Data and Analysis (Biology)

Question

1. A scientist wants to test the effect of different sugars on the growth of yeast (yeast like to feed on sugar). They want to see if coconut sugar is better or worse than plain table sucrose (normal sugar) on the growth of yeast.

1. What would a good positive control be? 
2. What would a good negative control be? 
3. What is our independent variable? 
4. What is our dependent variable? 

Answer 1

Hi Gabriel,

To design an experiment, think about the possible outcomes of an experiment before you run it - and the meaning behind it. One of those outcomes would be "nothing worked" - and that isn't very informative - so you want to have some control to make sure that "experiment" was done right (you didn't forget something!). That's called the positive control. You also want the opposite - something that should result in a "zero" reading - this is your negative control. This is usually so you can check for contamination, or to "blank" your machine.

So with that in mind, let's think about a positive control - you want to have something that will 100% grow yeast, so a good positive control is a sugar that is known yeast can grow on.

I'll leave the rest up to you for now, with that start hopefully you can do the rest. If not, let's schedule a quick tutoring session to talk!