ExpertEasy1 markMultiple Choice
AQA GCSE · Question 03.5 · Homeostasis and Response
What is a suitable control variable for the investigation?
What is a suitable control variable for the investigation?
Answer options:
A.
Keep each seedling at the same temperature.
B.
Keep each seedling the same height above the floor.
C.
Use the same size cardboard box for each seedling.
How to approach this question
A control variable is a factor that is kept the same for all groups in an investigation to ensure a fair test. The independent variable is the one you change (light direction), and the dependent variable is the one you measure (direction of shoot growth). Which of the options is a factor that could affect plant growth and therefore needs to be kept constant?
Full Answer
A.Keep each seedling at the same temperature.✓ Correct
Keep each seedling at the same temperature.
In a scientific investigation, control variables are factors that are kept constant to ensure that only the independent variable is affecting the dependent variable. In this experiment, factors that could affect the rate or direction of plant growth must be controlled. Temperature affects the rate of enzyme reactions involved in growth, so it must be kept the same for all seedlings. Other control variables would include the amount of water, the type of seedling, and the volume of soil/cotton wool.
Common mistakes
✗ Confusing control variables with the independent or dependent variables.
✗ Choosing a factor that has little to no impact on the experiment's outcome.
Practice the full AQA GCSE Biology Foundation Tier Paper 2
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