Science Buddies: "Ask an Expert"

Hi there.
Today I got given a practical.
We have to test whether cleaning detergents can help extract DNA from an onion.
We have to list 3 independant and dependant variables.
I am so confused.
So the onion would be independant?
and the cleaning detergent dependant?
Or have I got this completely wrong.
Amber

Hi,

Your questions are very good. Here’s an explanation of independent and dependent variables:

When designing an experiment, the independent variable is the experimental parameter that is changed, while all other conditions are carefully controlled. The dependent variable is the measurable result that occurs due to the independent variable.

In your experiment, the type of detergent used could be one independent variable. You would include a standard detergent that would serve as the control. The onion, all of the reagents, time, temperature, the concentration of detergent, and all other experimental conditions would be identical (controlled). The dependent variable could be the quantity of DNA that you are able to extract from the onion using each of the detergents.

Can you think of other independent variables that you could use? Remember, for each experiment, there should be only one independent variable.

The Science Buddies website includes a really good discussion on this topic that should be useful to you.

https://www.sciencebuddies.org/science- ... bles.shtml

I hope this helps.


Donna Hardy