Web view(c) Fuel-burning power stations may produce air pollution. Why does a wind generator not...

P1 07 Generation of Energy

336 minutes

336 marks

Q1. (a) The bar chart shows the start-up time for different types of fuel-burning power stations.

Which type of power station would be the quickest to start producing electricity?

.....................................................................................................................................(1)

(b) A fuel-burning power station is more reliable than a wind generator at producing electricity. Explain why.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

(c) Fuel-burning power stations may produce air pollution. Why does a wind generator not produce any air pollution?

.....................................................................................................................................

.....................................................................................................................................(1)

(Total 4 marks)

Q2. The diagram shows how electricity is distributed from power stations to consumers.

(a) (i) What name is given to the network of cables and transformers that links power stations to consumers?

...........................................................................................................................(1)

(ii) What does a step-up transformer do?

...........................................................................................................................(1)

(iii) Explain why step-up transformers are used in the electricity distribution system.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(b) Most of the world’s electricity is generated in power stations that burn fossil fuels.

State one environmental problem that burning fossil fuels produces.

.....................................................................................................................................

.....................................................................................................................................(1)

(c) Electricity can be generated using energy from the wind. A company wants to build a new

wind farm. Not everyone thinks that this is a good idea.

(i) What arguments could the company give to persuade people that a wind farm is a good idea?

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(ii) What reasons may be given by the people who think that wind farms are not a good idea?

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(Total 9 marks)

Q3. Much of the world’s electricity is generated in power stations that burn fossil fuels.

(a) The bar chart shows the start-up times for the three types of fossil fuel power station.

Which of these power stations would take the longest to start generating electricity?

.....................................................................................................................................(1)

(b) Which two of the following statements are good reasons for using fossil fuels to generate electricity?

Put a tick ( ) in the box next to each of your choices.

Supplies of fossil fuels are limited.

Fossil fuels can be used to generate electricity at any time.

Fossil fuels are non-renewable.

A few large power stations can generate the electricity for a million homes.

Burning fossil fuels produces carbon dioxide. (2)

(c) Electricity can be generated using energy from the wind.

(i) Why does a wind-powered generator not produce carbon dioxide?

...........................................................................................................................

...........................................................................................................................(1)

(ii) Which form of energy is transferred from the wind to generate electricity?

Draw a ring around your answer.

heat kinetic light sound(1)

(iii) Many people say that wind-powered generators are a good idea because:

“when the wind blows they generate electricity”“they produce no pollution”“they generate electricity cheaply”

But not everyone wants more wind-powered generators to be built.

What reasons may be given by the people who think that wind-powered generators are not a good idea?

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(Total 7 marks)

What reasons may be given by the people who think that wind-powered generators are not a good idea?

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(Total 7 marks)

Q4. The diagram shows how electricity gets from power stations to consumers.

(a) Complete the following sentences by drawing a ring around the correct line in each box.

(i) The network of cables and transformers linking power stations to consumers is

called the national

grid

line

network

(1)

(ii)

A step-up transformer

decreases voltage

increases current

increases voltage

(1)

(iii)

Electricity is supplied to consumers’ homes at

230 V

25 000 V

400 000 V

(1)

(iv)

Making the current in the cables smaller will

increase

make no difference to

reduce

the

energy lost in the cables.(1)

(b) Transformers always waste some energy.

(i) What effect does the waste energy from a transformer have on the air around the transformer?

...........................................................................................................................(1)

(ii) Which one of the following describes the efficiency of a transformer?


always 100 % less than 100 % more than 100%(1)

(Total 6 marks)

Q5. There is an increasing demand for electricity and the reserve of fossil fuels is decreasing. A way to meet increasing demand for electricity is to build new nuclear power stations. Some people feel that no new nuclear power stations should be built because of the risks associated with nuclear fuels.

(a) Outline the arguments that a scientist working in the nuclear power industry could use to justify the building of more nuclear power stations in the future.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(3)

(b) Nuclear waste is a problem that must be dealt with. One possible solution would be to bury the waste deep underground.

Suggest one reason why some people are against burying nuclear waste.

.....................................................................................................................................

.....................................................................................................................................(1)

(c) Electricity can also be generated using renewable energy sources.

Look at this information from a newspaper report.

• The energy from burning bio-fuels, such as woodchip and straw, can be used to generate electricity.

• Plants for bio-fuels use up carbon dioxide as they grow.

• Farmers get grants to grow plants for bio-fuels.

• Electricity generated from bio-fuels can be sold at a higher price than electricity generated from burning fossil fuels.

• Growing plants for bio-fuels offers new opportunities for rural communities.

Suggest why, apart from the declining reserves of fossil fuels, power companies should use more bio-fuels and less fossil fuels to generate electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(3)

(Total 7 marks)

Q6. (a) Solar energy is a renewable energy source that can be used to generate electricity.

(i) What is meant by an energy source being renewable?

..........................................................................................................................(1)

(ii) Name two further renewable energy sources used to generate electricity.

1 .......................................................................................................................

2 .......................................................................................................................(1)

(b) A householder uses a bank of solar cells to generate electricity for his home.The solar cells are tilted to receive the maximum energy input from the Sun.

The data in the table gives the average energy input each second (in J/s), to a 1 m2 area of solar cells for different angles of tilt and different months of the year.

MonthAngle of tilt

20° 30° 40° 50°

February 460 500 480 440

April 600 620 610 600

June 710 720 680 640

August 640 660 640 580

October 480 520 500 460

December 400 440 420 410

(i) Use the data in the table to describe how the average energy input to the solar cells depends on the angle of tilt.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

(2)

(ii) The bank of solar cells used by the householder has an area of 8 m2.

The efficiency of the solar cells is 0.15

Use the equation in the box to calculate the average maximum electrical energy available from the bank of solar cells each second in June.

efficiency =

Show clearly how you work out your answer.

..........................................................................................................................

..........................................................................................................................

Maximum energy = .................................................. joules/second(3)

(c) The graph shows how the householder’s electrical energy needs change over one year.

Why would it be advisable for the householder to remain connected to the National Grid?

....................................................................................................................................

....................................................................................................................................(1)

(Total 8 marks)

Q7. (a) Different energy sources are used to generate electricity.

Which two of the energy sources in the box are likely to be used up first?

Draw a ring around each of your answers.

gas oil Sun tides waves wind

(2)

(b) The diagram shows a geothermal power station. Hot rocks in the Earth’s crust heat water to produce steam. The steam is used to drive turbines that turn electrical generators.

How is the way in which a geothermal power station generates electricity the same as the way in which a coal burning power station generates electricity?

...................................................................................................................................

...................................................................................................................................(1)

(c) The graph shows how the temperature of the rocks in the Earth’s crust depends on how far the rocks are below the Earth’s surface.

Estimate the temperature of the rocks 5 kilometres below the Earth’s surface.

Show clearly how you have used the graph to get your answer.

...................................................................................................................................

...................................................................................................................................

Temperature = ................................................. °C(2)

(d) Scientists have estimated that one quarter of the world’s electricity could be generated using geothermal energy.

Give one reason that scientists might use to persuade a government to spend large amounts of money building geothermal power stations.

...................................................................................................................................

...................................................................................................................................(1)

(Total 6 marks)

Q8. (a) Electricity is distributed from power stations to consumers along the National Grid.

(i) Transformers are part of the National Grid. Transformers are efficient devices. What is meant by a device being efficient?

...........................................................................................................................

...........................................................................................................................(1)

(ii) When electricity flows through a cable, some energy is transformed into heat.

Explain how the National Grid system reduces the amount of energy lost as heat.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(b) Read this information taken from a recent newspaper article.

• Researchers have found that children living close to overhead power cables are more likely to develop leukaemia.

• The researchers studied two groups of children. One group had developed leukaemia, the other group was healthy.

• Although the researchers found a link, they are unable to explain why it happened. They say that the results may have happened by chance.

• Other factors that have not been investigated, such as the environment, the geographical area or the children’s genes, could be important.

• A cancer research charity said that childhood leukaemia was most likely to be caused by factors that parents were unable to control.

(i) Why did the researchers study a group of healthy children?

...........................................................................................................................

...........................................................................................................................(1)

(ii) The information does not say how many children were studied.

Why should this data have been included in the article?

...........................................................................................................................

...........................................................................................................................(1)

(iii) The researchers could not be certain that the overhead power cables were responsible for the increased chance of children developing leukaemia.

Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(iv) The results of the research carried out by scientists may worry some people.

What do you think scientists should do?

Put a tick ( ) in the box next to your choice.

Scientists should publish their research findings straight away.

Scientists should not publish their research findings until they

have found out as many facts as possible.

Give a reason for your choice.

...........................................................................................................................

...........................................................................................................................(1)

(Total 8 marks)

Q9. (a) Water waves are a renewable energy source.

The government wants more electricity to be generated from renewable energy sources. Some people do not think this is a good idea.

What reasons could a government scientist give to show people that using more renewable energy sources is a good idea?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

(b) The diagram shows a wave-powered generator. The generator transforms kinetic energy from the waves to electrical energy.

AQA GCSE SCIENCE CORE FOUNDATION STUDENT’S BOOK by Graham Hill,Nigel Heslop, Christine Woodward,Steve Witney and Toby Houghton. Published byHodder and Stoughton 2006 © Reproduced by permission of John Murray (Publishers) Ltd

The following sentences describe how the wave generator works. The sentences are in the wrong order.

R Waves push air up and down a chamber inside the building.S The turbine turns the generator.T The generator transforms kinetic energy to electrical energy.U The air rushes through a turbine making it spin.V Strong waves move towards the wave-powered generator.

Arrange these sentences in the correct order. Start with letter V.

V

(3)(Total 5 marks)

Q10. The pie charts show the relative proportions of electricity generated in Japan from different energy sources in 1975 and 2005.

(a) Describe the main differences in the energy sources used in 2005 compared with 1975.

.....................................................................................................................................

.....................................................................................................................................(1)

(b) In the UK, nuclear fuels are used to generate about 21% of the total electricity supply.

(i) What is the name of the process by which a nuclear fuel produces heat?

...........................................................................................................................(1)

(ii) Explain how the heat released from a nuclear fuel is used to generate electricity in power stations.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(iii) Some people have suggested that more nuclear power stations should be built in the UK.

Give two reasons to support this suggestion.

1 ........................................................................................................................

...........................................................................................................................

2 ........................................................................................................................

...........................................................................................................................(2)

(iv) Nuclear power stations create dangerous waste.

Why is the waste from a nuclear power station dangerous?

...........................................................................................................................

...........................................................................................................................(1)

(c) A headline from a newspaper article is shown below.

Explain the possible link between climate change and coal-burning power stations.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

(Total 9 marks)

Q11. Electrical appliances that are left on standby still use energy.

The bar chart compares the average amount of ‘standby energy’ wasted each year in every home in five countries.

(i) In which country are the homes that waste, on average, the smallest amount of ‘standby energy’?


Australia France Japan UK USA(1)

(ii) Suggest a reason why an average value is used for the ‘standby energy’ wasted in the homes.

...........................................................................................................................

...........................................................................................................................(1)

(b) (i) Australia has one of the lowest electricity prices in the world.

How does this low price seem to affect the amount of ‘standby energy’ wasted?

...........................................................................................................................

...........................................................................................................................(1)

(ii) In Australia, most electricity is generated in coal-burning power stations.The Australian government wants less electricity to be wasted.

Wasting less electricity would be good for the Australian environment.

Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(c) Energy is not usually measured in kilowatt-hours.

Which one of the following units is usually used to measure energy?


hertz joule watt(1)

(d) (i) Electricity in Japan costs the equivalent of 17 pence per kilowatt-hour.

