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8.L.3 – UNDERSTAND HOW ORGANISMS INTERACT
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Explain how factors such as food, water, shelter, and space affect populations in an ecosystem. 8.L.3.1
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Ecosystems Complex interactive systems Consist of: Abiotic Factors: Physical components of the environment Biotic Factors: Biological communities Species Populations Communities Ecosystem Biosphere Species: groups of the same organisms
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Ecosytems Dynamic Their characteristics vary over time If there is a disruption to a physical or biological component, a population shift can happen Biodiversity: variety of species found in Earth’s ecosystems Population: group of organisms belonging to the same species that live in a particular area Population Density: the number of individual organisms living in a defined space
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Factors Influencing an Ecosystem Density-Dependent Competition (for food, water, shelter, space) Predation, parasitism, disease Triggered by crowding Density-Independent Mostly abiotic, human factors, natural disasters Ex: Weather Changes, Pollution, Fires Abiotic Ex: Water, nitrogen, oxygen, salinity, pH, soil nutrients, temperature, amount of sunlight, precipitation Biotic Bacteria, Fungi, Plants, Animals
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Summarize relationships among producers, consumers, and decomposers; including positive and negativeconsequences 8.L.3.2
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Interactions between organisms Generate stability within the ecosystem Facilitate or restrain growth Enhance or limit the size of populations Change both the biotic and abiotic characteristics
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Stable Ecosystems Ecosystem: a community (all organisms in area) and the abiotic factors that affect them Stable Ecosystems: Population numbers fluctuate at a predictable rate Supply of resources of the physical environment fluctuates at a predictable rate Energy flows through the ecosystem at a constant rate over time
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Stability of Ecosystems Predation: an interaction between species in which one species (the predator) eats the other (the prey) Helps regulate the population Competition: a relationship that occurs when two or more organisms need the same resource at the same time Can occur between the same organism or different organisms that share the same niche Niche: the role of an organism in its environment including type of food it eats, how it gets food, how it interacts with other organisms
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Stability of Ecosystems Symbiotic Relationship: exists between organisms of two different species that live in direct contact, where the relationship between the two usually helps each other Types: Parasitism: one organism benefits at the expense of the other organism Ex: Tapeworms, heartworms, fleas Mutualism: where both organisms benefit Ex: Pollenation, Anemone fish and Anemones Commensalism: where one organism benefits without affecting the other Ex: Remora sharks, which eat leftover food from a whale and "hitch a ride"
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Examples
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Explain how the flow of energy within food webs is interconnected with the cycling of matter 8.L.3.3
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Energy in Ecosystems The SUN is the ultimate source of energy Energy is transferred by producers into chemical energy by photosynthesis Food provides molecules that serve as fuel and building material for all organisms Proteins The amount of matter remains constant, though its form and location changes
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Food Chains/Webs/Pyramids All of the above are models of how energy and matter are transferred between producers and consumers Each level of the transfer of energy in a food chain is called a Trophic Level.
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Trophic Levels Level 1 Consists of producers Capture the suns energy Ex: Green plants, phytoplankton Level 2 Primary Consumers Eat green plants and are called herbivores. Ex: Grasshoppers, rabbits, zooplankton Level 3+ Consumers Consumers that eat Primary Consumers are called carnivores. Consumers that eat both Producers & Primary Consumers are called omnivores. Ex: Humans, wolves, frogs, minnows
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Food Web Represents many interconnected food chains, describing the many paths energy can take through an ecosystem
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Ecological Pyramids Energy Pyramid Represents the energy available for each trophic level in an ecosystem Number Pyramid Represents the number of individual organisms available for energy at each trophic level Biomass Pyramid Represents the total mass of living organic matter at each trophic level
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Energy Pyramid
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Number Pyramid
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Biomass Pyramid
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