Aim
To investigate the effect of caffeine on daphnia by measuring its heart rate and how its heart rate changes with an increasing concentration of caffeine.
Hypothesis
I predict that the heart rate of the daphnia will increase with increasing concentration of caffeine solution. I think this because caffeine is a stimulant which increases the amount of neurotransmitters to be released, which increases the frequency of impulse along the neuron. If the concentration is increased then the stimulant becomes stronger and more transmitter chemicals are released, in turn increasing the heart rate.
Rationale
Daphnia are an effective organism to use for this experiment due to its simplistic anatomy. They have simple nervous systems, transparent skin and a translucent exoskeleton. These all allow for clear visualization of the internal organ which makes it easy to measure the heart rate through a microscope. Other organisms are more complex and therefore would need much more advanced technology to measure the heart rate which would not be accessible for me.
Risk assessment
Risk presented How the risk was prevented
Plug sockets exposed to water which could cause an electric shock if they come into contact. Place the beakers of water and caffeine solution well out of reach from the plug sockets and always have paper towels close by incase spillages occur
The daphnia could die if left in the solution too long We only left each daphnia in caffeine solution for 1 min 30 seconds and placed it in an ice bath after each test to allow the heart rate to rest
Dropping the microscope on yours/ someone else’s toes which may cause serious damage. Carry the microscope to and from the work area with both hands walking slowly and sensibly.
Spilling the caffeine solutions could cause splashes which may enter the eye causing irritation. Wear protective eye wear (goggles) and carry the caffeine solutions sensibly. Also make sure the caffeine solution is placed out of the...