Use the information in the bar chart and the equation in the box to calculate howmuch the ‘standby energy’ used in an average Japanese home costs each year.

total cost = number of kilowatt-hours × cost per kilowatt-hour


Give your answer in pence.

...........................................................................................................................

...........................................................................................................................

Cost = ........................................ pence(3)

(ii) In Japan, the largest proportion of electricity is generated using nuclear fuels.

Which one of the following statements gives a good reason for using nuclear fuels to generate electricity?

Put a tick ( ) in the box next to your answer.

A nuclear power station is very expensive to build.

A small amount of nuclear fuel generates a large amount of electricity.

It is easy to store nuclear waste safely. (1)

(Total 10 marks)

Q12. Wind and tides are renewable energy sources that are used to generate electricity.

(a) Complete each sentence by putting a tick ( ) in the box next to the correct answer.

(i) The wind is:

a predictable energy source.

a constant energy source.

an unreliable energy source. (1)

(ii) The tides are:

a predictable energy source.

a constant energy source.

an unreliable energy source. (1)

(b) If wood is to be used as a renewable energy source, what must be done each time a tree is chopped down?

.....................................................................................................................................

.....................................................................................................................................(1)

(c) In the UK, electricity is generated using renewable and non-renewable energy sources.The graph shows the percentage of electricity generated using renewable energy sources between 1990 and 2005.

Complete the following sentence by drawing a ring around the correct line in the box.

In 2015, the percentage of electricity generated using renewable energy sources is most

likely to be

greater than 4%

equal to 4%

less than 4%

.

(1)(Total 4 marks)

Q13. Electricity is generated in power stations. It is then sent to all parts of the country through a network of cables.

(a) Complete the following sentence by using one of the words in the box.

Grid Power Supply

The network is called the National ............................................................................ .(1)

(b) In the diagram, A, B, C and D are transformers.

(i) Which transformer, A, B, C or D, is a step-up transformer?

Transformer ..............................(1)

(ii) Which transformer, A, B, C or D, will supply homes, offices and shops?

Transformer ..............................(1)

(c) Complete the following sentence by drawing a ring around the correct line in the box.

In a step-down transformer, the potential difference (p.d.) across the

less than

primary coil is the same as the p.d. across the secondary coil.

more than

(1)(Total 4 marks)

Q14. The bar chart shows how the UK’s electricity demands in 2007 were met.

(a) What proportion of electricity was generated using renewable energy sources?


.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................(2)

(b) By 2020, most of the UK’s nuclear reactors and one-third of coal-fired power stations are due to close, yet the demand for electricity is expected to increase.

Four students, A, B, C and D, were asked how a demand of 380 billion kilowatt-hours could be met. They made the suggestions given in the table.

Student Fossil fuels Nuclear Renewable Bought from other countries

A 200 100 40 40

B 80 240 40 20

C 160 80 100 40

D 280 0 100 0

(i) Which student has made the suggestion most likely to result in the lowest carbon dioxide emissions?

...........................................................................................................................

Give a reason for your answer.

...........................................................................................................................

...........................................................................................................................(2)

(ii) Suggest one realistic way in which a householder could help to reduce the annual electricity demand.

...........................................................................................................................

...........................................................................................................................(1)

(c) To increase the amount of electricity generated using renewable energy resources would probably involve erecting many new wind turbines.

The graph shows the power curve of a wind turbine.

(i) Describe, in detail, how the power output of the turbine varies with the wind speed.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(3)

(ii) Give one disadvantage of using wind turbines to generate a high proportion of the electricity required in the UK.

...........................................................................................................................

...........................................................................................................................(1)

(Total 9 marks)

Q15. The bar chart shows the different energy sources used to generate the UK’s electricity in 2007.

(a) (i) The wind is a renewable energy source.

Name one more renewable energy source used to generate electricity.

...........................................................................................................................(1)

(ii) Complete the following sentence by drawing a ring around the correct line in the box.

decrease

Using less fossil fuels to generate electricity will not change the

increase

amount of carbon dioxide emitted into the atmosphere.

(1)

(b) The graph shows how the demand for electricity in the UK varied over one day in the winter.

(i) Describe how the demand for electricity varied between 4.00 am and 10.00 am.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(ii) Which type of power station has the fastest start-up time?


coal natural gas nuclear oil(1)

(Total 5 marks)

Q16. The picture shows a solar-powered aircraft. The aircraft has no pilot.

Photo by NASA.

(a) Use words from the box to complete the following sentence.

electrical heat light sound

Solar cells are designed to transform .............................................................. energy into

.............................................................. energy.(2)

(b) On a summer day, 175 000 joules of energy are supplied to the aircraft’s solar cells every second. The useful energy transferred by the solar cells is 35 000 joules every second.

(i) Use the equation in the box to calculate the efficiency of the solar cells.


...........................................................................................................................

...........................................................................................................................

Efficiency = ..............................................................(2)

(ii) What happens to the energy that is not usefully transferred by the solar cells?

...........................................................................................................................(1)

(c) The aircraft propellers are driven by electric motors. As well as the solar cells, there are fuel cells that provide additional power to the electric motors.

(i) Suggest one advantage of the aircraft having fuel cells as well as the solar cells.

...........................................................................................................................(1)

(ii) Give one environmental advantage of using electric motors to drive the aircraft propellers rather than motors that burn a fuel.

...........................................................................................................................

...........................................................................................................................(1)

(iii) Eventually, the designers want to produce an unmanned aircraft that can fly at twice the height of a passenger jet for up to six months.

Suggest one possible use for an aircraft such as this.

...........................................................................................................................

...........................................................................................................................(1)

(Total 8 marks)

Q17. The diagram shows the National Grid system.

Transformers X and Y are an essential part of the National Grid system.

Explain why.

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................(Total 4 marks)

Q18. The pie charts show the relative proportions of electricity generated in Japan from different energy sources in 1975 and 2005.

(a) Describe and suggest a reason for two differences in the energy sources used in 2005compared with 1975.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(2)

(b) Mining for coal often releases large amounts of methane gas. Methane is both explosiveand a greenhouse gas. At the Sihe coal mine in China the methane is diverted to a gas burning power station where it is used to generate electricity.

(i) A newspaper reported a scientist as saying:

If the concentration of greenhouse gases in the atmosphere doubles, the average temperature of the Earth will increase by up to 5 °C over the next 100 years.

What has been stated in the newspaper?

Draw a ring a round your answer.

a fact a guess a prediction


...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(ii) Explain an environmental advantage of taking the methane gas from coal mines andusing it to generate electricity.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(c) The average person in Britain uses 1930 kWh of electricity each year. Many people in the world’s poorest countries do not have access to electricity.

Giving examples, explain why electricity is essential for both improving public health and for modern communications.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(3)

(Total 9 marks)

Q19. (a) The block diagram shows the important parts of a coal burning power station.

Use words from the box to complete the block diagram

boiler condenser furnace generator(2)

(b) The diagram shows the energy transformations in a coal burning power station.

Calculate the efficiency of the power station.Write down the equation you use, and then show clearly how you work out your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

Efficiency = ............................................(2)

(c) Draw a ring around the correct answer to complete the following sentence.

If fewer coal burning power stations are used to generate electricity the amount of

decrease.

not change.

increase.

carbon dioxide emitted into the atmosphere will

(1)

(d) Some types of power station generate electricity by burning a biofuel.

Give one example of a biofuel.

........................................................................................................................(1)

(e) Nuclear power stations generate electricity without burning a fuel.

Name the process by which a nuclear fuel provides the energy needed to generate electricity.

........................................................................................................................(1)

(Total 7 marks)

Q20.The map shows the positions of two towns on either side of a very large coastal bay in England. The map also shows where a bridge may be built to link the towns. The road journey from one town to the other is about 60 kilometres at present.

(a) It is estimated that building turbines and generators inside the legs of the bridge would produce enough electricity for both towns. In addition, enough electricity would be generated to run electric buses over the bridge between the two towns.

(i) If the bridge is built, what form of renewable energy will be used to generate the electricity?

...............................................................................................................(1)

(ii) Most people living in the area are in favour of the proposed bridge.

Suggest three reasons why people would be in favour of building the bridge and the associated electricity generating scheme.

Reason 1 ..............................................................................................

...............................................................................................................

Reason 2 ..............................................................................................

...............................................................................................................

Reason 3 ..............................................................................................

...............................................................................................................(3)

(b) Even with the proposed bridge, the two towns will need to stay connected to the National Grid.

The diagram shows part of the National Grid.

(i) Give one reason why the towns need to stay connected to the National Grid.

...............................................................................................................

...............................................................................................................(1)

(ii) Explain how the step-up transformer increases the efficiency of the National Grid.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(Total 7 marks)

Q21. Four students are talking about the different energy sources used to generate electricity in the areas where they live.

(a) Draw one line from where each student lives (List A) to the energy source in their area (List B).

Draw only four lines.

List AWhere each student lives

List BEnergy source

Wind

Where I live is the sunniest partof the country.

Waves

Where I live, the land is very flatand it always seems to be windy.

Solar

Where I live, it is not safe to swim.The sea is always too rough.

Tides

Where I live, you can see steamcoming out of the ground.

Geothermal

(4)

(b) All of the energy sources given in part (a) can be used to generate electricity.

What else do all these energy sources have in common?

........................................................................................................................

........................................................................................................................(1)

(c) In a hydroelectric power station, the energy from falling water is used to generate electricity.

Which one of the following gives a disadvantage of a hydroelectric power station?


has a fast start-up time

large areas of land are flooded

polluting gases are produced

(1)(Total 6 marks)

Q22.Over the next 15 years, some of the older nuclear power stations will be closed down, and the process of decommissioning will start. In the same period, several countries plan to build a number of new nuclear power stations.

(a) (i) What does it mean to decommission a nuclear power station?

...............................................................................................................

...............................................................................................................(1)

(ii) How does decommissioning affect the overall cost of electricity generated using nuclear fuels?

...............................................................................................................

...............................................................................................................(1)

(b) Uranium is a fuel used in nuclear power stations to generate electricity.

Graph 1 compares how the electricity generated from one kilogram of nuclear fuel changed between 1980 and 2005 in three different types of nuclear power station.

(i) Compare the efficiency of the three types of power station, K, L and M,between 1980 and 2005.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

Graph 2 shows two different predictions for the global growth in uranium demand over the next 15 years.

(ii) Suggest reasons why it is not possible to predict accurately how much uranium will be needed in 2025.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(Total 6 marks)

Q23. (a) Most electricity in the UK is generated in power stations that burn fossil fuels.

The bar chart shows how much carbon dioxide is produced for each kilowatt-hour of electricity generated using a fossil fuel.

(i) Which fossil fuel produces the smallest amount of carbon dioxide for each kilowat-hour of electricity generated?

............................................................(1)

(ii) Which one of the following statements gives the reason why the data has been shown as a bar chart and not as a line graph?


Both variables are categoric.

Both variables are continuous.

One variable is categoric, the other is continuous.

(1)

(iii) Why does a nuclear power station not produce any carbon dioxide?

...............................................................................................................

...............................................................................................................(1)

(b) Some types of power station generate electricity by burning straw.

(i) Use words from the box to complete the following sentences.

boiler gas generator steam turbine water

Straw is burned in a ............................................ Water is heated to make

...................................... which is used to drive a ....................................

This turns a ....................................... to produce electricity.(4)

(ii) Straw is a type of renewable energy source known as a biofuel.

Name one other type of renewable energy source used to produce electricity.

...............................................................................................................(1)

(iii) A power station generates 36 000 000 watts (36 MW) of electrical power by burning straw. The average power used in each home in the UK over one year is 2000 watts.

