Effect of Caffeine on Heart Rate in Daphnia free essay sample

At high levels of consumption caffeine has been linked to restlessness, insomnia and anxiety, causing raised stress and blood pressure. This can lead to eart and circulation problems. Hypothesis: Daphnia subjected to a caffeine solution will show a rise in heart rate as caffeine is a stimulant that speeds up the body affecting the nervous system and rate in which the nerve pulses are sent and received in humans. (Caffeine increases the heart rate of Daphnia. ) Null Hypothesis: There is no significant difference between the heart rate of Daphnia in distilled water compared to that in caffeine. Safety: Handle cavity slide carefully to prevent breakage. Ethics for the Daphnia: 1. Every possible attempt to keep Daphnia alive. 2. Use low concentration of caffeine so not to harm the Daphnia. 3. Place the Daphnia in the presence of pond water instead of distilled water. 4. Use the same Daphnia throughout the whole experiment and handle it with care. We will write a custom essay sample on Effect of Caffeine on Heart Rate in Daphnia or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page 5. Turn off the microscope light between observations to prevent the Daphnia from overheating while on the microscope. Materials: Culture of Daphnia (water fleas), cavity slides, dropping pipettes, distilled water or pond water, 0. 5% of caffeine solution, stopwatch, paper towels, microscope. Independent variables: Type of treatment- distilled water/ pond water and 0. % caffeine solution. Dependent variables: Number of heart beat per 20s Other variables: 1. Size of daphnia 2. Volume and concentration of caffeine 3. The time of Daphnia being immersed in the caffeine solution 4. Surrounding temperature 1. Have ready the 0. 5% of caffeine solution, the Daphnia culture, a stopwatch, cavity slides, pipettes and other materials. 2. Catch a daphnia with the pipette and place into well on a deep well cavity slide. 3. Use the microscope to get the daphnia in focus. If the Daphnia isnt too large, use a cover slip to hold it in place. . Add two or three drops of the 0. 5% of caffeine solution. Leave the Daphnia immersed in the 0. 5% caffeine solution for 1 minute before removing the excess of the caffeine solution by using a pipette. 5. Using your stopwatch, count how many times the Daphnias heart beats in 20 seconds. Each heartbeat is recorded by tapping a pencil on a piece of paper and counting up the pencil marks after the specified time. 6. Repeat Step 5 for 2 times and record heart rates. Find the average heart rate of Daphnia with a 0. 5% caffeine solution. 7. Repeat all the above steps for the control (pond water). Results: Table Treatment Heart beat rate/beat per 20s Mean heart rate / beat per 20s beat per min repeat 2nd repeat 3rd repeat Distilled water/ pond water 94. 00 95. 00 96. 00 95. 00 285. 00 Mean heart rate / 0. 5% caffeine solution 110. 00 100. 00 100. 00 103. 33 310. 00 Graph: Discussion: 1 . It is considered ethical to use invertebrates such as daphnia rather than large organisms e. g. monkey or human in scientific studies. Daphnia has reduced awareness of pain because of the lack of a well developed nervous system. It is transparent and its heart is visible without the need for dissection. Daphnia is abundant in nature and there is no threat to it or its dependent species (food chains). Some people also feel that it is bred for fish food and will thus die anyway. Daphnia can reproduce asexually and may be clones, therefore there is no loss of genetic variation. At the other extreme, some research on animals involves suffering or loss of life. Animals that are kept in confinement on University premises are normally species that have been bred for many generations in captivity e. g. mice,