Energy Flow

1. Energy Flow Food webs Pyramids

2. Classifying Organisms • Producer: organisms that can use inorganic sources to make their own food (e.g. plants) • Consumer: organisms that eat other organisms to obtain energy • Predator: animals that catch and feed on other live animals • Prey: animals that are hunted and eaten by others • Top carnivore: organism at the top of the food chain that is not hunted or consumed by another organism

3. Types of Consumers • Herbivore: eat plants • Carnivore: eat animals • Omnivore: eat both plants and animals • Decomposer: breakdown organic matter and release nutrients back into the ecosystem • Scavenger: carnivores that eat remains of animals, usually freshly killed (e.g. vultures) • Detritivore: eat remains of plants and animals and animal waste (e.g. earthworms, maggots, bacteria)

4. The source of all energy is the SUN. PLANTS use the suns energy to make food. Most of the sun’s energy never reaches the Earth’s surface but is reflected or absorbed by gases in the upper atmosphere. Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or Earth’s surface and 70% is absorbed. Greenhouse gases allow energy from sun to enter but prevent energy from leaving. Energy in Ecosystems

6. Energy in Ecosystems • Albedo Effectis the measurement of the percentage of light an object reflects • The HIGHER the albedo, the GREATER the object’s ability to reflect sunlight • Substances that have high albedo: snow, clouds • Substances that have low albedo: soil

7. Energy Movement • Food chains show simple feeding relationships • Food chains do not exist in nature • Food webs are a number of interconnecting food chains • Even food webs aren’t accurate http://www.geographyalltheway.com/ib_geography/ib_ecosystems/imagesetc/food_web.gif

8. Which is more accurate and why? http://www.biologycorner.com/resources/foodweb1.gif http://www.freewebs.com/tlittle/fdchain3.jpg

9. Trophic Levels • Trophic levels: feeding levels that describe the position of an organism along a food chain • 1st trophic levels always contain producers • 2nd trophic levels contain herbivores • 3rd trophic levels contain consumers that eat herbivores • Classification of organisms at the trophic levels • Primary consumer: eats producers • Secondary consumer: eats primary consumers • Tertiary consumer: eats secondary consumer • An organism can change its trophic level depending on the food chain

10. Trophic Levels http://www.zoomschool.com/subjects/foodchain/samplefoodchains.GIF http://pack152.net/AcademicsAndSports/WildlifeConservation/FoodChain.gif

11. Different Forms of Energy • Sound, solar, kinetic, potential, thermal, electric, nuclear energy

12. Laws of Thermodynamics • Thermodynamics is the study of energy transformations • First Law: Energy can be transformed (changed) from one form to another but it cannot be created or destroyed

13. Examples of Energy Transfer • Light bulbs convert electrical energy into light and heat energy • People eat food (chemical energy) which provides fuel for their bodily functions (running) which corresponds to kinetic energy, thermal energy and sound energy • Cars convert chemical energy (gas) to kinetic energy, thermal and sound energy

14. Energy Loss • There is always a loss of energy with each level because: • some energy is released to the environment as thermal energy (heat) • not all parts of an organism is eaten • Only about 10% of energy taken in by an individual is passed onto the next level • Organisms at the highest trophic levels have less energy available to them than species at the bottom

15. Laws of Thermodynamics • Second Law: During any energy transfer, some energy is lost because it is converted to an unusable form such as heat

16. Ecological Pyramids • Displays relationships between trophic levels in an ecosystem • Three types of ecological pyramids: • Energy • Numbers • Biomass

17. Energy Pyramid • Illustrates energy loss and transfer between trophic levels • Size of each layer represents amount of energy available at each level http://www.mlms.logan.k12.ut.us/~mlowe/EnergyPyramid.gif

18. Pyramids of energy are difficult to measure because it is hard to measure the amount of energy in an organism without killing the organism. Energy is measured using kilojoules (kJ)

19. http://www.mesa.edu.au/friends/seashores/images/energy_pyramid.gifhttp://www.mesa.edu.au/friends/seashores/images/energy_pyramid.gif

20. Pyramid of Numbers • illustrates the number of organisms at each trophic level • As the trophic levels increase the number of organisms often decrease • Example: grass  mouse  fox

21. Pyramid of Numbers • Sometimes the number of organisms increase up the trophic level • Example: trees  insects  parasites

22. Pyramid of Numbers http://www.geographyalltheway.com/ib_geography/ib_ecosystems/imagesetc/pyramids_number_biomass.jpg

23. Biomass Pyramid • Biomass is the dry mass of an organism after water is removed from its tissues • Pyramid illustrates the total mass of individuals at each trophic level

24. Pyramid of Biomass • Biomass pyramids usually take on the same shape as the corresponding numbers pyramid

25. Some Exceptions • Comparing Pyramids: number vs biomass

29. Gizmo • www.explorelearning.com • Grade 9-12 biology • Ecology and interdependence • Food chain