This is the part everyone rushes and everyone regrets. A weak research question makes every later stage harder — you cannot design a clean method, and you cannot analyse data that was never worth collecting. Spend your time here and the rest of the investigation gets easier.
📚 What you need to know
Exploring means turning curiosity plus background reading into a focused question you can actually test.
Investigate one independent variable and one dependent variable, properly. Two at once is the classic mistake.
A good research question is focused and specific: it names the IV with its range, the DV with how you will measure it, and the organism.
Background research gives you the scientific context — the theory, values to compare against, and a method that works.
A hypothesis is not a guess. It predicts the outcome and justifies it with biology, using “If…, then…, because…”.
Without the “because”, you have only a prediction. The justification is what makes it scientific.
Check feasibility early: equipment, organisms, time. Be ready to change your idea.
Start ordinary, then add your own twist
You do not need a brand new idea. Almost every strong investigation starts as a standard class practical, with one thoughtful change made to it.
Take a familiar experiment: measuring how temperature affects the rate of an enzyme reaction. That is fine, but it is what everyone does. Now turn it into a comparison:
Does catalase from potato and catalase from liver have the same optimum temperature?
Does the pigment in beetroot leak at the same temperature in young and older tissue?
Does pondweed from a shaded pond respond to light differently from pondweed grown in full sun?
Each of these asks something about the link between an organism’s environment and how its biology works. That is what “insight” looks like to an assessor, and it costs you nothing extra in equipment.
Struggling to think of anything is completely normal. Two reliable starting points: a result from a class practical that surprised you or did not work, and a standard lab run on a different organism, enzyme or tissue. Neither is cheating — it is how real research usually begins.
Narrowing a broad idea down
Your first thought will always be too big. That is fine — the job is to funnel it down.
Most students jump straight from the top box to the bottom one. The middle stage is what makes the question specific enough to be worth answering.
Where to do the reading
Background research is not decoration. It does three jobs: it tells you the underlying theory, it gives you published values to compare your results against, and it points you at a method that actually works.
Your own notes and textbook — start here, they are pitched at the right level
The IB data booklet — for standard values and units
Scientific databases — PubMed for research papers, GenBank for gene and protein sequences
Practical guides from exam boards and universities — for tested methods and sensible ranges
What the reading buys you. If you know from your research that catalase works best somewhere near body temperature, you can choose a sensible range to test around it. Without that, you are guessing at your own experiment — and a range that misses the interesting part of the curve wastes the whole investigation.
What makes a research question good
A question like “How do abiotic factors affect plants?” cannot be answered. There is no single variable, no measurement and no organism. Compare it with a question that has all three built in.
Write the species name in italics the first time you use it. It is a small thing, but it signals that you are writing like a biologist.
Too vague
Why it fails
Focused version
How does temperature affect enzymes?
No range, no named enzyme, no measurement
What is the effect of temperature (20 to 60 °C) on the rate of oxygen production by catalase from potato?
Do plants grow better in the light?
“Better” is not measurable
What is the effect of daily light exposure (2 to 10 hours) on the mean height of cress seedlings after 7 days?
How do light and CO2 affect photosynthesis?
Two independent variables at once
Pick one. Investigate light intensity thoroughly, and control CO2.
From question to hypothesis
A hypothesis is a testable statement that says what you think will happen and why. The structure to use every time:
Hypothesis structure
If <the IV changes like this>, then <the DV will do this>, because <the biology>
Look at the difference the last part makes.
Prediction only: “If the temperature increases, the rate of reaction will increase.” True, but it could have been written by someone who has never studied biology.
Full hypothesis: “…because higher temperatures give molecules more kinetic energy, so enzyme and substrate collide more often and more successfully — until the temperature passes the optimum, when hydrogen bonds in the tertiary structure break, the active site changes shape and the enzyme denatures.”
The “because” must rest on established biology: enzyme structure, osmosis and water potential, diffusion, ecological interactions. That is where your background reading pays off.
If your “because” would still make sense with the biology words taken out, it is not a justification. “Because the rate goes up when it gets hotter” just repeats the prediction in different words.
Worked examples
WORKED EXAMPLE 1
Exploring a membrane investigation. Broad idea: “I want to know what damages cell membranes.”
Step 1: what the reading tells you
Beetroot cells hold a red pigment in the vacuole. If the membranes are damaged, pigment leaks out and colours the water.
Membranes are made of phospholipids and proteins. Heat increases molecular movement and can denature the membrane proteins, leaving gaps.Step 2: choose one variableTemperature, not temperature and pH togetherStep 3: the research question
“What is the effect of temperature (30 to 70 °C) on the leakage of pigment from beetroot (Beta vulgaris) discs, measured as absorbance at 530 nm?”
Step 4: the hypothesisIf the temperature is raised from 30 to 70 °C, then the absorbance of the surrounding water will increase, because higher temperatures increase the movement of phospholipids and denature membrane proteins, so the membrane becomes more permeable and more pigment escapes.
One IV, one measurable DV, a named organism and a biological reason
WORKED EXAMPLE 2
Exploring an enzyme investigation with a comparative twist. Broad idea: “Enzymes are in lots of different tissues.”
Step 1: find the interesting angle
Catalase breaks hydrogen peroxide into water and oxygen. It is found in many tissues, but those tissues live at different temperatures.
Step 2: turn it into a comparisonDoes the source of the enzyme change its optimum temperature?Step 3: the research question
“To what extent does the source of catalase (potato tuber or celery stalk) affect the temperature at which it produces oxygen fastest, over 20 to 60 °C?”
Step 4: the hypothesisIf catalase from the two sources is tested across the same temperature range, then both will show an optimum but the peaks may fall at different temperatures, because each enzyme has its own amino acid sequence and tertiary structure, so the temperature at which the active site starts to lose its shape is not the same in both.
A standard practical made comparative — same equipment, much better questionNote the IV here is still one thing: temperature. The source is a second condition, tested as two separate series.
WORKED EXAMPLE 3
Checking feasibility. A student proposes: “What is the effect of soil nitrate concentration on the biomass of oak saplings after one year?”
Step 1: is the biology sound?
Yes — nitrate is needed to make amino acids and proteins, so it should affect growth
Step 2: is it practical?One year is far too long, and oak saplings are large and slowStep 3: refine rather than abandon
Keep the biology, change the organism and the timescale
“What is the effect of nitrate concentration (0 to 20 mmol dm−3) on the mean dry mass of radish seedlings after 14 days?”Changing your idea after research is not failure. It is what the scientific process looks like — and assessors give credit for it.
💡 Exam tip
Write the question as one sentence containing the IV, its range, the DV, how it is measured, and the organism.
Use the “If…, then…, because…” structure and check that the “because” names real biology.
Name the species properly, in italics, the first time it appears.
Say which sources you used and what they told you — that is what shows scientific context.
One IV only. If your question has an “and” in the middle of it, split it.
Check equipment and time before you commit. Plant growth takes weeks; plan around that.
⚠ Common mix-up
Calling a prediction a hypothesis. No justification means no hypothesis.
Two independent variables in one question. You cannot tell which one caused the change.
Leaving the range out. “The effect of temperature” is not specific until you say from what to what.
Using an unmeasurable dependent variable such as “how healthy the plant looks”.
Doing the reading after choosing the question. The reading is what makes the question good.
Sticking with an idea you cannot actually carry out because you have already written it down.
Up next: Designing an Investigation — turning that question into a method detailed enough for someone else to repeat exactly.
Want this explained one-to-one?
Book a free session with an experienced IB Biology tutor and get your trickiest topics made simple.
