The Effects of
Drugs on Daphnia
Student Study and Analysis Sheet
36W 1258
Pre-Lab
Introduction
-
Knowledge
Probe
Curiosity
Daphnia, often called water fleas, are arthropods, related to crabs, lobsters, and other crustaceans. One way
that they differ from those crustaceans is that their carapace is transparent. This allows for observation of their
internal organs, it is easy to observe certain life functions in Daphnia. Perhaps the most dramatic are the move
ment of food through the digestive system and the beating of the heart.
Besides being able to view the heart actively beating, you will be able to detect changes in heart rate after
changing the environment that the Daphnia live in. Chemicals that cause the heart rate to accelerate are
called stimulants, those that slow it down are called depressants.
Stimulants and depressants are chemicals that are naturally produced by many organisms. Have you ever
wondered what causes your heart to speed up when you are afraid and how does it slow back down? There
must be some chemical at work here. Besides your natural body chemicals, stimulants and depressants are
formed by many other organisms such as plants and fungi.
One of the chemicals we will be experimenting with in this activity is a compound called caffeine. This mate
rial is found in a multitude of plants and is produced and stored in their leaves, stems, seeds and roots. It
comes from a material in plants called caffeic acid. Interesting enough, the function of this material is not
exactly known. It is thought that it may have a role in antibacterial and antifungal protections as well as a nat
ural insecticide. Another fairly common plant derived substance is nicotine, found in great abundance in
tobacco leaves. Again not much is known regarding the exact function of nicotine in plants, although it may
have a role in growth regulation.
Some chemicals that we use as drugs have no use at all for the organism that manufactures them. Some are
actually waste products that are excreted. An example of this would be alcohol. Alcohol, whether you use it
to rub on a wound or drink, is a molecule of glucose 0
12
H
(C
)
6
, they remove the energy and are left with
Carbon, Hydrogen and Oxygen. These atoms are reassembled in a new form, molecules of alcohol and CO
.
2
Some of the drugs that we use come directly from humans and other animals. An example of this is epi
nepherine, a common hormone in humans that was formerly known as adrenaline. This hormone is some
times referred to as the “fight or flight” hormone. It is produced by the body in times of stress and gets the
body ready for trauma. Another function of epinepherine is that it is used as a neurotransmitter.
Neurotransmitters are substances that help nerves communicate with each other as they transmit messages
from one part of the body to another.
In this activity, you will first learn the structures of a living Daphnia and the location of the heart. You will then
take the Daphnia and treat it with the chemicals described above. The counting of the rate of heartbeats will
allow you to tell if the chemical is a stimulant or a depressant.
Copymaster. Permiseon granted to make unlimeed copies for use in any one
school buiding. For educational use only, not for commercial use or resale.
O 1996 WARD’S Natural Saence All rights rfserved.
250.2061
Questions
1)
j
2
Observe the diagram of Daphnia included with this kit. What structures do you see that would contribute
to the Daphnia being classified as a Crustacean?
-+ Application
2)
One of the extended activities proposed in this lab will be to change the temperature around the Daphnia
and view the effect on heart rate. If this experiment were performed on humans, what results would you
expect? Explain.
Prediction a 4\c
3)
In this activity, we’ll be treating Daphnia with caffeine (a substance in coffee and chocolate), nicotine (a
substance in tobacco), epinephrine (a hormone produced when someone feels threatened), and alcohol.
Predict which substances you think will be stimulants and which will be depressants.
[Copymastei Permission granted to make unlimited copes lor use in any one
school building. For educational use on not for commercial use or resale.
V 1996 WARCYS Natural Science
All rights reserved.
3
Performing the Experiment
Objective
To learn to identify stimulants and depressants by their effect on the heart rate of Daphnia.
1
Materials
.J
Culture of Daphnia magna
Daphnia netting
Magnification chamber
Pipettes
Solutions of:
Caffeine
Epinephrine
Ethyl Alcohol
Nicotine
Unknown samples (optional)
Stopwatch or watch with a second hand
Daphnia Form and Structure Study Sheet
cJ
ci
h
Self-Direction
Mental Stimulation
Procedure
1)
2)
3)
Cut the daphnia netting into small squares and place in the bottom of the magnification chamber.
Using a pipette, draw up a few Daphnia from the culture dish, 1 or 2 will suffice. Place the Daphnia in the
magnification chamber, on top of the netting, with as little water as you can transfer. This will keep then
from swimming rapidly away.
Practice observing the Daphnia by holding the cover of the chamber approximately 2 inches above the top
of the chamber. Locate a large daphnia and its heartbeat. Use the diagram of Daphnia to locate the heart.
