Studying How Different Environments Affect the Heart Rate of Daphnia
Emily Wright (0522016): Year 11 Biology
Tania Balind
Table of Contents
Factors Affecting Heart Rate 1
Abstract 2
Introduction 2
Method 3
Risk Assessment and Ethical Considerations 4
Results 4
Discussion 5
Appendix 6
Abstract
This experiment aimed to find the effects of different substances on heart rate in Daphnia Magna. The two substances used were caffeine (a stimulant) and alcohol (a depressant) in three different concentrations (0.5%, 2.5% and 5%.) The hypothesis stated that the caffeine would increase the heart rate, increasing more as the concentration …show more content…
2014) due to its abilities to keep the body ‘awake’ for longer by blocking adenosine causing the central nervous system to be stimulated, increasing the heart rate and stimulating hormones such as adrenaline and noradrenaline which can cause feelings of restlessness and twitching. (ABC, 2013) According to a study done at SVS Medical College Mahabubnagar, caffeine causes the heart rate to increase, on average by 4.4 beats per minute (from an average of 72.9 to 77.3) as well as increasing blood pressure. (Geethavani, G. 2014) In this experiment, caffeine will be administered to Daphnia magna in concentrations of 0.5%, 2.5% and …show more content…
When using alcohol to change the heart rate, the higher concentration of alcohol, the slower the heart rate should have been. In this particular experiment, our results swayed slightly from the expected, however the averages fit the expected results. Alcohol is classified under the banner of depressant due to its effect on the nervous system, causing less signals to be sent to the heart and brain, slowing down movement and heart rate and brain stimulation. In a way, it depresses the signals.
The higher concentrations of the caffeine increased the heart rate of the Daphnia by just over 100 beats. This was due to its effect on the central nervous system, making it more alert and increasing the rate of signals to the heart and to the brain, which also made the Daphnia move a lot more, in a twitch-like manner, making it harder to count the heart rate. Caffeine is classified as a stimulant due to its effect on the central nervous system and its ability to increase the amount of signals sent to both the brain and the