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Grade 7 Science Unit 1. Interactions Within Ecosystems Chapter 2. Symbiosis. Interactions between the biotic parts of the environment. There are 3 types: Parasitism Mutualism Commensalism. 1. Parasitism .
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Grade 7 ScienceUnit 1 Interactions Within Ecosystems Chapter 2
Symbiosis • Interactions between the biotic parts of the environment. • There are 3 types: • Parasitism • Mutualism • Commensalism
1. Parasitism • One organism will benefit (the parasite) and the other is harmed (the host). Ex: tape worm; dwarf mistletoe
2. Mutualism • Both organism benefit. Lichen = algae + fungus
3. Commensalism • One organism benefits while the other neither gains or loses.
Symbiosis Work with a Partner. Come up with 3 examples of each type of symbiosis (parasitism, mutualism, commensalism). Be able to explain how each organism is affected in each example.
Roles of Organisms in the Ecosystem • Producers • Consumers • Decomposers • Scavengers
1. Producers • Plants can produce their own food from the abiotic environment. (photosynthesis) Water + carbon dioxide + Sunlight Food (sugar) + oxygen
2. Consumers • Animals must consume, eat other organisms. (the biotic environment) • Can be classified as... herbivores, carnivores, or omnivores.
Herbivore: • Animals that eat ONLY plants (producers).
Omnivore: • Animals that eat both plants AND animals.
Carnivore: • Animals that eat ONLY other animals.
3. Decomposers • Organisms that break down dead and waste materials into their basic parts. • They release chemicals that break apart dead tissues and cells and absorb the nutrients for their own use.
Examples include bacteria and other microorganisms, fungi and worms.
4. Scavengers • Animals that eat decaying animals and waste materials. • Examples include vultures, dung beetle larvae, houseflies, crows and some gulls.
Microorganisms... • are found in a variety of habitats (air, soil, water) • play important roles in relation to human food supplies • have been studied to enhance food preservation techniques
Conditions that affect Microorganism Growth • Temperature • Moisture • Light • Acidity • Salinity
Food Preservation • Creates an environment which destroys existing decomposers and then prevents or slows down their growth rate.
Methods of Food Preservation • Pickling • Salting • Drying • Smoking (the above started out of necessity )
Refrigerating • Freeze-drying • Radiation • Canning (These are more modern and technology based.)
Food Chains • The transfer of energy from organism to organism. Arrows show the direction of energy flow. • Green plants are the food (energy) source for all consumers and decomposers.
Producers Primary Consumers Secondary Consumers
Food Webs • Interconnecting food chains.
Energy Pyramids • Describes the gradual loss of energy in food chains • About 10% is lost as you move from one level to the next and 10% of the new energy is lost as you move up and so on.
Note: Energy pyramids are not exact. Energy is transferred to other types (eg. heat) as it moves from one level to the next. ie. Not all of the 10% is transferred. Energy in hawk: 10 J Energy in weasel: 100 J Energy in mice: 1000 J Energy in grass: 10 000 J
Nutrient Cycles • Nutrients, such as nitrogen and carbon, are recycled in the environment. • All organisms are eventually recycled and their nutrients are returned to the soil by the action of decomposers.