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.
Edexcel questions courtesy of Pearson Education Ltd.
Sample question 1 - Foundation
Question
This is a table that shows the surface area (SA) to volume (V) ratio in three different sized cubes
| Cube size (cm) | Surface area / SA (sq cm) | Volume / V (sq cm) | SA:V ratio |
| 2 | 24 | 8 | |
| 4 | 96 | 64 | 1.5:1 |
| 6 | 216 | 216 | 1:1 |
| Cube size (cm) | 2 |
|---|---|
| Surface area / SA (sq cm) | 24 |
| Volume / V (sq cm) | 8 |
| SA:V ratio |
| Cube size (cm) | 4 |
|---|---|
| Surface area / SA (sq cm) | 96 |
| Volume / V (sq cm) | 64 |
| SA:V ratio | 1.5:1 |
| Cube size (cm) | 6 |
|---|---|
| Surface area / SA (sq cm) | 216 |
| Volume / V (sq cm) | 216 |
| SA:V ratio | 1:1 |
Calculate the SA:V ratio for the 2 cm cube. [2 marks]
24 梅 8 = 3
Ratio = 3:1
Sample question 2 - Higher
Question
A student recorded the change in oxygen levels in three containers of germinating peas (A, B and C) over a 30-minute period.
The unit they used was O2 used/ml.
The results are shown below.
A - 10 mins 0.8 ml, 20 mins 1.6 ml, 30 mins 2.4 ml
B - 10 mins 0.1 ml, 20 mins 0.1 ml, 30 mins 0.1 ml
C - No change
Complete the table for these results. [2 marks]
1 mark for a headed table with units
1 mark for putting the results in the right places
| A | B | C | |
| O2 used/ml at 10 mins | 0.8 | 0.1 | 0.0 |
| O2 used/ml at 20 mins | 1.6 | 0.1 | 0.0 |
| O2 used/ml at 30 mins | 2.4 | 0.1 | 0.0 |
| O2 used/ml at 10 mins | |
|---|---|
| A | 0.8 |
| B | 0.1 |
| C | 0.0 |
| O2 used/ml at 20 mins | |
|---|---|
| A | 1.6 |
| B | 0.1 |
| C | 0.0 |
| O2 used/ml at 30 mins | |
|---|---|
| A | 2.4 |
| B | 0.1 |
| C | 0.0 |
Question
Calculate the rate of oxygen consumption per second for the results in respirometer A. [2 marks]
2.4 梅 (30 脳 60)
= 0.0013 ml/second
Or 1.6 梅 (20 脳 60) = 0.0013 ml/second
Or 0.8 梅 (10 脳 60) = 0.0013 ml/second