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Edexcel IAL Biology 6P.8 Processing practical data

Write the formula, convert quantities to compatible units, substitute unrounded values and report a suitably rounded result before interpreting the comparison.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
A2

Exam points

  • Calculate percentages, rates, ratios or differences from tables and graph values.
  • Substitute data into statistical or geometric formulas and retain working and units.
  • Compare processed values by stating ranked differences, similarities and biological meaning.

6P.8—Processing and analysing practical data question 1

[Maximum number: 2]

The photograph shows a young locust eating the leaves of a plant.

Figure for Question 6P.8—Processing and analysing practical data question 1 — Edexcel A-Level Biology A2

Locusts can breed in large numbers and destroy crops, such as sorghum, in East Africa. A scientist observed that some varieties of sorghum were more likely to be eaten by young locusts. The scientist collected the seeds of two varieties of sorghum (A and B) and grew them in trays. Locust eggs were collected and hatched into young locusts. Twenty young locusts were placed in a cage containing 100 g of fresh sorghum leaves of variety A. The cage was kept at 30C30^{\circ} \mathrm{C}. After 24 hours, the leaves were removed and the mass of leaves eaten was calculated. This method was repeated with fresh sorghum leaves of variety B. The method was repeated six times for these two varieties of sorghum leaves. The results: Mass of leaves eaten of variety A 17.317.217.517.016.716.9 Mass of leaves eaten of variety B 17.817.917.717.617.817.4

The student analysed the data using the t test formula:

t=(xˉAxˉB)(SA)2nA+(SB)2nBt=\frac{\left(\bar{x}_{A}-\bar{x}_{B}\right)}{\sqrt{\frac{\left(S_{A}\right)^{2}}{n_{A}}+\frac{\left(S_{B}\right)^{2}}{n_{B}}}}

Where: x\overline{\mathrm{x}} is the mean value for each treatment n is the number of samples for each treatment (SA)2=0.084\left(\mathrm{S}_{\mathrm{A}}\right)^{2}=0.084 and (SB)2=0.032\left(\mathrm{S}_{\mathrm{B}}\right)^{2}=0.032

Calculate the value of t.

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