Calculate the number of homes that the power station could supply electricity to.


...............................................................................................................

...............................................................................................................

Number of homes = ..................................................(2)

(Total 10 marks)

Q24. (a) The diagram shows a solar powered device being used to recharge a mobile phone.

On average, the solar cells produce 0.6 joules of electrical energy each second.The solar cells have an efficiency of 0.15.

(i) Use the following equation to calculate the average energy input each second to the device.


...............................................................................................................

...............................................................................................................

Average energy input each second = .................................... J/s(2)

(ii) Draw a labelled Sankey diagram for the solar cells.The diagram does not need to be drawn to scale.

(1)

(iii) Energy from the Sun is stored by a rechargeable battery inside the device.

Suggest one factor that would affect the time it takes to fully charge the battery.


...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(b) Scientists have developed a new type of solar cell with an efficiency of over 40 %.The efficiency of the solar cell was confirmed independently by other scientists.

Suggest why it was important to confirm the efficiency independently.

........................................................................................................................

........................................................................................................................(1)

(c) The electricity used in homes in the UK is normally generated in a fossil fuel power station.

Outline some of the advantages of using solar cells to generate this electricity.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(2)

(Total 8 marks)

Q25. (a) By 2023, nearly all of the existing nuclear power stations in the UK will be closed down.

(i) Before a nuclear power station can be demolished, the remaining nuclear fuel, radioactive waste materials and reactor must be carefully removed.

What is this process called?


decommissioning

decontaminating

dismantling

(1)

(ii) The workers are exposed to radiation as they remove the reactor. One of the biggest risks is from the isotope cobalt-60, which has a half-life of 5.3 years.

Explain the advantage of waiting 11 years after a nuclear power station has closed down before starting to remove the reactor.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(b) It is almost certain that new nuclear power stations will be built in the UK.

The table shows the results of surveys asking people in the UK whether they were in favour of, or against, the building of new nuclear power stations.

2001 2005 2007

Percentage (%) in favour 20 41 65

Percentage (%) against 60 28 20

Percentage (%) not sure 20 31 15

(i) From these surveys, how did public opinion on the building of new nuclear power stations change between 2001 and 2007?

...............................................................................................................

...............................................................................................................(1)

(ii) Suggest a reason why some people may think that the results from these surveys are unreliable.

...............................................................................................................

...............................................................................................................(1)

(iii) Give one reason in favour of building new nuclear power stations.

...............................................................................................................

...............................................................................................................(1)

(c) The government of one Middle Eastern country has decided to build its first nuclear power station. The oil that would have been used to generate electricity can then be sold to other countries.

On what is this decision based?


economic issues

ethical issues

social issues

(1)(Total 7 marks)

Q26. The diagram shows a small-scale, micro-hydroelectricity generator which uses the energy of falling river water to generate electricity. The water causes a device, called an Archimedean screw, to rotate.The Archimedean screw is linked to the generator by a gearbox.

(a) Each second, the micro-hydroelectricity generator transforms 80 000 joules of gravitational potential energy into 60 000 joules of electrical energy.

(i) Fill in the missing word to complete the energy transformation diagram.

Gravitational potentialenergy of the falling water

................................ energy

of the Archimedean screw

Electrical energygenerated

(1)

(ii) Use the equation in the box to calculate the efficiency of the micro-hydroelectricitygenerator.


...............................................................................................................

...............................................................................................................

Efficiency = ............................................................(2)

(b) The power output from a conventional large-scale hydroelectric power station is 100 000 times more than the power output from a micro-hydroelectric system.

Give one disadvantage of a conventional large-scale hydroelectric power station compared to the micro-hydroelectric system.

........................................................................................................................

........................................................................................................................

(1)

(c) The electricity generated by a micro-hydroelectric system is transferred via a transformer directly to local homes. The electricity generated by a conventional large-scale hydroelectric power station is transferred to the National Grid, which distributes the electricity to homes anywhere in the country.

(i) What is the National Grid?

...............................................................................................................

...............................................................................................................(1)

(ii) Explain why transferring the electricity directly to local homes is more efficient than using the National Grid to distribute the electricity.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(Total 7 marks)

Q27. (a) An electricity company claims to generate all of its electricity from environmentally friendly energy sources.

The energy sources used by the company are shown in the pie chart.

Do you think that the claim made by the company is correct?


Yes No Maybe

Explain the reasons for your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(2)

(b) The government is committed to increasing the amount of electricity generated from renewable sources. A newspaper reported that:

Why is the statement made in the newspaper incorrect?

........................................................................................................................

........................................................................................................................(1)

(Total 3 marks)

Q28. The diagram shows a small-scale, micro-hydroelectricity generator which uses the energy of falling river water to generate electricity. The water causes a device, called an Archimedean screw, to rotate.The Archimedean screw is linked to the generator by a gearbox.

(a) Complete the following sentence by drawing a ring around the correct word in the box.

The gravitational potential energy of the falling water is transformed

chemical

into the

electrical energy of the Archimedean screw.

kinetic

(1)

(b) A micro-hydroelectric generator is very efficient. Most of the input energy from the falling water is transformed into useful electrical energy.

Which one of the following Sankey diagrams, X, Y or Z, shows the energy transformations produced by this generator?

Write your answer, X, Y, or Z, in the box.

Sankey diagram X

Sankey diagram Y

Sankey diagram Z

Sankey diagram

(1)

(c) A micro-hydroelectric system generates about 60 kW of electricity, enough for 50 homes. A conventional large-scale hydroelectric power station may generate more than 5 000 000 kW of electricity.

(i) Give one advantage of a conventional large-scale hydroelectric power station compared to a micro-hydroelectric system.

...............................................................................................................

...............................................................................................................(1)

(ii) Which one of the following statements gives a disadvantage of a conventional large-scale hydroelectric power station compared to a micro–hydroelectric system?


Energy is wasted as heat and sound.

Large areas of land are flooded.

A constant flow of water is needed.

(1)

(d) The electricity generated by the micro-hydroelectric system is transferred directly to local homes. The electricity generated by a conventional large-scale hydroelectric power station is transferred to homes anywhere in the country through a system of cables and transformers.

(i) What name is given to the system of cables and transformers used to transfer electricity to homes anywhere in the country?

..............................................................................(1)

(ii) Using short cables to transfer electricity to local homes is much more efficient than using very long cables to transfer electricity to homes anywhere in the country.

Why?

...............................................................................................................

...............................................................................................................(1)

(e) Nepal is a mountainous country with over 6000 rivers. In Nepal, 9000 kW of electricity are generated using micro-hydroelectric generators.

Suggest one reason why in the UK much less electricity is generated using micro-hydroelectric generators, than in Nepal.

........................................................................................................................

........................................................................................................................(1)

(Total 7 marks)

Q29. (a) The pie chart shows the energy sources used by one company to generate electricity.

(i) Which two energy sources used by the company do not produce any polluting gases?

............................................. and .............................................(1)

(ii) Calculate the percentage (%) of electricity that is generated using energy sources that do not produce any polluting gases.

Percentage = .............................................(1)

(b) Which graph, A, B or C, is most likely to show the electrical power output from a wind turbine over one day?

Write your answer, A, B or C, in the box.

Graph A

Graph B

Graph C

Graph

(1)

(c) The government has said that more electricity must be generated from renewable energy sources. A newspaper reported that:

Why is the statement in the newspaper incorrect?

........................................................................................................................

........................................................................................................................(1)

(Total 4 marks)

Q30. A farmer has installed a biogas electricity generator on his farm. This device generates electricity by burning the methane gas produced from rotting animal waste. Methane is a greenhouse gas. When methane burns, carbon dioxide and water are produced.

The animal waste rots in an anaerobic digester. The digester and the generator are kept inside a farm building and cannot be seen from the outside.

(a) The animal waste used in the anaerobic digester is a renewable energy source.

What is meant by an energy source being renewable?

........................................................................................................................

........................................................................................................................(1)

(b) Suggest one reason why farmers have been encouraged to install their own biogas generators.

........................................................................................................................

........................................................................................................................(1)

(c) The farmer’s monthly electricity bill using the mains electricity supply was £300.The biogas generator cost the farmer £18 000 to buy and install.

Assuming the biogas generator provides all of the farmer’s electricity, what is the pay-back time for the generator?

........................................................................................................................

Pay-back time = ............................................................

(1)

(d) It would have been cheaper for the farmer to have bought and installed a small wind turbine.

Give two advantages of using the biogas generator rather than a wind turbine, to generate the electricity used on the farm.

1 .....................................................................................................................

........................................................................................................................

2 .....................................................................................................................

........................................................................................................................(2)

(Total 5 marks)

Q31. (a) Geothermal energy and the energy of falling water are two resources used to generate electricity.

(i) What is geothermal energy?

...............................................................................................................

...............................................................................................................(1)

(ii) Hydroelectric systems generate electricity using the energy of falling water.

A pumped storage hydroelectric system can also be used as a way of storing energy for future use.

Explain how.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Read the following extract from a newspaper.

Discuss the advantages and disadvantages of the plan to build thousands of offshore wind turbines around Britain and the suggested electricity power link between Britain and Iceland.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(6)

(Total 9 marks)

Q32. In the UK, most electricity is generated in power stations that burn fossil fuels.

(a) Which type of fossil fuel power station has the shortest start-up time?

........................................................................................................................(1)

(b) The diagram shows how electricity is distributed around the UK.

(i) Which of the parts labelled in the diagram form the National Grid?

...............................................................................................................(1)

(ii) A step-up transformer is used near the power station.

Draw a ring around the correct answer in each box to complete each sentence.

current.

A step-up transformer increases the power.

voltage.

less dangerous.

Using a step-up transformer makes the distribution of electricity more efficient.

work faster.

(2)

(c) Electricity in the UK is also generated without using fossil fuels.

The graph shows how the percentage of electricity generated in the UK without using fossil fuels changed between 1990 and 2010.

What does the data in the graph suggest will probably happen to the percentage of electricity generated in the UK without using fossil fuels over the next 10 years?

........................................................................................................................

........................................................................................................................(1)

(Total 5 marks)

Q33.The world’s biggest offshore wind farm, built off the Kent coast, started generating electricity in September 2010.

(a) The graph shows how wind speed affects the power output from one of the wind turbines.

In one 4-hour period, the wind turbine transfers 5600 kilowatt-hours of electrical energy.

Use the equation in the box and the data in the graph to calculate the average wind speed during this 4-hour period.

energy transferred = power × time


........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

Average wind speed = ........................................ m/s(3)

(b) The wind turbines are linked to the National Grid by underwater cables.

(i) What is the National Grid?

...............................................................................................................

...............................................................................................................(1)

(ii) How is the National Grid designed to reduce energy losses during transmission?

...............................................................................................................

...............................................................................................................

...............................................................................................................(1)

(c) Read this extract from a newspaper.

Explain one way in which the islanders could try to ensure that a similar power crisis doesnot happen in the future.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(2)

(Total 7 marks)


(a) One advantage of using the wind to generate electricity is that it is a renewable energy source.

(i) Give one other advantage of using the wind to generate electricity.

...............................................................................................................

...............................................................................................................(1)

(ii) Name one other renewable energy source used to generate electricity.

...............................................................................................................(1)

(b) The graph shows how wind speed affects the power output from a large wind turbine.

(i) What is the maximum possible power output from this wind turbine?

........................................................(1)

(ii) Read this part of a newspaper article.

Use the graph to explain why the power output from the wind turbines was less than one sixth of the maximum.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

(2)

(iii) Having more nuclear power stations will help to avoid power cuts in the future.

Which two of these reasons explain why?

