Title
Toxicology of Alcohol
(estimated time: 2 hours)
Table of Contents
I.
Pre-requisite knowledge
2
II.
Massachusetts Science and
Technology/Engineering Frameworks
Compliance
2
III.
Content to be Taught
2
IV.
Rationale
3
V.
Goals
3
VI.
Objectives
3
VII.
Background for Teacher
3
VIII.
Engagement
4
IX.
Exploration: Lab Protocol
4-7
X.
Explanation
7
XI.
Evaluation
7
XII.
Appendix
8
XIII.
Toxicology Lab Prep
9-10
1 2 How much is too much?
Daphnia/Toxicology lab
I.
Pre-requisite knowledge
Students should be familiar with the use of microscopes and the basics of
graphing.
II.
Massachusetts
Compliance
Science
and
Technology/Engineering
Frameworks
SIS1. Make observations, raise questions, and formulate hypotheses.
Observe the world from a scientific perspective.
Pose questions and form hypotheses based on personal observations,
scientific articles, experiments, and knowledge.
SIS2. Design and conduct scientific investigations.
Articulate and explain the major concepts being investigated and the
purpose of an investigation.
Select required materials, equipment, and conditions for conducting an
experiment.
Identify independent and dependent variables.
Write procedures that are clear and replicable.
Employ appropriate methods for accurately and consistently
-making observations
-making and recording measurements at appropriate levels of precision
-collecting data or evidence in an organized way
SIS3. Analyze and interpret results of scientific investigations.
Present relationships between and among variables in appropriate forms.
Represent data and relationships between and among variables in
charts and graphs.
Use appropriate technology (e.g., graphing software) and other tools.
SIS4. Communicate and apply the results of scientific investigations.
-Develop descriptions of and explanations for scientific concepts that
were a focus of one or more investigations.
-Review information, explain statistical analysis, and summarize data
collected and analyzed as the result of an investigation.
-Explain diagrams and charts that represent relationships of variables.
III.
Content to be Taught
A. Alcohol depresses the nervous system
B. Alcohol causes the heart rate of Daphnia to decrease.
C. A toxin is a substance can harm humans or animals and is related to
dosage.
3 IV.
Rationale
The knowledge that alcohol has toxic properties and negatively affects the
regulation of vital life processes deepens students understanding of the
physiological consequences of alcohol use and abuse.
V.
Goals
Students will understand that alcohol is a central nervous system depressant
that has toxic properties.
VI.
Objectives
Students will do the following:
A. Measure the effects of alcohol on the heart rates of Daphnia
B. Define toxicity as the property of a substance to substance to harm
humans or animals and is related to dosage
C. Graph heart rate vs. alcohol concentration
D. Interpret data to conclude that alcohol negatively affects the regulation of
heart rate in Daphnia
VII.
Background for Teacher
Ethanol (Ethyl alcohol) is a central nervous system depressant that has a
wide range of effects on the human body. It specifically affects the parts of the
brain that control, thinking, coordination, and the control centers for heartbeat,
breathing, and the gag reflex.
Although alcohol is a depressant, it is often thought of as a stimulant because
it frequently causes decreased inhibition and increased pleasure seeking.
Alcohol depresses a class of receptors in the brain known as GABA that
impairs coordination, thinking, heartbeat, and breathing. Anterograde
amnesia, also known as blacking out, may also occur.
Acute effects of alcohol in humans include increased heart rate at low blood
alcohol concentration (BAC) due to the dilation of the blood vessels. As the
BAC increases, the depression of the central nervous system causes the
heart rate to decrease.
Chronic effects of alcohol intake include high blood pressure and
cardiomyopathy. Dilated cardiomyopathy is serious condition of the heart
muscles that causes heart chambers to become enlarged resulting in the
decreased efficiency of the heart. The body compensates by increasing blood
volume thus increasing blood pressure.
4 Alcohol causes Daphnia heart rates to decrease providing evidence that
alcohol acts as a depressant.
VIII.
Engagement
A. Review the ADH lab.
1. Focus attention on the alcohol that is not broken down by ADH.
2. Ask, “What effects will the excess alcohol have on the body?”
B. Encourage the students to identify criteria for toxicity. Ask True/ False
questions about whether bleach, cyanide, lead, and water are toxins (They
all are toxic.). Develop a definition of toxic as - "the degree to which a
substance can harm humans or animals and is related to dosage."
(thefreedictionary.com).
C. Lead a discussion around the question, "Is alcohol a toxin?" This is the
essential question for the lesson.
D. Ask, "What evidence would we need to determine whether alcohol is a
toxin?"
1. Ans. Evidence that it harms organisms depending on dosage
E. Ask "How can we test the toxicity of alcohol without using human
subjects?"
1. Ans. Use an animal model
F. Introduce the animal model Daphnia magna, as a model organism. Show
the video of a Daphnia at (http://www.ebiomedia.com/BiologyClassics/The-Biology-Classics-Daphnia-Heart.html)
G. Project an anatomical chart of Daphnia (provided below).
1. Ask, "What part of the Daphnia could provide evidence to detect
the effect of alcohol on the organisms?" Suggest the heart.
2. Ask the students to predict the effect of alcohol on Daphnia heart
rate.
IX.
Exploration: Toxicology Lab Protocol (Option: use the video of daphnia
exposed to various concentrations of alcohol provided on this website.)
1. Present a picture of the crustacean Daphnia Magna. Emphasize
the following anatomical parts: Eye,
Heart, Antennae, Brood Chamber
with eggs, Intestine, and Legs.
