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5.2.1Tools

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

5 min read 5 parts Lesson 5 of 10

📚 IB Biology HL Hub / Topical Revision
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Part 1 of 5Sensors and Data Loggers

5.2.1 Applying Technology to Collect Data in Biology
Sensors
  • Input devices that detect a change, for example in temperature, light, pH, oxygen, carbon dioxide or heart rate,
    • and turn it into an electrical signal.
Data logger
  • A device that records the signals from sensors at set time intervals and stores the readings or sends them to a computer.
Continuous monitoring
  • Readings can be taken for hours or days, even when no one is present, such as night-time respiration in a pond.
Sampling interval
  • The time between readings must be short enough to show rapid changes but long enough to avoid too much data.

Part 2 of 5Digital Imaging and Remote Collection

Digital Imaging and Remote Collection
Digital microscope
  • A camera on a microscope records images that can be measured and shared, which helps when counting cells or measuring structures.
Time-lapse
  • Images captured at regular intervals show slow processes such as germination, growth or cell division.
Camera traps
  • Motion-activated cameras record wildlife without disturbing it, giving data on species presence and behaviour.
GPS tracking
  • Tags on animals record positions, which show migration routes and habitat use over time.
Spectrophotometry
  • Light absorbance is measured electronically, which can be calibrated to find the concentration of a solution.

Part 3 of 5Using Technology Well

1
Choose the sensor that matches the variable and the range expected, and check that it can measure to the resolution needed.
2
Calibrate the sensor against a known standard before use, for example a pH buffer solution.
3
Set the sampling interval and total duration to suit the speed of the process being studied.
4
Check the first readings for sensible values and make sure that the probe is fully in contact with the sample.
5
Save the file with a clear name and note the units, sampling rate and calibration in the lab notebook.
AdvantageLimitation
Frequent, objective readingsExpensive equipment
Remote or long recordingsSensors need calibration and can drift
Large data sets easily sharedRequires power and technical skills

Part 4 of 5Worked Example

Question

  • A data logger records oxygen concentration every 5 seconds for 10 minutes.
  • How many readings are taken during the 10 minutes, not counting the one at the start?

  1. Convert 10 minutes to seconds: 10 × 60 = 600 s.
  2. Divide by the sampling interval600 ÷ 5 = 120.
  3. If the reading at time zero is counted too, the total is 121.

Answer 120 readings after the start (121 including the reading at zero).

Part 5 of 5Exam Checklist & Tips

5.2.1 – Key Points for the Exam

  • Sensor A device that converts a physical or chemical change into an electrical signal.
  • Data logger A device that records sensor readings over time.
  • Sampling rate How often a reading is taken.
  • Calibration Adjusting an instrument against a known standard.

Common Mistakes

  • Assuming that electronic readings are always accurate without being calibrated.
  • Choosing a sampling interval too long to detect fast changes.
  • Forgetting to record units and sampling conditions with the data.
  • Thinking that more readings always mean better data, regardless of whether they are relevant.

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