Most of the biological investigations start with an observation. After selecting, specific biological problem, observations are made to collect relevant information. For example; take the case of Malaria. Malaria is the greatest killer disease of man for centuries. Malaria was one among many other diseases for which a cure was needed.
In 1878, A French physician, Laveran, studied the blood sample of Malaria patient under microscope and observed tiny creatures in it. These creatures were later called Plasmodium.
To solve a scientific problem, one or more possible propositions are made on the basis of the observations. Such a proposition is called a Hypothesis. The hypothesis is tested by scientific method.
A good hypothesis has the following merits:
1. It is close to the observed fact.
2. One or more deductions can be made from this.
3. These deductions should be confirmed doing experiments.
4. Results whether positive or negative should be reproducible.
To know the cause of malaria, following hypothesis was made:
Plasmodium is the cause of Malaria.”
Note: One or more than one possible deductions can be made from the hypothesis.
The logical conclusion drawn from a hypothesis is called deduction. Testing one deduction and finding it correct does not necessarily mean the hypothesis is correct and scientific problem is solved. Actually, if more deductions are found to be correct; the hypothesis will be close to solution of the problem.
Following groups are designed to perform experiments:
- Experimental Group:
It is the group of those people who are affected in some way and we do not know the real cause e.g. a group of malarial patients.
- Control Group :
It is the group of unaffected people e.g. persons group of healthy persons.
By keeping both of these groups under similar conditions, the difference between them is determined. To know the real cause of malaria, the experts examined the blood of about 100 malarial patients (experimental group). On the other hand, the experts examined the blood of about 100 healthy persons (control group).
During the experiments mentioned above; the plasmodium was found in blood of most of malarial patients. The plasmodium was absent in the blood of healthy persons. These results verified the deductions and thus the hypothesis i.e. the plasmodium is the cause of Malaria, was proved to a considerable extent.
If hypothesis is proved to be correct from repeated experiments and uniform results, then this hypothesis becomes a theory.
When a theory is again and again proved to be correct, then it is called a scientific principle.
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