1. Effect of Caffeine on Lumbriculus variegatus By: Monica Benjovsky and Kellie O’Hearn Introduction: What is the effect of caffeine on a Blackworm? This experiment tests the pulse rate of a Lumbriculus variegatus with a caffeine solution. Caffeine is a drug that 90% of America consumes daily. It is a stimulant drug that can sometimes kill or paralyze insects and small organisms. For humans it is a stimulant to the nervous system, restoring alertness and getting rid of drowsiness. L. variegatus are used in this experiment because of their transparent skin which makes it easy to see pulse rates. Also, Blackworms have distinct behaviors, the Blackworm habitat consists of shallow water; therefore they are easy to store, and access. Hypothesis: If Blackworms are placed in a caffeine solution then the pulse rate will be higher than those Blackworms placed in distilled water. Procedure: Label three specimen cups distilled water, caffeine low, and caffeine high; place 15mL of each solution in he appropriate dishes. Label three specimen cups distilled water recovery, caffeine low recovery, and caffeine high recovery; add 15mL of distilled water to each dish. Place ten blackworms in each of the solution dishes and let sit for ten minutes. When time is up, testing one at a time, place blackworms on a well slide under 10x magnification. Record the pulse rate at the midsection for one minute. After being tested place worms in appropriate recovery dishes. Caffeine Solution: Low- 0.0005M (194g/1M)=.0097g High- 0.005M (194g/1M)=.097g Materials : Microscope, pipette, well slide, coverslip, distilled water, caffeine solution(.0005M,.005M) stopwatch, three specimen cups (for solutions), three specimen cups (for recovery), thirty Blackworms. Results: The average pulse rate of the Blackworms in high caffeine solution (53.2/min) and the average pulse rate of Blackworms placed in Caffeine low solution (42.2/min) was higher than the average pulse rate for the distilled water (32/min) Conclusion: Our results supported our hypothesis because the average pulse rates of the Blackworms did increase when placed in both caffeine solutions. The Caffeine solutions may have had effect on the Blackworms placed in the caffeine solutions. We noticed when transferring some Blackworms from the well slide to the recovery dish, that they began to separate. Although, we did not notice a change in color. While transferring the worms the worms into the solution cups, the solutions may have been diluted from the distilled water in the pipette. Also, because some of the pulse rates were only counted for 30 seconds error might have occurred. The amount of distilled water could have been decreased by squirting more water out of the pipette. This would decrease the source of error. To improve our experiment we could have performed more trials. Variables: Independent: Caffeine Solutions (low/high) Dependent: Pulse Rate Constants: Species of worm, well slide, temp. Control: Worms kept in distilled water Reference: www.eeob.iastate.edu/faculty/Drewesc.htdoc www.eeob.iastate.edu/faculty/Drewesc.htdoc www.howstuffworks.comwww.howstuffworks.com (Marshall Brian, Charles Bryant, Matt Cunningham)