Put a tick ( ) in the boxes next to your answers.


The radioactive waste produced must be stored for many years.

Nuclear power stations do not depend on the weather to generate electricity.

(1)(Total 6 marks)


(a) One advantage of using the wind to generate electricity is that it is a renewable energy source.

(i) Give one other advantage of using the wind to generate electricity.

...............................................................................................................

...............................................................................................................(1)

(ii) Name one other renewable energy source used to generate electricity.

...............................................................................................................(1)

(b) The graph shows how wind speed affects the power output from a large wind turbine.

(i) What is the maximum possible power output from this wind turbine?

........................................................(1)

(ii) Read this part of a newspaper article.

Use the graph to explain why the power output from the wind turbines was less than one sixth of the maximum.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(iii) Having more nuclear power stations will help to avoid power cuts in the future.

Which two of these reasons explain why?

Put a tick ( ) in the boxes next to your answers.


The radioactive waste produced must be stored for many years.

Nuclear power stations do not depend on the weather to generate electricity.

(1)(Total 6 marks)

M1. (a) gas1

(b) fuel burning stations produce electricity at any time / all the timeaccept fuel available all the time

1

wind generator can only produce when the wind is strong enoughaccept it’s not always windy

1

(c) no fuel is burnt or no fuel is used or uses only energy from wind ordoes not emit harmful gases / soot / smoke

do not accept wind is natural / environmentally friendly / renewableanswer must be in terms of wind, not negative of fuel burningspecific examples of gases CO2, SO2,acid rain and greenhouse gases can be acceptedozone negates credit

1[4]

M2. (a) (i) national grid1

(ii) increases voltage / potential difference

accept decrease currentaccept step-up / boosts the voltagedo not accept increases energy / power / currentignore reference to voltage going through

1

(iii) any two from:

• reduce currentignore increased voltage / pd

• reduces energy loss / power loss (from cables)accept reduces heat lossdo not accept stops energy loss

• increases efficiency (of distribution)2

(b) any one from:

• produces pollutant gasesaccept produces carbon dioxide / sulfur dioxide / nitrogen oxidesaccept global warming / greenhouse effect / carbon emissions / air pollution / acid rainignore ozone layerdo not accept carbon monoxide

• produces solid waste / ash / smokeaccept global dimmingignore produces pollution

1

(c) (i) any two from:any two valid points gains the marks

• using renewable energyaccept don’t use up non-renewable / fossil fuelsaccept named fuels

• non-renewable fuels can be used for other processes

• no pollutant gases producedaccept the opposite of (b)ignore no pollution

• land can still be used for farmingignore economic issues

2

(ii) any two from:

• cause noise pollution

• cause visual pollutionaccept spoils the landscapeaccept sunlight flicker

• may interfere with TV / radio / mobile phone signals

• need to put in new infrastructureaccept new roads needed

• not reliable owtte

• dangerous to birds

• lots of concrete needed for the bases or producing cement is environmentally damaging

accept reduces house pricesignore any references to cost / jobs / number requiredignore takes up a lot of landaccept reference to obstruction of shipping etc. if clear reference tooffshore wind farm

2[9]

M3. (a) coal1

(b) fossil fuels can be used to generate electricity at any timeif more than 2 boxes ticked, mark incorrect boxes first

1

a few large power stations can generate the electricity for a million homes1

(c) (i) no fuel is burntaccept a named fuelaccept nothing is burntaccept does not use (fossil) fuel

1

(ii) kinetic1

(iii) any two from:

accept causes pollution for 1 mark

• need concrete for bases

• new roads / infrastructure needed

• may interfere with TV / radio / mobile

phone signals

• dangerous to birds

• do not generate all of the time accept generates only when the wind blows do not accept ‘generate when the wind blows’

• need a lot of generators do not accept ‘take up a lot of space / land’

• high initial / capital costs

• reduces house prices2

[7]

M4. (a) (i) gridaccept any way of indicating correct answer

1

(ii) increases voltageaccept any way of indicating correct answer

1

(iii) 230 Vaccept any way of indicating correct answer

1

(iv) reduceaccept any way of indicating correct answer

1

(b) (i) increases the temperatureaccept make it hotter / heat goes into the airaccept convection currents

accept sensible comment eg sound energy / it buzzesignore pollutes the air

1

(ii) less than 100%1

[6]

M5. (a) only accept answers in terms of the argument of the nuclear power scientist any threefrom:

• produces a lot of energy for a small mass of fuel or is a concentrated energy sourceaccept amount for mass

• it is reliable or it can generate all of the time

• produces no pollutant gasesaccept named gas or greenhouse gases do not accept no pollution

• produces only a small volume of (solid) wasteaccept amount for volume

• advances in technology will make fuel reserves last much longeraccept an argument in terms of supply and demand

3

(b) any one from:

• may leak into the ground / environment

• geological changesaccept earthquakes etc

• may get into the food chaindo not accept answers in terms of property prices or ‘damages the environment’

• over time if location not correctly recorded it may be excavated1

(c) any three from:

• overall add no carbon dioxide to the environmentaccept do not add to global warmingaccept they are carbon neutral

• power companies can sell electricity at a higher priceaccept power companies make more profit

• opportunity to grow new type cropaccept specific examples e.g. growing plants in swampsaccept extends the life of fossil fuel reserve

• more jobs

• more land cultivated or different types of land utilised3

[7]

M6. (a) (i) replaced faster than it is usedaccept replaced as quick as it is usedaccept will never run outdo not accept can be used again

1

(ii) any two from:two sources required for the mark

• wind

• waves(*)

• tides(*)(*)do not accept water / oceansaccept OTEC

• fall of wateraccept hydroelectric

• biomass

• geothermalaccept a named biomass / biofuel eg wood

1

(b) (i) any two from:

• increases from 20° to 30°

• reaches maximum value at 30°

• then decreases from 30°

• same pattern for each monthaccept peaks at 30° for both marksaccept goes up then down for 1 mark

ignore it’s always the lowest at 50°2

(ii) 864an answer of 108 gains 2 marksallow 1 mark for using 720 value only from tableallow 2 marks for answers 852, 816, 768, 825allow 1 mark for answers 106.5, 102, 96, 103 (.125)

3

(c) the solar cells will not meet demand at all times of the year / dayaccept to maintain a constant supply of electricity / energy

or to make up the shortfall in energy required at certain times of the year

or to be able to sell surplus electricity (to the National Grid)accept to provide energy at nightdo not accept because it’s cloudy on it’s own

1[8]

M7. (a) gas1

oil1

(b) (both) use steam to drive a turbineaccept (both) use turbines to drive generatorsdo not accept both have a turbine /generator / use steammust describe a step in the processaccept heat / thermal energy transformed to kinetic / electrical energy

1

(c) 140 (°C)correct answer onlyallow 1 mark for method clearly shown on graphaccept a cross or other indication at correct position on the lineaccept correct descriptionaccept even if numerical answer is incorrect

2

(d) any one from:do not accept answers purely in terms of disadvantages of other methods except for fossil fuels are running out

• very large energy source / reserves

• no polluting / harmful gases producedaccept named gas CO2 SO2 NOx

accept reduces harmful carbon emissions

• reduces carbon emissionsaccept does not contribute to global warming

• no fuel needed

• energy is free

• can generate energy for a long timeaccept energy available for a long time

• renewable (energy source)

• fossil fuels are running outaccept it saves fossil fuels / non-renewableaccept reduces the amount of fossil fuels being burntaccept a named fossil fuelBetter for the environment / environmentally friendly insufficientit is cheaper is insufficient

1[6]

M8. (a) (i) small proportion of energy / power is wastedaccept little / less energy / power / heat is wasteddo not accept it wastes no energy / power

or transfers most / more / a lot of energy power usefully1

(ii) it decreases the current / uses low current

or it increases the voltage / potential differenceaccept pd for potential difference

1

or uses high voltage / potential difference

smaller the current the smaller the energy lossaccept power / heat for energy

1

(b) (i) as a control

accept to make a comparisondo not accept fair test on its own

1

(ii) so people know how much data the link was based onaccept idea that larger numbers are better

or

people can judge the significance / reliability of the linkdo not accept significance / reliability on its ownignore reference to accuracy

1

(iii) other possible factors may be responsible1

or have not been investigated

named factor eg environment / genetic1

(iv) first box ticked plus reasonacceptable reason such as so people know there may be a risk as soon as possible / so that other scientists can use findings

or second box plus reasonacceptable reason such as no point to worry / confuse / panic people (until the research has been confirmed)accept idea that it may lead to wrong advicedo not accept in case they are wrong

1[8]

M9. (a) any two from:

• (burning) fossil fuels produces greenhouse gases / pollutant gases / acid rain / leads to global warming

accept a named fossil fuelaccept a named pollutant gas

• nuclear fuels produce dangerous wasteaccept radioactive for dangerousaccept reference to dangers of nuclear fuels

• fossil fuels are non-renewableaccept running out of fuels

• renewable energy resources produce no pollutant gases

• large amounts of energy are availableaccept renewable won’t run out

• running costs are lowaccept any reasonable benefit of renewablesaccept any reasonable drawback of non-renewablesdo not accept better for the environment on its own

2

(b) R U S Tall in correct orderallow 2 marks for 2 correctallow 1 mark for one correct

3[5]

M10. (a) decrease in oil

PLUS

any one from:

• increase in (proportion of) coal

• increase in (proportion of) nuclear

• increase in (proportion of) gasmust have decrease in (proportion of) oil and increase in (proportion of) coal / nuclear / gas

1

(b) (i) (nuclear) fissionaccept fisiondo not accept any answer that looks like fusion

1

(ii) water heated to produce (high pressure) steam1

steam turns turbine which drives generator1

(iii) any two from:

• produces no pollutant gases

accept named gas or greenhouse gasesaccept no atmospheric pollutionaccept harmful for pollutantaccept does not contribute to global warmingdo not accept no pollution on its owndo not accept better for the environment unless qualified

• it is reliable or can generate all of the time

• concentrated energy source or produces a lot of energy from a small mass

• produces only small volume of (solid) waste

• fossil fuels will last longeraccept a named fossil fuelaccept fossil fuels are running outdo not accept fossil fuels are non-renewable unless qualified

• will need to buy less fuel from other countriesaccept no new fossil fuel power stations neededdo not accept it is cheapdo not accept import less electricity

2

(iv) it is / can be radioactivedo not accept answers in terms of kills cells / cancer

or emits radiation (from the nuclei)accept emits gamma (rays)

1

(c) coal (burning) power stations / burning coal produces carbon dioxidethey refers to coal-burning power stationsaccept sulfur dioxide / nitrogen oxides for CO2

1

(increased) CO2 increases / contributes to / causes global warming /greenhouse effect

mention of ozone layer negates this markdo not accept CO2 warms atmosphere

1[9]

M11. (a) (i) France1

(ii) any one from:

• different homes have different appliances(*)

• different homes have different numbers of appliances(*)(*) accept all homes are different

• standby power not the same for all appliances

• some people will switch appliances offaccept named appliancesaccept people waste different amounts of energy

• homes have different numbers of residents

• can’t measure every (individual) homeaccept any sensible suggestionsdo not accept answers in terms of accurate / precise etc

1

(b) (i) increases amount of energy wastedaccept (encourages) people to leave appliances on (standby)accept increases it

1

(ii) any two from:

• less electricity needed / generated

• fewer power stations needed

• less coal is burneddo not accept coal is non-renewable / running outanswers in terms of fuel stocks neutral

• less pollutant gases producedaccept named gasesaccept harmful for pollutantaccept greenhouse gasesaccept reduce / slow / stop global warmingaccept reduces acid rain

