Experiment Vocab Flashcards
Ordered variables
Non numerical data can be ranked on a scale (eg abundant, common, rare)
Categorical variable
Values are described by labels or categories (eg eye colour)
Discrete variable
Data that can only be whole numbers (eg number of children)
Continuous variable
Variable that can have any numerical value (eg height)
Independent variable
Variable that is changed by the researcher in an experiment
Dependant variable
Variable that is measured by the researcher
Control variable
Variable that is kept constant by the researcher
Valid
An experiment that is controlled and had only one independent variable
Reliable
An experiment with consistent results
Accurate
Results are close to true value
Precise
Data have a high degree of detail
Why make an experiment valid, and how?
Why: changing other variables could affect the results
How: keep other variables constant (the same)
Why make an experiment precise, and how?
Why: obtain a more accurate (closer to the true value) result
How: use an instrument that measures to a high degree of detail
Why make an experiment reliable , and how?
How: repeat experiment, compare results with those of others
Why: repeating experiments helps you spot anomalous results and to obtain an average from the non-anomalous results
How would you make an experiment accurate?
Use correct equipment and method for experiment (eg weighing scales that ate calibrated correctly)
How can you test for heat production during respiration
Using germinating peas in vacuum flasks
Control
A control experiment is when the independent variable (the one you do or change) is omitted from the experiment so you can compare the result to the experiment with the independent variable
How to test for carbon dioxide during respiration
Turns limewater cloudy
3 ways to demonstrate osmosis
Membrane bags
Potato tissue
Observing plant cells
Test for starch
Reddish-brown iodine solution turns blue-black with starch
Test for glucose
Blue benedict’s solution turns orange-red when heated
Determine energy content of a food sample
Burn it and use it to heat a measured sample of water
Why should you use a water bath to heat a test tube of water, rather than heating it directly in a Bunsen flame?
To avoid the heated liquid jumping out of the tube
