General Skills Required Flashcards
Give one precaution taken to ensure that the results would be valid?
To improve validity, only the one variable being investigated should be altered while the other variables should be kept constant.
Describe a suitable control?
The control should be identical to the original experiment apart from the one factor being investigated.
Give possible examples of variables that need to be controlled and kept constant to ensure results would be valid?(9)
Temperature pH Concentrations Mass Volume Length Number Surface area Type of tissue
Explain why a control experiment would be necessary ?
A control experiment allows a comparison to be made and allows you to attribute any change or difference in the results to the factor or variable being altered.
Why is it good experimental procedure to….?
If the effect of temperature on enzyme activity is being investigated, it is good practice to allow solutions of enzyme and substrate to reach the required temperature before mixing them to ensure that the reaction starts at the experimental temperature.
It is good experimental practice to use a percentage change when you are comparing results because this allows a fair comparison to be made when the starting values in an investigation are different.
Give possible examples of precautions to minimise errors?
Washing apparatus such as beakers/syringes, or using different ones if the experiment involves different chemicals or concentrations.
This prevents cross-contamination
Why is the experiment left for a certain time - this requires you to state that this allows enough time for particular events to take occur. Give examples. (4)
Diffusion or absorption of substances into tissue
Growth taking place
Effects of substances becoming visible
A reaction occurring
Give a reason for the experiment being repeated ?
To improve reliability of experiments and the results obtained, the experiment should be repeated.