2

(c) joule1

(d) (i) 6800accept £68 for 3 marks an answer of 68 gains 2 marksallow 2 marks for correct substitution ie 400 × 17allow 1 mark for obtaining 400answers of 7480, 4760, 12920, 4080 gain 2 marks

3

(ii) a small . . . . . . electricity

1[10]

M12. (a) (i) an unreliable energy source1

(ii) a predictable energy source1

(b) plant / grow (at least) one new tree1

(c) greater than 4 %1

[4]

M13. (a) gridaccept any unambiguous indication

1

(b) (i) A (only)1

(ii) D (only)1

(c) more thanaccept any unambiguous indication

1[4]

M14. (a) 1/25 or 1:25 or 0.04

accept 4 % or or 1 in 25 for both marks

allow 1 mark for total of 375allow 1 mark for a clearly correct method using a clearly incorrect total

do not accept 1:262

(b) (i) Bdo not credit reason if B is not chosen

1

(only) burning fossil fuels produces carbondioxide / carbon (emissions)or nuclear fuels don’t produce carbon dioxide

insufficient – smallest amount of fossil fuelsaccept less carbon dioxide

1

(ii) accept anything reasonable eg

increased level of insulation

use energy efficient light bulbs

do not leave appliances on standby

switch thermostats down (1°C)

generate own electricity

install solar panelsaccept insulateaccept specific examples eg loft

1

(c) (i) any three from:

• no power output until wind speed exceeds 4m/s

• output rises rapidly after 4m/s

• output begins to level out / rises less rapidly at /after 13m/s

• output peaks at 21 / 22m/s

• output constant between 21 / 22 and 25 / 26 m/s

• output falls (rapidly) after 25 / 26m/saccept for 1 mark goes up then comes down

3

(ii) any one from:

• unreliable energy source

• dilute energy source

• take up too much landaccept wind does not always blowaccept need thousands / lots of turbinesignore reference to visual / noise pollutionignore reference to kill birds

1[9]

M15. (a) (i) any one from:

• wavesdo not accept water

• tides

• falling wateraccept hydroelectric

• biofuel / biomass

• solaraccept sun / sunlightdo not accept lightaccept solar cells / panels

• geothermaldo not accept heat

1

(ii) decrease1

(b) (i) increases from 4am (to 8am) remains constant from 8am (to 10am)accept increases from 30 000accept stays constant from 40 000allow 1 mark for goes up then stays the samefor full credit must be some indication of time or power

2

(ii) natural gas1

[5]

M16. (a) light1

electricalcorrect order only

1

(b) (i) 0.2 or 1/5accept 20% for both marksallow 1 mark for correct substitution answer of 0.2%or 20 gains 1 markignore units

2

(ii) wastedaccept transformed to heat / other formsaccept transferred to the air / surroundings sound = neutral

1

(c) (i) any one from:

• can fly at nightaccept can fly when it is cloudyaccept as a back-up

• can stay in the air for longer

• can fly in the winter

• can fly fasterincreases power is neutral

1

(ii) any one from:

• produces no (pollutant) gases

or no greenhouse gasesaccept named gasaccept no air pollutiondo not accept no pollutionaccept less global warmingaccept harmful for pollutantaccept produces no carbondo not accept environmentally friendly

• produces no / less noise

• less demand for fuelsaccept any other sensible environmental advantage

1

(iii) accept any sensible suggestion eg, map the Earth’s surface / weather forecasting / spying / monitoring changes to the Earth’s atmosphere, etc

do not accept ideas in terms of transportingaccept use as a satellite

1[8]

M17. transformer X reduces the current through the transmission cablesaccept increases p.d. across the cables

1

this reduces the energy loss from the cables1

which increases the efficiency of the distribution system1

transformer Y is essential as it reduces the p.d. to a safeworking value for consumers

1[4]

M18. (a) decrease in (proportion of) oil as reserves are decreasing1

increase in (proportion of) coal / nuclear / gas / as newreserves / more nuclear power stations built

1

no marks are awarded for simply describing the differences

(b) (i) a prediction1

forecast based on scientific evidence1

(ii) less methane goes into the atmosphereaccept air for atmosphere

1

therefore making global warming less rapid1

(c) idea that many devices transform electricity into other useful

forms of energy1

example related to public health eg refrigeration / production ofvaccines / X-ray machines

1

example related to modern communications eg internet / telephones1

[9]

M19. (a) boiler1

generator1

(b) 0.3 or 30%allow 1 mark for substitution of 2 correct values taken from the Sankey diagram into correct equation

2

(c) decrease1

(d) any named biofuel eg wood, ethanol, straw1

(e) (nuclear) fission1

[7]

M20. (a) (i) tidal / tidesdo not accept water / waves

1

(ii) any three from:

• shorter journey timeaccept easier to go from town to townaccept less petrol / fuel used

• less pollution from trafficaccept CO2 / carbon emissions reduced

• energy source is free

• energy source / tides are predictable

• produces less / no pollutant gases (than fuel burning power stations)accept no CO2 / greenhouse gases producedaccept air pollution for pollutant gases

• conserves supplies of fossil fuels

• uses renewable energy (to generate electricity)

• provides employment

• no visual / noise pollutionless harm to the environment is insufficientthe electricity is cheaper is insufficientdo not accept produces no radioactive wastethe pollution mark scores twice only if it is clear one reference is to traffic and the other is to electricity generation

3

(b) (i) (sometimes) electricity demand may be greaterthan supply (of electricity from the system)

accept in case turbines / generators failorcan sell (excess) electricity (to the National Grid)

1

(ii) decreases the currentaccept increases the voltage

1

reducing energy loss (along cables)accept less heat / thermal energy lost / produced

1[7]

M21. (a) all 4 lines correct

allow 1 mark for each correct lineif more than 1 line goes from a box in List A then all those lines are incorrect

4

(b) all renewableaccept a correct description of renewableeg replaced faster than used or never run outdo not accept can be used againaccept any other common featureeg do not produce pollution / polluting (gases) no fuel is burnt (energy input) is freeeco-friendly / environmentally friendly / natural resources / sustainable sources are insufficient

1

(c) large areas of land are flooded1

[6]

M22. (a) (i) (dismantle and) remove radioactive waste / materials / fuelsaccept nuclear for radioactivedo not accept knock down / shut down

1

(ii) increases itdo not accept it has a negative effect

1

(b) (i)if efficiency is not mentioned it must be impliedanswers in terms of energygenerated only gains no credit

K most efficientorM least efficient

accept K and / or L are more efficient than M1

(efficiency) of K and L increases, (efficiency) of M (almost) constant /slightly reduced

all 3 power stations must be mentioned to get this mark1

(ii) any two from:

• do not know how many (nuclear) power stations there will be

• power stations may continue to increase in efficiency

• do not know what type of power station new ones will beaccept new methods may be found to generate electricity / energyaccept other ways of generating energy may be expanded

• do not know future energy / electricity demandsaccept we may become more energy efficient

• may be new uses for uranium2

[6]

M23. (a) (i) gas1

(ii) one variable is categoric, the other is continuous1

(iii) fuel is not burnedaccept nothing is burneddo not accept they don’t use fossil fuels

1

(b) (i) boiler1

steam1

turbine1

generator1

(ii) any one from:

• windaccept wind turbines

• waves

• tidalaccept tide

• geothermal

• solaraccept the Sun / sunlightaccept solar panels / cellsdo not accept light

• falling wateraccept hydroelectricdo not accept waterdo not accept any named biofuel

1

(iii) 18 000allow 1 mark for showing a correct methodie 36 000 000 ÷ 2 000an answer of 0.018 gains 1 mark

2[10]

M24. (a) (i) 4allow 1 mark for correct transformation and substitution

ie substitution only scores if no subsequent steps are shown

2

(ii) diagram showing two output arrows with one arrow wider

than the other with the narrower arrow labelledelectrical / electricity / useful

1

(iii) any one from:

• time of day / year

• position of solar cells

• angle of solar cells (to the Sun)

• latitude

• cloud cover

• solar cells covered in dust / dirtaccept charger for solar cellsaccept any reasonable suggestion that would lead to a change in intensity of sun(light)the weather is insufficientdo not accept any physical changes to the charger eg area

1

causes a change in intensity of sun(light)accept brightness for intensityaccept a description of the reduction of intensity

1

(b) any one from:

• to check reliability / validity / accuracy

• to avoid bias1

(c) any two from:

• produce no / less (air) pollutionaccept named pollutantaccept produces no waste (gases)

• energy is freeaccept it is a free resourcedo not accept it is free

• (energy) is renewable

• conserves fossil fuel stocks

• can be used in remote areas

• do not need to connect to the National Grid2

[8]

M25. (a) (i) decommissioning1

(ii) level of radiation or radiation dose (to workers) decreasedaccept the isotope / cobalt(-60) has decayed (a lot)accept the isotope / cobalt(-60) has decayed in 2 half livesaccept exposed to less radiationdo not accept no radiation left

1

less hazardous / dangerous (to workers' health)accept saferdo not accept there is no hazardaccept allows reactor to cool (down)an answer of radiation levels decrease by 75 % or drops to 25 % gains 2 marks

1

(b) (i) more in favourorfewer against

quoting figures alone is insufficientdo not accept it increasesignore any reasons given

1

(ii) any one from:

• sample too small

• do not know how many (people) were asked

• different people asked (in different years)

• sample not representative (of population)

• people did not understand the questions

• do not know who carried out the surveysdo not accept they are biased unless acceptable reason for bias given

• do not know if surveys asked same questions1

(iii) any one from:

• no / less pollutant gases producedaccept a named gasaccept does not contribute to global warming

• reliable source (of energy / electricity)

• running out of fossil fuelsaccept a named fossil fuel

• conserve fossil fuelsaccept fossil fuels won’t have to be used

• meet increasing demand

• less reliance on imported fossil fuels / electricityaccept named fossil fuel

• concentrated energy source(s)

• lower transportation costs for fuel

• to replace old nuclear power stationsignore references to efficiency / job creation / local economy / selling electricity

1

(c) economic issues1

[7]

M26. (a) (i) kineticaccept KEdo not accept movement

1

(ii) 0.75

allow 1 mark for correct substitution ie or75 %

an answer 0.75 % or 0.75 with a unit gains 1 mark onlyan answer 75 with or without a unit gains 1 mark only

2

(b) any one from:

• large areas of land are floodeduses large areas of land / takes up large areas of land is insufficient

• people's homes may be destroyed

• habitat (of animals and plants) lost / damagedconstruct is neutralvery noisy is neutral

1

(c) (i) system of cables and transformersboth required for the markaccept power lines / wires for cablesignore reference to pylonsinclusions of power stations / consumers negates answer

1

(ii) less energy loss / wasted (in the cables)accept heat for energydo not accept no energy lossdo not accept electricity for energy

1

as the cables are shorter1

[7]

M27. (a)marks are awarded only for the reason but must match theringed answerfor both marks a MAYBE answer should include a YES and NOresponse answers in terms of the sources being renewable ornon-renewable are insufficient

any two from:

YES answers may include:

• wind produces no pollutant gasesaccept wind burns no fuelaccept CO2 / SO2 / oxides of nitrogen / greenhouse gas for pollutant gases

• nuclear produces no pollutant gasesaccept nuclear burns no fuel

• (burning) gas does not produce SO2

accept gas does not cause acid raindo not accept they don’t / none produce pollutant gases

NO answers may include:

• nuclear produces radioactive waste

• (burning) gas produces CO2 / pollutant gases / air pollutionaccept contributes to global warming / greenhouse effect

2

(b) nuclear power stations use a non-renewable fuelaccept uranium / plutonium is non-renewabledo not accept some are unrenewable

