The Effect Of Chemical And Environmental Changes On The Heart Rate Of A Daphnia

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I. Purpose This experiment was designed to introduce students to the laboratory equipment and methods by subjecting a Daphnia to several environmental and/or chemical strains and evaluating the effect on the creature’s heart rate. II. Abstract The Effect of Chemical and Environmental Changes on the Heart Rate of a Daphnia M. Kolb, Biology 18b, Brandeis University. Previous research has found that Daphnia are excellent organisms to use in biological study because of their high sensitivity to changes in their environment. This experiment involved firstly, subjecting several daphnia to various temperatures of plain water and observing the change in heart rate and secondly, observing the changes in heart rate after the application of several…show more content…
Daphnia are cold-blooded organisms and therefore are not able to thermogregulate (Gerritsen,1982). This means that, adding water above room temperature to the daphnia’s environment would likely cause an increased heart rate while water colder than room temperature would likely decrease the heart rate. Temperature variances were expected to change the heart rate because creature’s metabolism changes in response to temperature in order to conserve energy or prevent from over heating. Also tested was the daphnia’s response to chemical changes in their environment. Diphenhydramine is the active ingredient in the common allergy medication Benadryl. In humans, this drug is often used to treat allergy symptoms including itching and hives as well as common cold symptoms like runny nose and excess mucus. Its main action is to block the receptors that the histamine usually bind to and thus inhibiting the action of histamines. I expected diphenhydramine to increase the heart rate because one of the common side effects in humans is increased blood pressure and heightened heart rate. I was also prepared for a decrease in heart rate because diphenhydramine is also know to cause drowsiness (it is also an active ingredient in many common sleep aids) which could indicate that it will the daphnia’s lower heart rate Both temperature and chemical changes to the environment were observed to effect the daphnia’s heart rate. Increasing water temperature

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