Lumbriculus Variegatus Pulse Rate With caffeine . By Brett Rosato , Rick Stacey.
By Brett Rosato, Rick Stacey
Introduction: The Lumbriculus Variegatus otherwise knows as the California Blackworm, are found in wet areas near bodies of water. We have chosen this worm to test the difference between the worms pulse rate while its resided in regular water and while its resided in caffeine solution.
About caffeine: (C8H10N4O2) Caffeine is a stimulant that directly affects the central nervous system. It is widely used in food and beverages designed to increase levels of alertness like coffee and soda. Caffeine is also useful in biomedical research, as it increases intracellular levels of cAMP, which is a signaling molecule in many biological processes. When you get sleepy, adenosine molecules bind to receptors stimulating drowsiness. Because caffeine is similar in structure to the adenosine molecules, it connects to the receptors instead, keeping you from getting tired.
About the worm: The worm is transparent, which allows us to see its pulse rate while it is under a microscope. The dorsal vessel of the worm pumps the blood of the worm segment by segment in a closed system, which is how we count its pulse rate.
Hypothesis: If you put a black worm in a caffeine solution then the heart rate will go up.
Materials: microscope, 4 petri dish\'s , 15 black worms, flask, graduated cylinder, scale, spoon, eye droppers, well slide, cover slip.
Independent variable: 1.5 mM Caffeine solution
Dependent variable: the black worms pulse rate
Create a 1.5 mM solution with the pure caffeine and distilled water.
Get two petri dishes, one with the caffeine solution in it and plain water in the other (2-5) label two more caffeine recovery, and plain recovery.
Fill a petri dish with (2-5)mm of the caffeine solution
Put 10 worms in the petri dish with the caffeine for 15 minutes
As soon the 15 minutes are up start counting your worms heart rate using a well slide and a cover slip to hold the worm in place one.
Find the pulse rate and record each worm once (30 secconds/ then double) to get one minute.
put that worm that was tested in a different distilled recovery container
Repeat step 6, 7, and 8 with the other 9 worms.
Now get 5 worms and put them in a petri dish with distilled water
And repeat steps 5,6 and 7 with these 5 worms for the control group.
Conclusion: With the solution added to the black worms their heart rate will go up, these results agreed with our hypothesis. The average heart rate for a worm in the pure caffeine and distilled water solution was 35.2 peats per minute and the average for the worm in distilled water was 26.4. The only problem we found with this experiment was the black worms were in the solution for different amounts of time because we added them all at the same time to the solution and then waited 10 minutes to start counting their heart rate. You could solve this by staggering the time when you put the worms in the solution.