1[3]

M28. (a) kinetic1

(b) Z1

(c) (i) generates a lot more energy / electricity / powerneed fewer conventional large-scale hydroelectric powerstations is neutral

or

can supply (energy / electricity / power) to more homes1

(ii) Large areas of land are flooded.1

(d) (i) National Gridthis answer only

1

(ii) less energy / heat loss (from the cables)accept wasted for lossaccept answers in terms of fewer transformers neededdo not accept less electricity lost / wasteddo not accept no energy lost

1

(e) any one from:

• fewer rivers (suitable for generators)

• less mountainous (so rivers fall smaller distances)accept answers in terms of difficulty linking villages and towns to grid (in Nepal)accept answers in terms of more isolated communitiesaccept answers in terms of UK having more resources for large-scale power stations

1[7]

M29. (a) (i) solar and windboth required for mark either order

1

(ii) 37(%)accept their two sources in a(i)correctly added as an error carried forward (ecf)

1

(b) A1

(c) gas is non-renewabledo not accept they are not all renewablestatements such as gas produces CO2 is neutral

1[4]

M30. (a) can be replaced as fast / faster than it is usedaccept will not run outcan be used again negates this mark

1

(b) any one from:

• reduce demand on power stations / National Grid (system)

• to increase the amount of electricity generated (from renewable energy)

• to conserve fossil fuelsaccept use less fossil fuels

• plenty of animal waste / fuel (available)accept so animal waste can be used usefullyaccept to save money / sell the electricity

produces less harmful gases / SO2 is insufficientbetter for environment is insufficient

1

(c) 60 (months) / 5 (years)ignore any unit given

1

(d)answers must be in terms of the biogas generator

any two from:

• reliable energy sourceordoes not depend on the weather

accept works all of the time

• uses up waste productsaccept animal waste readily available

• not visually polluting

• concentrated energy source

• quieterignore it is renewabledo not accept generates more electricity (than wind turbine)

2[5]

M31. (a) (i) energy from hot rocks in the Earthaccept heat that occurs naturally in the Earthaccept steam / hot water rising to the Earth’s surfaceaccept an answer in terms of the energy released by radioactive decay in the Earthheat energy is insufficient

1

(ii) water is pumped / moved1

up (to a higher reservoir)this mark point only scores if first mark point is awarded

1

(b) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.Examiners should also refer to the Marking Guidance and apply a ‘best-fit’ approach to the marking.

0 marksNo relevant content

Level 1 (1-2 marks)There is a brief description of at least one advantage or disadvantage for either the planned wind turbines or the suggested electricity power link.

Level 2 (3-4 marks)There is a description of advantages and disadvantages for either the planned wind turbines or the suggested electricity power link.orA description of the advantages or disadvantages for both the planned wind turbines and the suggested electricity power link.

Level 3 (5-6 marks)There is a clear and detailed description of at least one advantage and one disadvantage for both the planned wind turbines and suggested electricity power link.

examples of the points made in the response

Offshore wind turbines

advantages

• renewable (energy resource)

• low running costs

• energy is free

• no gas emissions (when in use)accept a named gas eg CO2

accept no fuel is burnedaccept less dependent on fossil fuels

• land is not used (up)

disadvantages

• unreliable – accept wind does not always blowignore references to destroying or harming habitats

• hazard to birds / bats

• visual pollution – do not accept noise pollutiondo not allow if clearly referring to onshore wind turbinesdo not accept spoils landscape

• difficulty of linking turbines to the National Grid

• large initial cost

• difficult to erect / maintainaccept a lot of maintenance needed

• CO2 emissions in manufacture (of large number of turbines)

Suggested Link

advantages

• income for Iceland

• using Iceland’s (available) energy (resources)accept using (Iceland’s) renewable energy (resources)do not accept reduce the amount of Iceland’s wasted energy

• provide electricity when wind does not blow / reliable

• provide electricity at times of peak demand

• even out fluctuations in supply

• excess electricity from Britain (windy days) to Iceland and used to pump water up to store energy

• Britain less dependent on fossil fuelsaccept Britain needs fewer (new) power stationsaccept conserves fossil fuels

disadvantages

• large initial costaccept expensive (to lay cables)

• power loss along a long cable

• (engineering) difficulties in laying / maintaining the cableaccept difficult to repair (if damaged)

6[10]

M32. (a) gas (burning)1

(b) (i) (transmission) cables and (step-up and step-down) transformersif transformers are named ie step-up transformer then both step-up and step-down must be givenmention of power station or consumer negates mark

1

(ii) voltage1

more efficient1

(c) increase1

[5]

M33. (a) 9allow 2 marks for power = 1400 (kW)if a subsequent calculation is shown award 1 mark onlyorallow 1 mark for correct substitution and transformation

power = allow 1 mark for using a clearly incorrect value for power to read a corresponding correct value from the graph

3

(b) (i) system of cables and transformersboth required for the markignore reference to pylonsinclusion of power stations / consumers negates the markwire(s) is insufficient

1

(ii) (uses step-up transformer to) increase pd / voltageaccept (transfers energy / electricity at) high voltage

or(uses step-up transformer to) reduce current

accept (transfers energy / electricity at) low currentignore correct references to step-down transformers

1

(c) build a power station that uses a non-renewable fuel or biofuelaccept a named fueleg coal or wood

orbuy (lots of) petrol / diesel generators

1

stockpile supplies of the fuel

accept fuel does not rely on the weatherorfuel provides a reliable source of energy

accept as an alternative answer idea of linking with the National Grid (1)and taking power from that when demand exceeds supply (1)orwhen other methods failorwhen it is neededanswers in terms of using other forms of renewables is insufficient

1[7]


• produces no (air / atmospheric) pollutionaccept named pollutant eg CO2

accept no harmful gasesaccept produces no emissionsaccept does not add to global warmingenvironmentally friendly is insufficient

• energy (source) is freeaccept no fuel costsaccept the wind / it is free

1

(ii) any one from:

• waves

• tides

• falling wateraccept hydroelectricdo not accept water (flow)

• solaraccept Sun / sunlightaccept solar panels / cells

• geothermal

• biofuel / biomassaccept a named biofuel

1

(b) (i) 3000 (kilowatts)accept 3 megawatts / MWaccept 3 000 000 watts / W

1

(ii) (average) wind speed below 6 m/sanswers giving a wind speed greater than 3 but less than 6 m/s gain both marksallow 1 mark for calculating the output as 500 kW (maximum)andallow 1 mark for wind speed too low or wind not strong enoughdo not accept wind above 25 m/sdo not accept the turbines are frozen

2

(iii) A small amount of nuclear fuel generates a large amount of electricity.both required

Nuclear power stations do not depend on the weather to generate electricity.1

[6]


• produces no (air / atmospheric) pollutionaccept named pollutant eg CO2

accept no harmful gasesaccept produces no emissionsaccept does not add to global warmingenvironmentally friendly is insufficient

• energy (source) is freeaccept no fuel costsaccept the wind / it is free

1

(ii) any one from:

• waves

• tides

• falling wateraccept hydroelectricdo not accept water (flow)

• solaraccept Sun / sunlightaccept solar panels / cells

• geothermal

• biofuel / biomassaccept a named biofuel

1

(b) (i) 3000 (kilowatts)accept 3 megawatts / MWaccept 3 000 000 watts / W

1

(ii) (average) wind speed below 6 m/sanswers giving a wind speed greater than 3 but less than 6 m/s gain both marksallow 1 mark for calculating the output as 500 kW (maximum)andallow 1 mark for wind speed too low or wind not strong enoughdo not accept wind above 25 m/sdo not accept the turbines are frozen

2

(iii) A small amount of nuclear fuel generates a large amount of electricity.both required

Nuclear power stations do not depend on the weather to generate electricity.1

[6]

E1. This question was well answered.

(a) A common error was to misread the data, giving the answer ‘coal’ because the bar was the longest.

(b) The unpredictable nature of the wind was well understood but fewer candidates were able to produce a suitable explanation of the reason for the reliability of fuel-burning power stations.

(c) Most candidates had the right idea although a significant number simply repeated the stem of the question.

E2. This question was generally well answered.

Answers to part (a)(iii) contained a lot of errors. Common mistakes involved the idea of spreading electricity round the country better or making sure there was enough to go round. Many candidates think that voltage had to be high in the cables so that it can be shared by all the consumers.

The answer to part (b) was well known. The few candidates that did not gain credit had not read the question properly and gave answers in terms of fossil fuels running out.

In part (c) reasons against wind farms were better known than arguments in favour of wind farms. In part (c)(i) most candidates made at least one acceptable point but some candidates only talked vaguely about wind power being environmentally friendly without giving any examples and/or that wind power is free once the wind farm has been built. In part (c)(ii) the majority of candidates made two good points. The most common answers included visual pollution, noise pollution and the unreliability of wind. A significant number of candidates referred to bird related problems.

E3. Most candidates correctly chose coal in part (a).

Part (b) was well answered with most candidates choosing the correct two responses. It was pleasing to note that very few candidates selected more than two answers.

Part (c)(i) was well answered by the better candidates but the weaker candidates produced vague and incorrect answers, such as “because there is very little carbon dioxide in the air”. Some candidates described how a wind turbine worked rather than why there was no carbon dioxide produced. In part (c)(ii) the majority of candidates scored at least one mark with many scoring both. Most responses were in terms of visual pollution, noise pollution, reduction in property values and unreliability. However an alarming number of candidates believed that wind-powered generators generate wind, and were thus talking about the danger of all the crops being blown away by the huge winds that would be generated.

E4. In part (a) most candidates could score 2 out of the 4 marks. Surprisingly few candidates knew the voltage of the mains.

In part (b)(i) only the better candidates realised that the waste energy would go into heating the air. An alarming number of candidates thought that the air would become radioactive, electrified, polluted with carbon dioxide or filled with thick black smoke. The most common incorrect answer was simply that it ‘pollutes the air’. In part (b)(ii) just over half of all the candidates made the correct choice.

E5. Part (a) was not well answered with almost 50% of candidates scoring no marks. Many candidates wrote negatively about fossil fuels rather than about the merits of nuclear fuel. There were many vague comments about a lot of energy, with the stronger candidates being able to relate this to the amount of fuel being used. Some candidates wrote about reliability but some did not gain credit due to the vagueness of their answers.

The vast majority of candidates gained no credit in part (b) most ignored the fact that the waste was buried deep, or that it would be in any way contained.

In part (c) some candidates did not use the information they had been given and others ignored the question’s emphasis on the power companies. Many candidates did not distinguish between biofuels and electricity, thinking the power company would be selling the biofuels. The idea of carbon neutral was well identified by stronger candidates, but the weaker ones did not appear to be aware that burning biofuels also gives rise to carbon dioxide emission. A large number of candidates (40%) were unable to use any of the information presented to them and gained no credit at all.

E6. (a) (i) Most candidates correctly identified renewable energy as a source which does not run out. Some candidates continued to say that it was replaced as quickly as, or more quickly than, it was used. The most frequently seen incorrect answer was to say that the source could be used again.

(ii) A well answered question with most candidates able to successfully identify two renewable energy sources. If the mark was lost it was mostly for including solar (which was given in the question) or for simply using the word water.

(b) (i) Whilst the majority of candidates correctly selected the maximum energy input at an angle of 30°, few responded in terms of the pattern of increase to and decrease from this maximum.

(ii) Some candidates completed the calculation correctly to obtain all 3 marks. Most candidates made a start on the calculation but common mistakes were to use the average energy input rather than the maximum, to overlook the area of the solar cells, or to divide the energy input by 0.15 instead of multiplying.

