Science is the systemized knowledge derived from observations and experiments.These experiments are carried out to determine the principles about how nature operates. Scientists like chemists,biologists and physicists use the same scientific method to make and test new theories.
In this chapter, we will study the steps of biological method. We will study malaria as an example to understand the steps in detail.
2.1 Biological Method
Questions about living things have provided problems that man has investigated to aid his own survival and to satisfy his desire to know. The scientific method in which biological problems are solved, is termed as biological method. It comprises the steps a biologist adopts in order to solve a biological problem.
Biological method has played an important part in scientific research for almost 500 years. From Galileo’s experiment (in the 1590s) to current research, the biological method has contributed to the advancements in medicine, ecology, technology etc. Biological method also ensures the quality of data for public use
Man has always been a biologist. He had to be a biologist in order to live. Early in history, he was a hunter of animals and a gatherer of fruits, seeds, roots etc. The more he knew about animals and their habitat, the more successful hunter he was. The more he knew about plants, the better he distinguished between edible and non-edible plants.
2.1.1 Biological problem, hypothesis, deductions and experiments
In biology (like other sciences), new things are being discovered and long-held theories are being modified or replaced with better ones as more data/knowledge is accumulated. This happens when biologists recognize some biological problem and go for its solution. In solving a biological problem, biologist takes following steps;
• Recognition of biological problem
• Observations
• Hypothesis formulation
• Deductions
• Experimentation
• Summarization of results (create tables, graphics etc)
• Reporting the results
The details of these steps are as under:
1. Recognition of the Biological Problem
Biologists go for adopting biological method when they encounter some biological problem. A
biological problem is a question related to living organisms that is either asked by some one or
comes in biologist’s mind by himself.
2. Observations
As the first step in solving a biological problem, biologist recalls his/her previous observations or
makes new ones. Observations are made with five senses of vision, hearing, smell, taste and touch.
Observations may be both qualitative and quantitative. Quantitative observations are considered
more accurate than qualitative ones because the former are invariable and measurable and can
be recorded in terms of numbers. Examples of qualitative and quantitative observations are given
below.
Qualitative observations
• The freezing point of water is colder than
the boiling point.
• A liter of water is heavier than a liter of
ethanol.
Quantitative observations
• The freezing point of water 0 oC and the
boiling point is 100 oC.
• A liter of water weighs 1000 grams and a liter
of ethanol weighs 789 grams.
Observations also include reading and studying what others have done in the past because
scientific knowledge is ever-growing.
Biologists can’t usually check every situation where a hypothesis might apply. Let’s consider a
hypothesis:
“All plant cells have a nucleus”. Biologist cannot examine every living plant and every plant that
has ever lived to see if this hypothesis is false. Instead, biologists generate deduction using
reasoning. From the above hypothesis, a biologist can make the following deduction: “If examine
cells from a blade of grass, then each one will have a nucleus”.
3. Formulation of Hypotheses
Observations do not become scientific observations until they are organized and related to a
question.Biologist organizes his/her and others’ observations into data form and constructs a
statement that may prove to be the answer of the biological problem under study. This tentative
explanation of observations is called a hypothesis. It may be defined as a proposition that might be
true. A hypothesis should have the following characteristics:
• It should be a general statement.
• It should be a tentative idea.
• It should agree with available observations.
• It should be kept as simple as possible.
• It should be testable and potentially falsifiable. In other words, there should be a way to show
the hypothesis is false; a way to disprove the hypothesis.
A great deal of careful and creative thinking is necessary for the formulation of a hypothesis.
Biologists use reasoning to formulate a hypothesis.
4. Deductions
In the next step, biologist draws deductions from hypotheses. Deductions are the logical
consequences of hypotheses. For this purpose, a hypothesis is taken as true and expected results
(deductions) are drawn from it.
Generally in biological method, if a particular hypothesis is true then one should expect (deduction)
a certain result. This involves the use of “if-then” logic.
5. Experimentation
The most basic step of biological method is experimentation. Biologist performs experiments to
see if hypotheses are true or not. The deductions, which are drawn from hypotheses, are subjected
to rigorous testing. Through experimentations, biologist learns which hypothesis is correct.
