The Heart Rate of Daphnia Under Different Conditions

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                              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.

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Method:

  • Identify a daphnia from a beaker of pond water.
  • Take a pipette and remove the daphnia out and put it in a watch glass.
  • Put some cotton wool with some water in the watch glass to keep the daphnia a live.
  • Put the daphnia under a dissecting microscope, to make sure it’s a daphnia.
  • Take it and put it in a regular microscope in order to identify the heart beat.
  • After identifying the heart beat, count how the hearts beats in 10 seconds.  
  • Record this in forms of dots.
  • Repeat this three times and take the ...

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