An Investigation to Show the Effect of Temperature on Daphnia

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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.

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· 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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