Ecological Niche

• Is how an organism makes a living
• Every relationship that an organisms may have 
• Behavior 
• where it lives, how it responds to resources available predators,competitors

What is a system?

SYSTEM 

  Is an essamble of parts and the relationships between them, which together constitue a whole.

 System composition :

• storages: matter and energy 
• flows: inputs and outputs
• processes: tranfer and transfromation 
• feed back mechanisms: positive feedback and negative feedback

Types of systems: 

• Open system: Exchanges both  energy and matter
• Closed system: Exchanges energy but not matter
• Isolated system: Neither matter or energy crosses

Digestive system is an open system. 

                                                            A fishbowl is a closed system

Biological Organization

1. Atmosphere
2. Hydrosphere
3. Lithosphere
4. Ecosphere
5. Biosphere
6. Ecosystem
7. Community
8. Population 
9. Species
10. Multicellular organisms
11. Organism
12. Organ System
13. Organ
14. Tissue
15. Cell
16. Organell
17. Molecules 
18. Atom 
19. Subatomic particle 

Population

Are all the members of one species inhabiting the same area.

What is a Community ?

• Is the interaction of two or more populations of different species living and interacting in the same area. 
• Group of populations living and interacting with each other in a common habitat.
• contains all the biotic components of a habitat. 

Ecosystem: Comes from the Grek word OIKOS which means home and system.
- A community together with its nonliving surroundings.
- Interaction of biotic and abiotic factors.

 Abiotic factors: Nonliving components.

There are two kinds of abiotic factors:

1. Physical:  sunlight and shade, amount of precipitation, altitude and latitude, nature of soil and wind. 
2. Chemical:  salinity of water, level of dissolved O2 and other gases, level of plant nutrients, pH of solid and water and level of natural and artifitial toxic substances.   

 Biotic factors: Living components in an ecosystem. 

1. Autotrophs: photoautotrophic and chemoautotrophic. 

                Photoautotrophs: has clorophyll and carry on photosyntesis.

                Chemoatotrophs: bacteria that obtain energy from the oxidation of inorganic compounds. 

      2. Heterotrophs: 

• Need a source of pre formed nutrients 
• consume tissues of the other organisms
• consumers are classified according to the type of food they eat  

• 

Biosphere

What is Biosphere? 
 is that part of the Earth inhabilited by living organisms; includes both the living and nonliving components.