(c) Most candidates were able to successfully make the link between the amount of energy required and that provided by the solar cells, realising that the National Grid would be needed to supply the shortfall. A small number of candidates evidently did not know what the National Grid was and some thought the purpose of remaining connected was to monitor the household use of electricity. Some gave the impression that they thought the National Grid was the only way to get electricity or that this was needed to ensure safety and/or the correct voltage.

E7. (a) Most candidates correctly chose gas and oil as being the two energy sources likely to be used up first. A few candidates ignored the rubric and selected more than two energy sources.

(b) Many answers to this question were very vague, such as “they both have turbines”. The correct response required a reference to a step in the process.

(c) A well-answered question, with the majority of candidates obtaining the correct answer of 140 °C. Some candidates misread the scale and gave a wrong answer of 40 °C.

(d) Candidates usually realised that one advantage of geothermal energy was either that it saved using fossil fuels or that it is a renewable energy source. Some candidates simply restated the question, saying that the scientists would tell the government that this method could generate one quarter of the world’s electricity.

E8. Foundation tier

(a) (i) The majority of candidates did not appear to understand what is meant by the termefficient in a scientific context. Many were quoting an ‘everyday’ sense of the word, such as ‘reliable’, ‘gets the job done’ or ‘works quickly’.

(ii) Although a few of the better candidates knew that the current was decreased, hardly any realised why. Many candidates thought that the cables were covered with an insulating material to prevent heat loss, whilst others thought that the National Grid stored the heat energy and used it to heat people’s homes.

(b) (i) A minority of candidates correctly stated that the reason was for the purpose of comparison or to act as a control. Most candidates simply stated that it was to make it a fair test.

(ii) Again, a common response that gained no marks was ‘to make it a fair test’. Others simply repeated the question by stating ‘so that they know how many children were studied’.

(iii) Most candidates did not score any credit. Weaker candidates, perhaps reading the stimulus passage too quickly, said that the children had developed leukaemia because their parents were unable to control them.

(iv) Most candidates opted to tick the second box, and were able to support this choice with a sensible reason. Those candidates who ticked the first box were less successful at providing a satisfactory reason.

Higher tier

(a) (i) Many candidates did not appear to understand what is meant by the term efficient in a scientific context. Quite a number of answers referred to no energy being wasted.

(ii) Many candidates realised that transformers played a part, but either did not know the specific details or wrote vague statements such as ‘it steps up the voltage and then steps it down again’. The majority answered correctly that the voltage was increased, but many failed to link this with a reduction in current, thereby reducing energy loss as heat.

(b) (i) It was pleasing that many candidates understood the need for a control.

(ii) Whilst a large number of candidates realised that this was linked to reliability, the majority of candidates confused this term with ‘accuracy’ or ‘fair test’. Of those who used the correct word, most answered correctly in terms of the reader making a judgement about the reliability of the data, or that a larger sample would make the results more reliable.

(iii) This was answered better, with a majority of candidates scoring both marks.

(iv) Most candidates opted to tick the second box, and were able to support this choice with a sensible reason. Those candidates who ticked the first box were less successful at providing a satisfactory reason.

E9. (a) Some candidates were not reading the question with sufficient care and thought that the question read “What could a government scientist do …” This interpretation led them to answers such as “Give a slide show” or “Produce a leaflet”. Of the candidates who were able to provide reasons, most were able to suggest that fossil fuels are running out. Many answers however were vague; examiners frequently saw answers such as “It is bad for the environment”

(b) Usually well answered, although some candidates used the same letter twice.

E10. (a) This question was generally well answered though some candidates had misread the key and confused hydro with oil. Some candidates only gave a simple response about the decrease in oil and had not read the question well enough to spot that it contained a plural.

(b) (i) Surprisingly only just over half of the candidates could correctly name the process. Most incorrect answers gave the name of a chemical process.

(ii) Only the better candidates were able to gain full credit for a clear explanation of the process. Many candidates failed to gain any credit for omitting the word ‘steam’ and/or giving descriptions of ‘heat’ turning turbines. Some candidates tried gave an explanation of nuclear fission, clearly having not read the question.

(iii) Few candidates gained both marks. The majority gained one mark for stating a ‘no CO2 released’ type answer or that nuclear power stations are reliable. The most common incorrect responses were ‘nuclear fuel is efficient’/ ‘nuclear fuel will not run out’/ ‘nuclear fuels produce more energy’/ ‘nuclear fuel is renewable’. A worrying proportion of candidates talked about burning the nuclear fuel.

(iv) This was well answered with the majority of candidates knowing that the waste was radioactive. Extra information was often given such as the effect on tissue, food chains, etc and the long half-life. Weaker responses referred to the waste as reactive or were concerned with greenhouse gases or acid rain.

(c) Many good answers were seen. The second mark was often lost because of a reference to CO2 destroying the ozone layer or simply repeating the given phrase ‘climate change’.

E11. (a) (i) Most candidates were able to identify France as being the country with the smallest amount of standby energy.

(ii) Few candidates were able to offer a sensible suggestion as to why an average value of the standby energy is used.

(b) (i) The majority of candidates were able to spot the correct relationship and gain credit. However a significant minority of candidates clearly misunderstand the term ‘standby energy’ believing it to be some kind of reserve store of energy that could be used if the mains supply failed.

(ii) Only the better candidates were able to score both marks for this question. Many answers were very vague and simply talked about there being less pollution, without specifying what type of pollution would be reduced. There were many answers that talked about the general benefits of conservation, and the fact that the coal would one day run out did not answer the question that asked for an explanation of how the environment would benefit.

(c) Surprisingly only half the candidates identified the joule as being the usual unit of energy.

(d) (i) It was encouraging to see that a large number of candidates were able to complete the calculation correctly and earn all three marks available. Many of the weaker candidates were able to substitute the correct numbers into the equation that was given, but then failed to complete the arithmetic correctly nevertheless, they could still score marks by showing the correct method.

Some candidates converted their answer into pounds, but then failed to put a pound sign in front of the number. This lost them a mark as the units ‘pence’ had already been put into the answer line for them.

(ii) Most candidates correctly identified an advantage of using nuclear fuels.

E12. (a) (i)(ii) Surprisingly less than half of the candidates realised that the wind is an unreliable energy source and that the tides are a predictable energy source. A significant proportion of candidates thought that both were a constant energy source.

(b) The great majority of candidates were able to state that a new tree or trees must be planted to replace the one that had been chopped down. Some candidates however misread the question and talked about what must happen to the tree after it had been chopped down, eg being made into paper.

(c) The majority of candidates were able to interpret the graph correctly, and so deduce that the percentage is most likely to be greater than 4 %.

E13. Nearly all candidates knew that the network is called the National Grid, and most could identify the appropriate transformers and, most knew that, in a step-down transformer, the p.d. across the primary coil is more than the p.d. across the secondary coil.

E14. (a) Some candidates had problems reading all 4 values from the graph correctly, but did gain one mark for showing correct working. A significant number of candidates, having read the values correctly, were unable to calculate a proportion.

(b) (i) This was generally well answered. The most common one-mark answers chose student B but failed to explain the link between fossil fuels and carbon dioxide emissions.

(ii) This was very well answered with candidates showing a practical understanding of the problem. The most common response being ‘don’t leave appliances on standby’.

(c) (i) Whilst many candidates were able to score one or two marks for picking out a couple of significant features of the graph, detailed answers were not common. A number of candidates failed to gain any credit for answers which tried to describe the action of a wind turbine. Some candidates seemed to think that because the line went down after 25 m/s, this was showing that the wind speed was falling. A cause for concern was the idea that it is the wind turbines that create the wind!

(ii) This was well answered by many candidates, the most common error being a general description of wind turbines such as noisy and an eye-sore.

E15. (a) (i) The majority of candidates were able to offer the name of a suitable renewable energy resource. A few candidates were not sufficiently specific in their answers, and wrote answers such as ‘water’. A significant minority of candidates simply repeated the stem of the question and gave the answer as wind.

(ii) Most candidates realised that using less fossil fuel will decrease the amount of carbon dioxide emitted.

(b) (i) A large number of candidates do not appear to know the difference between am and pm and were therefore describing what happened to the demand during the evening. An equally large number of candidates also thought that the question asked them to describe why the demand varied rather than how the demand varied. They were therefore going into great detail about how people were getting up for work after 4 am and switching on their kettles.

Of those candidates who did attempt to describe how the demand varied between 4.00 and 10.00 am many only obtained one of the two marks. This was because they had failed to describe what the graph showed in sufficient detail. When asked to describe what a graph shows, it is always a good idea to quote some figures from the graph, particularly for points of inflection.

(ii) Only the better candidates seemed to realise that a gas-fired power station would have the shortest start-up time.

E16. (a) Most candidates correctly stated that solar cells are designed to transform light energy into electrical energy. The most common mistake was to state that they transform heat energy into electrical energy.

(b) (i) The majority of candidates could substitute the correct numbers into the correct places in the equation. However, some candidates then found that they could not cope with a fraction where the denominator was larger than the numerator; they therefore inverted the fraction and ended up with the answer 5 instead of 0.2. It is possible that some candidates did not use a calculator in the examination.

Some candidates tried, unnecessarily, to express the answer as a percentage. Those who correctly answered 20% gained both marks; those who erroneously stated it to be 0.2% were only awarded one mark.

(ii) Most candidates correctly stated that the energy that is not usefully transferred is wasted.

(c) (i) Most candidates correctly stated that either the fuel cells were to act as a backup for the solar cells, or that this enabled the aircraft to fly at night or when there was insufficient light.

(ii) Most candidates were able to state that burning fuels releases gases such as carbon dioxide into the atmosphere. Candidates whose answers were very vague such as “it reduces pollution” were not awarded a mark.

(iii) Many candidates believed that such an aircraft would be able to fly into space or be used to visit the moon. Another common mistake was to misread the question and instead of suggesting a possible use for the aircraft, some candidates were giving an advantage of this aircraft over conventional passenger jets.

E20. (a) (i) Surprisingly only just over a third of candidates scored this mark, ‘wave’ and ‘hydro-electric’ were the most common incorrect answers.

(ii) Many candidates were able to score two marks for sensible responses. Marks were often lost because of terms such as ‘eco-friendly’, ‘green energy’ ‘not harmful to the environment’ etc, which should have been expanded on in terms of carbon dioxide emissions or air pollution to score a mark.

(b) (i) This was poorly answered with only just over a third of candidates giving an acceptable reason. Although the information given had said that the new scheme would produce enough electricity for both towns, many answers indicated that candidates had not read this.

(ii) There were many good answers to this question with just under half of the candidates scoring both marks.

E21. (a) Most candidates could score well on this question, with just over half of the candidates scoring full marks. The most common error was to link ‘The sea is always too rough’ to ‘Tides’ as the energy source, rather than linking it to ‘Waves’.

(b) Most candidates realised that all the energy sources listed were renewable sources. However describing them as ‘natural’ sources was a common answer that did not gain a mark, and some candidates gave answers that were even more vague, such as ‘environmentally friendly’.

(c) Nearly three fifths of candidates correctly realised that one disadvantage of a hydroelectric power station is that large areas of land are flooded. A significant number of candidates chose ‘polluting gases are produced.’.

E22. (a) (i) There were few correct answers, most candidates referred to closing down the

power station but few discussed the removal of radioactive material from the site.

(ii) A mix of answers with many candidates attempting to give a reason.

(b) (i) A large number of answers failed to mention the efficiency, which is what the question was about. Of those candidates which did, some compared the efficiency of the three power stations to each other, some discussed the change in efficiency of each power station over the years, but very few gave both answers.

