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Ecosystems - PowerPoint PPT Presentation

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Ecosystems. A study of balance and cycles. Key Terms. Ecosystem Consists of a biotic community and the abiotic factors that affect it Ex – a rain forest, including the animals, plants, soil, rain, sunlight, and temperature Biotic factors

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A study of balance and cycles

Key terms
Key Terms

  • Ecosystem

    • Consists of a biotic community and the abiotic factors that affect it

    • Ex – a rain forest, including the animals, plants, soil, rain, sunlight, and temperature

  • Biotic factors

    • Living or once-living organisms in the environment

    • Ex – gorilla, red-eyed tree frog, moss, bacteria

  • Abiotic factors

    • All the non-living, physical features of the environment

    • Ex. sunlight, soil, water, and temperature

Levels of organization
Levels of organization

  • Organism

    • A single individual in a population

    • Ex – the oak tree growing in my yard

  • Population

    • All of the individuals of one species that live in the same area at the same time

    • Ex. – All oak trees in my neighborhood

  • Community

    • Populations of different species that interact in some way

    • Ex. – Oak trees, squirrels, rabbits, mice, grass, robins, humans

Levels of organization cont
Levels of Organization, cont.

  • Ecosystem

    • Communities and abiotic factors that affect them

    • Ex. Community + soil, light, temperature, etc.

  • Biosphere

    • All the ecosystems on Earth


  • Population density

    • The number of organisms in a given area

    • Formula - # of organisms / area

    • The more organisms in a given space, the denser the population

  • Limiting factor

    • Any biotic or abiotic factor that restricts (limits) the number of individuals in a population

    • Ex. Food supply, # of predators, disease, available shelter

Limiting factors
Limiting Factors

  • 1. Choose an organism.

  • 2. Write five limiting factors for that organism. Be as specific as possible.

  • Ex. Cow

    • 1. Disease - Mad cow disease

    • 2. Humans – Humans slaughter cows for food

    • 3. Living space – Farms have limited space to house the cows.


  • Symbiosis

    • Any close relationship between two or more species

    • Parasitism, mutualism, and commensalism are all types of symbiosis

  • Parasitism

    • Relationship that benefits one (the parasite) and does definite harm to the other (host)

    • Ex – Tapeworms benefit by getting nutrients from a dog, but the dog is harmed by the tapeworms

Relationships cont
Relationships, cont.

  • Mutualism

    • A relationship in which both organisms benefit

    • Ex Yucca moth and desert yucca plant – moth gets a food source and place for eggs; plant gets its flowers pollinated

  • Commensalism

    • A relationship in which one organism benefits, but the other is neither harmed nor helped.

    • Ex. Sea anemone and anemone fish – The fish are protected by the sea anemone, but the sea anemone are not affected by the fish


  • Many abiotic factors change form as they travel through a cycle

  • Matter is not destroyed, but it changes form

  • Examples

    • Water

    • Carbon

    • Nitrogen

Water cycle
Water Cycle

  • Evaporation – Liquid water found in lakes, oceans, ponds, rivers, etc. evaporates when heat is added. The water takes the gaseous form of water vapor

  • Condensation – Gaseous water vapor condenses when it is cooled and has a solid on which it can condense. The water becomes liquid form.

  • Freezing – Some clouds are high enough in the atmosphere that the water freezes, forming snow or hail

  • Precipitation –Liquid or solid water collects in clouds, and as more water collects, it becomes heavy enough to fall as rain, snow, or hail

Water cycle cont
Water Cycle, cont.

  • Run-off – Precipitation hits the ground, is not absorbed, but flows from high elevation to low elevation.

  • Ground water – Precipitation hits the ground and is absorbed into the ground

  • Hydration of living organisms – Organisms take in water by drinking, eating, taking water in through roots, and osmosis

  • Excretion – Animals release water in their liquid wastes

  • Transpiration – Plants release water from stomata

Carbon cycle
Carbon Cycle

  • Photosynthesis – Plants remove carbon dioxide from atmosphere to make carbohydrates

  • Respiration – Other organisms eat the plants. In respiration, they use the energy from the carbohydrates. Carbon dioxide is released as a waste product

  • Decay – Organisms die. The carbon in their decaying remains is returned to the ground

  • Combustion – Carbon is released into the atmosphere when fossil fuels (ex coal and oil) are burned

Nitrogen cycle
Nitrogen Cycle

  • Nitrogen is a gas in our atmosphere. It is also found in organisms in proteins and nucleic acids.

  • Nitrogen gas – In the atmosphere, nitrogen will combine with oxygen in the presence of high temperatures and pressures (lightning) to form nitrogen dioxide

  • Nitrogen dioxide combines with rain to form an acid, which falls to the ground with the rain.

  • In the ground, bacteria “fix” nitrogen so that it can be used by plants

Nitrogen cycle cont
Nitrogen Cycle, cont.

  • Plants use nitrogen as a fertilizer. The nitrogen is used to build proteins, which are necessary for growth

  • Animals eat plants, taking in the proteins containing nitrogen.

  • Animals release wastes, which contain nitrogen. These wastes may be used as fertilizer.

  • Some bacteria convert nitrogen in the soil back into nitrogen gas, which is released into the atmosphere

Energy in ecosystems
Energy in Ecosystems

  • Energy travels through an ecosystem, changing form

  • Common forms of energy include light, chemical, mechanical, and heat energy

  • Organisms gain energy by:

    • Using light or chemical energy to produce their own food (producers)

    • Eating other organisms (consumers)

Producers vs consumers
Producers vs. Consumers

  • Producers

    • Plants and some bacteria

    • Photosynthesis – use light energy to create carbohydrates

    • Chemosynthesis – use chemical energy to create carbohydrates

      • Found in organisms deep in ocean ridges

  • Consumers

    • Eat other organisms for energy

    • Ordered by primary (eat consumers), secondary (eat primary consumers), and tertiary (eat secondary consumers)

  • Food chains and food webs
    Food Chains and Food Webs

    • Food chains show relationships among a select group of producers and consumers.

    • The chain shows the flow of energy as one organism eats another.

    • Chains are RARELY more than five organisms long

      • Consumers get only a fraction of the energy contained in the organism they eat.

      • Some energy is used by the original organism

      • Much energy is lost as heat energy

    Food chains and food webs cont
    Food Chains and Food Webs, Cont.

    • Food webs

      • Show the complexity of consumer/producer relationships in an ecosystem

      • Used to show that more than one organism may eat a producer or prey AND that an organism may have more than one food source

      • Typically, producers are near the bottom of the web and secondary/tertiary consumers are near the top

      • Arrows indicate the direction of energy flow

    Energy pyramid
    Energy Pyramid

    • Diagram used to show producer and consumer relationships

    • Emphasizes the relationship of number of prey per organism and the amount of energy that gets transferred from one level (ex. producer) to another level (ex. primary consumer)

      • Only about 10% of the energy from one level is passed on to the next level

        • Not all parts of an organism are eaten

        • Not all organisms at one level are eaten

        • Some energy is “lost” as heat energy

  • Therefore, in an ecosystem, we have MANY producers and primary consumers. As we move up the energy pyramid, the ecosystem can sustain fewer and fewer organisms because there is less and less energy available

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