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Investigating the effect of chemicals on the rate of heart beat of Daphnia.

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Investigating the effect of chemicals on the rate of heart beat of Daphnia Planning Aim The aim of the experiment is to look into the effects of the chemicals: ethanol and adrenaline and on the rate of heartbeat of the water flea, Daphnia. Background Information Daphnia: A small poikilothermic (body temperature affected by temperature of environment) fresh water crustacean. It is relatively transparent so its internal organs can be observed though a light microscope, therefore the heartbeat can be seen. The heart and nerves involved with it: Heartbeats are controlled mainly by nerve pulses. These impulses are caused by pacemaker neurons situated in a group of nerve cells called the cardiac ganglion. ...read more.


Dependent variable: Rate of heartbeat, this will depend on the chemical/concentration of chemical used Controlled variables: Temperature: The entire experiment will be carried out at room temperature and must be maintained, Daphnia are poikilothermic so changes in temperature of the environment will effects its rate of heartbeat. If the temperature of the surrounding environment is increased, the metabolic rate will also increase, this requires energy, which is supplied through respiration, which requires increase in pumping of blood around the body to supply cells with oxygen for respiration, therefore rate of heartbeat is affected by temperature. Amount of Chemical: The amount of chemical must be maintained, different volumes of chemical will affect the rate of heartbeat, more will increase it. ...read more.


Adrenaline, also as predicted speeds up the rate of heart beat, doubling it from the normal rate. Using just water (as the control) the average heart beats per minute was 42, when 1% ethanol was added it was proved that it did have an effect as the average rate of heart beat was slowed down to 19 beats per minute, when 10% ethanol was it added, the average rate of heartbeat was slowed down to 11 beats per minute proving increasing the concentration does decrease rate of heart beat. When adrenaline was added the rate of heartbeat was increased to 90 beats per minute, proving that adrenaline is a stimulant and increases rate of heartbeat. Winston Wong ...read more.

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