How much are definitions worth?

Terminology is an important part of science communication. In exams definitions score marks directly, but in an indirect way they also allow you to answer questions where knowing what the terminology means is essential. But how many marks are available for knowing your definitions? Of course, it varies from year to year and from exam board to exam board, but as a first example take the AQA Jun 13 Chemistry GCSE (Higher Tier). This exam comprised three written papers and the coursework unit - each contributing 25% of the overall GCSE.

The two tables below summarise how the definition marks were awarded across the three papers, and how this related to the grade boundaries for the papers. The three tables that follow look at each unit in more detail - all the definitions highlighted are in the Dr. P GCSE Chemistry App.

Summary Overview
Unit 1 5 marks direct (8% of paper) 9 marks indirect (15% of paper) 14 marks total (23% of paper)
Unit 2 3 marks direct (5% of paper) 7 marks indirect (12% of paper) 10 marks total (17% of paper)
Unit 3 7 marks direct (12% of paper) 6 marks indirect (10% of paper) 13 marks total (22% of paper)
Totals from Written Papers 15 marks (8% of papers) 22 marks (12% of papers) 37 marks (20% of papers)
% of GCSE including coursework 6% 9% 15%


Grade Boundaries
A* A B C D
Unit 1 47 37 27 17 8
Unit 2 44 35 26 18 10
Unit 3 44 40 34 28 22

Difference D to C grade : 23 marks
Difference C to B grade : 24 marks
Difference B to A grade : 25 marks
Difference A to A* grade : 23 marks

It is clear that the marks awarded for definitions make more than a grade’s difference.

Papers :
Grade boundaries :



AQA June 13 Chemistry GCSE

These three tables look at each unit in more detail and illustrate the breakdown of marks for direct and indirect questioning of definitions.

Unit 1
Direct Definition Marks Indirect Definition Marks
Q1a(ii) “Name the two sub-atomic particles in the nucleus”

definition : nucleus
1 mark Q2b(iv) “Pure copper is produced by electrolysis of copper sulphate solution. Which electrode do,the copper ions move towards? Give a reason for your answer."

definition : cathode
1 of 2 marks
Q3a(i) “Name the type of reaction that releases energy from a fuel”

definition : exothermic
1 mark Q3a(ii) “Fuels react with oxygen to produce carbon dioxide. The reaction of a fuel with oxygen can,produce a different oxide of carbon. Name this different oxide of carbon and,explain why it is produced."

definition: incomplete combustion
2 marks
Q7b(i) “Describe how the process of fermentation is done”

definition : fermentation
2 marks Q4c(ii) “Describe, in terms of molecules, how poly(ethane) is produced in Reaction 2.” (Reaction 2 shows the displayed formulae for the polymerisation of ethane)

definitions : addition polymer, polymerisation
2 marks
Q2b(v) “What is used in phytomining to remove copper compounds from the land”

definition : phytomining
1 mark Q4d “Complete the displayed structure of the product in the equation” (an equation shows a styrene monomer and a reaction arrow to two C atoms not joined by chemical bonds.)

definitions : addition polymer, polymerisation.
2 marks
Q7b(ii) “Carbon neutral fuels do not increase the amount of carbon dioxide in the atmosphere. Suggest why using a biofuel, such as ethanol or rapeseed oil, is thought to,be carbon neutral.”

definition : carbon neutral
2 marks
Totals 5 marks (8% of paper) 9 marks (15% of paper)


Unit 2
Direct Definition Marks Indirect Definition Marks
Q3c(i) “Which ion makes ammonia solution alkaline?”

definition : alkali
1 mark Q1a(ii) “State the type of energy transfer for this reaction.” (candidates are given a table of data where temperature falls during an experiment)

definition : endothermic
1 mark
Q6b(i) “What is the purpose of gas chromatography?”

definition : chromatography
1 mark Q3c(ii) “Name the type of reaction between aqueous ammonia solution and an acid"

definition: neutralisation reaction
1 mark
Q6c(ii) “Name the ion which makes sulfuric acid solution acidic”

definition : acid
1 mark Q4c(i) “The student tried to electrolyse molten potassium chloride to produce potassium. Potassium metal was produced at the negative electrode. Describe how potassium atoms are formed from potassium ions"

definition : cathode
2 marks
Q6d “The atmosphere of Venus contains the isotopes 2H and 1H. Describe the similarities and differences in the isotopes 2H and 1H. You should refer to the sub-atomic particles in each isotope"

definition : isotope
3 marks
Totals 3 marks (5% of paper) 7 marks (12% of paper)


Unit 3
Direct Definition Marks Indirect Definition Marks
Q1a(ii) “Which ion causes the solution to be alkaline?”

definition : alkali
1 mark Q2a(ii) “Complete the sentences. The ethanoic acid is produced from the reaction between ethanol and ……. This type of reaction is ……."

definition : oxidation
1 of 2 marks
Q2a(ii) “Complete the sentences. The ethanoic acid is produced from the reaction between ethanol and ……. This type of reaction is …….”

definition : carboxylic acid
1 of 2 marks Q4a(iii) “Another student at the campsite boils some of the hard spring water in a pan. The inside of the pan becomes coated with a white solid. Explain how the white solid is produced.”

definition: temporary hardness
3 marks
Q2b(i) “Draw a ring round the functional group for this series (of organic compounds) on the displayed structure of propyl ethanoate” (a displayed structure of the molecule is shown)

definition : ester
1 mark Q4b(ii) “An ion exchange column is used for a few weeks. Sodium chloride solution now needs to be passed through the ion exchange column. Suggest why.”

definition : ion exchange
1 mark
Q2b(ii) “Name the series of organic compounds with this functional group”

definition : ester
1 mark Q6e(ii) “In the Haber process iron is used as a catalyst. Draw a line on the energy level diagram to show the effect of adding a catalyst” (an energy level diagram of an exothermic reaction with an activation energy hump is shown)

definition : catalyst
1 mark
Q4b(i) “Describe how an ion exchange column softens water”

definition : ion exchange
3 marks
Totals 7 marks (12% of paper) 6 marks (10% of paper)