Energy - Six-mark questions

Six-mark questions are extended open response questions. These require longer answers than the structured questions with fewer marks. It is wise to plan your answer rather than rushing straight into it, otherwise you may stray away from the key points.

Six-mark questions are marked using a levels-based mark scheme because they are open ended. To gain full marks, you need to:

  • support explanations using scientific knowledge and understanding
  • use appropriate scientific words and terms
  • write clearly, linking ideas in a logical way
  • maintain a sustained line of reasoning, rather than getting lost or bogged down

You are likely to see command words such as:

  • 'describe' - you need to give an account but no reason
  • 'explain' - you must give reasons or explanations
  • 'devise' - you must plan or invent a procedure using your scientific knowledge and understanding
  • 'evaluate' - you must review information, including identifying strengths and weaknesses, and make a supported conclusion

Six-mark questions may be synoptic questions. These questions bring together ideas from two or more topics. For example, a question about atoms could include ideas about atomic structure, isotopes, radiation and nuclear reactions. Remember that the topics covered in the first paper are assumed knowledge for the second paper, so questions in the second paper may need knowledge and understanding of those topics too.

The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain six marks, but you do need to write in full sentences, linking them logically and clearly.

Questions courtesy of Eduqas.

Sample question 1 - Foundation


A householder sticks a shiny silver coated sheet of plastic bubble wrap on the wall behind the radiator in the lounge in order to save energy.

Explain how this can reduce heat loss from the lounge by conduction, convection and radiation. [6 marks]

The silver sheet reflects infrared radiation back into the radiator [1] and reflects heat back into the room [1]. The ridged panels/bubble wrap trap insulating pockets of air between the radiator and the wall [1], reducing heat lost through the wall by conduction [1]. Plastic is also an insulator [1]. The outside air temperature of the wall will be reduced by both factors above, so convection will be reduced [1].

Answering tip: Briefly plan the key points you want to include in your answer. For example:

  • include all three heat transfer types in your explanation
  • consider the material and how its properties help reduce heat loss

Sample question 2 - Foundation


The table below gives information about generating electricity from wind and nuclear power:

A wind turbineA nuclear power station
Overall cost of generating electricity (p/kWh) 5.62.8
Maximum power output (MW)23,600
Lifetime (years)1545
Waste producedNoneRadioactive waste
Lifetime carbon footprint (g of CO2/kWh)4.64/5.25 (onshore/offshore)5
Commissioning cost (£ million)34,000

Use your knowledge and information from the table to compare the cost-effectiveness and environmental impact of the two methods of generating electricity. [6 marks]

The cost of generating electricity using nuclear energy is cheaper than wind [1]. To generate the same power output requires 1,800 turbines for every nuclear power station [1]. That would cost £5,400 million compared with £4,000 million [1]. Also, during the lifetime of a nuclear power station, wind turbines would need to be replaced three times [1]. There is no waste produced by wind but with nuclear power there is radioactive waste to dispose of which adds cost and has an impact on the environment due to radiation hazards [1]. Onshore wind power would produce less of a greenhouse effect than nuclear but offshore wind would produce more [1].

Answering tip: Briefly plan the key points you want to include in your answer. For example:

  • quote actual figures from the table
  • look for advantages and disadvantages for each source of energy

Sample question 3 - Higher


Use your knowledge of the kinetic theory of matter to explain how heat energy is transferred by conduction in metals and by convection in gases. [6 marks]

Conduction in solids occurs because the atoms are regularly positioned and are close together [1]. The atoms in the hot part of the solid vibrate faster than those elsewhere [1]. They pass on their energy to their neighbours by collisions and so the energy travels through the solid [1]. In metals, this is improved by free electrons that move at speed from the hot region, colliding with metal ions in the lattice, transferring their energy in the process [1].

Convection occurs in gases because the particles in the hotter region have more energy and push each other further apart in violent collisions [1]. This region becomes less dense and rises above the cooler region, setting up a circulating current, transferring thermal energy to all parts of the gas [1].

Answering tip: Briefly plan the key points you want to include in your answer. For example:

  • consider vibrating particles
  • consider free electrons
  • consider the separation of particles and density

Sample question 4 - Higher


Discuss how the National Grid maintains a reliable supply of electricity to consumers. [6 marks]

Some types of power station continue working for 24 hours a day and for 365 days a year [1]. These include nuclear, coal and oil-powered stations that take a long time to shut down and to start up again [1].

Through the day, however, demand changes; the demand being small at night while most of the population is sleeping but during the daytime, there are peaks of demand, notably at breakfast time, and again in early evening [1]. To meet this demand some power stations are needed which can be brought on stream at very short notice [1]. This is where hydroelectric power stations are very useful because they can start up within seconds by just opening a valve to let the water flow [1]. They, along with reserve oil and gas-powered stations, can also be used to maintain supply during maintenance or breakdown times of other stations [1].

Answering tip: Briefly plan the key points you want to include in your answer. For example:

  • how the demand for electricity changes through the day
  • which types of power stations generate electricity continuously
  • why hydroelectric power stations are so useful to the National Grid