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Practical: the effect of caffeine on heart rate.

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Practical: the effect of caffeine on heart rate. In order to investigate the effect of caffeine on the heart rate, we used a tiny multicellular freshwater crustacean which is widely used for biological research. The daphnia species have a transparent body and a projecting head. They entail a pair of pronged antennae used primarily for swimming while also entailing a single compound eye. A daphnia has a divide of the head which lies between the head and the abdomen and five pairs of these form an efficient filter-feeding mechanism. Caffeine is a bitter alkaloid used in coffee that is responsible for their stimulating effects. Caffeine binds to receptors on the surface of heart muscle cells which leads to a faster heartbeat. ...read more.


The more caffeine in the solution should reflect the concentration in heart beat. To carry out this experiment, I need: - Daphnia - 9 cavity slides - Distilled water - Pipettes - Stopwatch - Microscope - Caffeine solutions - Test tubes - Cotton wool First of all, to limit the movement of the daphnia, I placed cotton wool onto the 9 cavity slides. In turn, this will make is easier to observe the daphnia under the microscope. Instead of obtaining the daphnia from the large container, I filled up test tubes and acquired them from the test tube. Using pipettes, I placed the 9 daphnia onto the cavity slide and cotton wool. ...read more.


I knew not to exceed this amount so avoided deaths of the daphnia. I left each on the side for another five minutes. I placed each under the microscope for the second time and did the same thing as before. I then put all of Daphnia I had used back into the distilled water. It is quite hard to avoid death in this experiment considering we're dealing with such small organisms; one could easily crush a daphnia, or it could even die due to stress. I didn't use one daphnia to record three different solutions, as when I first tried this, it proved difficult and the daphnia died. Instead I used three daphnia for the three solutions and instead of comparing the repeats, I need to measure the rate of increase from 0 and manipulate the average from that. ...read more.

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