Effect of caffeine on Daphnia heart rate

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