Revise Safety, Risk Assessment & Ethics for Biology 3 (IAL) WBI13 (AS Level) — revision notes and instant AI marking. Free to start.
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Edexcel IAL Biology • Unit 3: Practical Skills in Biology I
Safety, Risk Assessment & Ethics
⚠️ Big idea: A risk assessment is not a list of hazards — it is a set of matched pairs. For every hazard you name, you must say what harm it could do and what specific precaution reduces it. Marks are awarded for the pairing, never for the list.
Summary — What This Topic Covers
The difference between a hazard and a risk
Writing a risk assessment that pairs hazard → harm → precaution
The hazards that come up repeatedly in the Core Practicals
Handling living organisms and microorganisms responsibly
Ethical considerations in fieldwork and in work with animals
1. Hazard vs Risk
Key Terms
A hazard is something with the potential to cause harm — a hot water bath, a scalpel, a corrosive solution.
A risk is the likelihood that the hazard actually causes harm, in the way you are using it.
Concentrated acid in a sealed bottle on a shelf is a serious hazard at low risk. The same acid being poured by a class of thirty is the same hazard at much higher risk. Precautions reduce the risk; they rarely remove the hazard.
Analogy
A lion is a hazard whether it is asleep or not. The risk is what changes when you walk into the enclosure.
2. Writing a Risk Assessment That Scores
The structure
Every line must have three parts: hazard → the harm it could cause → a specific precaution.
✗ "Wear goggles." ← precaution with no hazard
✗ "Hot water is dangerous." ← hazard with no precaution
✓ "The water bath at 80 °C could scald the skin, so tubes are moved
with tongs and the bath is placed away from the bench edge."
✓ "Iodine solution is an irritant and can stain or irritate the eyes,
so safety goggles are worn and spills are rinsed with water."
Where students lose the marks
Writing "be careful" or "handle with care". These name no action. A precaution has to be something an examiner can picture you doing.
3. The Hazards That Recur in the Core Practicals
HAZARD HARM PRECAUTION
──────────────────────────────────────────────────────────────────────
Scalpel / sharp blade deep cuts cut away from the body,
on a tile, not in the hand
Water bath 60-80 °C scalds tongs; bath away from edge
Bunsen flame burns, fire tie hair back, safety flame
when not heating
Benedict's solution irritant to eyes/skin goggles; wash off spills
Iodine solution irritant, stains goggles; rinse with water
Ethanol highly flammable no naked flames; water bath
only
Glassware cuts from breakage check for cracks; sweep up,
never pick up by hand
Microorganisms infection aseptic technique; tape lids;
incubate below 30 °C
Ethanol and flames
Ethanol is used in several practicals and is highly flammable. It must be heated in a water bath, never over a Bunsen. This pairing appears in mark schemes repeatedly.
4. Working with Microorganisms
Culturing microorganisms carries its own rules, and they are examined as a set.
Work near a Bunsen flame — the convection current carries airborne contaminants upwards, away from the plate
Flame the loop before and after use, and let it cool before touching the culture
Lift the lid of the Petri dish at an angle, only as far as needed, and for as short a time as possible
Seal with tape at two or four points — never all the way round, which would create anaerobic conditions favouring dangerous species
Incubate at 25 °C or below in schools, so organisms that thrive at human body temperature are not selected for
Why 25 °C
Human pathogens grow best at around 37 °C. Incubating below 30 °C deliberately avoids favouring organisms that could infect people — this is a safety decision, not a biological convenience.
5. Ethics — Organisms and Fieldwork
Ethical points are marks in planning questions, and they are cheap to earn if you know what to say.
Use the minimum number of organisms needed for a valid result
Cause no unnecessary harm or stress — handle gently, keep out of water for the shortest possible time, return to the same place
Invertebrates collected for study should be returned to their habitat unharmed after the investigation
In fieldwork, minimise trampling and damage to the habitat; leave the site as you found it
Obtain permission before sampling on private or protected land
Easy marks
One sentence on returning organisms unharmed and one on minimising habitat damage will pick up the ethics marks in almost any fieldwork planning question.
Practice Questions
Practice Question 1
Distinguish between a hazard and a risk, using an example from a practical you have carried out.
Practice Question 2
A student writes "Iodine is dangerous so be careful." Rewrite this as a risk assessment entry that would gain credit.
Practice Question 3
Explain why school microbiological cultures are incubated at 25 °C rather than 37 °C, and why Petri dish lids are taped at only two or four points.
Practice Question 4
A student plans to investigate the distribution of invertebrates in a stream. State two ethical considerations they should include.
What to Memorise
Hazard = potential to harmRisk = likelihood of harmEvery entry: hazard → harm → precautionNever "be careful"Ethanol → water bath, never a flameFlame the loop, angle the lidTape at 2 or 4 points, not all roundIncubate below 30 °CReturn organisms unharmed
Concepts Checklist
Exam Tips
What mark schemes look for
Three parts to every entry: the hazard, the harm it could cause, and a precaution someone could actually carry out. Two out of three usually scores nothing.
The trap
"Wear goggles" on its own is a precaution attached to no hazard. Name what you are protecting yourself from.
Easy marks
Ethanol heated in a water bath rather than over a flame, and plates incubated below 30 °C, are two answers that recur across papers. Learn them as pairs.
Worth remembering
Ethics marks are among the easiest in a planning question and among the most often skipped. One sentence on organisms, one on the habitat.