3b) Humans and Their Environment Flashcards
Why is deforestation done?
Provide timber for building material
Clear more land for farming
Produce paper from wood
What is happening to the worlds population?
Rapidly increasing
Exponential growth
What problems arise from deforestation?
More methane in the atmosphere
More carbon dioxide in atmosphere
Less carbon dioxide taken in
Less biodiversity
What are bogs?
Areas of land that are acidic and waterlogged
How do human use land?
Buildings
Farming
Dumping waste
Quarrying for metal ores
Where can carbon dioxide be sequestered (stored) ?
Oceans, lakes and ponds
Green plants that remove CO2 from the atmosphere
Peat Bogs
How do greenhouse gases cause global warming?
Gases released get trapped in the ozone layer of the atmosphere
Act as an insulating layer
Absorb most of the heat normally radiated out into space
Re-radiate heat back to Earth
Earth is heated up
Why does deforestation mean there will be more methane in the atmosphere?
Forests cleared to rear cattle - more cattle means more methane
More decomposers from crops that produce methane
Why does deforestation mean there will be more carbon dioxide in the atmosphere?
Carbon dioxide released when trees are burnt to clear land
Microorganisms feed on dead wood can release carbon dioxide when respiring
Why don’t plants that live in pray bogs fully decay?
There’s no enough oxygen
How does destroying peat bogs add more carbon dioxide to the atmosphere?
When the peat bogs are drained it starts to decompose
Carbon stored in plants are released
Why are peat bogs drained?
Are can be used for farmland
Peat is cut up and dried to use as fuel
Peat sold as compost
What are some of the problems that global warming will cause?
Melting of ice caps - rising sea levels - flood risks
Changed weather patterns - more extreme weather like hurricanes
Biodiversity reduces - unable to survive in change in climate
How can biofuels be made?
Fermentation of natural products
What is fermentation?
When bacteria or yeast break down sugars using anaerobic respiration (without oxygen)
How is ethanol made?
Yeast using anaerobic respiration to break down sugar
What is gasohol?
Mixture of ethanol and petrol
Where can we get sugar from to make ethanol?
Sugar cane juices
Glucose can be derbies from maize starch using carbohydrase enzyme
How is biogas made?
Anaerobic fermentation of waste martial
What is a fermenter used to make biogas called?
Digester
or Generator
What are the two types of biogas generators?
Batch generator - small batches, manually loaded, by products cleared away after each session
Continuous generator - waste is continuously fed in, run all the time, biogas produced at a steady rate
Why does biogas have to be used straight away?
It can’t be stored as a liquid as if needs to high a pressure
Why do biogas generators need to be kept at a constant temperature?
To keep the microorganism respiring
Why is biogas better for the environment?
Energy obtained from waste
Otherwise waste would rot naturally and methane would be released
What do all biogas generators need to have?
Inlet for waste material
Outlet for digested material
Outlet do biogas can be piped
Explain the disadvantages and disadvantages if each biogas generator
Continuous - more expensive - machine costs, more convenient
Batch - cheaper, less convenient - have to be continually loaded, emptied and cleaned
What are some of the advantages of using biogas generators as a whole?
Carbon neutral
Doesn’t produce sulphur dioxide or nitrogen oxide (no acid rain)
Methane isn’t released in process
Raw materials needed are cheap and easily available
Waste disposal system
Produces fertiliser to grow crops
What happens if the temperature in the biogas generator falls below 35oC?
Production will be slower
Enzymes work slower - need optimum temperature
Why should a generator be insulated?
To keep warm
Maintain optimum temperature
Enzymes work better
Faster production
Where should biogas generators be placed and why?
Away from homes - smell of waste
Close to a waste source - less transport costs
Outline 3 ways that the efficiency of good production can be improved
Reducing number of stages in the food chain
Restricting the energy lost by farm animals
Developing new food sources like Mycoprotein
Why does reducing the number of stages in the food chain make food production more efficient?
Less energy and less biomass every time you move up a stage
Less energy lost as less stages
Can produce more food
Explain the disadvantages and disadvantages if each biogas generator
Continuous - more expensive - machine costs, more convenient
Batch - cheaper, less convenient - have to be continually loaded, emptied and cleaned
What are some of the advantages of using biogas generators as a whole?
Carbon neutral
Doesn’t produce sulphur dioxide or nitrogen oxide (no acid rain)
Methane isn’t released in process
Raw materials needed are cheap and easily available
Waste disposal system
Produces fertiliser to grow crops
What happens if the temperature in the biogas generator falls below 35oC?
Production will be slower
Enzymes work slower - need optimum temperature
Why should a generator be insulated?
To keep warm
Maintain optimum temperature
Enzymes work better
Faster production
Where should biogas generators be placed and why?
Away from homes - smell of waste
Close to a waste source - less transport costs
Outline 3 ways that the efficiency of good production can be improved
Reducing number of stages in the food chain
Restricting the energy lost by farm animals
Developing new food sources like Mycoprotein
Why does reducing the number of stages in the food chain make food production more efficient?
Less energy and less biomass every time you move up a stage
Less energy lost as less stages
Can produce more food
Why should animals be kept close together indoors?
Keep them warm, less movement
Saves then wasting energy on movement and heat
Transfer of energy from animal feed to animals more efficient
Animals grow faster on less food
Cheaper - less money spent on feed
What is Mycoprotein?
Protein from fungi (mainly Fusarium)
Used to make meat substitutes for vegetarian meals like Quorn
How is Mycoprotein made?
Fungus is grown in fermenters using glucose syrup as food (from maize starch)
Fungus respires aerobically (oxygen in supplied)
Mycoprotein if harvested and purified
How are other microorganisms prevented from growing in the fermenter?
Fermenter is sterilised using steam
Incoming nutrients are heat sterilised
Air supply is filtered
Why is Mycoprotein an efficient source of food production?
Microorganisms grown very quickly
Don’t need much space
Can feed on waste material
What are some of the problems that arise from efficient food production?
Animal rights
Spread of diseases - animals kept in crowded conditions
Antibiotics given to animals can promote bacteria developing anti-biotic resistance
Fossil fuels burnt to keep animals warm
What is sustainable food production?
Having enough food without using resources faster than they can renew themselves
How can fish stocks be maintained?
Fishing quotas - limits on number and size of fish caught in certain areas - prevents overfishing
Bigger net size - allows unwanted fish and younger fish to escape that are usually accidentally caught
Why are fish stocks declining?
Overfishing
