1. Maths and Graphs for Biologists
L.O: to use ratios, calculate percentage increase and percentage decrease
to improve graph vocabulary
Starter: We require a GCSE Maths grade B for Biology A Level… so why might you need good maths skills in Biology?

2. Using Ratios
Why?
How?

3. Using Ratios
Why?
Used for calculating proportions, e.g. sufferers of Cystic Fibrosis are more frequently female than male, in a ratio of 2:1

4. Using Ratios
Why?
Used for calculating proportions, e.g. sufferers of Cystic Fibrosis are more frequently female than male, in a ratio of 2:1. Population size = 200,000
How?
Step 1: Add the ratio together (x) (2 + 1 = 3)
Step 2: Divide the population size by x (200,000 / 3 = 66666)
Step 3: Multiply by the part of the ratio you are interested in (66666 x 2 = 13,3333)

5. Percentage Increase
Why?
How?

6. Percentage Increase Why?
Used to calculate the rise of diseases in populations, the effectiveness of medicines… etc… E.g. TB deaths in 1986 = 50,000 and rose to 86,000 in What is the % increase?

7. Percentage Increase Why?
Used to calculate the rise of diseases in populations, the effectiveness of medicines… etc… E.g. TB deaths in 1986 = 50,000 and rose to 86,000 in What is the % increase?
How?
Step 1: Find the two values ‘new’ and ‘old’ (86000 and 50000)
Step 2: Find the difference between these two values (86,000 – 50,000 = 36,000)
Step 3: Divide by the ‘old’ value (36000/50000 – 0.72)
Step 4: Multiply by 100 and remember to your units!
(0.72 x 100 = 72%)

8. Percentage Decrease
Why?
How?

9. Percentage Decrease Why?
Used to calculate the effectiveness of a medicine, the decline in disease, loss of white blood cells, red blood cells…etc!
How?
Step 1: Find the two values ‘old’ and ‘new’
Step 2: Find the difference between these values
Step 3: Divide by the ‘old’ value
Step 4: Multiply by 100 & remember your units! %

10. Remember to ask for help 
Exam Examples!
Solve the past exam questions on the sheet provided…
Your knowledge of the topic is not required, just your mega maths skills!
Remember to ask for help 

11. 5a Answers Standing up/fastest rate: 22.8 Sat down : 14.1
= 8.7
8.7 / 14.1 = 0.617
0.617 x 100
Answer = 61.7 / 62%

12. 5b Answers
118 – 30 = 88
88 / 118 =
x 100
Answer = 74.5 %

13. 5c Answers ‘old’/january = 1,800 ‘new’/august = 5,800
5800 – 1800 = 4000
4000 / 1800 = 2.222
2.222 x 100 = 222
Answer = 222%

14. 15 Answers ‘old’/sea level: 5.1 ‘new’/above sea level: 6.5
6.5 – 5.1 = 1.4
1.4 / 5.1 =
x 100 = 27.45
Answer = 27.5%

15. 4ci Answers ‘old’/1997: 20,000 ‘new’/2006: 33,500
33,500 – 20,000 = 13,500
13,500 / 20,000 = 0.675
0.675 x 100
Answer = 67.5%

16. 6aii Answers Add the ratio 1.5 + 1 = 2.5
Divide popn size 60,000 by 2.5 = 24,000
Multiply by 1.5 (24,000 x 1.5)
Answer = 36,000

17. 10ciii Answers ‘old’/1996: 9 ‘new’/2006: 14 14 – 9 = 5 5 / 9 = 0.5556
x 100 = 55.56
Answer = 55.56%

18. Command Words
Match up the command word to the correct explanation

19. 1 5 2 3 3 7 4 6 5 8 6 1 7 2 8 4

20. Graph Verbs! Split half a page of your notes into two columns.
At the top of one column write ‘up’ and at the top of the other column write ‘down’.

21. ‘Up’

22. ‘Down’

23. Graph Adverbs!
Adjective (describing word) + verb (‘doing’ word / action) = adverb!

24. Application of Knowledge