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To Determine the Effect of Caffeine upon Heartrate

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To Determine the Effect of Caffeine upon Heart rate Introduction and Aim Caffeine is a drug considered to be a stimulant as well as a mild diuretic. The substance itself can be sourced in beans, leaves and even the fruit of some plants where it exists as a natural pesticide. Upon consumption by humans, caffeine acts as a metabolic stimulant upon the central nervous system (CNS), resulting in the temporary relief from drowsiness along with an increase in general mental alertness. Caffeine, even though it's addictive nature is widely known, is still regularly consumed by most adults daily and resides in a wide range of readily available store-bought products. Currently, in the UK there exist no laws restricting the purchase of caffeine to certain groups of individuals despite many conducted studies concluding that the substance may result in negative implications upon particular persons such as young children or pregnant women. The following experiment will investigate the effects of caffeine upon the heart rate of daphnia (water flea) via the use of specific, controlled methods and the restriction of both variables and fixed conditions. Hypothesis I predict that as the concentration of caffeine to which the daphnia is exposed increases, the heart rate of the daphnia will increase likewise. ...read more.


The measurement of the heart beats per minute will also be judged by the same person throughout the investigation to disallow for any variations in subjective results. Furthermore, a blind study will be conducted where the individual who determines the heart beats of the daphnia will remain unaware of the concentration in which the organism is currently submerged. This means that experimenter effects by which the expectance of a result influences the actual result gained, thus the use of a blind study will eliminate such occurrences. It is also to be noted that the period of time for which the daphnia is left in the solution can be controlled by the implementation of a stop watch to time all procedural occurrences throughout the investigation. Finally, the amount of solution in which the daphnia is submerged can be standardised by allowing only 2 drops of solution drip from the pipette onto the cavity slide each time. Independent Variable: Concentration of Solution Dependant Variable: Heart rate of Daphnia Potential Extraneous Variables * Caffeine tolerance of organism * Exposed surface area of daphnia * Stress tolerance of daphnia Health and Safety Measures * Take care when handling glassware. ...read more.


Also, continuing with this point, the daphnia could have been left in an undisturbed state for 48 hours previous to the start of the investigation to allow them time to settle and once again remove the stress factor of new surroundings affecting their heart rate. Also, the heat produced from the heat lamp was much too fierce and as a result it would be of benefit to the experiment as a whole to alter the light source used in order to reduce the risk o overheating to the water fleas. Finally, it may also prove advantageous to use water from the daphnia's natural habitat rather than distilled water in the cavity slides so that the organisms have greater access to Oxygen supplies when necessary. Yet again, this would help to reduce the risk of death or physical impairment to the daphnia and improve the ethical status of the investigation. Going further Should time allowances be made it may be interesting to take matters further and pursue other aspects of the experiment such as; * Using a greater variation of caffeine solution concentrations * Investigating the role of other substances upon heart rate * Using alternate daphnia species to conclude whether the effects prove different or dissimilar. ?? ?? ?? ?? Susy Lumsden 12D ...read more.

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