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5.2.2Tools

Applying Technology to Process Data in Biology — IB Biology HL Revision Notes & Topical Questions

5 min read 5 parts Lesson 6 of 10

📚 IB Biology HL Hub / Topical Revision
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Part 1 of 5Spreadsheets and Statistics

5.2.2 Applying Technology to Process Data in Biology
Calculations
  • Formulae in a spreadsheet calculate means, rates, percentages and totals quickly and consistently for large data sets.
Functions
  • Functions such as AVERAGE, STDEV.S, T.TEST, CORREL and CHISQ.TEST carry out statistical calculations.
Graphs
  • Charts are plotted from the data, with labelled axes, error bars and trend lines added using the program.
Checking
  • Entries must be checked for typing errors, and formulae should be tested on a few values worked by hand.

Part 2 of 5Specialist Software

Specialist Software
Image analysis
  • Programs such as ImageJ measure lengths, areas and counts in digital images, for example the area of a leaf or the number of cells.
Bioinformatics
  • Programs compare DNA and protein sequences and search databases, supporting studies of evolution and gene function.
Simulations
  • Computer models allow experiments that would be too slow, costly or dangerous, such as predicting population change.
Databases
  • Large shared collections of data allow results from many studies to be combined and compared.
Statistical packages
  • Software performs tests on bigger data sets and gives a p value directly.

Part 3 of 5Processing Data Step by Step

1
Enter raw data into columns with clear headings and units, keeping a separate copy of the original values.
2
Use formulae to calculate means, standard deviations and any rates needed, rather than typing results by hand.
3
Plot the data using an appropriate graph type, with correct axis titles and units.
4
Apply a suitable statistical test and note the test statistic, degrees of freedom and probability.
5
State clearly in the analysis which software tool was used and for which processing step.

Part 4 of 5Worked Example

Question

  • Five repeated measurements of leaf length (cm) are 12, 14, 15, 13 and 16.
  • Calculate the mean and the sample standard deviation.

  1. Mean = (12 + 14 + 15 + 13 + 16) ÷ 5 = 70 ÷ 5 = 14 cm.
  2. Deviations from the mean are −2, 0, 1, −1 and 2, with squares 4, 0, 1, 1 and 4.
  3. Sum of squares = 10; divide by n − 1 = 4 to give 2.5.
  4. Standard deviation = √2.5 = 1.58 cm.

Answer Mean 14 cm, sample standard deviation 1.6 cm (to 2 significant figures).

Part 5 of 5Exam Checklist & Tips

5.2.2 – Key Points for the Exam

  • Spreadsheet A program that stores data in cells and calculates with formulae.
  • Image analysis Using software to take measurements from digital images.
  • Bioinformatics Use of computing to analyse biological data such as sequences.
  • Simulation A computer model that imitates a biological system.

Common Mistakes

  • Relying on software output without checking whether the right test or data range was chosen.
  • Using population standard deviation when the data are a small sample.
  • Allowing the spreadsheet to round numbers early in a calculation.
  • Presenting a graph made by default settings without axis titles or units.

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