Biology is the scientific study of life
so how do we study it? We have lots of
tools to help us but they are all
worthless
without you! As a biologist and scientist,
you must not only learn how to utilize
all the cool tools but also how to
analyze the information these tools help
you collect. In the end, we are trying to
learn more about ourselves and the world
around us. There are a couple of ways we
can do this. We can study science by the
discovery method, in which we observe and collect data and later analyze it.
We have no initial concept, which is
called a hypothesis, that we want to test
for. This is a common way researchers
study biology in the field. Also called
descriptive science, discovery science
allows scientists to use inductive
reasoning to make conclusions based on
observations. Jane Goodall, an expert on
chimpanzees and other apes, has conducted most of her research this way. This type
of research can lead to hypothesis
testing. We can also study life by
testing hypotheses. This type of research
is commonly done in a laboratory setting
where all factors in the experiment can
be controlled. First we generate a
hypothesis, which is a possible
explanation to the question we have
about the subject, then we perform an
experiment to test our hypothesis. We
must analyze the data collected to
determine if our hypothesis was correct
or not. In hypothesis testing, scientists
use deductive reasoning to predict the
results of an experiment based on
logical assumptions. The cause of cystic
fibrosis was determined by this type of
research. Cystic fibrosis is caused by
the build-up of excess mucus in the
lungs and digestive system, leading to
respiratory problems and organ failure.
Scientists determined through testing
that this disease occurred because of a
mutation in the gene that determines the
viscosity -or thickness- of mucus secreted by the cell
An here is one of those questions you love so much.
Hypothesis testing is accomplished
through the scientific method. The basic
steps of the scientific method are
observation of a phenomenon, asking a
question about the phenomenon, forming a hypothesis based on the question,
experimentation and collection of data,
analyzing the data, and exception or
rejection of the hypothesis. The
hypothesis can be revised if necessary.
And you do need to report your findings
to the scientific community. Let's go
through these steps with an example. You
eat an ice-cream cone rather quickly and
observe that you get a splitting
headache. Why did you get the headache?
Let's answer that question to form our
hypothesis. Hmm there must be something
about icecream that causes a headache.
But is that a good hypothesis? Let's
check. A good hypothesis must be testable, meaning you can test it. Can we test...
something? No, we have to be more specific. A good hypothesis must be repeatable,
meaning you need to be able to test the
hypothesis many times. Also, other
researchers must be able to test your
hypothesis.
And a good hypothesis must be
falsifiable. I know, it doesn't sound like
a real word. But this means you have to
have the ability to prove your
hypothesis to be false. Consider the
hypothesis: Aliens live on a planet a
thousand light-years from Earth. Can you
gather evidence to show that these
aliens do not exist? No, because we don't
have the technology to do this. And the
scientific method cannot test this
because it is not falsifiable.
So what hypothesis would answer our
question about something in ice cream
causing headaches and be testable and be repeatable and to be falsifiable. What is
a characteristic about ice cream we can
test? Temperature, did you say? Okay.
So let's give a tentative explanation. It
is the temperature of ice cream that
causes the ice cream headache. Now it's
time to make a prediction based on our
hypothesis. If we are correct about
our hypothesis then we must be able to
link the cold temperature of the ice
cream to the ice cream headache. How can
we do that? It seems simple, right?
Just get some people to eat ice cream
and they should get a headache. Okay...
start eating!
They all got headaches. I'm right! But am
I?
Does that really test the temperature? No.
Why not? Oh yes, it could be something
else in the ice cream, not just the
temperature. Okay, so what do we do? We need more groups of
people to test to make sure it is the
temperature, not just something else
about the ice cream that causes
headaches.
So we can't use only regular ice cream
what else can we use to make sure it's
the temperature? That's it, melted ice
cream! if the only thing different is the
temperature then only those who eat the
frozen ice cream should get the headache.
So our ice cream is a variable in our
experiment because it can be changed
and it is specifically called the
independent variable, as we are directly
altering this variable: Frozen or melted
ice cream. There's another variable
called the dependent variable. If we
change the independent variable the
dependent variable will change as well.
But we cannot directly change the
dependent variable. What do you think the
dependent variable is in our experiment?
The headache! Per our hypothesis, if we
used melted ice cream
there should be no headache. But if we
use frozen ice cream there should be a
headache.
So the headache variable depends upon
the ice cream variable. Now all the other
variables in the experiment need to be
the same. So when our two different
groups are tested the lighting needs to
be the same, the temperature needs to be
the same, the noise level needs to be the
same, even the chairs and tables need to
be the same. Why?
well we went to test for just the ice
cream. Right? Could any of these other
factors affect our results? Yes. So all
the other factors must be controlled so
that they are as similar as possible. And
now we are finally ready to set up our
experiment. Okay, here's our test subjects.
Let's randomly divide them into two
groups. Let's give these guys frozen ice
cream. They are called the experimental group,
as they are testing our hypothesis, which
is based on the temperature of the ice
cream.
And these guys get the melted ice cream
they're called the control group, as they
are not testing for the hypothesis, but
to make sure that no other factor is
affecting our results. Okay, let's give
them their treatments.
Okay, let's wait and see who gets a
headache.
Oh, five out of six subjects who ate
frozen ice cream got a headache. Now it
is time to analyze our results. A
whopping 83% of those who ate frozen ice cream developed headaches, while none of
those who ate the melted ice cream did.
So what's next? Ah, we need to make a
conclusion. Should we accept or reject
our hypothesis?
Please keep in mind we can only reject
or support hypotheses we cannot prove
them. The word prove in science means
that it will happen 100% of the time and
we cannot perform enough tests to show a hypothesis is always correct. But the
more tests we perform, the more certain
we can be about our hypothesis. Since
such a large percentage of our
experimental group got headaches, this
supports our hypothesis that the
headache is linked to the temperature of
the frozen ice cream. And the more
experiments we perform that support our
hypothesis, the more certain we are that
those brain-freeze headaches are linked
to the temperature of the frozen ice
cream. Now the more hypothesis is
supported, the more certain we are that
it is true. And a hypothesis can be
elevated to the theory status. There are
a few theories in biology, but the best
known are the cell theory and the theory
of evolution.
Think about what is at the end of Tyrone's sentence.
