B3 Humans And The Enviroment Flashcards
How is the increase in the population affecting the enviroment?
More resources are needed to support the population.
People also have a better standard of living. This means that more energy and resources are needed to make things for them.
Unfortunately, many of theses resources are being used up faster than they are being replaced , meaning they will one day run out.
Why has the population increased?
There is more modern medicine and farming methods. The is reduced the number of people dying from disease and hungar.
How are humans producing too much waste?
The air is being polluted with gases like sulphur dioxide which can cause acid rain.
Toxic chemicals for farming, nuclear waste and household easte is polluting the land.
Sewage and toxic chemicals from industry are getting into rivers, lakes and oceans, affecting plants and animals that rely on them.
What human activities are reducing the amount of land available?
Building, farming, dumping waste, quarrying for metal ores.
How is carbon dioxide being stored?
It is sequestered on natural stores like:
Oceans, lakes and ponds.
Green plants where it is stored as carbon compounds.
Peat bogs.
What are the two main greenhouse gases?
CO2 and methane.
Explain deforestation.
It is the cutting down of forests. It is done to: Provide timber as a building material. Clear land to grow food, farm cattle or produce crops for biofuel. Produce paper.
What are the four main problems of deforestation?
More methane and co2 in the atmosphere, less co2 being taken in and less biodiversity.
Explain deforestation and more methane.
Rice is grown in warm, waterlogged conditions where the trees were. This means decomposes which produce methane.
Cattle also produce methane.
Explain deforestation and more CO2.
CO2 is produced she the wood is burnt.
Microorganisms feeding on dead wood produce CO2 when they respire.
Explain deforestation and less CO2 taken in.
There are less trees to absorb CO2 in photosynthesis.
Explain deforestation and less biodiversity.
It is the variety of different species in a habitat.
Tropical rain forests have a large number of different species. When they are destroyed many species may become extinct and biodiversity is reduced.
This means there could have been lots of useful products that were destroyed and we can’t use. They could have been new sources of food, fibres or medicines.
Explain the destruction of peat bogs and how this releases CO2.
Bogs are acidic and waterlogged areas of land. Plants can’t decay as there isn’t enough oxygen. The partly rotted plants build up.
They store carbon.
However bogs are drained so they are used as farmland or the peat it used as fuel or compost.
Then the bogs are drained, the peat decays producing CO2.
The demand for peat can be reduced if people buy peat free fertiliser.
How does global warming cause a rise in sea levels?
The sea water expands as it gets hotter. Also ice caps melt and this produces more water. This cusses sea levels to rise.
Those living in low-lying areas like the Netherlands, east anglia and the Maldives will be effected.
What are the consequences of global warming?
Rising sea levels.
More extreme weather like longer droughts and more hurricanes as they form over warm water.
Plant and animal distributions will change. Those that need a cooler environment have smaller areas to live and those who need hot environments will take over more space.
Biodiversity will be affected as some species won’t be able to survive the changes.
Different migration patterns. Some birds will migrate further north.
How are all biofuel made?
The fermentation of natural products is used. These can often be waste products.
Fermentation is when bacteria or yeast break sugars down by anaerobic respiration.
How is ethanol made?
Yeast breaks glucose down.
Glucose = ethanol + CO2 + energy.
Sugar cane juice can be used or glucose can come from maize starch when it is broken down by a carbohydrase.
The ethanol is distilled to separate it from the yeast and remaining glucose.
What is biogas usually made of ?
70% methane and 30% CO2.
How is biogas made?
Lots of different microorganisms can be used.
Plant and animal waste can be used which contains carbohydrates. Sludge waste from sewage works or sugar factories is used on a larger scale.
It is made in a digester called a generator or digester.
They must be kept at a constant temperature.
Biogas can’t be stored as a liquid so it must be used at once for heating, cooking, lighting or for making electricity.
How can biogas generators be used on in the developing world?
Small biogas generators can provide enough for a village or a family so they can cook.
Human waste, animal waste or food waste can be used.
By products are used to fertilise crops.
What are the two main types of biogas generators?
Batch and continuos.
Describe batch generators.
They create biogas in small batches.
Usually manually loaded with waste, which is left to digest and the by products are cleared away at the end of each session.
