The purpose of the experiment was to determine if soaking blackworms in vodka for increasing time intervals would cause their pulse rate to steadily increase. Blackworms were placed in a 40% vodka solution for 10 minute intervals from 0-50 minutes. Their pulse rates were measured after each interval. The results showed that the worms' average pulse rate increased linearly as the time spent in vodka solution increased, supporting the hypothesis. However, there were limitations due to uncontrolled variables like stress on the worms and human error in counting. Repeating trials could reduce outliers and improve accuracy.
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Effect of time spent in vodka on black worm pulse rate nicole t
1. Nicole Tsetsilas
Block6
Effect of time spent in vodka on black worm pulse rate
Purpose: If blackworms are soaked in vodka for 10 minute intervals for 50 minutes then their
pulse rate will steadily increase.
MATERIALS:
Capillary tubes (75mm)
Shallow pan (27cm X 22cm)
Stereoscope
Cork Stoppers
1mL Pipette
Stop watch
Vodka Solution (.1mM)
1. LAB PROCEDURE:
(*Fore note: This procedure is most possible with multiple persons measuring the pulse rate of
the worms.)
1. Choose at least 60 blackworms (it is highly recommended that you choose more) at random
from a stock container.
2. Obtain a baseline pulse rate of the Lumbrisculus worm by recording its pulse rate with the
following procedure. Take up an individual worm into the pipette and gently squeeze it into a
capillary tube. Then balance the tube on top of two cork stoppers under the stereoscope at x40
magnification and count its pulse for 1 minute. Repeat 9 more times to complete the trial. Record
in a data table.
3. Fill a shallow pan with 40% vodka (.1mM) solution and quickly transfer at least 60 worms
into it at approximately the same time. Note the time/begin timing.
4. Wait 10 minutes from the initial time and quickly record the pulse rate of 10 ideal specimens
from the vodka solution. Do this by taking up an individual worm into the pipette and gently
squeezing it into a capillary tube. Then balance the tube on top of two cork stoppers under the
stereoscope at x40 magnification and count the pulse for 1 minute. Record in a data table.
5. Repeat step 4 for 10 minute intervals up to 50 minutes.
6. Collect data
2. Nicole Tsetsilas
Block6
Research: Lumbriculus variegates is the scientific name for the black worm. The
worm is indigenous to shallow, muddy water areas in the United States. When areas such as
these become contaminated by chemicals the black worm can be a useful biological detector of
this.
Black worms have similar nervous and endocrine systems to humans. Oxygenated blood
is pumped from the posterior of the worm to the anterior at a constant rate. When drugs are
diffused in worms their pulsation rate is affected, similar to humans. The worms, then, can be
observed to determine the effect of drugs on pulsation rate.
Alcohol is a vasodilator; it dilates the blood vessels causing an increase in blood flow.
The blood flow is forced to cover a larger body volume. The heart rate then increases to send
sufficient blood throughout the body. Due to the similarities in human and black worm nervous
systems black worm pulse rate in conjunction with alcohol should produce similar results;
increased pulse rate.
4. Nicole Tsetsilas
Block6
Line Graph:
Standard deviation: Control- 4.0, 10 minutes- 5.4, 20 minutes- 5.9, 30
minutes-6.1, 40 minutes- 7.1, 50 minutes- 7.2
y = 1.3343x - 23.924
R² = 0.9454
-10
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 40 45 50 55 60
10minuteintervals
Average pulse rate per minute
Pulse rate of black worms per 10 minute intervals
Series1
Linear (Series1)
5. Nicole Tsetsilas
Block6
Conclusion: The data collected from the 60 worms supports the hypothesis and research. Due
to in increase in time spent in the vodka the worms had an increased pulse rate per minute. The
graph depicts this steady increase from 0 minutes spent in vodka to 50 minutes. The averages of
the 10 worms at each interval clearly show this increase, refer to the data table.
When working with live test subjects it is important to the know that the actual organism
is an uncontrollable variable. The worms could easily move in the capillary tubes which affected
the count of the pulse rate. Each interval included outliers that skewed the averages to be higher
or lower than accurate. The stress of being handled could be an uncontrollable variable upon the
experiment as well. Random error due to human counting also skewed the results. The worms
pulse rate is quicker at the posterior end. This means the pulse rate fluctuates depending on
where it is being recorded from the worm.
There are several steps you can take to decrease errors. To reduce outliers conduct more
trials to make a more accurate average. To reduce the error caused by the fluctuation of the
worms heart rate in relation to where it is being recorded on the worm one should chose a single
segment of the worm and record the pulse rate of each worm at that same segment.
