MathBench > Microbiology

Experimenting with Meningicocci

Making a media

So, we want to make defined media. Let's try making a media that corresponds to Frank's blood first. Obviously, we expect the meningicocci to do well here, so we know the media should contain everything that the bacteria need. What's going to be in YOUR media? Check off below:

glucose

sodium

elemental iron vs. pig's blood

eye of a newt

toe of a frog

 

ANN -- I need a better list here!! And I need to know what actually goes in...

Now we need to make our second media, and in order to do that, we need to decide exactly what we are testing. In other words, we need a pair of hypotheses (null and alternative).

The null hypothesis is easy -- it is simply that there is no difference between the effects of the two treatments (in this case, between the conditions in Frank's bloodstream and the conditions in his nose).

Ho: Meningicocci will grow at the same rate in both treatments

The alternative hypotheses states that you DO expect to see differences, and why:

Ha: The "nose" treatment will cause slower growth because it includes nasal spray.

The alternative hypothesis now drives how you create your media: the two dishes are exactly the same, exact that one contains nasal spray and the other does not.

Remember the Deep Hole of Doom, or We-tried-to-make-everyone-happy-by-testing-everything? Don't do it! Pick ONE hypothesis to test, and let that define ONE way that your dishes are different.

Practice:

Student E, who had the flu while everyone else was having The Endless Argument about What to Test, comes back to class and insists that the difference between the nose and the bloodstream is the presence of dust. After all, the nose is where dust gets filtered out of the air, so it doesn't end up in your lungs or your body.

What hypothesis does E want to test?

Ho:

 

Ha:

In order to create the treatments, E would make two identical dishes with identical media, except ...