1. Ecology Review Living things do not live in vacuums, their daily lives are based on _interactions_ with both _living_ and _nonliving_ things. What is an ecosystem? Groups of organisms and their physical environment 34-1

2. There are two main components of an ecosystem: __ Biotic (living) _& _ Abiotic (nonliving) __ Descriptions: populations of inorganic nutrients, organisms. physical features, water, temperature, and wind. 34-2

3. Biotic Components: A Closer Look Autotrophs are producers that produce food for themselves and for consumers. How do autotrophs make food? Photosynthesis and chemosynthesis Heterotrophs are consumers that take in premade food. 34-3

4. Biotic components 34-4

5. Consumers Vocabulary: Herbivores – animals that eat plants Carnivores – animals that eat other animals Omnivores – animals that eat plants and animals Decomposers - bacteria and fungi, that break down dead organic waste. Detritus - partially decomposed organic matter in the soil and water; beetles, earthworms, and termites are detritus feeders. 34-5

6. Consumers 34-6

7. Consumer Levels Primary consumer – an organism that gets its energy from plants (producers) Secondary consumer – an organism that gets its energy from primary consumers Tertiary consumer – carnivores that eat other carnivores; a top-level consumer, usually the top predator in the food chain 34-7

8. Energy Flow What is energy flow? The movement of energy through the organisms in an ecosystem What direction does energy flow through an ecosystem? Sun  Producers  Various levels of consumers 34-8

9. Energy Flow As energy flows from _autotrophs_ (producers) to _heterotrophs_ (consumers) much of the energy is lost before the consumer can use it. In what forms is energy lost? Heat Initial energy from an ecosystem comes from a consistent supply of _solar_ energy **Remember energy in an ecosystem may be transferred or converted but will not be created nor destroyed** 34-9

10. Energy balances 34-10

11. Nature of an ecosystem 34-11

12. Food chains vs. food webs What is a food chain? A diagram that links organisms together by who eats whom Starts with _plant life_ and ends with an _animal_. Most food chains have no more than _4 or 5_ links Arrows show the direction _energy is flowing_ EXAMPLE: grass  zebra  lion 34-12

13. Food chain 34-13

14. FOOD WEB Most consumers feed on and are eaten by _more than one_ other consumer What is a food web? A combination of several food chains showing all of the possible energy pathways What is a trophic level? All of the organisms that feed at a particular link of the food chain/web 34-14

15. Grazing food web – The upper portion of a food web based on a living plant as the producer Detrital food web – The lower portion of a food web based on detritus 34-15

16. Forest food webs 34-16

17. Ecological Pyramids Why are food chains so short? Only about 10% of energy is useable from one trophic level to the next The number organisms drastically _decreases_ as you go up in level of a food chain What is an ecological pyramid? A series of blocks representing the biomass of particular organisms on a particular trophic level What is biomass? The amount of living material in the population of an organism 34-17

18. Ecological pyramid 34-18

19. Biochemical cycles What are biochemical cycles? The path by which important nutrients/molecules travel through an ecosystem. 3 Important Cycles: Water Cycle Carbon Cycle Nitrogen Cycle 34-19

20. The Water Cycle Water movement: Land  Atmosphere: Liquid  Gas Evaporation from rivers, lakes and oceans Transpiration from plants Atmosphere  Land Gas  Liquid Precipitation over land and bodies of water Runoff forms bodies of water (lakes, rivers, oceans) Ground water seepage into aquifers 34-20

21. The water cycle 34-21

22. The Carbon Cycle Carbon Movement: Land/Water  Atmosphere Respiration Combustion Atmosphere  Land/Water Photosynthesis Dissolved CO 2 ** Carbon is stored as _fossil fuels__ from decaying organisms.** 34-22

23. The carbon cycle 34-23

24. The Nitrogen Cycle Nitrogen Movement: Nitrogen Fixation  _Bacteria_ found in legume roots converts N 2 gas into _Ammonia (NH 4 )_ _Decomposers_ break down waste and organic remains into _Ammonia (NH 4 )_ Nitrification  bacteria convert ammonia into _Nitrite (NO 2 )_ and _Nitrate (NO 3 )_ to be used by _plants_ Denitrification  Bacteria converts _ammonia_ back into _Nitrogen gas (N 2 ) 34-24

25. The nitrogen cycle 34-25