daphnia experiment help!

I need some help for the experiment of how different caffeine concentrations affect the heart beat rate of daphnia. what i need are the limitations of this expirement (i have already found one - the microscope lamp increases the temperature and might cause the heart rate to go up) and also some help for the "going further" part... read my experiment(it's attached) and tell me what to do...

also... if anyone has the notes for the new biology course of edexcel plz send them to me!!

daphnia.doc594.4KB

Reply 1

AshMashMash

Someone else asked me to help the with this experiment. In the evaluation part, I wrote this, if its any help?

In here: what would you change next time? What made the erroneous results? Was there enough results (probs no). Was it easy enough taking the results (reading heart rates)? How accurate is your reading of HR’s? Would diff water affect it? What about the fact that by adding solution to the daphnia you are increasing the amount in the beaker… could have done a control by adding just more water to check that didn’t affect it (I know it wouldn’t, but they like you to say it). Was the caffeine evenly distributed? Did you stir it? If you did: that might affect it. If you didn’t, that might be why some are high, and others aren’t.

Reply 2

elle17

Hey, i'm doing something similar in biology at the moment!
For the "going further part" why not suggest comparing caffeine (a natural stimulant) to a natural depressant, for example alcohol (ethanol). Also, in the evaluation part you could mention that you took the HR for 30s and doubled it with in introducing the large assumption the the HR remained a the same rate for the following 30s, which could have introduced errors.

Reply 3

kostas93

thanks!! those are gr8 ideas!!

Reply 4

justanotherindigo

Oh wow thanks everyone! I have this experiment tomorrow! :biggrin:

Reply 5

Trinitybabe

Original post by justanotherindigo

Oh wow thanks everyone! I have this experiment tomorrow! :biggrin:

so how did it go in the end? did you get a good grade for your paper (in your attachement?) im reviewing all the practicals for AS in January....not an easy task! :frown:

Reply 6

justanotherindigo

Original post by Trinitybabe

so how did it go in the end? did you get a good grade for your paper (in your attachement?) im reviewing all the practicals for AS in January....not an easy task! :frown: