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The Effect of Caffeine on Daphnia Heart Rate

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´╗┐The Effect of Caffeine on Daphnia Heart Rate Daphnia, commonly known as water flea, are planktonic crustaceans. They are between 0.3 and 5mm in length. The life span of a Daphnia is does not exceed one year and is mainly temperature dependant. They are mainly found in lakes and are herbivorous often feeding on small green algae. In any inland water they are one of the major food sources for larger fish. Caffeine, often found in tea, coffee and cocoa is used as a flavour enhancer, it has medicinal uses in aspirin and is often found in weight loss drugs. It is a stimulant often seen in drinks like Red Bull. In humans caffeine is a stimulant drug which causes the increase in stimulatory neurotransmitters to be released. Caffeine at high levels of consumption have been linked to insomnia, anxiety, restlessness, blood pressure and raised stress. ...read more.


Add a couple of drops of distilled/pond water to the Daphnia 5. Focus on either the Daphnia's heart or their moving legs to be able to count their heart beat 6. Use a stop watch to record the number of heart beats during 30 seconds (advisable to work in pairs so that one person can count and one person can time) 7. Tap a pencil on a piece of paper to represent the heart beats and then count the number of heart beats at the end of 30 seconds 8. Repeat the procedure 5 times using different Daphnia for each concentration of caffeine solution 9. Record your findings in suitable table to give you the results of your experiment Risks 1. Use goggles to prevent water entering your eyes 2. Take care with the cavity side and if broken take great care in cleaning it up 3. ...read more.


I then took an average for accuracy and plotted my data. In future I would make sure that the Daphnia I used were about the same size. I would also control their environment before the experiment. I found that counting the heart rate of Daphnia was tricky which left room for error. Dotting on a piece of paper also allowed room for error when trying to count the dots. This problem would be solved by using electronic technology to count the Daphnia heart rate or using a tap counter in order to count the heartbeat. You should always make sure you do not use the same Daphnia twice. This is because they will end up with high amounts of caffeine in the Daphnia effecting the results. You can ensure not to use the same Daphnia twice by putting them in a separate container when you have finished with them. I have concluded that the percentage of caffeine concentration does increase the heart rate of Daphnia. ...read more.

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