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What is Ecology??
• The study of interactions that take place between organisms and their environment .
• It explains how living organisms affect each other and the world they live in.
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• Habitat is the place a plant or animal lives
• Niche is an organism’s total way of life copyright cmassengale 3

The Nonliving Environment
• Abiotic factors - the nonliving parts of an organism’s environment.
• Examples include air currents, temperature, moisture, light, and soil.
• Abiotic factors affect an organism’s life.
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The Living Environment
• Biotic factors - all the living organisms that inhabit an environment.
• All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection.
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Abiotic or Biotic?
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Abiotic or Biotic?
Abiotic copyright cmassengale 7

Abiotic or Biotic?
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Abiotic or Biotic?
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What are the Simplest Levels?
• Atom
• Molecule
• Organelle
• Cell
• Tissue
• Organ
• System copyright cmassengale 11

Levels of Organization
• Ecologists have organized the interactions an organism takes part in into different levels according to complexity .
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1 st Level of Organization
• Organism:
An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops copyright cmassengale 13

2 nd Level of Organization
• Population:
A group of organisms, all of the same species , which interbreed and live in the same place at the same time .
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3 rd Level of Organization
• Biological
Community:
All the populations of different species that live in the same place at the same time.
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4 th Level of Organization
• Ecosystem:
Populations of plants and animals that interact with each other in a given area with the abiotic components of that area.
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5 th Level of Organization
• Biosphere:
The portion of
Earth that supports life.
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The Biosphere
• Life is found in air, on land, and in fresh and salt water.
• The BIOSPHERE is the portion of Earth that supports living things.
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What level of organization?
Organism copyright cmassengale 19

What level of Organization?
Community copyright cmassengale 20

What level of Organization?
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4.2 Community Interactions
• Community interactions, such as competition, predation, and symbiosis, can powerfully affect an ecosystem.
– Competition occurs when living things try to use the same resources. Competition often results in one organism dying out.
– Predation occurs when one organism (the predator) captures and eats another (the prey).

Community Interactions
– Symbiosis occurs when 2 species live close together in one of three ways.
• Mutualism: Both species benefit from the relationship.
• Commensalism: One species benefits. The other is neither helped nor harmed.
• Parasitism: One species benefits by living in or on the other. The other species is harmed.