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The effect of caffeine concentration on the heart rate of Daphnia

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Introduction

The effect of caffeine concentration on the heart rate of Daphnia Abstract The following experiment details the effect of different concentrations of caffeine on the heart rate of daphnia. Caffeine also known as trimethyl-xanthine, C5H(CH3)3N4O2,H2O, is an alkaloid contained in the seeds of Coffea arabica, and other species of Cola, and in a few other plants. The binding of caffeine to receptors in the central nervous system causes the release of excitatory neurotransmitters and stimulation of the sympathetic nervous system. This can lead to increased heart rate, stress and a raise in blood pressure. The purpose of this experiment is to determine the effects of caffeine on the heart rate of daphnia. To determine this effect daphnia were exposed to differing concentration of caffeine and the heart rate counted. This experiment shows that there is a direct relationship between the concentration of caffeine and heart concentration. Introduction Caffeine is produced by plants as a natural insecticide, to ward off dangerous pests. In tests is has been demonstrated that caffeine and compounds containing caffeine, interfered with the behaviour and growth in many insects and insect larvae. For example, larvae show signs of confusion after ingestion of these compounds1. As well as its insecticidal properties, caffeine is also a known stimulant and has for many years been used to combat fatigue and weight loss. There are millions of neurones (nerve cells) in the brain that convey the electrical signals. When the brain receives a stimulus from an organ or receptor in the skin, a series of messages will be passed along these neurones. ...read more.

Middle

Furthermore, there is a small risk of killing the fleas during the experiment and putting them under unnecessary suffering. If this experiment is created on a mass scale, then there is a danger disrupting the food chain. Therefore we will analyse aspects of the experiment, which may endanger the daphnia and produce other methods which will be safer and less harmful for the daphnia. To ensure the daphnia is not killed- o Distilled water placed on the cavity for the flea, so it does not suffocate and instead of tap water because the chlorine may be toxic. o Vasoline will be added to restrict movement of the daphnia out of the slide. o Large sized pipettes will be used so the flies aren't squashed. o Distilled water will be added on the slip, so the flea is not poisoned. o A cover slip will not be used, which can squash the daphnia. o Excess water on the sides of the cavity slip will be absorbed using filter, giving a sufficient supply of oxygen. o Generally, at each stage of the experiment, the daphnia will be treated with extreme care to ensure the daphnia is not harmed; by doing so, this will prevent us from using too many daphnia, which is wasteful and unethical. Perhaps the most dangerous factor would be the high concentration of caffeine which could kill the daphnia; therefore the solutions will be diluted to a safe level. We will keep the microscope within the edge of the table so it does not fall and cause injury. ...read more.

Conclusion

1. The purpose of this experiment was to determine what affect caffeine had on the heart rate of daphnia. To this the rate was measured by directly observing the heart beat under a microscope. The light from the microscope will heat the solution that the daphnia is in as the experiment proceeds. The hotter the temperature of the solution the faster the heart will beat. To prevent this from being a major factor the light from the microscope overheating the solution it was turned off between observations. 2. There is a bias in the experiment in that as you are increasing the concentration of the caffeine added you are expecting to see an increase in the rate at which the heart beats. Therefore it would be better to repeat this experiment as a blind study. In that the rate at which the heart beats is measured by someone who does not know the concentration of the caffeine being added. 3. Daphnia can be injured and stressed as a result of the transfer from the container to the microscope. This will have an affect on the rate at which the heart beats. It was therefore paramount that all daphnia were given adequate time to acclimatise to their new surroundings before any experiment was carried out. 1 Caffeine As an Insecticide | eHow.com http://www.ehow.com/about_6080295_caffeine-insecticide.html#ixzz12WIPFN00 ?? ?? ?? ?? This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ ...read more.

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