THE HEART RATE OF DAPHNIA UNDER DIFFERENT CONDITIONS.
Aim:
To investigate the heart rate of daphnia under different conditions, such as drugs.
Theory:
There are different types of drugs. Some are depressants and some are stimulants. By depressants we mean that they slow down the rate of metabolism. Stimulants increase the body’s metabolism. Heart rate is one indicator of increased or decreased metabolism. Drugs affect the heart rate of daphnia the same way as humans. Caffeine and nicotine are stimulants they will increase the heart rate of daphnia as well as humans. Ethanol, alcohol and aspirin are depressants and they will slow down the heart rate of daphnia.
Because of different concentrations of alcohol we have to do a serial dilution. Example:
If we have 10% of alcohol to start with and the final is 2%, then volume of water is 0.8 and alcohol is 0.2. So the dilution factor is 5 (1 part original, 4 parts of water).
Materials;
Pipette, dissecting microscope, regular microscope, cotton wool, stop watch, a watch glass, caffeine, aspirin, 1%alcohol, 10% ethanol, nicotine.
