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The Making of the Fittest:
The Birth and Death of Genes
DEMONSTRATION
TEACHER MATERIALS
VISCOSITY OF ICEFISH AND NON-ICEFISH BLOOD
OVERVIEW
This demonstration serves as an extension to the Howard Hughes Medical Institute’s short film The Making of the Fittest:
The Birth and Death of Genes (http://www.hhmi.org/biointeractive/making-fittest-birth-and-death-genes). Icefish blood
lacks red blood cells, an adaptation that reduces the blood’s viscosity. This demonstration simulates how having thinner
blood enables icefish to pump it more efficiently and distribute oxygen without hemoglobin.
KEY CONCEPTS AND LEARNING OBJECTIVES
Students will be able to explain the advantage of thin blood to icefish.
CURRICULUM CONNECTIONS
Curriculum
NGSS (April 2013)
Common Core (2010)
AP Biology (2012–13)
IB Biology (2009)
Standards
MS-LS1-1, MS-LS4-4
MS.LS4.B, MS.LS4.C, MS.PS1.A
HS-LS4-2,
HS.LS1.A, HS.LS4.B, HS.LS4.C
ELA-Literacy.SL.8.1, ELA-Literacy.SL.8.1c, ELA-Literacy.SL.8.1d, ELA-Literacy.SL.9-10.1,
ELA-Literacy.SL.9-10.1c, ELA-Literacy.SL.9-10.1d
1.A.1, 1.A.2, 3.C.1, 4.C.1
4.1, 4.3, 5.4, 6.2, 7.5
KEY TERMS
hemoglobin, red blood cell, viscosity
TIME REQUIREMENTS
This demonstration and the follow-up discussion were designed to be completed within 5–10 minutes; additional time is
required for the extension activity.
SUGGESTED AUDIENCE
This demonstration is appropriate for middle school life science, high school biology (all levels including AP and IB), and
introductory college biology.
PRIOR KNOWLEDGE
Students should watch the short film The Making of the Fittest: The Birth and Death of Genes before they watch this
demonstration.
MATERIALS
•
bottle of corn syrup (i.e., Karo syrup) and a screw-top container for storage
•
container of red food coloring
•
four 60–cubic centimeter syringes (without needles)
•
two equal-sized, wide-mouthed containers with screw caps
•
two 250-milliliter beakers or clear plastic cups
•
water
•
felt-tipped marker
Viscosity of Icefish and Non-icefish Blood
www.BioInteractive.org
Published March 2012
Revised October 2013
Page 1 of 4
The Making of the Fittest:
The Birth and Death of Genes
DEMONSTRATION
TEACHER MATERIALS
TEACHING TIPS
•
Refrigerate the corn syrup after use. That way it should keep from year to year.
•
Instead of doing the demonstration in front of the class, you could have student groups perform it, make
observations, and provide a written analysis relating their observations to the ability of icefish to survive in the
Southern Ocean.
•
If you choose to do the extension activity, have tubing and smaller and larger syringes available.
•
You may wish to print the background in the In-Depth Film Guide (http://www.hhmi.org/biointeractive/classroomactivities-birth-and-death-genes) for students to read for homework.
•
Discussion questions with answers are available on page 3.
PROCEDURE
SETUP
1. Prepare the non-icefish and icefish “blood.”
a. To prepare the non-icefish blood, pour 100 milliliters corn syrup into a jar
with a screw cap. Add a few drops of red food coloring to simulate
hemoglobin. The mouth of the jar should be large enough for you to insert
the 60–cubic centimeter syringe.
b. To prepare the icefish blood, add 100 milliliters plain water to the second
jar.
2. Label one 250-milliliter beaker (or plastic cup) “icefish blood” and the other
“non-icefish blood” or “other fish blood” (Figure 1).
3. Fill two syringes with 40 cubic centimeters non-icefish blood and two others
with 40 cubic centimeters icefish blood.
Figure 1: Setup
DEMONSTRATION
You can do this demonstration with one or two student volunteers.
Option A: One Student Volunteer
•
Ask the student to hold a syringe loaded with icefish blood in one hand and a
syringe loaded with non-icefish blood in the other.
•
Have the student hold the syringes over the appropriately labeled beakers.
Direct the student to be ready to push both plungers when you give the signal
(Figure 2).
•
Have the student repeat the process holding the syringes in the opposite
hands.
Option B: Two Student Volunteers
•
Ask one student to hold a syringe loaded with icefish blood over the icefish
blood beaker and the other student to hold the syringe loaded with nonicefish blood over the non-icefish blood beaker.
•
Direct each student to be ready to push the plunger when you give the signal.
•
Have the students repeat the process after switching the syringes.
Figure 2: One-student version
Viscosity of Icefish and Non-icefish Blood
www.BioInteractive.org
Page 2 of 4
The Making of the Fittest:
The Birth and Death of Genes
DEMONSTRATION
TEACHER MATERIALS
QUESTIONS
Some possible discussion questions and answers follow.
1. Ask the class which type of simulated blood appeared to be the easiest to pump. What evidence do students have to support
this?