The incorrect hypotheses are rejected and the one which proves correct is accepted. An accepted
hypothesis makes further predictions that provide an important way to further test its validity.
6. Summarization of results
Biologist gathers actual, quantitative data from experiments. Data for each of the groups are then
averaged and compared statistically. To draw conclusions, biologist also uses statistical analysis.
What is “Control” in experiments?
In science when doing the experiment, it must be a controlled experiment. The scientist must
contrast an “experimental group” with a “control group”. The two groups are treated exactly alike
except for the one variable being tested. For example, in an experiment to test the necessity of
carbon dioxide for photosynthesis, one can contrast the control group (a plant with freely available
carbon dioxide) with an experimental group (a plant with no carbon dioxide available). The necessity
of carbon dioxide will be proved when photosynthesis occurs in the control group and does not
occur in the experimental group.
7. Reporting the results
Biologists publish their findings in scientific journals and books, in talks at national and international
meetings and in seminars at colleges and universities. Publishing of results is an essential part of
scientific method. It allows other people to verify the results or apply the knowledge to solve other
problems.
Study Of Malaria - An Example Of Biological Method
We know malaria is a common disease in many countries including Pakistan. We will go through
the history of this disease to know how biology solved the biological problem concerning the cause
and transmission of malaria. In ancient times (more than 2000 years ago), physicians were familiar
with malaria. They described it as a disease of chills and fevers with recurring attacks. They also
observed that the disease was more common among people living in low, marshy areas. It was
thought that the stagnant water of marshes poisoned the air and as a result of breathing in this
“bad air”, people got malaria. This belief led to the name of this disease. The Italian words “mala”
means bad and “aria” means air. For further clarification of the observation, some volunteers
drank stagnant water from the marshes. They did not develop malaria.
In the 17th century when the New World (America) was discovered, many plants from America were
sent back to Europe to be used as medicines. The bark of a tree known as quina-quina was very
suitable for curing fevers. It was so beneficial that soon it was impossible to carry enough bark to
Europe. Some dishonest merchants began to substitute the bark of another tree, cinchona which
closely resembled quina-quina. This dishonesty proved much valuable for mankind. Cinchona bark
was found to be excellent for treating malaria. We now know the reason: cinchona bark contains
quinine that is effective in treating the disease
At that time, physicians treated malaria with cinchona without understanding the cause of malaria.
Two hundred years later, it was found that some diseases are caused by tiny living organisms. After
this discovery, it also became a belief that malaria, too, might be caused by some microorganism.
In 1878, a French army physician Laveran began to search for the “cause” of malaria. He took a
small amount of blood from a malarial patient and examined it under microscope. He noticed some
tiny living creatures. His discovery was not believed by other scientists. Two years later, another
physician saw the same creatures in the blood of another malarial patient. Three years after the
second discovery, the same creatures were observed for third time. The organism was given a
name Plasmodium.
In the last part of nineteenth century, many different causes of malaria were being suggested. By
that time, there were four major observations about malaria.
• Malaria and marshy areas have some relation.
• Quinine is an effective drug for treating malaria.
• Drinking the water of marshes does not cause malaria.
• Plasmodium is seen in the blood of malarial patients.
We know that a scientist uses whatever information and observation he has and makes one or
more hypotheses. The hypothesis made in this case was;
“Plasmodium is the cause of malaria.”
Scientist does not know whether his hypothesis is true or not, but he accepts it may be true and
makes deductions. One of the deductions from the above hypothesis was;
“If Plasmodium is the cause of malaria, then all person ill with malaria should
have Plasmodium in their blood.”
The next step was to test the deduction through experiments which were designed as;
“Blood of 100 malarial patients was examined under microscope. For the purpose of having a
control group, the blood of 100 healthy persons was also examined under microscope.”
The results of experiments showed that almost all malarial patients had Plasmodium in their
blood while 07 out of 100 healthy persons also had Plasmodium in their blood (now we know that
Plasmodium in the blood of healthy people was in incubation period i.e. the period between the
entry of parasite in host and the appearance of symptoms). The results were quite convincing and
proved that the hypothesis “Plasmodium is the cause of malaria” was true.
Malaria has killed more people than any other disease. The account of malaria is an example of
a biological problem and of how such problems are solved.
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