Try timing the heart rate. To do this, have your partner start the stopwatch and tell you when to begin
counting. Count for 10 seconds. Enter this heart rate in the Data Tables and compute the heart rate per
minute by multiplying by 6.
5) Repeat this procedure 2 more times and find the average heart rate of a Daphnia. Enter this information
into the data table.
6) Add a drop of caffeine solution to the Daphnia. Wait one minute for the solution to be absorbed, and com
pute the average heart rate as performed above. Enter whether caffeine is a stimulant or depressant.
4)
7) After you have computed the caffeine effected heart rate, discard your Daphnia as per your teacher’s
instructions. Rinse out and dry your chamber and net.
8) Repeat steps 2 through 7 with each of your remaining test solutions and any unknowns that your teacher
might include.
Copymaster. Permisaon granted to make uqlirated copies for use in any one
school building. For educational use only, not for commercial use or resale.
C 1996 WARDS Natural Science
All rights reserved.
4
Analysis
Data Tables
Heart Rate
Per Mm. (X6)
Control
Heart rate/lO sec. Trial
Heart rate/lO sec. Trial 1
Heart Rate
Per Mm. (X6)
Treated with Caffeine
ii
Trial 21
Trial 2j
Trial
Trial
3J
Average heart rate per minute
Average heart rate per minute
Stimulant or Depressant
l
Control
Integrity
Rate
observationerHeart
Mm. (X6)
ii
Trial 21
Trial 3f
Heart rate/lO sec. Trial
Heart rate/lO sec. Trial 1
Trial
Trial
Average heart rate per minute
Average heart rate per minute
ata
Heart Rate
Per Mi (X6)
Treated with Epinephrine
Stimulant or Depressant
na ysis
Claim
Scv\
Heart Rate
Per Miii. (X6)
Control
Heart rate/b
sec. Trial 1
Trial
21
Trial
Heart Rate
Per Mi (X6)
Treated with Ethyl Alcohol
Heart rate/lO sec. Trial
if
Trial
21
Trial
31
Average heart rate per minute
Average heart rate per minute
Stimulant or Depressant
Heart Rate
Per Mm. (X6)
Control
Heart rate/b
sec. Trial 1
Heart rate/lO sec. Trial 1
Trial 2
Trial 2
Trial 3
Trial 3
Average heart rate per minute
Heart Rate
Per Mm. (X6)
Treated with Nicotine
Average heart rate per minute
Stimulant or Depressant
copymaster. Permission granted to make unlimited cop for use in arr one
school building For educational use only not for commercial use or resale
C 1996 WARDS Natural Science
All rights reserved.
5
Questions
-+ Application
1) Which substances were stimulants, which were depressants?
2) Would it be safe to conclude that these materials would act the same way in humans? Explain your answer.
3) There are many substances made in the body that act as stimulants and depressants. Propose a situation
where your body might need to produce a stimulant. Propose a situation for a natural depressant.
4) Why was it necessary to start with a new Daphnia after each substance?
5)
Design an experiment that would test the effect of temperature on the heart rate of Daphnia.
—+ Application
Further Investigations
Critical Thinking
Creative Thinking
1) Design an experiment to test the effects of pollutants on the Daphnia heart rate. Investigate materials such
as pH, trying to simulate the pH found in an acid polluted lake.
2) Go out with a small aquarium net to a pond and run it through some weeds along the side. Put the crea
tures that you catch into a jar. There should be some Daphnia there. Bring these Daphnia back to the lab
and investigate their heart rates. Compare the durability of a wild Daphnia to a lab raised Daphnia.
[Copymaster. Permission granted to males untrrsted copies fix use in any one
I school building. For educational use on’. not for commercial use or resale.
o
1996 WARDS Natural Science
All rights reserved.
Level of Inquiry
VAEI Community of Scientific Practice
A Process of Scientific Inquiry
®)
2
(QPOE
Habits of Mind
.
.
Habits of Mind components not
currently included in my lesson design
Changes I will make to include these
components
Openness to New Ideas!
Informed Skepticism
•
•
QPOE components not currently
®
2
included in my lesson design
Changes I will make to include these
components
Question
Socially and Language Rich
Environment
•
•
Socially and Language Rich
Environment components not
currently included in my lesson design
Changes I will make to include these
components
Culture Supporting Risk Taking
13 ‘v
I5ercL
tc
1
f
t
Mss
ed
—* Knowledge
-
ervi rek
Probe
pcor
Persistence
Collaborative Structures
10
c
Explanation
C
—* Evidence
Adaptability
—+ Reasoning
Cooperative Interactions
L
0
5
Desc
WV\,\
I-k&
Discourse: Oral/Written
LlL
Id.
Skcrt
w/
-[Cc
Shared Control
Negot ated Meaning
S