Practical and Investigative Skills: Doing Biology Safely and Well
What you must understand
Practical skills are assessed through your ability to plan, conduct, record and evaluate hands-on biology. You need competence with common techniques: using a light microscope and preparing wet mounts, aseptic technique, using a colorimeter or spectrophotometer, measuring with pipettes and balances, preparing dilutions and standard curves, and handling living or biological material responsibly. You must also know how to write a risk assessment, keep a clear logbook, present raw data and processed data in appropriate tables and graphs, and evaluate sources of error.
Traps that appear in questions
- Describing a technique without its purpose (e.g., flaming a loop prevents contamination).
- Forgetting units, significant figures or axis labels in data presentation.
- Ignoring ethical and safety requirements for living organisms or human samples.
- Calling random error a mistake; distinguish random variation from systematic error.
- Failing to explain how a control or blank is used in colorimetric or dilution work.
- Omitting a conclusion that links back to the hypothesis.
Worked example and rule of thumb
To build a standard curve, prepare a series of known concentrations, measure absorbance for each, plot concentration on the x-axis against absorbance on the y-axis, and fit a line of best fit. Then read unknown concentrations from the curve. A blank sets the zero-absorbance reference. Rule of thumb: every practical answer should name the technique, state its purpose, and note one way to improve reliability or reduce error.