Six-mark questions

Six-mark questions are often the questions that people find the most difficult. In all longer answer questions, but especially the six mark ones, it is important that you plan your answer and not just rush into it. After all, you would plan an essay or short story before starting. Without a plan it is easy to stray away from the key point and lose marks, get steps in a process in the wrong order or forget key bits of information. Remember to write your answer in full sentences, not bullet points.

Six-mark questions will start with command words such as 'Describe...' or 'Explain...'.

Some command words are easy to understand such as:

  • 'Calculate...' or 'determine...' for maths questions
  • 'Choose...' for multiple choice questions
  • 'Complete...' to fill in a gap in a table or graph
  • 'Complete...' to fill in a gap in a table or graph
  • 'Suggest...' where you use your knowledge in an unfamiliar situation

The command words 'Describe...' and 'Explain...' can be confusing. If you are asked to describe a graph, you will be expected to write about its overall shape, whether it is linear or curved, the slope of gradients etc. If you are asked to explain why a pattern or trend is seen in a graph, you will be expected to use your science knowledge not just say what you see (which is a description), eg the graph shows that the incidence of disease increases. It does this because...

Explain how and why questions often have the word 'because' in their answer. Describe questions don't.

The number of marks per question part is given in this form '[6 marks]'. It is essential that you give as many different points in your answer as possible (ideally six).

These questions have been written by Bitesize consultants as suggestions to the types of questions that may appear in an exam paper.

Sample question 1 - Foundation

Question

Describe how the products of photosynthesis are used by a plant. [6 marks]

The following is a list of valid points that could be included in your answer. In your answer, it is important that you do not bullet point them, but link your ideas together.

Marking points are made from:

  • glucose is the product of photosynthesis
  • some glucose is used for respiration by the plant's cells
  • starch is built up and stored in the plant's cells, including those of storage organs
  • starch can be broken down and the glucose used when it is needed, eg for respiration during the germination of seeds
  • some glucose is converted into cellulose, used to construct cell walls
  • glucose is converted into amino acids, with the help of nitrates absorbed from the soil
  • amino acids built into proteins
  • glucose is converted into lipids, eg used as an energy store in seeds

Sample question 2 - Foundation

The graph shows the concentration of lactic acid in an athlete's blood before, during and after a training session.

A graph showing and explaining the changes in the athletes blood.
Question

Describe and explain the changes in the athlete's blood. [6 marks]

The following is a list of valid points that could be included in your answer. In your answer, it is important that you do not bullet point them, but link your ideas together.

Marking points are made from:

  • monitoring of lactic acid starts 3 minutes into exercise periods
  • lactic acid shows a small increase - from 1.2 mmol dm-3 to 1.75 mmol dm-3 - during warm-up period, 3 to 5 minutes into the activity
  • lactic acid produced by anaerobic respiration in muscle
  • when lungs and heart do not deliver sufficient oxygen to the muscles
  • lactic acid enters blood
  • greater increase - from 1.75 mmol dm-3 to 8.9 mmol dm-3 between 5 and 17 minutes when exercising to exhaustion
  • lactic acid concentration in blood decreases after exercise stops
  • lactic acid doesn't return to its normal concentration until 57 minutes - 40 minutes after exercise

Note:

  • make your answer quantitative, referring to lactic acid concentrations and times, do not simply make qualitative statements about trends
  • do not assume from the data that there are small quantities of lactic acid in the blood under normal conditions, as monitoring does not begin until three minutes into the exercise warm-up period
  • if you are working at Higher level, you may be asked to explain why the return of lactic acid to normal levels takes, in this instance, 40 minutes, owing to clearing the oxygen debt

Sample question 3 - Higher

Question

The graph shows how carbon dioxide affects the rate of photosynthesis in a plant.

Explain the shape of the graph and suggest how the rate of photosynthesis could be increased.

You can use a diagram to illustrate your answer. [6 marks]

A graph with rate of photosynthesis on the y axis and light intensity on the x axis.  The plotted line rise steeply and then levels off to horizonal.  During the steep part light is the limiting factor.  During the horizontal part another factor has become limiting.

The following is a list of valid points that could be included in your answer. In your answer, it is important that you do not bullet point them, but link your ideas together.

Marking points are made from:

  • increase in carbon dioxide concentration increases the rate of photosynthesis
  • carbon dioxide is a reactant in photosynthesis
  • until a factor such as light intensity or temperature is limiting
  • if light intensity or temperature is increased, the rate will continue to increase (because it is supplying the factor that was in short supply)
  • the graph will level off again/rate becomes constant
  • because the other factor - temperature or light - is limiting
  • if the other factor - temperature or light intensity is increased, the rate of photosynthesis will increase again
  • until another factor becomes limited
The graph shows how carbon dioxide affects the rate of photosynthesis in a plant

Tip: In the exam, as well as your written description, you could also include an annotated graph, or graphs, in your answer - it's often easier to explain difficult concepts than using words or concepts that would otherwise need lengthy explanations. But remember - this is a six mark question, so don't only use a graph for your response.

Sample question 4 - Higher

Question

Discuss how a commercial plant grower, with locations in the UK and across Europe, could increase yields in greenhouse and field crops. [6 marks]

The following is a list of valid points that could be included in your answer. In your answer, it is important that you do not bullet point them, but link your ideas together. You must make reference to both greenhouse crops and field crops in order to access all of the marks.

Marking points are made from:

Increased yields are dependent on rate of photosynthesis and reducing losses, eg by pests.

Greenhouse crops:

  • irrigate with optimum amount of water
  • increase greenhouse temperature using heating system
  • increase light intensity
  • increase carbon dioxide concentrations by piping in carbon dioxide gas
  • add fertiliser or use a hydroponics system
  • increase yields using appropriate pesticides or other control methods

Field crops:

  • select a location across Europe optimum for the growth of the crop, eg for sunlight and rainfall
  • use an irrigation system to provide the optimum amount of water
  • could not increase external carbon dioxide concentration (unless the plants were grown in polythene/plastic tunnels)
  • add fertilisers
  • reduce losses from pests using pesticides and/or growing genetically modified (GM) crops

Read questions of this nature carefully - look for clues in the question, for instance, that the crops are grown in locations across Europe, meaning that optimum climactic conditions could be chosen.

Use ideas also from different areas of the course, for instance the growing of GM crops.