1. Ecosystems

2. What is an ecosystem?
All the biotic and abiotic factors in a specific area
Biotic factors-All the living organisms in the ecosystem
Abiotic Factors-All the non-living things in the ecosystem

3. Biotic Factors
In an ecosystem many different types of organisms live together
A population is a group of the same species of organisms that live in the same area
For example, a squirrel population would include every squirrel in the area

4. Biotic Factors
Different populations fill different roles in the ecosystem
Producers-make sugar from sunlight
Consumers-get their energy from other organisms
Decomposers-break down waste and dead organisms

5. Energy Flow All energy for an ecosystem comes from the SUN
Producers turn sunlight into sugar
They use that energy to grow and develop
Consumers come along and eat the producers to get the sugar they store
Other consumers eat those consumers to the energy they took from the producers

6. Food Chains
A food chain is a way of describing who eats who in an ecosystem

7. Food Chains Predators- organisms that eat others
Prey- organisms that are eaten by others
Arrows in food chains start at the prey and point towards the predator

8. Food Webs
A Food Web shows all of the food chains that occur in an ecosystem
Consumers normally eat more than one type of food, and food webs let us see how the whole system works

9. Draw a food web for organisms in your neighborhood

10. Abiotic Factors
Anything that is not alive, but is still part of the ecosystem is an abiotic factor
There are 3 really important abiotic factors
Water
Carbon Dioxide
Nitrogen

11. Water Cells are mostly made of water
Without water cells do to not work correctly
Water moves through an ecosystem in a predictable way, called a cycle

12. The Water Cycle The sun makes water evaporate (gas)
The gas condenses (liquid) to make clouds
Clouds start precipitation (rain, snow)
Precipitation forms runoff as the water goes back to lakes and oceans

14. Pollution & the Water Cycle
Human activity (farms, factories, trash) can affect the water on the planet
When it rains, the water crosses the ground and picks up all the stuff that is on the ground (runoff)
The water then carries those contaminants to the rivers, lakes and oceans

15. The Carbon Cycle Plants take in Carbon Dioxide
Plants make sugar and oxygen (photosynthesis)
Animals eat plants and breathe oxygen
Animals use respiration to get energy
Animals breathe out Carbon Dioxide

17. The Carbon Cycle Carbon is the most important atom for living things
It is used to make cells, proteins and store energy
Organisms use the carbon they take in through the cycle to build their bodies
Without Carbon, organisms could not grow and develop

18. The Nitrogen Cycle Nitrogen is in the air free nitrogen (N2)
Bacteria change it to fixed nitrogen (NH3)
Plants take in fixed nitrogen
Consumers eat plants and take in fixed nitrogen
Decomposers break down dead consumers
Decomposers release free nitrogen (N2)

20. Nitrogen Cycle Organisms need Nitrogen to build their DNA
If there is not enough Nitrogen to copy the DNA cells will not divide
If cells do not divide, the organism cannot grow
This is why farmers use fertilizer to add Nitrogen to the soil
More nitrogen means more DNA can be made, which means more cells can divide