(ii) A large number of vague answers were seen, such as ‘anything could happen in the future’ or ‘we can’t predict that far into the future’. Just over half of the candidates scored at least 1 mark.

E23. (a) (i) Almost all candidates correctly identified gas as being the fuel that produces the smallest amount of carbon dioxide.

(ii) Disappointingly less than half of the candidates realised that one variable is categoric and the other is continuous.

(iii) A poorly answered question with few candidates realising that nuclear power stations do not burn any fuel.

(b) (i) A good response to this question, with many candidates obtaining all 4 marks. Where marks were lost, it was generally caused by confusing the turbine with the generator.

(ii) Surprisingly only just over half of the candidates were able to name a suitable energy source, usually wind or solar power. Many candidates failed to read the question with sufficient care and named another biofuel. A significant number of candidates named a fossil fuel or gave nuclear.

(iii) A good response to this question, with many candidates obtaining the correct answer. Some candidates however used the power of the power station in MW but kept the figure for the average power used in the home in watts ending up with a fraction of a home. Other candidates multiplied the figures ending up with an answer of 72 000 000 000 homes. It is unfortunate that such candidates do not realise how unrealistic these figures are.

E24. (a) (i) Less than half of the candidates answered this correctly. Many were unable to transpose the equation correctly.

(ii) Only about a third of candidates were able to draw something resembling a Sankey

diagram and label it appropriately. Whilst the majority of candidates obviously had some idea that a Sankey diagram had some arrows going in different directions, some drew a picture of solar cells, and over a tenth did not attempt the question.

(iii) This was answered reasonably well, with over three quarters of candidates gaining at least one of the two marks, usually for realising that a change in intensity of the sunlight would affect the time taken to charge the battery. However, less than half of these went on to score the second mark by giving a factor which would change the intensity.

(b) This question was correctly answered by the majority of candidates. However, many seem to have a dim view of company scientists, indicating that they would lie or falsify results.

(c) Nearly all candidates gained at least one mark, with more than half scoring both. The most common answers were that the Sun is a renewable resource and that solar cells do not produce pollutant gases.

E25. (a) (i) The majority of candidates opted for the wrong answer ‘decontaminating’ rather than the correct answer of ‘decommissioning’.

(ii) This proved to be a difficult question for most candidates, with less than a tenth achieving both marks. The most common mistake was to argue that, as the half-life was 5.3 years, this would mean that in 10.6 years all radiation would have ceased.

Many of the weaker candidates treated the term‘half-life’ rather too literally, and would talk about the isotope being ‘dead’ after 11 years. Another common misunderstanding was to talk about the half-life reducing as time went on. Some candidates even thought that the term‘half-life’ referred to the life span of the workers.

(b) (i) Most candidates realised that the percentage of people in favour of nuclear power stations had increased.Some candidates simply wrote‘it went up’, without specifying what‘it’ was.Some candidates failed to say how the percentages had changed, but instead suggested a reason why the figures might have changed.

(ii) The better candidates were able to suggest a sensible reason as to why some people might consider the results to be unreliable. Many candidates, however, thought that the results were unreliable simply because there was no data for the intervening years. Others suggested that the results could be biased, but offered no suggestion as to why they might be biased.

(iii) Few candidates were able to offer an acceptable reason as to why more nuclear power stations should be built. Most of the reasons offered were not specific to the building of a nuclear power station, eg‘to bring more jobs to the area’.

(c) Most candidates correctly identified this as being an economic reason.

E26. (a) (i) This was well answered.

(ii) The majority of candidates were able to substitute correctly into the given equation.

Mistakes made subsequently were to do the arithmetic incorrectly, or to give a wrong unit with a correct numerical answer, eg 75 J or 0.75 %.

(b) Few candidates scored this mark. A common insufficient answer was to say that it would take up a lot of land, without going on to explain the consequences. Few candidates seemed to realise that scaling up by a factor of 100 000 would require the area to be flooded.

(c) (i) As a simple recall of knowledge question it was surprising that very few candidates were able to give the correct answer. Common misconceptions included the idea that pylons carry the electricity; that the power station or consumer is part of the National Grid.

(ii) Despite the given information stating that the electricity from the micro-system was transferred to local homes via a transformer, a large number of answers stated that no transformers would be needed, indicating that many candidates had failed to read the question carefully.

E27. (a) The majority of candidates opted for the ‘no’ answer and were able to identify that gas, as a fossil fuel, would release carbon dioxide when burned. Of those who identified ‘nuclear’ waste as not being environmentally friendly, many failed to say that this was because it was radioactive. Over half of the candidates gave incomplete answers or such vague responses that they scored no marks.

(b) Surprisingly, only just over half of the candidates were able to identify that nuclear power stations did not use a renewable source. There were many vague answers stating ‘they are not all renewable’.

E28. (a) Most candidates correctly chose kinetic energy, the most common wrong answer being electrical.

(b) Most candidates correctly chose diagram Z.

(c) (i) This question was well answered by the majority of candidates with just over three quarters of candidates scoring the mark.

(ii) Surprisingly only the better candidates correctly chose ‘large areas of land are flooded’. The most common answer was ‘A constant flow of water is needed’.

(d) (i) Just over a third of candidates stated that this was the National Grid.

(ii) Only the better candidates were able to relate the use of short cables to the idea of energy losses. Common incorrect answers often referred to electricity being lost or to electricity travelling faster in shorter cables.

(e) This question was answered well by the majority of candidates.

E29. (a) (i) The majority of candidates correctly identified wind and solar as being the two energy sources that do not produce any polluting gases.

(ii) Most candidates correctly worked the percentage as 37%.

(b) About two-thirds of candidates correctly identified graph A as the one most likely to represent the output from a wind turbine.

(c) Almost half of the candidates were able to state that gas is not a renewable energy source. The other half missed the point that there was an incorrect statement in the report, and instead offered their opinion as to why any or all of these power stations should not be built. Often such arguments were based on the pollution from gas burning power stations.

E30. (a) Many responses stated that a renewable source can be ‘used again and again’ and therefore did not gain any credit. The idea of a source that ‘does not run out’ or that it is ‘replaced as fast as it is used’ was only presented by a small minority of students.

(b) Many vague assertions such as ‘better for the environment’ or ‘eco-friendly’ gained no credit. Other students thought that the waste consisted of ‘dead animals’. Most correct responses came from the idea of the availability of animal waste or the fact that the farmer “saves money” in this process.

(c) Over three fifths of students scored this mark, although the fact that units were ignored by examiners was a saving grace for some.

(d) Surprisingly only three fifths of students managed to score at least one mark for this

question. Those that did not usually discussed the advantages and disadvantages of wind turbines but made no reference to biogas generators. Some students thought that the products of combustion (carbon dioxide and water) could be used on the farm.

E31. (a) (i) Few students appear to understand what geothermal energy is. Just over a tenth of students did not attempt this question.

(ii) Most students that attempted this question simply described a hydroelectric system, missing the point about this being a pumped storage hydroelectric system. Many students thought that it was the energy or the electricity that was being pumped; others thought that it was the pump that stored the energy. Almost a quarter of students did not attempt this question.

(b) This was the 6-mark Quality of Written Communication (QWC) question in which students had to discuss the advantages and disadvantages of two proposals: building off-shore wind turbines or laying a cable to connect to renewable resources in Iceland. The best responses came from those who spent a couple of minutes making a grid to show the pros and cons of each in note form. They then used these notes to construct a full response. Most students could provide advantages and disadvantages for the wind turbines, but rather fewer responses successfully referred to the link to Iceland. Some students had clearly not read the question properly, and had failed to notice that the wind turbines were off-shore. Their answers therefore related to the countryside being ruined and land taken up with thousands of large turbines. There were many objections to the underwater cable on the grounds that ‘electricity and water don’t mix’. Just under a tenth of students failed to make an attempt at this question, however the majority wrote at length.

E32. (a) Few students were able to recall that gas-fired power stations have the shortest start-up;time. Almost a fifth of students did not even attempt an answer.

(b) (i) Very few students realised that the National Grid comprises of step-up and step-down transformers, as well as the transmission cables. Most thought that it was simply the transmission cables. A significant number of students included either the power station or consumer or even both

(ii) Just under half of students were able to score both marks for knowing what a step-up transformer does.

(c) Most students realised that the trend shown on the graph suggests that the percentage will increase over the next ten years.

E33. (a) Students made heavy weather of this calculation, often converting the time into seconds, and failing to realise that the 5600 kilowatt-hours was the energy rather than the power. Hence very large values (several hundred thousand), obtained from these calculations, were quoted as being the wind speed. Even students who correctly calculated the power output as 1400kW often seemed unable to relate this to the graph to obtain a corresponding wind speed.

(b) (i) As with a similar question in last year’s paper, very few correct responses were given. Transformers rarely featured, but many students seem to think that pylons carry electricity.

(ii) Many students knew that transformers were involved here, but answers were often not specific enough, for instance ‘step up and step down transformers are used’.

(c) Again, answers often failed to be specific enough, for example ‘use another way of producing electricity’. A significant number of answers referred to using wind turbines, indicating that students had not read the newspaper extract carefully.

E34. (a) (i) Surprisingly many students did not score this mark. Many students concentrated on explaining that wind was a renewable energy source, forgetting that this was given in the stem of the question. Others simply suggested that wind was ‘natural’ or ‘good for the planet’. Students found it difficult to differentiate between the cost of the wind as an energy source (free) and the cost of electricity from wind turbines, many imagining that it was free or very cheap.

(ii) Many students were able to give one example of a renewable energy source, solar being the most popular. ‘Water’ was not accepted as an energy source unless it was apparent that the answer referred to ‘falling water’.

(b) (i) Most students gained this mark.

(ii) Many students tried to explain the shape of the graph and ignored the question that they were asked. The students appeared to assume that the horizontal axis represented time and suggested that the ‘wind started low, gathered speed and then got so fast that the output dropped to zero – all in 25 seconds’. Others stated that there was either no wind or its speed was too high and so ‘no power’ would be generated. However, the question referred to power generation at a lower rate and so these answers were incorrect. Few students were prepared to give a wind speed appropriate to the scenario that the question outlined, but a minority were able to gain one mark for saying that the wind was too low during this time period. There were frequent references to the turbines freezing or icing up.

(iii) The majority of students gained this mark.

E35. (a) (i) Surprisingly many students did not score this mark. Many students concentrated on explaining that wind was a renewable energy source, forgetting that this was given in the stem of the question. Others simply suggested that wind was ‘natural’ or ‘good for the planet’. Students found it difficult to differentiate between the cost of the wind as an energy source (free) and the cost of electricity from wind turbines, many imagining that it was free or very cheap.

(ii) Many students were able to give one example of a renewable energy source, solar being the most popular. ‘Water’ was not accepted as an energy source unless it was apparent that the answer referred to ‘falling water’.

(b) (i) Most students gained this mark.

(ii) Many students tried to explain the shape of the graph and ignored the question that they were asked. The students appeared to assume that the horizontal axis represented time and suggested that the ‘wind started low, gathered speed and then got so fast that the output dropped to zero – all in 25 seconds’. Others stated that there was either no wind or its speed was too high and so ‘no power’ would be generated. However, the question referred to power generation at a lower rate and so these answers were incorrect. Few students were prepared to give a wind speed appropriate to the scenario that the question outlined, but a minority were able to gain one mark for saying that the wind was too low during this time period. There were frequent references to the turbines freezing or icing up.

(iii) The majority of students gained this mark.

Web view(c) Fuel-burning power stations may produce air pollution. Why does a wind generator not...

Documents

Transcript of Web view(c) Fuel-burning power stations may produce air pollution. Why does a wind generator not...