Learning focus
Develop transferable AO3 skills: plan, measure, record, process, interpret and evaluate biological investigations accurately and safely.
Scientific questions
A useful experimental question identifies a relationship that can be tested. “How does temperature affect amylase activity?” is testable because temperature can be changed and activity can be measured. “Why are enzymes important?” is too broad for one controlled investigation.
Hypotheses
A hypothesis is a testable explanation or proposed relationship. It should be biologically plausible and specific. For example, increasing temperature towards an optimum will increase amylase rate because particles have more kinetic energy and collide more frequently.
Predictions
A prediction states the expected result if the hypothesis is correct. It should identify the direction or pattern of change. Predictions may include a plateau, optimum or threshold rather than assuming a straight-line relationship.
Evidence and revision
Results may support a hypothesis, fail to support it or be inconclusive. A single experiment rarely proves a universal claim. Scientific reasoning remains open to revision when evidence is weak, anomalous or produced by an invalid method.
Practical or data skill
Turn five broad biology questions into testable experimental questions. For each, write an independent variable, dependent variable and directional prediction.
Examination tip
A prediction must be measurable. “The plant will be healthier” is vague; “mean shoot length will increase” is measurable.
Review questions and suggested answers
Question 1
What makes a question experimentally testable?
Suggested answer
It involves variables that can be changed and measured under controlled conditions.
Question 2
How does a hypothesis differ from a prediction?
Suggested answer
A hypothesis proposes an explanation; a prediction states the expected observation or result.
Question 3
Does supporting evidence prove a hypothesis?
Suggested answer
No. It supports it under the tested conditions but does not establish absolute proof.
