM WILL INCREASE OVER TIME”. 1.What is ENTROPY? “the spreading out or dispersal of energy” In other words, energy conversions are never 100% EFFICIENT. Some energy is transferred into WORK or WASTE HEAT. ENERGY = WORK + HEAT (and other waste energy)

8. CONVERSION PROCESS INPUT ENERGYUSEFUL ENERGY (WORK) HEAT

9. Each level is known as a TROPHIC LAYER. Because of ENTROPY, the amount of energy passed to the next TROPHIC LAYER decreases. At each layer, energy is lost as heat generated during work eg respiration.

10. Calculating Efficiency % Efficiency = work or energy produced x 100 energy consumed 1.Plants convert around 1-2% of the solar energy they receive into glucose (photosynthesis). 2.Herbivores assimilate (turn into animal matter) around 10% of plant energy they consume. 3.A carnivore’s efficiency is also around 10%.

11. Energy Loss in a Food Chain