Possible response: The icefish blood is the easiest to pump. Evidence is that the syringe of icefish blood emptied
more rapidly than the syringe filled with non-icefish blood.
2. Ask student volunteers which syringe was easier to pump. Then ask the class what the significance of this is for icefish and
other fish.
Possible response: The students should report that the syringe full of icefish blood was easier to pump. The
significance is that icefish blood carrying oxygen reaches the cells more rapidly with less energy expenditure than
non-icefish blood. If icefish blood had the same viscosity as the blood of other fish, it would flow more slowly and
the delivery of oxygen would be less energy efficient.
3. What does it mean that icefish blood is less viscous than the blood of other fish species? How does the absence of red blood
cells reduce the viscosity of icefish blood?
Possible response: It means that icefish blood is not as thick and sticky as non-icefish blood. It offers less
resistance to flow. Red blood cells are solid. Even though they are microscopic, they increase resistance to flow;
therefore, the reduction in red blood cells leads to easier blood flow.
4. Why was it important to switch hands or students during the demonstration?
Possible response: One person might be much stronger than the other, or an individual’s dominant hand may
push the plunger on the syringe with more force than the nondominant hand uses. By switching, the validity of
the experiment increases.
5. Icefish hearts are larger than those of non-icefish species of the same size. Icefish also have wider blood vessels than
comparable non-icefish species. How do these two factors also increase the ability of icefish to distribute oxygen to their cells?
How could you modify this experiment to simulate a larger heart and wider diameter blood vessels for icefish?
Possible response: A larger heart is able to pump a larger volume of blood per beat. Wider diameter vessels
provide less resistance to flow. Consequently, icefish blood is pumped from the heart with greater force and
meets less resistance than the blood in a comparable non-icefish species. The increased rate of blood flow
enhances the icefish’s ability to deliver oxygen to the cells.
Modifications could be to use a smaller syringe to represent the non-icefish heart and attempt to pump the same
volume of fluid (icefish and non-icefish blood). Another modification would be to connect a narrow diameter tube
to the non-icefish syringe and a larger diameter tube to the icefish syringe.
6. Oxygen dissolves in cold water much better than in warm water. The concentration of oxygen dissolved in –1.8°C water is
about twice as much as in 25°C water. The higher oxygen concentration makes it possible for icefish to survive without
hemoglobin. What would happen if you put an icefish in a fish tank in this room?
Possible response: It would get too little oxygen and die.
Viscosity of Icefish and Non-icefish Blood
www.BioInteractive.org
Page 3 of 4
The Making of the Fittest:
The Birth and Death of Genes
DEMONSTRATION
TEACHER MATERIALS
7. The globin gene, which codes for hemoglobin, is no longer functional in icefish, yet this gene is very important in almost
every other fish species. Based on the information provided in the short film, explain how icefish are able to survive without the
globin gene and how the gene came to be eliminated from the icefish genome.
The nonfunctional globin gene is the result of a series of mutations. Icefish obtain an adequate supply of oxygen
from the cold ocean water, which has a lot of dissolved oxygen. A number of variations including scaleless skin,
large capillaries, and a large volume of blood all make it possible for icefish to survive without a functional globin
gene. (Note: Since hemoglobin was no longer necessary for the survival of icefish, the mutated globin gene was
degraded and only a small remnant of the original gene remains as a “DNA fossil record.”)
EXTENSION ACTIVITY
If you have the time, you could provide materials for students to come up with an experiment to answer Question 5. We
provide a rubric (below) on how to score their work.
POSSIBLE SCORING RUBRIC FOR EXPERIMENT
Task
Designing and
performing the
experiment
Concept
understanding
4
3
2
1
The student’s
hypothesis and
experiment are
reasonable. The
experiment shows
the larger heart and
wider diameter
vessels increasing the
rate of flow.
The student’s
hypothesis and
experiment are
mostly correct. The
experiment shows
the larger heart and
wider diameter
vessels increasing the
rate of flow.
The student’s
hypothesis and
experiment are
flawed. Even so, the
experiment shows
the larger heart and
wider diameter
vessels increasing the
rate of flow.
The student’s
hypothesis and
experiment are
incomplete and/or
incorrect. The
experiment does not
show the larger heart
and wider diameter
vessels increasing the
rate of flow.
The student
demonstrates a
mastery of the
concepts of natural
selection and
adaptation as related
to icefish survival and
experimental design.
The student
demonstrates a good
understanding of the
concepts of natural
selection and
adaptation as related
to icefish survival and
experimental design.
The student
demonstrates a
partial understanding
of the concepts of
natural selection and
adaptation as related
to icefish survival and
experimental design.
The student
demonstrates a weak
understanding of the
concepts of natural
selection and
adaptation as related
to icefish survival and
experimental design.
AUTHOR
Mary Colvard, Cobleskill-Richmondville High School (retired), New York
FIELD TESTERS
Dave Kenyon, Paw Paw High School; Tina Larson, Marian High School; Tamara Watson, Westwood High School
Viscosity of Icefish and Non-icefish Blood
www.BioInteractive.org
Page 4 of 4