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B9: Energy Flow in Ecosystems 1. Read p224-225 in your ‘Biology for IGCSE’ textbook. 2. Match the term with the correct definition: Food chain An organism that make its own organic nutrients, usually through photosynthesis, using sunlight. Food web Microorganisms (bacteria & fungi) that get energy by breaking down dead or waste organic matter. Producer A chart showing the flow of energy (food) from one organism to the next, beginning with a producer. Consumer An organism that eats animals to get energy, Herbivore An animal that gains energy by eating other animals. Carnivore An organism that gets its energy by eating plants. Decomposer The position of an organism in a food chain or food web. Ecosystem A network of interconnected feeding relationships showing energy flow through part of an ecosystem. Trophic level Burning of a fuel in oxygen. Combustion A unit containing all of the organisms and their environment, interacting together, in a given area. 3. Complete these sentences about ecosystems: There are ______________ different feeding types in an ecosystem. _________________ (e.g. green ______________) make their own food from raw materials such as carbon dioxide and water. In the process of __________________________, sunlight is used to produce sugars (6CO2 + ___________ → C6H12O6 + _______). Because other organisms, called __________________, eat the chemical energy produced by the plants, sunlight is considered to be the source of energy for all organisms in almost all ecosystems (there are exceptions, but you don’t need to know them.) All animals have to eat (consume) other organisms (either plants or other animals) to gain energy. _____________________ are animals that eat only plants; carnivores will eat other animals. Decomposers are fungi and _____________ that feed on dead and decaying matter. 4. Label the following food chains with the trophic level (see p225) Rose Aphid Lady bird P_________________ P_________ C___________ S___________ C_____________ Carrot P_________________ Rabbit Wolf P_________ C___________ S___________ C_____________ 5. Draw 2 food chains of your own making. Each one should contain at least 3 trophic levels. Ensure the arrows show the direction of energy flow. 6. Read “Energy losses” on pages 228-229. 7. Energy losses occur between trophic levels as a result of respiration, and in waste materials produced. This energy loss helps to explain why there are usually fewer than 5 trophic levels in a food chain. Copy in figure 18.3.2 from p 229 to show the energy lost in an ecosystem. 8. Read “The carbon cycle” pages 230-231. 9. Complete the diagram of the carbon cycle using the processes in the box below. Each process may be used more than once. Combustion Respiration Feeding Photosynthesis Arrow Process A B C D E F E B D A C F Plants and producers For an animation giving more information on the carbon cycle, go to this website: http://nortonbooks.com/college/biology/animations/ch38a03.htm 10. Complete the following sentences, using the words in the box provided, to discuss the effects of the combustion of fossil fuels and the cutting down of forests on the oxygen and carbon dioxide concentrations in the atmosphere. Vegetation Carbon Carbon dioxide Combusted Decrease Increase Oxygen Atmosphere Forests Photosynthesis Deforestation is the cutting down of trees in established ______________. This reduces the number of trees, worldwide. The process of ______________________ removes atmospheric carbon dioxide and produces oxygen; the effect of fewer trees would be an _________________ in the concentration of ______________________ in the atmosphere, and a _____________________ in the concentration of ________________. Fossil fuels form over millions of years from dead _________________________. They are a store of ______________. When fossil fuels are _____________________ (burned), the carbon is converted into carbon dioxide, which is released into the atmosphere. The process of combustion requires oxygen, so the concentration of oxygen in the _________________ will increase.