6.5 Ecosystems

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  • Created by: elbungay1
  • Created on: 18-05-19 14:03
What is an ecosystem?
A community of animals, plants and bacteria interrelated with the physical and chemical environment
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What is a habitat?
The place where an organism lives
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What is a population?
All of the organisms of one species, who live in the same place at the same time, and who can breed together
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What is a community?
All the populations of different species, who live in the same place at the same time, and who can interact with each other
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What is a niche?
The role of each species in an ecosystem. Impossible for two species to occupy exactly the same niche in the same ecosystem. Niche can be what they feed on, what they excrete and how it reproduces
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What are the biotic factors that affect ecosystems?
Producers (plants that supply chemical energy to all other organisms). Consumers, primary consumers are herbivores which are eaten by carnivorous secondary consumers. Decomposers (feed on waste material or dead organisms).
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What are abiotic factors?
Describes the effects of all non-living components of an ecosystem. pH, relative humidity, temperature and concentration of pollutants are all examples.
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What are the three types of change in ecosystems that affect population size?
Cyclic changes (repeat in a rhythm such as movemnt of tides). Directional changes (not cyclic and go in one direction, lasts longer than organisms life, e.g. erosion of coastline). erratic/unpredictable changes (no rhythm or constant direction)
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What is a Trophic level?
The level at which an organism feeds in a food chain
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What is biomass transfer?
Transfer of biomass from one trophic level to another
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How is biomass lost in the food chain?
Organisms need energy to carry out life processes, glucose is used in respiration and some energy is lost as heat and materials like CO2 and H2O are lost. Biomass is also lost from a food chain in dead organisms and waste materials
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How is the efficiency of biomoass transfer calculated?
(Biomass at higher trophic level) / (Biomass at lower trophic level) x 100
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What is the productivity of a producer?
The rate at which new biomass is produced by producers
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How do you increase the Gross Primary Productivity of producers?
Increasing light intensity, modifying plants to carry drought resistance, using greenhouse to increase temperatures, crop rotation to prevent depletion of nutrients, Pesticides prevent pests removing biomass, fungicides, herbicides kill weeds
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How do you improve secondary productivity?
Young animals invest energy in growth so harvest before adulthood to prevent loss, selective breeding to produce better phenotypes, Antibiotics avoid loss to pathogens, zero grazing reduces waste of energy in finding food
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What are saprotrophs
Organisms that feed saprotrophically, decomposers that break down waste organic material
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What are the stops of saprotrophic decomposition?
saprotrophs secrete enzymes onto dead and waste material, enzymes digest the material into small molecules, which are then absorbed into the saprotroph's body. Having been absorbed, the molecules are stored or respired to release energy.
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What roles do bacteria play in Recycling nitrogen
Ammonification, nitrogen fixation, nitrification and denitrification
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Describe nitrogen fixation
Nitrogen gas cannot be used by plants directly, plants need a supply of 'fixed' nitrogen as ammonium ions NH4+ or nitrate ions NO3-. Can occur when lightening strikes or by nitrogen fixing bacteria. Azotobacter in soil or Rhizobium in root nodules
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What is ammonification and nitrification?
Ammonium ion are released through ammonification by bacteria in putrefaction of waste. Chemoautotrophic bacteria obtain energy by oxidising ammonium ions to nitrites (nitrosomonas) other nitrites to nitrates (nitrobacter). Only occurs aerobically.
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What is denitrification?
Other bacteria convert nitrates back to nitrogen gas. when bacteria are growing in anaerobic conditions (waterlogged), they use nitrates as a source of oxygen for respiration, producing N2 gas and nitrous oxide N2O
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What is a climax community?
The final stable community that exists after the process of succession has occurred. In the UK, it is deciduous woodland
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What is succession?
The progressive change in a community of organisms over time?
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What is a pioneer species?
The species that begins the process of succession, often colonising an area as the first living things there
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What is deflected succession?
When succession is stopped or interfered with. Can occur by mowing lawns, agriculture, burning, fertilisers. Sub-climax community that results is called a plagioclimax.
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What data can be collected using a quadrat?
Presence or absence of each species (distribution). 50% of plant needs to be in to be counted. Number of individuals (abundance), either estimated with percentage cover or counted.
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What needs to be decided before starting sampling?
Where to place quadrats, which corner at each coordinate, random sampling using random numbers to plot coordinates, or at regular distances in systematic sampling. How many samples to take, sampling needs to be representative of whole area
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What is a transect and how can they be used?
Line across a habitat. Line transect- regular intervals make note of species touching tape. Belt transect- regular intervals place a quadrat. Use data to plot kite diagram, distance against popualtion
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Other cards in this set

Card 2

Front

What is a habitat?

Back

The place where an organism lives

Card 3

Front

What is a population?

Back

Preview of the front of card 3

Card 4

Front

What is a community?

Back

Preview of the front of card 4

Card 5

Front

What is a niche?

Back

Preview of the front of card 5
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