Factor that can change and be changed eg. Light, CO2, temperature, pH.
What is an independent variable?
The factor that is changed in an experiment.
What is a dependent variable?
The effect or outcome that you are measuring.
What is a controlled variable?
These are not allowed to change and are controlled by you.
What is a control experiment?
This differs in just one way from the main experiment. So if there is a difference in results it is due to the difference in this variable. (For comparative purposes)
What are the principles of experimentation?
Plan and design the experiment
Be aware of safety procedures
Select organisms at random
Use a large enough sample size
Use a control group
Use double blind testing
Change one factor at a time.
Measure changes
Analyse results
State possible sources of error
Repeat experiment
What are the limitations of the value of the scientific method?
Extent of our own basic knowledge
The basis of the investigation
Our ability to interpret results
It’s application to the natural world that is s always subject to change
Accidental discoveries
What does ethics refer to?
Ethics refers to whether issues are morally right or wrong eg. the use of animals to test cosmetics.
What are some other ethical issues included?
Abortion
Evolution
Cloning animals or humans
Use of stem cells from embryos to form new tissues and organs
Freezing sorry and embryos (Case June 2006)
What is double blind testing?
Where neither the organism tested nor the tester knows who’s getting the placebo.