IB Biology SLSkill Set 1 — Experimental TechniquePaper 1 & 2Practical skill~8 min read
Safety, Ethics & the Environment
Every practical you do — in the lab, on a rocky shore, or with a spirometer strapped to a friend — comes with three questions you have to answer before you start. Could someone get hurt? Is it fair on the living things involved? And what happens to the mess afterwards? Examiners ask about all three, and the marks go to students who are specific.
📘 What you need to know
A hazard is something that can cause harm. A risk is how likely that harm is, and how bad it would be.
A risk assessment does three jobs: identify the hazard, assess the risk, then minimise it.
Hazard warning symbols are drawn as a red diamond on a white background. Nine of them exist; six turn up again and again in biology.
Work with animals only when there is no other way, keep any harm or distress to a minimum, and never be cruel.
Anyone taking part in an experiment as a human subject must give fully informed consent.
Waste has to leave the lab safely, and fieldwork has to leave the habitat roughly as you found it.
Hazard and risk are not the same word
Students mix these two up constantly, and it costs marks because the question usually asks for one of them, not both. Here is the difference in one line: the hazard belongs to the thing, the risk belongs to the situation.
Concentrated hydrogen peroxide is corrosive. That is a hazard, and nothing you do changes it — it is a property of the chemical. But the risk of it hurting you is small if you use a dilute solution in a small beaker with goggles on, and much larger if you pour the concentrated stuff into an open dish with bare hands. Same hazard, very different risk.
If a question asks you to name a hazard, name the thing. If it asks about risk, talk about how likely the harm is and how severe.
A quick test: if your sentence still makes sense when nobody is in the room, you have described a hazard. If it only makes sense when someone is doing something, you have described a risk.
Reading hazard warning symbols
Every chemical bottle carries symbols, and every safety data sheet repeats them. They are standardised, so the same picture means the same thing in any lab in the world. All of them sit inside a red diamond on a white background, and there are nine in total.
Check the bottle before you plan the practical, not after. The symbol is the quickest way to work out what precaution you need.
Symbol
What it warns you about
Where it shows up in biology
Health hazard
Irritates skin or eyes, or is harmful if swallowed
Iodine solution in starch tests
Corrosive
Burns skin, and can damage eyes permanently
Acid and alkali used to set pH for enzymes
Flammable
Catches fire near a flame or a hot surface
Ethanol in the emulsion test and in staining
Acute toxicity
Can be life-threatening even in small amounts
Some fixatives and older biological stains
Harms the environment
Damages aquatic life if it reaches waterways
Stains and metal salts — never down the sink
Oxidising
Feeds a fire, or starts one
Concentrated hydrogen peroxide in catalase work
Writing a risk assessment that earns marks
A risk assessment is not a paragraph about being careful. It has a shape, and if you follow the shape you cannot really go wrong.
🧩 The three moves, in order
Identify — name the hazard exactly. Not “chemicals”, but “iodine solution, which is an irritant”.
Assess — say how likely the harm is and how serious it would be. This is the step almost everyone skips.
Minimise — change something about the procedure so the harm is less likely or less severe, and say why that change works.
The lab coat trap. “Wear a lab coat and goggles” scores nothing on its own, because that is standard practice everywhere. The mark is for linking a named hazard to a precaution and explaining what the precaution prevents.
WORKED EXAMPLE
You are testing leaf discs for starch and will use iodine solution. Write a safety precaution that would get the mark.
Name the hazard first
Iodine solution is an irritant — it stings the eyes and stains and irritates skin.
Now the precaution, with the reason attached
Wear eye protection while pouring, and wash any splash off the skin straight away with plenty of water.
Why that works
Goggles stop the splash reaching the eye at all; washing removes the iodine before it has time to irritate.
Hazard named + precaution + reason = full marksCompare with “be careful with the iodine”, which names nothing and explains nothing.
WORKED EXAMPLE
Your class is using quadrats on a rocky shore. Give a full risk assessment for one hazard.
Identify
Rocks covered in wet seaweed are slippery.
Assess
Slipping is quite likely on a wet shore, and a fall onto rock could mean bruises, cuts or a twisted ankle.
Minimise
Wear footwear with a good grip, step around seaweed-covered rock rather than onto it, and walk slowly.
Likelihood lowered, severity loweredFieldwork answers work exactly like lab answers — same three moves, different setting.
Ethics: you are working with living things
Biology is different from the other sciences here. A lot of your practicals involve organisms that can feel stress, and the IB expects you to think about that before you plan, not after.
The IB policy on animals in schools is strict. Investigations should only involve animals when there is genuinely no alternative. If an animal has to be involved, the work must not be cruel, and you must build in steps that remove causes of distress.
First, ask if you need the animal at all. A simulation, a set of published data or a plant-based version often answers the same question.
Keep exposure short. A choice-chamber run of a few minutes is very different from leaving woodlice under a lamp all lesson.
Handle as little as possible, and gently. Every pick-up is a stress event.
Return them. Organisms collected from a habitat go back to that habitat when you have finished.
Humans count too. If your investigation involves people — measuring breathing rate with a spirometer, timing reaction speed, taking heart rate after exercise — every participant must give fully informed consent. Informed means they know what you will do, what it involves, and that they can stop at any point.
WORKED EXAMPLE
A student plans to investigate how light intensity affects woodlouse movement using a choice chamber. Outline two ethical points they should build into the plan.
Point 1 — limit the stress
Keep each run short and use low light levels, so the woodlice are not left in conditions that could dry them out or overheat them.
Point 2 — return them safely
Collect them from a damp, dark place and put them back there at the end, unharmed.
Notice both points name a real cause of distress and then remove it. Vague words like “treat them well” are not enough.Two clear, specific measures
Looking after the environment
Your investigation has an effect that carries on after you have packed up. In the lab that mostly means waste; in the field it means the habitat itself.
In the lab
Nothing toxic goes down the sink. Sink waste ends up in the water system, which is exactly what the environmental hazard symbol is warning you about.
Sharps go in a sharps bin — scalpel blades, broken slides, needles. Never in the general bin, where someone else will meet them.
Biological waste is treated before disposal. Petri dishes with bacterial growth and anything dissected have their own route out of the lab, usually autoclaving first.
In the field
Work in small groups so you trample less ground.
Stay out of sensitive spots — nesting areas, fragile dune systems, rare plants.
Take every bit of equipment and litter home with you, including string, tape and markers.
A good habit: before you leave a site, look back at it. If someone walking past could tell that thirty students were there an hour ago, you have made too much of a mark.
💡 Exam tip
Always name the hazard. A precaution with no named hazard rarely scores.
Say what the precaution prevents. That is the sentence the examiner is looking for.
Match your answer to the setting. A fieldwork question wants fieldwork hazards, not “wear gloves in the lab”.
If the question involves animals, mention both reducing harm and returning them.
For anything with human participants, the words informed consent are worth writing down.
In your internal assessment, safety, ethics and environmental impact should appear in your method — not bolted on at the end.
⚠ Common mix-up
Hazard written where risk is asked for. “Ethanol is flammable” is a hazard; the risk is how likely a fire is and how bad it would be.
“Wear a lab coat and goggles” as the whole answer. Standard practice, so no mark.
Thinking ethics only means animals. Human participants and habitats are ethical questions too.
Consent that is not informed. Someone agreeing without knowing what will happen has not given consent.
Assuming dilute means safe. Dilution lowers the risk; the hazard symbol on the bottle stays the same.
Tipping stains down the sink because they look harmless. Check the environmental symbol first.
Up next: Measuring Variables — choosing the right instrument, reading it properly, and knowing how much you can trust the number you wrote down.
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