Using the earth's resources

Question 1

Identify some of the earths resources which are needed for life

Answer 1

Rocks
Fossil fuels
Plants and animals
Water, fresh and seawater
Air
Sunlight
Wind

Question 2

Explain the difference between finite resources and renewable resources giving examples

Answer 2

A finite resource cannot be replaced once used, fossil fuels are finite, so are metal ores. Eventually they will run out.
Renewable resources we can replace once we have used them or will always be present. Biofuels which come from crops are renewable as more crops can be planted. Solar power from the sun and wind power from turbines are also renewable.

Question 3

Explain the term sustainable development and give some practical examples

Answer 3

Sustainable development is when resources are used today in such a way that it will not prevent people in the future from being able to use them.
Examples are recycling metals to reduce ore extraction and using solar power to generate electricity rather than use fossil fuels.

Question 4

Identify and describe two methods to reduce the use of finite resources.

Answer 4

1. Reuse materials such as washing and reusing glass bottles for milk, beer etc
2. Recycling materials by melting and reforming them such as using metal, glass and plastic to form new products

Question 5

Describe how iron/steel can be recycled

Answer 5

1. It is separated from other waste using a magnet
2. It is heated to a high temperature to melt it
3. It is reformed into other substances

Question 6

Describe how glass can be recycled

Answer 6

1. It is separated from other waste and into brown ,green and clear.
2. It is then crushed
3. Heated to a high temperature to melt it
4. Reformed into new products

Question 7

Describe how plastics are recycled

Answer 7

1. They are separated into different types- high or low density poly(ethene), polystyrene, PVC, PET etc. Symbols on plastic products help identify the type.
2. They are melted.
3. They are reformed into new products.

Question 8

Explain the term life cycle assessment

Answer 8

It is an examination of the impact of a product on the environment throughout its life. Factors that they take into account are

• use and sustainability of all of the raw materials used, including packaging
• use of energy at all stages
• use of water at all stages
• production and disposal of all waste products and pollutants at all stages
• transportation and distribution at all stages

Question 9

Explain the term value judgement

Answer 9

When looking at issues especially life cycle assessments some factors may not be as easy to quantify as others and you may have to come up with your own opinion on whether a product is good or bad using your own judgement.

Question 10

Describe some of the factors used to make a lifecycle assessment for a plastic bag

Answer 10

1. Raw materials, unsustainable crude oil, which uses a lot of energy for extraction and can cause environmental issues during transport eg oil spillages in the oceans.
2. Manufacture, fractional distillation requires a lot of energy
3. Use, transport uses energy
4. Disposal, in landfill they do not rot, incinerating produces carbon dioxide a greenhouse gas, recycling requires energy and can cause some pollution

Question 11

Describe some of the factors used to make a lifecycle assessment for a paper bag

Answer 11

1. Raw materials, wood can be sustainable if more trees are planted but they take a long time to grow. habitats are destroyed when trees are cut down, transport of logs requires fuel
2. Manufacture, uses a lot of water and some dangerous chemicals. chemical leaks could cause pollution
3. Use, transport uses energy
4. Disposal, in landfill they rot releasing greenhouse gases including methane, incinerating produces carbon dioxide a greenhouse gas, recycling requires energy and can cause some pollution, they are relatively easy to recycle

Question 12

What is meant by the term potable water

Answer 12

Water that is safe to drink

Question 13

Identify and describe different types of water

Answer 13

1. Pure water- contains only molecules of H2O nothing else
2. Potable water- safe to drink, has low levels of dissolved substances
3. Fresh water- found in lakes, rivers, polar ice caps and glaciers, has low levels of dissolved substances
4. Ground water- found in underground streams and in porous rocks, has low levels of dissolved substances
5. Sea water- found in the seas and oceans, has high levels of dissolved substances
6. Waste water, used water from homes, industry and agriculture, has high levels of dissolved substances

Question 14

Describe the two main processes which are used to make fresh water potable

Answer 14

1. Filtration- this removes solids by passing the water across filtration beds which are usually made of sand.
2. Sterilization- microbes are removed, this can be done by adding small amounts of chlorine. Other less usual methods are treating with ozone and using ultraviolet light.

Question 15

What is desalination of water and where is it likely to be used.

Answer 15

Desalination is the method of turning sea water into potable water. It uses a lot of energy so is used in areas where there is very little fresh water but good fuel resources such as Saudi Arabia and the United Arab Emirates.

Question 16

Identify two methods of desalination

Answer 16

1. Distillation

2. Reverse osmosis

Question 17

Explain how potable water can be produced from seawater using distillation

Answer 17

Sea water contains dissolved substances such as salt which need to be removed before it can be potable.
This is done by heating it the water turns to steam leaving the dissolved substances behind.
The water vapour is then passed through a condensor where it cools and condenses into potable water.
It requires a lot of energy.

Question 18

Explain how potable water can be produced from seawater using reverse osmosis

Answer 18

Seawater is passed through a semi permeable membrane under pressure. The water molecules can pass through the membrane but the dissolved substances cannot. It is the opposite of normal osmosis where water would move in the opposite direction.
Reverse osmosis requires a lot of energy but is cheaper than distillation

Question 19

Identify the sources of waste water

Answer 19

Domestic use- homes and other buildings
Industrial use- factories
Agricultural use from farms

Question 20

Describe the key stages in the treatment of waste water

Answer 20

1. Screening and grit removal - this removes large solids from the water
2. Sedimentation - this removes human waste as sludge leaving the rest of the water called effluent, the two are separated
3. Aerobic treatment (effluent) - air is passed through the effluent in aeration tanks where useful bacteria kill harmful bacteria
4. Anaeobic treatment (sludge) in the absence of air, bacteria produce methane gas from the sludge which provides thermal energy and can generate electricity.

Question 21

What is an ore?

Answer 21

A rock from which metal can be extracted

Question 22

Describe methods of extracting copper from low grade ore.

Answer 22

1. Phytomining -growing plants in soil containing copper compounds. The plants are then burned leaving copper in the ash.
2. Bioleaching - copper is extracted from the plant ash or low grade ore using bacteria which produce soluble metal compounds from the insoluble metal compounds. The solution is called leachate.
3. Leaching - using an acid such a sulfuric acid to produce soluble metal compounds from the insoluble metal compounds, also producing leachate.
4. Electrolysis or displacement reactions are used to extract the copper from the leachate.