Over 350 of you medical research detectives correctly identified the
pathogen which caused the hemorrhagic disease in Episode Two of the
Here are this episode's prize winners, selected at random
from all the correct entries, and a small sample of the over 350 correct
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Individual Winners and Their Solutions
Cecily Dubusker, 11th grade, Wickliffe High School
I think it is bacteria because, first of all, the pathogen that infected
the mice was larger than .5 microns and smaller than 10 microns. However,
I am sceptical of this because some virus could have infected the bacteria.
Also, the more bacteria that was grown the more it made the mice bleed
(the pathogen growing couln't have been fungi because it was too large).
Also, it couln't straightforwardly have been a virus or a chemical because
these substances are too small and their test results came up negative.
The only logical explaination would be a bacterium.
Laurie Bourque, 12th grade, East High School
Size of the pathogen. less 10 microns more .5 microns Mice bleeding
( ma f5a cwa) Good growth in petri dish
Kelly Sayles, 9th grade, City Honors School
Bacteria is between a half-micron and 10 micros in size. The mouse that
was exposed to the milk that did not pass through the half-micron filter
but did pass through the 10 micron filter was bleeding. Also bacteria
excels at growing in a petri dish and the white culture that was found
in the petri dish with the "evil milk" in it (but not in the dish with
the "good milk" in it) made the mouse that was exposed to it bleed.
Patrizia Zucaro AND Lisa Grossman, 10th grade, Staples High School
The pathogen we thought that was in the milk is bacterium. The mouse
test MA showed a mouse bleeding from its paws. This test was conducted
with the evil milk. The results of the test showed it was produced by
a single cell organism which bacteria is a singled cell organism. The
second test F5A turned out quite bloody, the F5A measured the size of
the cell which was between 10 and .05 microns. A one celled creasure
anywhere between this size is a bacteria. The last test that was bleeding
profusely was CWA and it contain white stuff in the culture test, the
PDA contain white growth PDB did not. In conclusion we figured it was
the bacterium for the reasons above.
Justin Kaufman and Brandon Rockwell, 9th grade, Bancroft School
It's a bacterium firstly because of elimination. Viruses and chemicals
are less than half a micron, and everything that caused blood came from
a material that was from .5-10 microns big. A fungus is above 10 micons
big, which cancels out both of those options. A bacterium practically
fits all categories. They saw a uni-cellular organism. Perhaps a bacterium.
They also said that they saw identical black sheets from the machine
that tests for chemicals which would lead one to believe that the chemicals
are safe. The bacteria probably grew in the heat. The large white growth
in the petri dish that didn't grow in the good milk was probably because
of the fact that the bad milk wasn't pasteurized. The growth came from
the any bad materials that were left in the milk because of the lack
Classroom Winners and Their Solutions
10th grade class, Wrenshall
Bacteria is usually between 10 and .5 micronometers. It also grows well
in petri dishes and the mouse that was bleeding profusely was exposed
to the petri dish.
9th grade class, Staples High School
In the bottle of filtered materials, vial F5 turned up "Quite Bloody."
F5 refers to organisms between 10 and .05 microns in size. Fungi has
a size of more than 10 microns, so it would be filtered into the non
bloody bottle (F100). Virus is typically less than .05 microns in size,
so it would be filtered into vial F0. Bacteria, however, is between
10 and .05 microns in size, so it was filtered into vial F5, the bloody
vial. When the milk was burned, both samples turned up the same, and
there were no traces of metal salts in Evil Milk A, So chemicals can
be ruled out.
12th grade class, Genetics, Fontana High School
The Pathogen must be from milk A because it came from the crime scene
and CWA, MA, and F5A all caused the test mice to begin bleeding profusely,
while all of the test mice exposed to the substances from milk B(MB,
F5B, F0B, and CYB) were okay. The microfuge filters filtered the different
sized substances from the milk. The only sized substance that caused
any reaction was the F5A. This placed the pathogen as being between
.05 and 10 microns, and the only pathogen which falls within this range
is a bacterium. Viruses and chemicals are too small, and fungi are too
large. Also, both milk samples contained the same amounts of the same
chemicals. The white substance growing on petri dish A(CWA) was the
culprit. So, the pathogen which is causing Troy and Isabella to bleed
profusely is a bacteria from evil milk A.
11th and 12th grade classes, Period 7 Biology II, Presque Isle (Maine)
The pathogen in the milk has to be a bacterium. The evidence all points
in that direction. The mouse in F5A was infected with a sample larger
than 0.5 microns and smaller than 10 microns. Chemicals and viruses
are too small to fit this description while fungi are too large. Also,
when cultures from the smear plates were tested, the white stuff growing
in Petri Dish A, the one with the affected milk, caused the mouse to
exhibit symptoms. Also bacteria are known to grow well on agar plates.
The photomoter test showed that chemicals in the two milk samples were
identical, thereby ruling out chemicals as the cause of the illness.
