I think that caffeine enters the daphnia's body then the heart rate will increase dramatically

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Emily Lewis                                    Core Practical                                      31/12/2006

Does Caffeine Affect Heart Rate

Hypothesis:  

I think that caffeine enters the daphnia’s body then the heart rate will increase dramatically. This is because caffeine acts as a stimulant making muscles work faster. I will count the heart beats from daphnia in water and then in caffeine and see the difference.

Suitable equipment:

We used a pipette to pick up the daphnia. This could injure the daphnia. Also this could startle the daphnia which would increase its heart rate therefore making it an unfair test.

Risk assessment:

Ethical Issues:

You have to use ice water on a separate slide underneath the daphnia so that the heat from the microscope doesn’t burn it.

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Use cotton wool to stop the Daphnia from moving about to much, this makes it easier to keep the daphnia to see and count the heart beats.

Use pond water do that they are in there natural environment rather than plain water.

After the experiment they are put in a fish take to be fed to the fish, they aren’t wasted.

Variables:

Independent variable: Caffeine, this is the quantity that I am controlling, I am going to control the amount of caffeine out onto the daphnia.

Dependant variable:  heart rate, this is the quantity under ...

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