Science calculations
Maths questions often start with the command words 'calculate' or 'determine'. They will then have a blank space for you to show your working. It is important that you show your working; don't just write the answer down. You might earn marks for your working even if you get the answer incorrect.
In some maths questions you will be required to give the units. This may earn you an additional mark. Don't forget to check whether you need to do this.
Maths questions might include graphs and tables as well as calculations. Don't forget to take a ruler and calculator.
If drawing graphs, make sure you:
- put the independent variable on the x-axis and the dependant variable on the y-axis
- construct regular scales for the axes
- label the axes appropriate
- plot each point accurately
- decide whether the origin should be used as a data point
- draw a straight or curved line of best fit
If you are asked to calculate an answer and it has lots of decimal places, don't forget to use the same number of significant figures as the data in the question. For example, if two significant figures are used in the question, then usually your answer would also be to two significant figures. Don't forget to check your rounding.
Sample question 1 - Foundation
Question
Some students are investigating lichens. Lichens are often studied because they are sensitive to pollution. The students decide to use lichens to try and work out how polluted their school grounds are. They read about a scale called the Lichen Diversity Value (LDV).
The students put their results in a table showing the number of lichens in each quadrat.
| Tree number | North quadrat | East quadrat | South quadrat | West quadrat |
| 1 | 3 | 11 | 18 | 7 |
| 2 | 4 | 12 | 17 | 8 |
| 3 | 5 | 10 | 15 | 12 |
| 4 | 4 | 15 | 12 | 9 |
| Mean | 4.0 | 12.0 | 15.5 |
| Tree number | 1 |
|---|---|
| North quadrat | 3 |
| East quadrat | 11 |
| South quadrat | 18 |
| West quadrat | 7 |
| Tree number | 2 |
|---|---|
| North quadrat | 4 |
| East quadrat | 12 |
| South quadrat | 17 |
| West quadrat | 8 |
| Tree number | 3 |
|---|---|
| North quadrat | 5 |
| East quadrat | 10 |
| South quadrat | 15 |
| West quadrat | 12 |
| Tree number | 4 |
|---|---|
| North quadrat | 4 |
| East quadrat | 15 |
| South quadrat | 12 |
| West quadrat | 9 |
| Tree number | Mean |
|---|---|
| North quadrat | 4.0 |
| East quadrat | 12.0 |
| South quadrat | 15.5 |
| West quadrat |
The LDV is found by adding together the four mean values.
The students calculate the mean number of lichens on the north, east and south sides of the trees.
Calculate the mean for the west side and use this is calculate the LDV. [2 marks]
OCR Gateway, GCE Biology, Paper J247, 2016.
Mean for west side = (7 + 8 + 12 + 9) ÷ 4 = 9.0
LDV = 4.0 + 12.0 + 15.5 + 9.0 = 40.5
Show all your working and make sure it is clear which number is your answer for the mean for the west side and which number is your answer for the LDV.
OCR Gateway, GCE Biology, Paper J247, 2016.
Sample question 2 - Foundation
Question
Some students measured the temperature inside a compost heap. They also measured the external temperature. On five occasions they mixed up the compost heap with garden forks. The graph shows their results.
The rate of temperature increase is greatest before the compost is mixed for the first time. Explain how the rate of temperature change can be calculated. [1 mark]
OCR Gateway, GCE Biology, Paper J247, 2016.
Change in temperature ÷ time OR tangent drawn from line and used to calculate rate
Sample question 3 - Higher
Question
A group of ladybirds ate 752 grams of aphids. The biomass of the ladybirds was 235 grams. Calculate the percentage efficiency of biomass transfer. [2 marks]
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
% energy efficiency = (235 ÷ 752) × 100
= 31.3 % energy efficiency
Your answer should be given to 3 significant figures as the data in the question has three significant figures.