Describe continuous generators.
Biogas is made constantly.
Waste is continually fed in and biogas is produced at a steady rate. They are more suited to large scale projects.
What three things do all biogas generators have?
An inlet for waste to be put in.
An outlet for biogas and digested material.
What four things have to be considered when designing a biogas generator?
Cost, convince, efficiency and position.
Explain cost when designing a biogas generator?
A continuous generator is more expensive as waste and digested material has be mechanically pumped in and out.
Explain convenience when designing a biogas generator.
Batch generators are less efficient as they have to be continually loaded, emptied and cleaned.
Explain efficiency when designing a biogas generator.
The rate of gas production is highest at 35C. Some generators need to be insulated to keep them warm or kept warm by solar heaters. The generator shouldn’t have an leaks.
Explain position when designing a biogas generator.
It may smell so it should be away from homes.
It should be as close to the waste source as possible.
What are the environmental effects of using biogas?
They are carbon neutral.
Using them doesn’t produce lots of sulphur dioxide or nitrogen oxides meaning less acid rain.
Methane is a green house gas. Using it in biofuel means it isn’t released into the atmosphere.
What are the social and economic effects of using biogas?
The raw materials used are cheap and plentiful.
The digested material acts as a better fertiliser meaning more crops are grown and more money is made.
They act as a way of disposing animal and human waste. This means diseases can’t spread and water surpluses won’t be polluted.
In some developing rural communities women have to spend hours each day collecting fire wood. Biogas means they don’t have to do this.
How can the efficiency of food production be increased?
Reducing the number of stages in food chains, restricting the energy lost by farm animals and developing new types of food
Use pestersides
Explain how reducing the number of steps in a food chain increases the efficiency of food production.
With every step in a food change, there is less energy and biomass.
For a given area of land, it would be more effect to grow crops than farm cattle as the number of stages is reduced.
However, people still need a balanced diet and there is still a demand for meat. Also some areas may be unsuitable for crops like mores lands or hillsides. Sheep and dear might be the beat way to get fruit from the land.
Explain how restricting energy lost by farm animals increases the efficiency of food production.
Animals may be kept in small pens in side.
This means energy is saved as they don’t have to around. They are also kept warm so less energy is used in maintaining body temperature.
This makes the transfer of energy from animal food to animal more efficient. They will grow faster on less food.
This makes it cheaper.
Also chickens can be protected from foxes when inside.
Explain how new food sources are being developed?
Mycoprotein can be developed. It is protein that came from fungus. Fusarium is the main source.
It can make meat substitutes.
It is grown fermenters using glucose syrup as food. This is obtained by digesting maize starch with enzymes.
The fungus respires aerobically.
Other microorganisms can’t be in the fermenter. At first it is sterilised using steam. Incoming nutrients are heat sterilised and the air supply is filtered.
The mycoprotein is harvested and purified.
What are the advantages of mycoprotein
In developing nations, it can hard to find enough protein.
It replaces animals as a source of protein as they need a lot of space and food.
It is an efficient way of producing protein and can be made dry quickly. Not much space is needed and they can even feed on waste material that animals couldn’t eat.
What are the disadvantages of efficient food production?
Some feel it is cruel to battery farm animals.
The crowded conditions causes by battery farming means diseases can spread easily.
This means animals have to be given anti-biotics. These can enter humans and it means microbes that inflect humans can develop immunity to them.
They need to be kept warm inside and this means fossil fuels are used up.
Fish number are falling but a lot of intensively farmed animals are given fish.
What are the problems caused by food distribution?
Some food have a lot of food miles. They are transported along way before they are sold. This means that fossil fuels are burnt and CO2 is produced.
Explain fish numbers.
They are falling as we are fishing too much.
This means the price of fish goes up, food chains are disrupted and some types of fish may disappear in certain areas.
How can fish numbers be maintained?
Fishing quotas. There are limits on the number and size of fish that can be caught in a certain area.
Net size. There are limits on mesh size depending on what’s being fished. This means less are accidentally caught like shrimp in cod nets and it stops young fish being caught meaning they can still reproduce.
What do you want a pesterside to do?
They have to be cost effective, to biodegrade, to be specific to certain pests and not accumulate.
