Caffeine effect on Daphnia’s heart rate
Prepared for: Androniki Kloni
By: Maria Mitsi
October 6, 2013
Caffeine is a bitter, white crystalline xanthine alkaloid and a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants, as well as enhancing the reward memory of pollinators. An experiment was held, on an aquatic invertebrate called ‘Daphnia’, to investigate the effect of caffeine on its heart rate. The fact that Daphnia is a transparent organism facilitates the experiment as it allows us to see its internal organs. Different caffeine solutions of different concentrations were used including one control solution without any caffeine in it at all. A caffeine solution is placed onto a Daphnia and the number of its heart beats within 10 seconds was counted. This procedure was repeated 10 times using the same concentration of caffeine but different Daphnia individuals each time. Afterwards this was repeated using different concentrations. All factors should be kept constant in order to be able to compare the results. The overall results were that as caffeine concentration increases, Daphnia’s heart rate increases too.
Caffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine is found in varying quantities in the beans, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. In humans, caffeine has a stimulant effect, causing increased amounts of stimulatory neurotransmitters to be released. If the consumption of caffeine is at high levels, it can cause restlessness, insomnia and anxiety., which result in raised stress and increased blood pressure. When used in moderation, caffeine acts as a mild stimulant to the nervous system, blocking the neurotransmitter adenosine and resulting in a feeling of well-being and alertness. Early experiments showed that low concentrations of caffeine may produce small decreases in heart rate in human, whereas higher concentrations may make the heart beat abnormally fast. Daphnia is a genus of small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style (although fleas are insects and thus only very distantly related). They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers. Due to the fact that they are transparent, they are commonly used by scientists , to perform a variety of experiments as this allow them to see through these organisms. In my opinion, that caffeine will increase Daphnia’s heart rate. The higher the concentration of caffeine placed on the organism, the higher its heart rate. this can be backed up well, since caffeine has a stimulant effect on humans and speeds up the rate in which nerve pulses are sent and received in humans. The objective of the experiment was to investigate the effect of caffeine on Daphnia’s heart rate. Different caffeine solutions of different concentrations were made up, including a control solution which had no caffeine in it. A Daphnia was placed under a microscope and its heart rate was monitored before and after the placement of caffeine solution on it. This was repeated 10 times using the same concentration solution and the same Daphnia. Then it was repeated using different concentrations.
For this experiment are needed culture of Daphnia, 3 cavity slides, 3...
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