Daphnia Bioassay

Essay by haideralli July 2004

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The initial variable to be considered will be the effect that caffeine and temperature has on the heart beat and if it has a direct or indirect effect on the daphnia's lifespan. If there is enough time to consider a second variable however, the effects of a temperature or alcohol on the daphnia's body system will also be considered alongside the initial variable of caffeine. These will then be slotted into the same graph which will show us how the figure correspond to the results.

In order to conduct a true experiment the following questions must be considered and answered and only then can acurate conclusion be drawn.

· How variable is the heart rate in an individual Daphnia?

· How does the drug caffeine affect the daphnia's heart beat?

· At what concentration is the heart rate slowest? The fastest?

· What indication in the graph is the optimum concentration for heart rate of Daphnia?

· What is the significance of the shape of the graph line when the data is plotted?

· · What would happen if you increased the temperature in 5C increments (if time is available)?

· What would happen if alcohol was added into the solution and why would this affect the daphnia's heart rate and general behavior.

To fully understand the way the daphnia works one must examine its body and the uses for the different parts of it:- (fig.1)

[1] - Second antenna, used for swimming and sensing the environment[2] - eye controlled by muscles with nerve connections to the brain[3] - legs used for gathering food stabilizing the animal as it slowly sinks[4] - An intestine where ground up food particles are digested[5] - A brood pouch for incubating young that hatch from large yolk filled eggs [6] - A protective...