1. Ecosystems

2. The Hierarchy of an Ecosystem
organism
population
community
ecosystem
Hierarchy – (noun) 1: a series of ordered groupings of people or things within a system

3. The smallest unit in an ecosystem is an organisms
The smallest unit in an ecosystem is an organisms. A habitat is a place where an organism lives and provides the things an organism needs to live.

4. All of the members of one species living together in a particular area form a population.

5. All of the different populations living together in an area form a community.

6. All of the communities in an area (biotic factors) interacting with the abiotic factors form an Ecosystem.

7. Biotic factor A living part of an ecosystem.
Plants are an important biotic factor in ecosystems.

8. Abiotic factor The non-living parts of an ecosystem, like temperature, soil, water, oxygen, and sunlight are abiotic factors.
The sun is an important abiotic factor in ecosystems.

9. Energy enters an ecosystem from sunlight.

10. Autotrophs use the energy of the sun to produce food and are therefore called producers. Trees are autotrophs (producers).

11. Heterotrophs get energy by eating other organisms and are called consumers.

12. Decomposers are heterotrophs that obtain energy by breaking down wastes and the remains of dead organisms.

13. Every animal (both consumers and decomposers) is a heterotroph.

14. A herbivore is an animal that eats plants.

15. A carnivore is an animal that eats other animals.

16. An omnivore eats both plants and animals.

17. decomposer
producer
consumers
A diagram called a food chain shows the flow of energy in an ecosystem. The energy flows from the sun  producers consumers  decomposers (once organisms are no longer living). A diagram called a food web shows how many food chains are connected.

18. A tropism is a growth response by plants away from or towards stimuli.
Organisms respond to external (outside) and internal (inside) stimuli.
A response is an action or change in behavior that occurs as a result of a stimulus.
A stimulus is a change in an organism’s surroundings that causes the organism to respond.
A tropism is a growth response by plants away from or towards stimuli.

19. The Cycles
The water cycle, the carbon and oxygen cycle, and the nitrogen cycle are all cycles where energy and matter interact within an ecosystem.

20. The Water Cycle Precipitation
Condensation
Water vapor cools and changes from a gas to a liquid. The water droplets clump together around tiny dust particles in the air, forming clouds.
Transpiration
Plants give off water vapor through their leaves.
Precipitation
Water droplets become so heavy they fall back to Earth as rain, sleet, snow, or hail.
The Water Cycle
Collection
Water collects underground, in lakes, ponds, rivers, and oceans.
Evaporation
Water absorbs energy from the sun to change from a liquid to a gas and rise into the upper atmosphere.

21. The Carbon – Oxygen Cycle
Producers take in _carbon dioxide__ gas to use to make food in a process called photosynthesis.
During photosynthesis, the producer releases oxygen into the air as a waste product during respiration.
During respiration, consumers release carbon dioxide into the air as a waste product.
Consumers take in the oxygen and eat the producers to make energy.
The Carbon – Oxygen Cycle

22. The Nitrogen Cycle

23. The nitrogen cycle is a representation of the various forms of N and how they relate to one another through many complex interactions. Nitrogen is the major component of earth's atmosphere.  It enters the food chain by means of nitrogen-fixing bacteria and algae in the soil.  This nitrogen which has been 'fixed' (combined with other elements) is now available for plants
to absorb in different nitrogen compounds.  These types of bacteria form a symbiotic relationship with legumes--these types of plants are very useful because the nitrogen fixation enriches the soil and acts as a 'natural' fertilizer. 

24. The nitrogen-fixing bacteria form nitrates out of the atmospheric nitrogen which can be taken up and dissolved in soil water by the roots of plants.  Then, the nitrates are incorporated by the plants to form proteins, which can then be spread through the food chain. 
When organisms excrete wastes, nitrogen is released into the environment.  Also, whenever an organism dies, decomposers break down the corpse into nitrogen in the form of ammonia.  This nitrogen can then be used again by nitrifying bacteria to fix nitrogen for the plants.

25. Biomass
Biomass is the total amount of living matter, and the remains of dead organisms in an area. The decay of biomass releases energy into an ecosystem and recycles the dead matter back into the environment.