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6.2.1Inquiry Process

Collecting Data in Biology — IB Biology SL Revision Notes & Topical Questions

5 min read 5 parts Lesson 6 of 10

📚 IB Biology SL Hub / Topical Revision
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Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
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Part 1 of 5Quantitative Raw Data

Raw data are the direct measurements made during the experiment, recorded before any calculation.

Table title
  • Table title Give the table a specific title that says what was measured and under what conditions.
Headers
  • Headers Put the quantity, unit and uncertainty in the column heading so the numbers in the body of the table stand alone.
Precision
  • Precision Record every reading to the precision of the instrument, so a balance reading to 0.01 g gives 1.50 g, not 1.5 g.
Raw only
  • Raw only The first table must contain only measured values, with no means, differences or other calculations.
Enough data
  • Enough data Collect at least five values of the independent variable with repeats at each, ideally five trials in biology.

Part 2 of 5Qualitative Observations

Observations that are not numbers often explain why the numbers behave as they do.

Qualitative Observations
Tissue state
  • Tissue state Note whether plant tissue feels firm and turgid or soft and limp, since this shows water gain or loss.
Appearance
  • Appearance Record colour changes, cloudiness or clearing, because they help interpret enzyme and indicator results.
Behaviour
  • Behaviour Record how organisms respond, such as woodlice moving towards or away from light or damp areas.
Use later
  • Use later Observations become evidence in the analysis and evaluation when results are unexpected.

Part 3 of 5Problems During Collection

Experiments seldom run perfectly, so problems must be noticed, recorded and handled openly.

1
If a reaction is too fast or too slow to time, adjust the concentration and record the change and the reason.
2
If one repeat differs greatly from the others, keep the value in the table and flag it as a possible anomaly.
3
Carry out an extra trial for that condition so there are enough concordant results to calculate a reliable mean.
4
If organisms are absent or inactive, reconsider the sampling site or conditions and note the decision made.
5
Keep dated lab notes of every change so the final report describes what was really done.

Part 4 of 5Worked Example

Question

  • A student tests 5 sucrose concentrations with 3 potato cylinders each, measuring the mass of every cylinder before and after soaking on a balance reading to 0.01 g.
  • How many readings are needed, and how should a mass of 1.8 g be written?

  1. Cylinders needed = 5 concentrations × 3 replicates = 15 cylinders.
  2. Each cylinder needs an initial and a final mass, so readings = 15 × 2 = 30.
  3. The balance reads to two decimal places, so every value must show two decimal places.
  4. A mass of 1.8 g must therefore be recorded as 1.80 g, with the uncertainty ±0.01 g in the column heading.

Answer 30 mass readings, with 1.8 g recorded as 1.80 g and the uncertainty shown in the header.

Part 5 of 5Exam Checklist & Tips

6.2.1 – Key Points for the Exam

  • Raw data Direct measurements recorded during the experiment before any processing.
  • Quantitative data Numerical data obtained by measurement.
  • Qualitative data Non-numerical observations such as colour, texture or behaviour.
  • Anomalous result A measurement that does not fit the pattern of the other repeats.
  • Replicate A repeat of the same treatment to check consistency.

Common Mistakes

  • Putting calculated values, such as differences or means, in the raw data table.
  • Writing units after every number in the table instead of once in the column heading.
  • Recording readings to fewer decimal places than the instrument can show.
  • Deleting an unusual result instead of recording it and repeating the trial.

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