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Environmental Biology & Genetics Energy Flow Ecosystems An ecosystem is a natural unit composed of living organisms and their non-living environment, e.g. a woodland. A habitat is the place where an organism lives, e.g. greenfly live on the leaves of the trees. An organism’s niche is the role it plays within the ecosystem e.g a tawny owl is top predator in a woodland. Monday, May 22, 2017 Mr G Davidson 2 Ecosystems Monday, May 22, 2017 Mr G Davidson 3 Ecosystems A population is the total number of organisms of one species living in a habitat, e.g. the total number of greenfly in the woodland. A community is made up of all the living organisms in a habitat, e.g. all the trees, grass, insects, birds, etc.. Monday, May 22, 2017 Mr G Davidson 4 Ecosystems Monday, May 22, 2017 Mr G Davidson 5 Ecosystems A species is a group of organisms which can interbreed to produce fertile offspring. Donkey Horses and donkeys can mate to produce a mule – but mules are not fertile so horses and donkeys are separate species Monday, May 22, 2017 Horse Mule Mr G Davidson 6 Ecosystems All of the energy required by all living organisms in an ecosystem comes from the sun. Light energy from the sun is converted to chemical energy by plants in a process called photosynthesis. Monday, May 22, 2017 Mr G Davidson 7 Producers & Consumers Producers are organisms which can produce their own food by photosynthesis – usually green plants. Consumers are animals which consume (eat) other organisms. They cannot make their own food. Monday, May 22, 2017 Mr G Davidson 8 Producers & Consumers A primary consumer is an animal which eats plants, and is also known as a herbivore. A secondary consumer is an animal which eats primary consumers, and is also known as a carnivore. Monday, May 22, 2017 Mr G Davidson 9 Producers & Consumers An omnivore can eat both plants and animals. Decomposers are bacteria and fungi which break down dead plants and animals for energy and release their nutrients back into the ecosystem. Monday, May 22, 2017 Mr G Davidson 10 Producers & Consumers An animal which hunts other animals for food is called a predator. An animal which is hunted by other animals as food is called prey. Monday, May 22, 2017 Mr G Davidson 11 Food Chains & Webs A FOOD CHAIN shows a feeding relationship. It is usually written as: Green plant herbivore carnivore The arrows in a food chain point from food to feeder and show the direction of energy flow. A food chain always starts with a producer (green plant). Monday, May 22, 2017 Mr G Davidson 12 Food Chains & Webs Energy is transferred in the form of chemical energy in food from plants to animals and then to other animals. A green plant (producer) can be eaten by a herbivore. The herbivore in turn can be eaten by a carnivore. Monday, May 22, 2017 Mr G Davidson 13 Food Chains and Food Webs ENERGY ENERGY Green Plant Rabbit Fox PRODUCER PRIMARY CONSUMER (HERBIVORE) SECONDARY CONSUMER Monday, May 22, 2017 Mr G Davidson (CARNIVORE) 14 Food Chains & Webs Feeding relationships are more complicated than food chains suggest. Food chains interconnect at many points. This interconnection of food chains is called a food web. Monday, May 22, 2017 Mr G Davidson 15 Food Chains & Webs WEASEL FOX HEDGEHOG FROG SNAIL RABBIT VOLE PRIMROSE PLANT Monday, May 22, 2017 OWL Mr G Davidson OAK 16 Energy Flow and Loss Every time one organism eats another, energy is transferred from the food to the feeder. The arrow indicates the direction of energy flow. E.g. Oak leaf Monday, May 22, 2017 Caterpillar Mr G Davidson Shrew Badger 17 Energy Flow and Loss Not all the energy available at each step in a food chain is passed onto the next step. Only about 10% is passed on. 90% of the energy is lost e.g. as: Movement Heat production Waste. Monday, May 22, 2017 Mr G Davidson 18 Pyramid of Numbers A pyramid of numbers is a diagram which represents the number of organisms at each stage in a food chain. A pyramid of numbers can look like: Monday, May 22, 2017 Mr G Davidson 19 Pyramid of Numbers Number of organisms decrease Thrush Size of organisms increase Ladybird Greenfly Grass Monday, May 22, 2017 Mr G Davidson 20 Pyramid of Numbers Thrush Ladybird Greenfly Grass Monday, May 22, 2017 Mr G Davidson 21 Pyramids of Energy A pyramid of energy is a diagram which represents the amount of energy available at each level of a food chain. It is usually measured in kilojoules of dry mass per square metre per year. Monday, May 22, 2017 Mr G Davidson 22 Pyramid of Energy 100 kJ 1 000 kJ 10 000 kJ 100 000 kJ Monday, May 22, 2017 Mr G Davidson 23 Pyramid of Biomass A pyramid of Biomass is a diagram which represents the total mass of organisms at each level of a food chain. Monday, May 22, 2017 Mr G Davidson 24 Pyramid of Biomass Sparrows Caterpillars Oak leaves The energy available to the caterpillars is less than the energy available to the sparrows, and therefore, the caterpillars produce a greater biomass than the sparrows. Monday, May 22, 2017 Mr G Davidson 25 Vocabulary ecosystem habitat niche population community producer primary consumer secondary consumer herbivore Monday, May 22, 2017 carnivore predator prey decomposer species pyramid of numbers pyramid of biomass pyramid of energy Mr G Davidson 26