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Effect of caffeine
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| Words: 374 | Submitted: 10-May-2011
96.8% | Number of pages: 0 | Filetype: Word .doc
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DescriptionEffect of caffeine
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers. Depending on water temperature, they can live up to one year and due to their short lifespan and reproductive capabilities, they can be particularly useful in certain environmental tests, effects of toxins on an ecosystem.
Hypothesis: As the concentration of caffeine increases from 0.00% to 0.50% the heart rate of Daphnia will become 1.5 times more.
I. Dependant: Heart rate
II. Independent: Caffeine concentration
III. Controlled: Time, Temperature, Volume of Caffeine and Water
Instruments: Daphnia, Cavity slide, 3 dropping pipettes, Pond water, Caffeine solution, Cotton wool, Pipettes, 5 test tubes, Stop clock, Paper towels, Microscope
I. We organize our instruments on the table in order to have everything at the right place.
II. We prepare different Caffeine solutions (0.00%, 0.25%, 0.50%, 0.75%, 1.00 %).
III. We put the beaker of the Daphnis in mixture of ice and water to lower the heart rate of Daphnia and prepare them for different caffeine solutions.
IV. We put a Daphnia in each of the solutions for 5 minutes. In order to prevent counting errors we repeat the experiment twice.
V. Then we take out the Daphnia and put them on the cotton wool prepared on the cavity slide in order to prevent the Daphnia from escaping, so that we can see the heart beat with the microscope.
VI. We use stop clock to measure different heart rates affected by different solutions in one minute.
VII. We record our results in a suitable table.
VIII. We compare our results with other groups and calculate the mean of the heart rate of the Daphnia in each solution.
IX. We present our results on an appropriate graph and we make a conclusion.
X. We clean up everything we used, put the used Daphnis in a separate beaker, wait for the affect of caffeine to wear off, and we put them back in the original beaker which contains pond water and other Daphnis.
Conclusion: According to our final results, the heart rate of Daphnia has increased constantly using different concentrations of caffeine (from 171.5 BPM to 285.667BPM). Therefore we assume by the increase of caffeine, the heart rate of Daphnia will constantly rise as well.
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