An Investigation to Show the Effect of Temperature on Daphnia
Plan:
I will submerge some daphnia contained in a test tube in water of
differing temperatures and measure their subsequent heart rates.
Hypothesis
I think that the heart rate of the daphnia will increase up until
around 40ËšC at which point most of the daphnia's enzymes will have
denatured and rate of metabolism will have stopped or decreased
sufficiently to have stopped the daphnia's heart rate.
Apparatus list
Test tube
Beaker
Different temperatures of water
Daphnia
Pipette
Stop clock
Microscope
Slide
Safety
Follow usual lab safety rules. There are no major safety
considerations in this experiment as the daphnia aren't harmful and
water above 40ËšC will not be used.
Method
To determine if temperature does have an effect on the daphnia, I
intend to carry out the following experiment. The experiment will
involve measuring the cardiac activity of the daphnia at different
temperatures, ranging from very cold (approx. 5 degrees Celsius) to
quite warm (approx. 40 degrees Celsius).
· A selection of similar sized/age Daphnia will be taken.
· A variety of different temperatures of water will be set up, these
temperatures will be kept constant whilst the daphnia are submersed in
them. The temperatures will be set up by using ice to cool tap water
down to lower temperatures and boiling water to heat it up. The
temperature will be measured to within 0.1°C on a mercury thermometer
to ensure accuracy. The temperatures will range from 10°C to
approximately 40°C and it will be done at 5°C intervals.
· The daphnia will be submersed in the water and left to equilibrate
for 3 minutes, after this time one of the Daphnia will be removed and
put onto a microscope slide, this will then be quickly put under the
microscope.
-1-
· Under the microscope, the Daphnia will be observed for 20 seconds,
this heart rate will be counted and recorded, this can the be
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