Hypothesis: Daphnia subjected to a caffeine solution will show a rise in heart rate
Scientific basis for hypothesis: Caffeine is a stimulant that speeds up the body therefore affecting the nervous system and rate in which the nerve pulses are sent and received in humans.
Independent Variable : The solution subjected to the Daphnia. Dependent Variable : The count of heart beats per minute (bpm) of the Daphnia. Controlled Variables : The temperature of the Daphnia. (Higher temperature results in increased heart rate.) The size of the Daphnia. (The larger the Daphnia the less caffeine with effect it.) The age of the Daphnia. (Older Daphnia are more likely to have a higher heart rate.)
1) Remove one Daphnia and place in cavity slide.
2) Remove pond water and replace with distilled water.
3) Leave for five minutes to acclimatise.
4) Observe under microscope and count the heart beats for 30 seconds.
5) Multiply number of heart beats per two to obtain a beats per minute reading.
6) Repeat with two more Daphnia and calculate a mean average bpm.
7) Repeat all above steps, replacing the distilled water with a low concentration caffeine...