5 2. Show the video demonstration of the Daphnia heart beating
(http://www.ebiomedia.com/Biology-Classics/The-BiologyClassics-Daphnia-Heart.html). Demonstrate how to determine the
heart rate by counting the number of heart beats in 10 seconds and
multiplying by 6 to obtain beats per minute.
3. Demonstrate the technique for preparing the Daphnia. We
recommend letting the students prepare their Daphnia slides as you
demonstrate.
a. Place a slide with a well depression on a level surface.
b. Dip a cotton swab in the petroleum jelly. Make a water
barrier by coating the circumference of the well with the
petroleum jelly.
c. Place a small dab of petroleum jelly in the center of the well.
This will be to capture the Daphnia.
d. Place the slide on the microscope stage.
e. Use a transfer pipette to pick up one Daphnia. Add the
Daphnia with one or two drops of water to the well to cover
the Daphnia with water.
f. Wick away the water surrounding the Daphnia with a paper
towel to immobilize the Daphnia in the center smear of
petroleum jelly. Add 1-3 drops of spring water to the well to
cover the Daphnia.
g. Turn on the microscope light and focus on the Daphnia
using 40X magnification.
h. Turn the light off and wait one minute. The light emits heat
that could affect the heart rate. Therefore minimize the
amount of time the light is on.
i. Turn the light back on and record the number of heartbeats
in 10 seconds. Turn off the light.
j. Multiply the number of heart beats in 10 sec by 6 and
record the number of heartbeats per minute in the 0%
alcohol row in Table 1.
k. Wait one minute and repeat step i and j two more times.
l. Record the results in rows labeled Trial 2 and Trial 3 in
Table 1.
m. Repeat steps f through l for the 4% and 8% alcohol
solutions. Be sure to rinse the Daphnia with spring water
prior to applying a different concentration of alcohol.
Table 1
%
Alcohol
0
Heart rate beats/min
Avg.Heart Rate
Trial 1 Trial 2 Trial 3 beats/per min
6 4
8
n.
X.
Have the students graph Average Heart rate vs. Alcohol
Concentration (cf. the student data sheet).
Explanation
A. Ask the students to propose their answer to the essential question, “Is
alcohol a toxin?” They must support their answer with data.
B. Confirm that the evidence supports a decrease in heart rate with
increased alcohol concentration in Daphnia. Explain that alcohol has
similar effects on humans. Acute effects of alcohol in humans include
increased heart rate at low blood alcohol concentration due to the dilation
of the blood vessels. Dilation increases the volume of blood vessels,
therefore the blood pressure decreases and the heart needs to pump
faster to move the blood throughout a larger volume. However as the
blood alcohol concentration increases, the heart rate decreases due to
alcohol’s depressant effect on the central nervous system that controls
heart rate.
XI.
Evaluation
A. Ask the students to respond to the following:
1. What does the data suggest for a relationship between alcohol
concentration and heart rate of Daphnia?
a. Answer: the heart rate decreases with increasing
concentrations of alcohol
2. Predict what would happen to the Daphnia heart rate if you added
20% alcohol to the Daphnia?
a. Answer: the heart rate would slow down considerably.
Students may extrapolate from the graph that the heart rate
will slow considerably, even assigning a numerical value.
They may also conclude that the heart rate will stop.
3. Explain whether the data supports the conclusion that alcohol is a
toxin.
a. Answer: The data supports the toxicity of alcohol because it
exhibits the potential to harm organisms as the dosage
increases.
7 XII.
Appendix
Name____________________________
Student Data Sheet
Table 1. Daphnia Heart Rate Data
%
Alcohol
Avg.Hea
rt Rate
in
10
Trial 1 Trial 2 Trial 3 sec
0
4
8
Average Heart Rate vs. Alcohol Concentration
Average heart rate 0 4
8 % Alcohol Concentration
8 Lab Prep for Daphnia Lab
A. Materials
Station Set-up- Each station will need:
1 depression slide (sticker side up)
1 plastic transfer pipette
1 p200 micropipette
1 tip box with tips
1 waste beaker
1 cotton swab
1 Petri dish with spring water and 3 Daphnia
1 tube of petroleum jelly
200 µl of an alcohol solution
1000uL spring water (0% ethanol)
1 timer
2 paper towels
I. Alcohol solutions
Make the alcohol solutions with an 80 proof clear alcohol such as vodka. Using lab
ready denatured ethanol contains other ingredients such as methanol that will affect the
Daphnia deleteriously.
Each group should receive 200 µl of the following solutions.
for 200 µl of 8%
solution
ETOH
4%
0%
ETOH ETOH
µl of 80 40
proof (40%)
Vodka
20
0
µl
of 160
springwater
180
200
9 2. Daphnia
Daphnia can be ordered at VWR. If you purchase the Daphnia care kit, the Daphnia can
be kept for up to six months. Make sure to change 10% of the water every week and
replace it with spring water. Do not remove the detritus on the bottom as it contains
Daphnia eggs that will sustain the population.
Sources:
http://www.ebiomedia.com/Biology-Classics/The-Biology-Classics-Daphnia-Heart.html
Carolina Protozoa and Invertebrates Manual, Carolina Biological Supply Company
http://www.sciencebuddies.org/mentoring/project_ideas/Pharm_p009.shtml.
Oslen, PhD. April 1st 2008.
Andrew
http://en.wikipedia.org/wiki/Blood_alcohol_content. September 15, 2009.
http://www.collegedrinkingprevention.gov/OtherAlcoholInformation/factsAboutAlcoholPoi
soning.aspx#WhatHappens.
http://www.ou.edu/oupd/bac.htm. The Police Notebook. 9/17/09
10