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. This can all lead to heart and circulatory problems.

The effects of caffeine on the heart rate of Daphnia can be investigated by putting Daphnia in a caffeine concentrated solution and then taking them out to put under a microscope. The unique structure of Daphnia allows us to measure its heart rate by the amount of times their legs move.

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The experiment is to find out the effect that caffeine has on the heart rate of Daphnia. My hypothesis is that the higher the percentage caffeine solution the faster the Daphnia heart rate. The independent variable is the percentage of caffeine concentration the Daphnia are submerged into for 2 minutes. The dependant variable in the Daphnia heart rate.

            Method

1. place cotton wall on a cavity slide. This helps to restrict the movement of Daphnia

2. Using a pipette transfer a Daphnia to a cavity slide

3. Remove water from ...

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