The Biosphere

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  • Created by: Abby
  • Created on: 11-11-12 18:36
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  • The Bisosphere
    • Investigating an Ecosystem
      • The biosphere is the part of the planet where organisms are found- can be divided  separate ecosystems
      • Sampling tecniques
        • Quadrat- plant samples
          • Frame divided into squares
          • Number of squares which contain the plant being studied is counted
        • Pitfall trap- animal samples
          • Cup is placed in a hole so the top is level with the ground
          • Some animals that fall in could be eaten by predators such as spiders which also fall in
      • The place where an organism lives is its habitiat
      • An investigation involves collecting and identifying the organisms, then measuring physical conditions
      • Abiotic Factors
        • A physical factor  such as light, moisture, oxygen, concentration or temperature.
        • Abiotic factors affect the organisms living in a particular habitat.
        • An abiotic factor can usually be measured by a meter.
        • A moisture meter is used to measure moisture. To avoid errors, be careful to place the moisture probe firmly in the ground and wipe it dry afterwards.
        • To measure light a light meter is used. To avoid errors, be careful not to shade the meter and always hold it the same way when making the reading.
      • Effects of Abiotic Factors
        • Green plants are not found in areas with low light density
          • The reason why is that plants need light for photosynthesis
        • Most land organisms are not found in very dry or very wet areas
          • The reason why is that in very dry conditions plants become dehydrated. In very wet conditions plant roots are deprived of oxygen
    • How an Ecosystem Works
      • An ecosystem is made up of living and non living things.
      • All parts of an ecosystem are inter-related.
      • Ecosystems can be divided into types of ecosystem such as coastal, mountain, river or forest.
      • All the organisms of one kind make up a population.
      • All of the organisms in a habitat make up the community
      • Community +  Habit  = Ecosystem
      • Food and Energy
        • All the energy in an ecosystem come from the sun, because plants use light energy from the sun to make food.
        • Producers- Green plants use the sun's energy to produce food energy
        • Consumer- animals that get their energy from eating other living things
      • Food Chains
        • The way energy, in the form of food, passes from plants to animals and then to other animals and then to other animals can be shown by a food chain.
        • The arrows in a food chain show the direction of energy flow
        • Food chains and webs begin with energy from the sun.
      • Food Webs
        • A food web gives us a more complete picture of who eats what.
        • Food webs are made up of many food chains linked together.
        • Food chains can be drawn for any environment.
        • What would happen if an animal was removed by disease or other factors?
          • Look at who would get eaten, who would go hungry, what they do about it and what effect it would have on the other animals in the food web.
    • Energy Loss in a Food Chain
      • As energy is passed along a food chain, each organism uses some of it.
      • Energy is 'lost' from the food chain at each stage.
      • Energy can be lost by being passed out as undigested food, lost as heat and used for movement.
      • 90% of the energy is not available to other animals in a food chain.
      • 10% of energy is passed onto other animals in the food chain.
      • Energy in a producer is eaten by primary consumers, released in respiration or lost to decomposers.
      • Energy in a consumer is lost as heat in respiration, in growth and in urine and faeces.
      • As you move along a food chain, very often the size of an organism increases but the number of the decreases. This can be shown in a pyramid of numbers.
      • A more accurate idea of the quantity of animal and plant material in a food chain is obtained by constructing a pyramid of biomass.
        • This represents the mass of all the organisms at each level.
    • Populations and Nutrient Cycles
      • The sizes of most populations tend to stay roughly the same.
        • The size of a population stays the same as long as the birth rate is the same as the death rate.
          • Populations can be limited by predators, disease, limited food supply and lack of space which could prevent breeding
      • If different organisms eat the same food then competition will occur.
        • Plants compete for light and water.Animals compete for food and a place to live.
          • When competition occurs some organisms will be more successful than others. These organisms will be more likely to survive.
      • Bacteria and fungi are very important in an ecosystem. They feed on dead plants and are known as decomposers.
        • Decomposers are important as they get rid of animals and plants. They also release chemicals from dead organisms which go into the soil and help keep it fertile. These chemicals are taken up as nutrients by living organisms organismsvas part of nutrient cycles
      • All living things need nitrogen to make protein. Plants obtain nitrogen from the soil by taking in nitrates. Animals obtain nitrogen by eating plants or other animals.
    • The Carbon Cycle
      • Carbon dioxide is a rare atmospheric gas. The amount in the atmosphere should stay the same as the carbon is recycled.
        • The amount of carbon released into the atmosphere balances the amount absorbed by plants.
      • Decomposition
        • Bacteria and fungi are decomposers. They break down dead material.
          • As well as helping to recycle carbon into the atmosphere, decomposers also recycle other nutrients into the soil.
        • Decomposition happens everywhere in nature, and also in compost heaps and sewage works.
          • The ideal conditions for decomposition are warmth, moisture and oxygen.
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