Effect of caffeine on Daphnia heart rate

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Independent: Caffeine conc.

Dependent: Daphnia heart rate

Control:

Temperature

Vol. solution

Daphnia stress

Daphnia size

Acclimatisation time

Daphnia species

Method:

Remove Daphnia & place in cavity slide w/ distilled water

Leave 5 mins acclimatise, then observe, count heart beat under microscope for 30s x 2 calculate beats/min.

Repeats w/ 2 Daphnias

Repeat again with diff. conc. caffeine solution.

5 diff conc. = 3 repeats in each conc.

Outcome: Caffeine conc. increased, heart rate increased.

Evaluation Notes:

Ensure Daphnia same size

If left too long under micropscope, temp increased (due to lamp) = increase heart rate

Count heart beat inaccurate

High conc. may kill Daphnia

Ensure enough data collected

Method