How Caffeine Affects the Heart Rate of Daphnia
IntroductionThe purpose of this experiment is to determine whether or not caffeine has an affect on the heart rate of DaphniaHypothesisThe Daphnia heart rate will increase with the concentration of caffeine.
I based my hypothesis on the fact that humans heart rates increase with caffeine as it acts as a stimulant drug.
In the experiment there will be several variables that I need to try and control, the temperature of the water is one of these because if the temperature is higher or lower on the day the results may end up being higher or lower, this would make my results inaccurate. I need to try and limit the human error in the experiment as the daphnia heartbeat is very quick so it will be hard to be completely accurate so we are using the blind method.
We need to use the same microscope throughout testing as others may have different strength lenses. I am also going to keep the species of daphnia the same, as different species may react differently to the caffeine. I will use the same type of caffeine and record the amount of time the daphnia spend in the caffeine before the counting begins, and try to keep this to a similar range.
The independent variable I will change is the concentration of caffeine in the water. I am going to be testing 0.1%, and 0.5% caffeine and also a distilled water trial. This means I will be able to see if the heart rate is greater with caffeine or not. The variable we are going to measure is the rate of the Daphnias heartbeat and to do this we will use a microscope to count the heartbeats of the Daphnia for 15 seconds. This makes it more accurate as the heartbeat is fast so we can the times the result by 4 to get the actual result for 1 minute.
I am going to be using a pipette to transfer the daphnia from the pond water to the cavity slide; this makes it easier for us to transfer the daphnia, without killing them. It also means we can reduce the amount of pond water on the slide making it more accurate. There is ethical issues
I based my hypothesis on the fact that humans heart rates increase with caffeine as it acts as a stimulant drug.
In the experiment there will be several variables that I need to try and control, the temperature of the water is one of these because if the temperature is higher or lower on the day the results may end up being higher or lower, this would make my results inaccurate. I need to try and limit the human error in the experiment as the daphnia heartbeat is very quick so it will be hard to be completely accurate so we are using the blind method.
We need to use the same microscope throughout testing as others may have different strength lenses. I am also going to keep the species of daphnia the same, as different species may react differently to the caffeine. I will use the same type of caffeine and record the amount of time the daphnia spend in the caffeine before the counting begins, and try to keep this to a similar range.
The independent variable I will change is the concentration of caffeine in the water. I am going to be testing 0.1%, and 0.5% caffeine and also a distilled water trial. This means I will be able to see if the heart rate is greater with caffeine or not. The variable we are going to measure is the rate of the Daphnias heartbeat and to do this we will use a microscope to count the heartbeats of the Daphnia for 15 seconds. This makes it more accurate as the heartbeat is fast so we can the times the result by 4 to get the actual result for 1 minute.
I am going to be using a pipette to transfer the daphnia from the pond water to the cavity slide; this makes it easier for us to transfer the daphnia, without killing them. It also means we can reduce the amount of pond water on the slide making it more accurate. There is ethical issues