A-Level Edexcel Biology Ratios and Percentages

Review A-Level Edexcel Biology ratios, fractions and percentages through biomass, disease data, surface-area-to-volume ratios and biological comparisons.

Exam points

calculate percentage change, decrease or difference from graph and table values
express biological comparisons as ratios such as SA:V, trophic energy or ion concentration
use fractions or percentages to find biomass, cell counts, deaths or energy conversion

[Maximum number: 2]

People can be infected by a number of different pathogens.

(a)

Pathogens can enter the digestive system in contaminated food or water.

[ 2 ]

(i)

Salmonella are bacteria that can cause food poisoning.

The chart shows the proportions of contaminated foods responsible for food poisoning caused by Salmonella in the European Union.

Figure for Question (i) — Edexcel A-Level Biology A2

The inside angle of the section representing poultry is $104^{\circ}$ .
Which percentage, to three significant figures, is caused by contaminated poultry?

A 28.0%
B 28.8\%
C 28.9\%
D 29%

[ 1 ]

(ii)

A group of people ate some food contaminated with Salmonella.

The table gives the time after eating the meal that people showed the first signs of food poisoning.

Table for Question (ii) — Edexcel A-Level Biology A2

The total number of people showing signs of food poisoning was 184.
Calculate the percentage showing signs of food poisoning in the first 24 hours.

[ 1 ]

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A.0.3—Ratios, fractions and percentages question 1

Question (a)

Question (i)

Question (ii)