AQA Biology Unit 3b-Human Impact on Their Environment

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  • Created by: Chad
  • Created on: 12-05-13 13:12
Give two reasons as to why the worlds population is rising exponentially
Due to modern farming and medicine keeping people alive longer
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What are the three types of pollution?
Air, Water Land
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Give an example of each type of pollution and how they affect our environnment
Air:Smoke and gases pollute the air Water:Sewage and toxic chemicals pollute lakes/rivers Land:Pesticides and herbicides and nuclear waste buried underground, also household waste in landfill sites
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What are the four main ways that humans reduce land usage for other organisms?
Building, Farming, Dumping waste and quarrying for metal ores
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Define sequestered
Locked up
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How can CO2 be sequestered?
In oceans, lakes and ponds, Green plants (photosynthesis) and in peat bogs
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What are the two main greenhouse gases?
CO2 and methane
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Describe how the greenhouse effect works?
CO2 and methane in the atmosphere have a natural insulating effect of trapping heat radiation. If there is too much CO2 and methane in the atmosphere this heating effect is increased-this is global warming.
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What is deforestation?
The cutting down of forests
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What are the main reasons we cut down forests?
To provide timber for building, to clear more land for farming and to produce paper from the wood
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What are the main problems of deforestation?
More methane and CO2 in our atmosphere, Less CO2 taken in by photosynthesis and less biodiversity
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Define biodiversity
The variety of species in a habitiat (the more species the greater the biodiversity)
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How does destroying peat bogs lead to more CO2 being released into the atmosphere?
Plants that live in bogs don't fully decay because there's not enough oxygen, so the carbon in the plants is stored in the peat instead of the atmosphere. When we drain/burn peat bogs this carbon is released as CO2 as the plants decompose with the O2
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What are the consequences of Global Warming?
Thermal expansion-Sea level rise-Ice caps melting, Changed weather patterns, hurricanes more droughts. The distribution of wild animals changed. Less biodiversity and changes in migration patterns for birds
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What is fermentation?
When bacteria or yeast break down sugars by anaerobic respiration
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How is ethanol made?
Yeast make ethanol when they break down glucose by anaerobic respiration
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What is the percentage of methane and CO2 in biogas
70% Methane and 30% CO2
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How does a biogas generator work?
It's the fermentation of waste material to produce biogas
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What are the two types of biogas generators?
Batch and continuous
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What is a large disadvantage of biogas?
It can't be stored easily so has to be used straight away e.g. for heating a home or to power a turbine to generate electricity
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Describe a batch biogas generator
A biogas generator makes biogas in small batches, it is manually loaded with waste which is left to digest and is then cleared out after each session
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Describe a continuous biogas generator
Continuous make biogas all the time, the waste is continuously fed into the generator and is made at a steady rate. These are more suited to large scale products
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What are the four factors to consider when making a biogas generator?
Cost, Convenience, Efficiency and position.
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Why is biogas carbon neutral?
because the CO2 released into the atmosphere was taken in by plants which lived recently.
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How do biogas generators prevent the release of methane from untreated waste?
Burning the waste as a biogas means it isn't released into the atmosphere
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The materials are cheap and readily available for a biogas generator. True/false
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A biogas generator acts as a waste disposal system why is this good?
It gets rid of human and animal waste which otherwise would sit around causing disease and polluting water supplies
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What are the three ways the efficiency of food production can be increased?
Reducing the number of stages in the food chain, Restricting the energy lost by animals(movement) Developing new food sources like mycroprotein
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Give examples of how we could reduce the amount of stages in a food chain?
Growing crops rather than raising cattle
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How would we restrict the energy loss by farm animals?
Keep them in cages, to restrict movement thus reducing energy loss and keep the animals in a heated environment to prevent energy being lost by the animals trying to maintain a constant temperature.
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How is mycroprotein made?
The fermentation of fusarium
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What are some of the advantages of creating mycroprotein?
Grown in a fermenter so doesn't take long to grow and doesnt need much space to grow either. Developing countries find it difficult to get protein so this would be ideal for them
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Define 'food-miles'
the distance that food has been transported which can add to global warming due to planes/trucks
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What are the two ways in which fish stocks can be maintained?
Quotas and net size.
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Card 2


What are the three types of pollution?


Air, Water Land

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Card 5


Define sequestered


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this is so useful thank you so much!!

nicole hogben

i used this before exam and it helped me so much I feel like I can actually get a good grade thank you so much

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