This is the part of an investigation where you get to think like a scientist rather than follow a recipe. You start with something you are curious about, read enough to understand what is already known, and end up with one sharp question and a prediction you can actually justify. Most weak investigations were lost right here, before any equipment came out of the cupboard.
📘 What you need to know
Exploring means turning curiosity plus existing biology into a focused research question and a testable hypothesis.
A strong investigation has one independent variable and one dependent variable, explored properly.
Background research first. It gives you the theory, values to compare against, and a method that works.
A research question must be focused and specific, and must state the link between the two variables.
A hypothesis is not a guess. Use “if…, then…, because…”, where the “because” is real biology.
Check feasibility early — equipment, organisms and time — and be willing to change your idea.
From a vague interest to a testable question
Nobody starts with a perfect research question. Everyone starts with something loose, like “I want to know how light affects plants”. The work is in narrowing that down until it is something you can actually measure in a school lab.
Notice the hypothesis comes last. Students who write the prediction first usually end up bending the question to fit it.
Showing independent thinking
Plenty of investigations start from a standard class experiment, and that is fine. What lifts one above the rest is doing something slightly your own with it.
The easiest way to show that is to make the question comparative. Instead of “how does temperature affect catalase activity”, ask how the source of the catalase changes the answer — potato against celery, say. Now you are thinking about the link between an organism’s environment and how its molecules behave, which is a genuinely biological idea rather than a procedural one.
The most common mistake is the opposite one: trying to investigate too much. A question like “how do light intensity and carbon dioxide concentration affect photosynthesis?” contains two investigations. Pick one factor and do it properly.
Consult a variety of sources
Background reading is not decoration for the introduction. It does three specific jobs:
It gives you the theory, so your “because” is real biology rather than a guess.
It gives you established values to compare your results against — a known optimum, a published rate.
It gives you a method that works, and often warns you about the step everybody gets wrong.
Sensible sources include your own notes, your textbook, the IB data booklet, and reliable scientific databases for research papers or genetic sequence data. What matters is that you can say where a claim came from.
If your research turns up a known value — an optimum pH, a typical rate — write it down. Comparing your result against it at the end is one of the easiest ways to show you understood the biology.
Writing the research question
A research question is focused, specific, and states the relationship being tested. “How do abiotic factors affect plants?” fails all three.
Adding the scientific name matters more than it looks. Pondweed could be several species, and different species give different rates.
WORKED EXAMPLE
Broad idea: “I want to see how light affects photosynthesis.” Turn this into a focused research question.
Step 1: what will you actually change, and how?
Light intensity, changed by moving a lamp to set distances from the plant.
Step 2: what will you measure, and how?
Rate of photosynthesis, measured as oxygen bubbles produced per minute.
Step 3: name the organism and state the range
Pondweed, Elodea canadensis, with the lamp at 10, 20, 30, 40 and 50 cm.
What is the effect of lamp distance (10–50 cm) on the rate of oxygen bubble production in pondweed, Elodea canadensis?Everything vague has gone. Anyone could pick this up and set it up the same way tomorrow.
Writing the hypothesis
Here is the distinction that decides marks. “If temperature increases, enzyme activity will increase” is a prediction — it says what will happen. A hypothesis also says why, using established biology.
A good “because” also tells you what shape of graph to expect, which makes your results much easier to discuss later.
WORKED EXAMPLE
Write a full hypothesis for the pondweed investigation above.
If — the change you make
If the lamp is moved closer to the pondweed, so light intensity increases…
Then — what happens to what you measure
…then the number of oxygen bubbles produced per minute will increase, and will eventually level off…
Because — the biology behind it
…because light provides the energy for the light-dependent reactions, so more light means more ATP and reduced NADP for carbon fixation. Above a certain intensity, light stops being the limiting factor and something else, such as carbon dioxide, limits the rate instead.
Prediction + justification = a scientific hypothesisNotice the “then” predicts a shape, not just a direction. That is what makes it properly testable.
WORKED EXAMPLE
A student proposes: “How do temperature and pH affect how fast yeast respires?” Explain the problem and improve the question.
The problem
There are two independent variables. If the rate changes you cannot tell which one caused it, so no clear conclusion is possible.
The fix: choose one, and control the other
Keep pH constant with a buffer, and investigate temperature alone.
The improved question
What is the effect of temperature (10, 20, 30, 40 and 50 °C) on the rate of carbon dioxide production by yeast, Saccharomyces cerevisiae?
One IV, one DV, a stated range, a named organismThe variable you dropped is not wasted — it becomes a controlled variable, and you explain how you held it steady.
Checking it is actually possible
A beautiful research question you cannot carry out is worth nothing. Before you commit, check three things.
🧩 The feasibility check
Equipment — does your school have it, and can you book it? A colorimeter you cannot get hold of is not a plan.
Organisms — can you get enough, of similar age and size, when you need them?
Time — plants and germination take days or weeks, not one lesson. Count the total number of runs and multiply by how long each takes.
Expect to change your mind. Your reading may show the first idea will not work, or a pilot run may show the reaction finishes in three seconds. Changing the question in response to what you learn is not failure — it is what scientists do.
When you are stuck for an idea
Start from something odd you saw in a class practical. A result nobody could explain is an excellent starting point.
Change one thing in a standard lab — a different enzyme, a different organism, a different tissue.
Apply a concept to a real problem — how salinity affects germination matters to farming near the coast.
Look for a comparison. Two species, two tissues, two habitats. Comparisons almost always produce more interesting discussion than a single curve.
💡 Exam tip
One independent variable. If your question has an “and” in the middle, cut it.
Put the range in the research question, not just the variable name.
Name the organism, with its scientific name in italics.
Say how the dependent variable will be measured — “rate” alone is not measurable, “bubbles per minute” is.
Always write the “because”. A prediction without justification loses the mark that matters most.
Reference the sources that shaped your question; it is the evidence you did the exploring.
⚠ Common mix-up
Confusing a prediction with a hypothesis. The “because” is the difference.
Two independent variables hiding in one question.
A research question with no range, so nobody knows what you actually tested.
A “because” that just restates the prediction — “because more light means more photosynthesis” explains nothing.
Choosing a question before doing any reading, then discovering the known optimum sits outside your range.
Ignoring feasibility until the week you were meant to collect data.
Up next: Designing an Investigation — turning that question into a method someone else could follow exactly, with the range, the repeats and the apparatus all justified.
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