Science Buddies: "Ask an Expert"

I have conducted my experiments for my science fair project: What effect does caffeine have on the heart rate of Daphnia Magna?
I was wondering if anyone will be willing to let me ask them a few questions because I have to have an interview included in my science fair project.

Thank you very much
Sincerely,
Hannah

Hi Hannah,
Congratulations on finishing your experiment. What did you find?
Please feel free to post your questions, and hopefully our experts will be able to answer them.
Chris

Thanks!
I found that the caffeine sped up the heart rate of the Daphnia depending on the different concentrations i had given it, but all of them sped it up!

I was wondering:

1.What different chemicals do you see altering Daphnias heart rates?
2. Does this happen each time you give caffeine to Daphnia, or have i gotten the wrong results?
3. What different type of concentration would you have you used, if you were to perform this experiment?
4. What do you specialize in and what made you pick a field in science?

Thank you very much!!

Hi Hannah,

A quick Google search of "what affects heart rate in daphnia" will help you with some of your questions, but here are my answers.

1.What different chemicals do you see altering Daphnias heart rates?
You can expect the same sort of chemicals that alter heart rates in humans to similarly alter heart rates in Daphnia. The reason you can expect this is because most chemicals will activate receptors for neurotransmitters, which control heart rate. Any drugs known to alter heart rate (including caffeine, nicotine, alcohol, and others) should alter heart rate in Daphnia.

2. Does this happen each time you give caffeine to Daphnia, or have i gotten the wrong results?
Yes, it should happen every time.

3. What different type of concentration would you have you used, if you were to perform this experiment?
I don't know what concentrations you used, and I don't have a sense of the exact concentrations I would use. However, like you, I would try different concentrations to see whether greater concentrations had a greater effect. At some point, I would expect to see that greater concentrations would not speed up the heart rate any further, which would tell me that I had reached a "saturation point."

4. What do you specialize in and what made you pick a field in science?
I specialize in the comparative physiology of vertebrates (mostly mammals). I have always been interested in how animals work, but a science teacher in high school really encouraged me to continue to pursue science. Once I took biology in college, I knew it was what I loved.

I hope that helps you!

Cheers,
Heather