1. Unit 2 Ecology Ch. 5 How Ecosystems Work

2. Section 5-1: Energy Flow in Ecosystems

3. Where does an organism’s energy come from? Ultimate source of energy is the sun Producers – make their own food, autotrophs Plants – photosynthesis Protists, bacteria in aquatic ecosystems – photosynthesis 6CO 2 + 6H 2 O + sunlight C 6 H 12 O 6 + 6O 2 carbon dioxide + water + sunlight  glucose + oxygen

4. Consumers – cannot make their own food, heterotrophs Describe the 4 types of consumers in your notes (p. 127)

5. Types of Consumers in an Ecosystem Herbivores – primary, eat only plants Carnivores – meat eaters, capture and eat herbivores (secondary) and other carnivores (tertiary) Omnivores – eat plants and meat Decomposers – bacteria and fungi that consume dead organisms and organic waste Recycles nutrients back into the environment

6. How do you think energy is transferred in an ecosystem?

7. How is energy transferred in an ecosystem? When organisms eat other organisms Food chain – a sequence in which energy is transferred from one organism to the next when organisms eat each other Begins with producers, then herbivores, then carnivores

8. Why do you think food chains are not the best way to illustrate the true transfer of energy in ecosystems? What could be used in place of food chains to better represent the transfer of energy in ecosystems?

9. Most organisms eat a variety of food so there are many food chains in an ecosystem Food web – network of food chains representing the feeding relationships among organisms in an ecosystem Changes in population of one organism have effects on many other populations i.e. Whales and krill More diverse food webs indicate a more stable ecosystem

10. What are trophic levels? Each step in a food chain = trophic level Layer in the structure of feeding relationships in an ecosystem 1 st level – producers, entry level of all energy, biggest level 2 nd level – primary consumers 3 rd level – secondary consumers 4 th level – tertiary consumers Omnivores, scavengers, and decomposers feed at all levels

11. Energy Pyramid (p. 131) Draw a pyramid in your notes. Indicate the following on your pyramid. Layers for producers, primary consumers, secondary consumers, and tertiary consumers Layers with highest and lowest energy Layers with highest and lowest number of organisms Layers with highest and lowest biomass (total mass of organisms)

12. Energy pyramids Shows the loss of energy from one trophic level to the next Amount of energy passes to next level decreases due to life functions (heat, cellular respiration) =only 10% moves to the next level Producers at the base and have the most energy, then herbivores, then carnivores Pyramid gets smaller at the top showing loss of energy Limits the number of trophic levels in an ecosystem Can show Energy at each level number of organisms at each level Biomass

13. Where Does the Energy Go? Open to p. 131 to find out!!!

14. Section 5-2: The Cycling of Materials

15. The Cycling of Materials in an Ecosystem Materials constantly being recycled and reused Matter is continually moving through an ecosystem back and forth between organisms and the environment Most abundant elements are: Nitrogen, Oxygen, Carbon, and Hydrogen

16. The Carbon Cycle Continual movement of carbon around and through the earth and it’s organisms Key players in the cycle = living things For example, Carbon is cycle through photosynthesis and cellular respiration Carbonates make up hard parts of bones and shells Carbon – also stored in rocks and fossil fuels Human effect on the carbon cycle Release carbon dioxide into atmosphere when we burn fossil fuels Contributes to global warming

18. The Nitrogen Cycle Continual cycling of nitrogen through the earth and it’s organisms Organisms require nitrogen to make proteins and new cells Nitrogen = 78% of gases in air Nitrogen-fixing bacteria convert N in air into a usable form called ammonia for living things Live in soil and legume roots (beans, clover, peanuts) Plants use the ammonia formed by bacteria Other bacteria consumes ammonia to produce nitrites and nitrates (fertilizer) Nitrogen is returned to soil by decomposers Human effect: create and use fertilizers that can runoff into ponds and hurt organisms

20. The Phosphorus Cycle Phosphorus – in cells of organisms Enters soil when rocks weather and from decaying matter or waste Plants get P from soil and water Animals get P from eating plants and animals that have eaten plants Slow cycle that doesn’t involve the air Human effect – fertilizers – runoff into ponds and lakes causing algae blooms

22. Section 5-3: How Ecosystems Change

23. How do ecosystems change over time? Always changing in response to natural and human disturbances Older inhabitants die out, new organisms move in Ecological succession – gradual process of change and replacement of some or all of the species in a community Can take hundreds to thousands of years Caused by slow changes in physical environment OR Caused by sudden natural disturbance

24. Complete the following data table in your notes (pp. 137-141) Primary SuccessionSecondary Succession Description Examples

25. What is primary succession? Succession on land where no soil previously existed Hardened volcanic lava or ash Rocks exposed from glacier melt Pioneer species – 1 st to populate an area i.e. Lichens Creates soil

27. What is secondary succession? Succession that occurs where an ecosystem has already existed More common than primary Follows a community changing disturbance Wild fires, humans clearing land, storms, floods, earthquakes, Climax Communities – ending point of succession – mature stable community Still goes through change over time

28. Old Field Succession Occurs on a field once used as farmland

29. Secondary Succession after a fire

30. Secondary Succession of a Lake