Biology Unit 4 Flashcards - Energy and Ecosystems

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What are 'Producers?'
Photosynthetic organisms that manufaction organic substances using light energy
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Give an example of a 'Producer'
Green plants
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What are 'Consumers?'
Organisms that obtain their energy by feeding on comsuming other organisms
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Name the 3 types of consumers
Primary, Secondary and Tertiary
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What are 'Decomposers?'
Saprobiotic organisms that break down these complex materials into single components again
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What happens when decomposers break down dead organisms
They release valuable minerals and elements that can be absorbed by plants
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Give 2 examples of Decomposers?
Fungi and Bacteria
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What are decomposers that are animals called?
Detritivores eg; earthworms
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What does the term 'Food Chain' mean?
Food chains describe a feeding relationship in which the producers are eaten by primary consumers
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What is each stage of food chain referred to as?
Trophic level
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What forms a 'Food web?'
Many food chains linked together
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What is the source of all energy in 'Ecosystems?'
The sun
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Name the 4 reasons why most of the sun's energy is not converted to organic matter by PS?
Over 90% is reflected, not all the wavelengths of light can be absored (eg; green light), light may not fall on a chlorophyll molecule and there may be a limiting factor
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What is the 'Gross Production?'
The total quantity of energy that the plants in a community convert to organic matter
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What is the 'Net Production?'
The rate at which plants store energy
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What is the equation for net production?
Net production = Gross production - Respiratory losses
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What % of the food stored in plants is used by primary consumers?
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Gives 3 reasons why the % energy transferred is so low
Some of the organism is not eate, some parts cannot be digested, some energy is lost in excretory materials, some energy is lost in respiration and heat
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Why do most food chains only have 4 or 5 levels?
As there is insufficient energy available to support a large enough breeding population
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What is energy available in food chains measured in?
Kilojoules per square metre per year (kJm-2 year-1)
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What is the equation for energy transfer?
Energy available after the transfer DIVIDED by energy available before the transfer X 100
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Name the 3 types of ecological pyramids
Pyramid of numbers, pyramid of biomass and pyramid of energy
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Describe the 'Pyramid of numbers'
Producers are generally in bigger numbers so the bottom bars are the biggest
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When can a 'Pyramid of numbers' be inverted?
When there is only 1 producer that sustains the whole food chain eg; an oak tree
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Describe the 'Pyramid of biomas'
Biomass is the total mass of an organism in one place making this pyramid more reliable
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What is biomass measured in?
Grams per square metre (gm-2)
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When is a 'Pyramid of biomass' is inverted?
Some aquatic systems are inverted due to the large intake of plankton
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Describe the 'Pyramid of energy'
This the most accurate representation of the energy flow through a food chain to measure the energy stored in organisms
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What is an 'Agricultural ecosystem?'
Landscape created by humans
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What are they mainly made up of?
Domesticated animals and plants used to produce food for mankind
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What is the point of 'Agricultural ecosystems'
To increase the amount of energy transferred through food webs to humans (normally at the third of fourth tropic level)
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If an agricultural ecosystem if successful what is increased?
The productivity of human food chain
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What is productivity?
The rate at which something is produced
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Where does the energy for agricultural ecosystem come from?
Energy for the farmers come from the food they eat and fossil fuels provide energy for fuel for machines
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Describe the difference in productivity in natural and agricultural ecosystems?
Natural ecosystems have low productivity and the aim of agricultural ones is to have high productivity
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How do agricultural ecosystems increase productivity?
By decreasing the limiting factors of photosynthesis and by using fertilisers and pesticides
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What kind of pests can they be?
Biological and chemical
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What are 'Pesticides?'
Poisonous chemicals that kill pests
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What should an effective pesticide be?
Specific, biodegradable, cost effective and not accumulate
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What are the advantages of Biological control?
They're specific, they do not need to be reapplied, pest do not become resistant
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What are the disadvantages of Biological control?
Take a while to start working, pesticides may become a pest themselves
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What are the disadvantages of a Chemical agent?
Need to be reapplied, always have an effect on other species, pests may develop genetic resistance
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What is the most effective pest control system?
Intergrated pest-control system
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Name ways intensive rearing of livestock increases productivity
Livestock is killed young, movement is restricted so less energy lost through heat, antibiotics are given to decrease the chance of illness, predators are excluded
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Suggest how feeding livestock antibiotics could be counter productive
It could lead to antibioic resistance
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Other cards in this set

Card 2


Give an example of a 'Producer'


Green plants

Card 3


What are 'Consumers?'


Preview of the front of card 3

Card 4


Name the 3 types of consumers


Preview of the front of card 4

Card 5


What are 'Decomposers?'


Preview of the front of card 5
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