Effects of different concentrations of ethanol on the heart rate of the water flea

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Effects of different concentrations of ethanol on the heart rate of the water flea

In this experiment I will be looking at the effects of different concentrations of ethanol on the heart rate of the water flea, Daphnia because using humans in a study to test the effects of Ethanol on heart rate would not be ethical.  Daphnia, like many animals, are prone to  intoxication, and make excellent subjects for studying the effects of the depressant on the  – due to the translucent exoskeleton, and the visibly altered .Ethanol is a small molecule,  of 43, so it crosses cell membranes by simple diffusion. The exoskeleton of Daphnia is not waterproof, so there are no waterproof waxy layers to cross. The gills are particularly thin-walled and optimised for diffusion. They live in various aquatic environments ranging from   to  lakes, ponds, streams and rivers. They are tolerant of being observed live under a microscope and appear to suffer no harm when returned to open water.

The experiment consists in preparing 5 different environments to put the water flea in, and observe how the heart rate responds to each change; the change will be the increase of ethanol concentration %. This will be the independent variable. The dependent variable is the heart rate of the Daphnia.

Hypothesis : Ethanol will decrease the heart rate of the Daphnia.

Null Hypothesis : Ethanol will have no effect on the heart rate of the Daphnia.

I will change the concentration of my Ethanol solution by dilution and will therefore plot a graph. In addition, a correlation and ANOVA test will be calculated to determine the relationship (If any) between the concentration of Ethanol and the heart rate of the Daphnia.

I have taken into consideration factors that will affect my overall conclusion

Factors:

Size of Daphnia - The size of the Daphnia will affect its absorption of Ethanol and also the metabolism of the drug in the liver. Different rates of metabolism will result in different heart rates. As a result I must ensure that I choose Daphnia which are the same size when conducting repeats. I will use a highly sensitive scale to confirm that both daphnia are of equal body mass.

Time kept in ethanol solution - The Daphnia must be kept in the Petri dish full of ethanol solution for a specific amount of time. If they are kept in the solution for too long they will become intoxicated which will result in abnormal heart beats that are hard to measure although they must be kept in the solution long enough for sufficient absorption of Ethanol. Each Daphnia will stay in the ethanol solution for exactly 3 minutes so that an equal volume of ethanol is absorbed.

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Activity of Daphnia - Some Daphnia tend to be more active than others and these will have a higher heart rate compared to ones that are idle. After allowing the Daphnia to swim in a specific solution of ethanol I will place them on a cavity slide so that I can observe the heart rate with a microscope. As I will be using a pipette to transfer the Daphnia from the Petri dish to the cavity slide excess fluid will be found on the slide which must be removed with tissue so that all Daphnia remain idle/immobile and not ...

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