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The effect of caffeine on heart rate

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Core Practical 1.1 the effect of caffeine on heart rate Aim: The aim of this experiment is to investigate the effect of different concentrations of caffeine on the heart rate of Daphnia (water fleas). Hypothesis: I predict that the concentration of caffeine will affect the heart rate. I believe this will be directly proportional to each other. For example, as concentration of caffeine in the blood increases, the heart rate of the daphnia will also increase. Caffeine is a drug that is classed as a stimulant because it stimulates the body's systems. It increases the activity of the neurotransmitters in your body which speeds up your heart rate, thus blood is pumped faster around the body. Variables: The dependant variable being observed and measured was the number of heart beats per minute of the Daphnia (water flea).The independent variable in this experiment was the concentrations of caffeine 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1%. Fair Testing: To make it a fair test: we kept the timing the same for each condition; the environment for the daphnia were kept the same; the type daphnia was kept the same. ...read more.


The results were then recorded using a tally chart. We recorded the heart rate for one minute. We repeated these steps three times, which helped us get a clear average. A blind study was firstly carried. This was done in order to reduce observer bias. 4. The procedure was then repeated with water fleas from a culture of different concentrations caffeine solution 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1%. We made sure we repeated it three times to find a clear average. Clean and fresh slides were used. 5. The results were recorded and used to produce graphs of suitable format. Risk Assessment: When performing an experiment, there's always possible dangers hanging around, thus it is vital to think about these and eradicate them. The table below shows the potential dangers and what actions were taken. Risk What is done to prevent it? Risk Level Microscope (Physical)- fragile, chance of it breaking Should be positioned on a desk where it can be used whilst staying stable. When moving around- handle with care. Medium Overdose of caffeine (Chemical) The water fleas should be placed in caffeine solutions with accurate and safe concentrations. ...read more.


but also a higher heart rate, and blood pressure. Evaluation: The advantages of this experiment were that it was repeated many times, producing similar results, which made reliable and the cotton wool was used to limit movement, stopping any unnecessary increases of the heart rate. The disadvantages of this experiment were: using different daphnia could affect the validity of the experiment, since size and shape of the daphnia was not controlled; since the daphnia was not in its normal environment, other factors could have increased the heart rate and finally the amount of time used to count the heart beat may not be enough as heart beat could increase after one minute. If I do the experiment again, I would obtain more results of the heart rate, making the results more reliable. Application to everyday life: Caffeine increases heart rate, thus a stimulant. Too much of this drug can lead to many diseases. One of these is heart disease. Heart disease is the number one cause of death of many people in the Western countries. Statistics convey that many other factors contribute to a large number of heart attacks. These factors are: smoking, high blood pressure and stress. Caffeine and coffee consumption badly affects cholesterol level and blood pressure, thus increasing chances of a heart disease. ?? ?? ?? ?? [Type text] ...read more.

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3 star(s)

A fairly good account overall. The risk assessment is excellent and the author has a sound grasp of how caffeine affects heart rate in humans. However, in places more attention to detail is needed and the author is too ready to assume that results on Daphnia are transferable to humans.

Marked by teacher Adam Roberts 05/09/2013

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