10th grade class, Bledsoe Co. High School
The bacteria was the only substance that could not fit through the filter.
The bacteria also grew on the petri dish and produced the most noticiable
results whenm exposed to the mice.
Some Other Individual Entrants and Their Solutions
Drew Adam Newcomer, 6th-8th grades, Willis Jepson Middle School
It's a Bacterium beacause it's between 10 and .05 microns and there was
white stuff growing in petri dish A. A-was the evil milk. All these things
had the mice bleeding some or alot.
Wiley Martin, 12th grade, Msgr. Scanlan High School
- Bacteria grow especially well in petri dishes.
- The mouse infected with the white stuff bled profusely.
- Another mouse was infected with the stuff that was caught with the
filter that catches 1/2-10 microns.
- Bacteria are one celled and are 1/2-10 microns in size.
Juliann K. Larsen, 9th grade, Service High School
In the tests on the mice the results were as follows:
According to these facts, a bacterium is the only likely cause.
- Only the mice innoculated with the "evil" milk started bleeding
- The mice innoculated from the F5A group started bleeding. According
to the library sources, the pathogen must have been >10 microns large
and <.5 microns large. The book said that bacterium were the only
possible pathogens to fit those spefications.
- The mice innoculated with the white growth from PDWA became sick
while the ones innoculated with the yellow growth from PDYA and B
Mike Berry, 11th grade, Churchill High School, Livonia, MI
It must be a bacterium due to the final lab results. First, it was narrowed
down to either Fungi or Bacterium, as those two are the substances which
grow in petri dishes. The white element in the petri dish is what made
the mice bleed, which proves proves the growth in the petri dish was
the pathogen. Then in the library it was learned that bacteria is between
.05 and 10 microns in size and fungi was larger than 10 microns. Testing
the mice with the material between .05 and 10 microns, gathered from
the filtration unit, the mice bleed quite a bit. With the material larger
than 10 microns, the mice stay healthy. Therefore, piecing the evidence
together, it must have been a bacterium.
Tim Chan, 9th grade, McCallie School
Only the fungus and the bacteria would grow in the petri dish. Since
the white substance cause the mouse to start bleeding, it must be linked
with the disease. That would mean that the white substance is either
a fungus or bacteria. Bacteria are one-celled organisms, and I saw one-celled
organisms in the microscope. Also only the bacteria(typically) would
be caught in the .05 to 10 micron filter. This strongly points to bacteria
as the cause of the disease.
Some Other Classroom Entrants and Their Solutions
6th-8th grade classes, Per. C students, Chico Jr. High School
The size is the same as a bacteria; viruses are too small, while fungi
are too big. The white stuff made the mouse bleed like the patients. The
microscope showed single-celled organisms; mice exposed to this stuff
bled at the paws.
6th-8th grade classes, Jepson Science Concepts, Willis Jepson Middle
The majority of our class feel that the pathogen is a bacterium because
the mice exposed to the substance from filter F5A were bleeding heavily.
F5A filters to the size of bacteria. The mice exposed to any of Evil
Milk A filtered in F100A were healthy, ruling out fungi and in F0A were
healthy ruling out viruses. The photometer tests show both evil milk
A and good milk B identical, so a different chemical in evil milk A
is not the cause.
9th and 10th grade classes, 6th period General Biology, Des Lacs-Burlington
We think the pathogen in the milk is a bacterium because of the following:
First of all, the size -- bacteria range in size from 10 - .05 microns
and this was the size of the particle that caused bleeding in the mice.
Both bacteria and fungus grow in the petri dishes, but since the larger
size particles caused no bleeding in the mice, we think that too supports
the fact that the pathogen was a bacterium. We also doubt that chemicals
would have been added intentionally to the milk because the milk was
supposed to be "natural". Since the milk was unpasteurized and since
the milk was allowed to warm up, we thought from the beginning the most
likely pathogen was bacteria. The test results of the filtration and
cultures support this hypothesis.
1th and 12th grade classes, Hoffman Estates High School
- The pathogen is a bacterium because it is larger than 0.5 microns
and smaller than 10 microns (which is bigger than both a virus or
a chemical and smaller than a fungi).
- The mouse injected with the evil milk F5A became bloody.
- The mouse that was exposed to the evil milk CWA that was grown in
the petri dish was bloody.
- The bacteria they saw in the microscope MA also caused the mouse
to become bloody.
11th grade class, MSC AP Biology, Winston Churchill High School
The bacterium is the pathogen as the filter sizing and gram stain identification
clearly demonstrate. In addition, the white growth on PDA (evil milk)
caused bleeding symptoms when injected into the test mice. A process
of elimination lead us to reject the fungus (too large), a chemical
(no apparent differences in MA and MB) and the virus (bacteria would
still be the host organism).The data given suggested that the pathogen
was a bacterium which was able to grow in MA (evil milk).
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