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Getting started: maths, data and command words in biology
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About one in ten marks in GCSE Biology need maths. You also need to know what each command word is asking for.
Percentages
percentage = partwhole × 100
percentage change = new value − original valueoriginal value × 100
A positive answer is an increase; a negative answer is a decrease.
percentage change = new value − original valueoriginal value × 100
A positive answer is an increase; a negative answer is a decrease.
Reading graphs and tables
To describe a trend, say what happens to the dependent variable as the independent variable increases, and quote data with units.
Example: "As temperature increases from 10 °C to 40 °C, the rate rises from 2 to 8 bubbles per minute."
rate = amount ÷ time, for example cm3 of oxygen per minute.
Example: "As temperature increases from 10 °C to 40 °C, the rate rises from 2 to 8 bubbles per minute."
rate = amount ÷ time, for example cm3 of oxygen per minute.
Command words
State / Give / Name: a short answer, no reason needed.
Describe: say what happens or what something is like.
Explain: give reasons: say why or how, often using "because".
Calculate: use numbers; show your working and give the unit.
The number of marks tells you roughly how many points to make.
Describe: say what happens or what something is like.
Explain: give reasons: say why or how, often using "because".
Calculate: use numbers; show your working and give the unit.
The number of marks tells you roughly how many points to make.
A student's heart rate rises from 70 to 105 beats per minute after exercise. Calculate the percentage increase.
- Change = 105 − 70 = 35
- 3570 × 100
Answer: 50%
Percentage change = (new − original) ÷ original × 100. Describe trends with data and units. Describe says what; explain says why.
Check you have got it
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