Effect Caffeine Has on Daphnia

Topics: Caffeine, Heart rate, Blood pressure Pages: 6 (1573 words) Published: April 26, 2009
Does caffeine affect heart rate?

Background Information:
Caffeine is a bitter white crystalline xanthine alkaloid that acts as a psychoactive stimulant drug. A German chemist, Friedrich Ferdinand Runge, discovered it in 1819. Plants produce caffeine as an insecticide. It is found in varying quantities in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyses and kills certain insects feeding on the plants. Cocoa in South America, coffee in Africa and tea in Asia has all been used for hundreds of years to produce ‘pick me ups’ containing caffeine. These days caffeine is also used as a flavour enhancer in a wide range of cola and other soft drinks. In addition, it has medicinal uses in aspirin preparations and is found in weight-loss drugs and as a stimulant in students’ exam-time favourites like Pro-plus and Red Bull. In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity. Caffeine is the world's most widely consumed psychoactive substance, but unlike most others, it is legal and unregulated in nearly all jurisdictions. In North America, 90% of adults consume caffeine daily. The U.S. Food and Drug Administration lists caffeine as a "Multiple Purpose Generally Recognized as Safe Food Substance". One 2008 study suggested that women consuming 200 milligrams or more of caffeine per day had about twice the miscarriage risk as women who had none, while another 2008 study found no link between miscarriage and caffeine consumption. At high levels of consumption caffeine has been linked to restlessness, insomnia and anxiety, causing raised stress and blood pressure. This can lead to heart and circulation problems.

HYPOTHESIS- Does caffeine affect heart rate?
PREDICTION-It is predicted that as the caffeine concentration increases so will the heart rates

• The experiment will be conducted at room temperature. on • Gather all equipment
• Make a range of caffeine solutions of different concentrations and a control solution that has no caffeine at all • Place a few strands of cotton wool on a cavity slide • Place the slide onto the stage of a light microscope and focus it • Using a pipette, transfer one large water flea to cavity slide • Then add one or two drops of distilled water or pond water • Use a stop watch to record the number of heart beats per minute of the water fleas under a microscope • Repeat this process again but replace the water with caffeine, continuously repeating the process with different concentrations of caffeine • Keep all the factors constant

Water fleas- I will be using the same size of fleas so that I can control the amount of caffeine intake by them. Cavity Slide- Same length, width and thickness
Dropping Pipettes- Closest to 1 nul, this leads to more valid results as having results to the actual value. in Measuring Cylinder- 1 nul due to reading being accurate, leading to test being valid Cotton Wool- Some thickness and brand as this allows same effect always.

|Equipment Used |Possible Risk |Risk Reduction | |Standard Glassware |Could fall and break |Keeping all beakers and measuring | | | |cylinders tucked away, far in the middle.| |Paper Towels |Litter can cause a drain block |Paper towels need to be put in the pin so| | | |that they do not litter our laboratories.| |Caffeine Tablets |They could be left out and little |Put...
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