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:

  1. put the independent variable on the x-axis and the dependant variable on the y-axis
  2. construct regular scales for the axes
  3. label the axes appropriate
  4. plot each point accurately
  5. decide whether the origin should be used as a data point
  6. 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.

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

The graph below shows the growth of two trees (A and B) during a period of 10 years.

Graph showing the difference in heights of two trees
Question

Give the difference in height between trees A and B at 10 years. [1 mark]

2.5 [1]

This number is generated by finding the height of both trees at 10 years on the graph and subtracting one from the other. In this case tree A = 5 m and tree B = 2.5 m, so 5 - 2.5 = 2.5 m difference in height between the two trees.

Question

The mean (average) growth rate of tree A over 10 years was 0.5 m per year.

Calculate the mean growth rate for tree B. [1 mark]

0.25 [1]

As the tree grew 0.25 m in 10 years the mean growth rate for the tree will be 0.25 ÷ 10 = 0.25 m per year.

Sample question 2 - Foundation

The height of 100 boys were measured on their 15th birthdays.

The results are shown in the table below.

Height (cm)Number of boys
150-1595
160-16916
170-17919
180-18925
190-19930
200-2095
Question

i) Draw a bar chart of the results on the grid below.

Blank graph with the axes labelled. Y axis is number of boys, x axis is their heights in cm

ii) The mean height of the boys was 180 cm.

Calculate the number of boys who were less than the mean height.

i)

Bar graph showing the heights of 100 boys on their fifteenth birthday

Marks will be awarded if all 6 bars are drawn to the correct height ±½ small square tolerance on height. Marks will not be deducted for uneven width bars although it is good practice to make them the same width and in this case as continuous data is shown the bars should be touching.

ii) 40

Question

Choose the correct word to fill in the blank in the sentence below.

age, diet, genes

The method used shows that variation in heights cannot be due to differences in __________.

Age

Sample question 2 - Higher

A high level of blood cholestrol increases the risk of heart disease. One cause of high blood cholestrol is the inherited condition known as FH (familial hypercholesterolaemia).

FH is caused by a dominant allele (B). The recessive form of this allele (b) results in low levels of cholestrol (non-FH).

Question

State the meaning of the terms:

i) allele [1 mark]

ii) recessive [1 mark]

i) One version of a gene [1]

ii) In a heterozygous organism the allele that is not expressed [1]

Question

i) Complete the Punnett square below to show the possible genotypes of the children produced by parents both of whom are heterozygous for FH. [2 marks]

Use the letters B and b.

Gametes

ii) What is the probability of two heterozygous parents producing a child with FH? [1 mark]

iii) What is the phenotypic ratio of the children produced? [1 mark]

i) Gametes correct [1] and mechanisms of cross correct [1]

GametesBb
BBBBb
bBbbb

ii) 75% / 0.75 / ¾ / 3 in 4 [1]

The probability can be given as a percentage or a fraction but not a ratio.

iii) 3 : 1 [1]