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Daphnia Pulex

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Background Information: Ecologists have noticed that the fish in a local river have started to die. Some have suggested that this be because of the pollution from a nearby brewery, which is disrupting the food chain. It is thought that the pollution could influence the heart rate of small invertebrates such as a Daphnia pulex, which will eventually die. Scientific Knowledge that alcohol is a depressant, which slows down the heart rate. The brain is the first organ to be affected by alcohol, because it has many blood vessels. It slows your thinking, affects your judgement, and dulls your senses. As more alcohol is absorbed into the blood stream, the cerebellum and medulla are affected. The co-ordination, balance, reaction time, and then vital body functions such as the heartbeat, breathing rate, and digestion are affected. If you continue drinking alcohol at this point the brain's functioning can slow enough to result in unconsciousness and even death. ...read more.


I am going to be using different amounts of concentration always using 100ml of solution I will be doing volumes of: - 0.5%, 1%, 1.5%, 2%, 2.5% and 3% So for 3% volume to make a total of 100ml I would use 3ml of ethanol and 97ml of distilled water I am going to repeat the experiment for each concentration 5 times so I can get an average set of results, which may be more reliable. I am going to leave the Daphnia Pulex's in the solution for 1 minute. I will then transfer one Daphnia with a pipette on to a dimple slide and cover gently with a slide cover so not to squash the Daphnia Pulex. When it is under the microscope I will measure its heart rate for a minute by timing it for a minute with the stopwatch and dotting on a piece of paper every time it heart beats After I have done this I will count the dots and record the data in my results table. ...read more.


Safe Test To ensure my test is as safe as possible I will have to do these things so I do not cause an accident while doing the experiment. * Wear safety goggles at all times. * Move bags, coats and stools right out of the way so that you do not trip over any of them or so that it can not cause an accident. * Make sure you know exactly what you are doing in the experiment before you start. * Tie longhair back. * Tuck in loose clothes and make sure shoelaces are tied. Results 1 2 3 4 5 Average 0% 250 275 258 289 336 181.6 0.5% 202 176 166 190 198 186.4 1% 110 122 103 123 153 122.2 1.5% 162 178 150 103 120 142.6 2% 139 182 139 144 127 146.2 2.5% 144 137 149 118 138 137.2 3% 150 74 44 76 64 81.6 Samantha Bellamy :) Biology Coursework :) Mr Harwood ...read more.

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