Biology Notes Class IX Karachi Board of Secondary Education
IX Biology - Chapter 1 - Introduction to Biology
******************************TOPIC NO 1*******************************Science
Our universe operates under certain principles. For understanding of these principles, the experiments are done and observations are made; on the basis of which logical conclusions are drawn. Such a study is called "Science". In brief science is the knowledge based on experiments and observations.
The Scientific study of living organisms is called Biology. The word biology is derived from two Greek words "bios" meaning life and "logos" meaning thought, discourse, reasoning or study. It means that all aspects of life and every type of living organism are discussed in biology.
Branches of Biology
Biology is divided into following branches:
The study of form and structure of living organisms is called morphology. It can be further divided into following two parts:
1. The study of external parts of living organism is called external morphology.
2. The study of internal parts of living organism is called internal morphology or anatomy.
the study of cells and tissues with the aid of the microscope is called Histology.
The study of structure and functions of cells and their organelles is called Cell Biology.
the study of different functions performed by different parts of living organism is called Physiology.
The study of organisms in relation to each other and their environment is called Ecology or Environmental Biology.
Living organisms are classified into groups and subgroups on the basis of similarities and differences. This is called classification Taxanomy is that branch of biology in which organisms are classified and given scientific names
The study of development of an organism from fertilized egg (zygote) is called embryology. The stage between zygote and newly hatched or born baby is called embryo.
The study of methods and principles of biological inheritance of characters from parents to their offspring is called genetics.
The body parts of ancient organisms or their impressions preserved in rocks are called fossils. The study of fossils is called paleontology. It also includes the study of origin and evolution of organisms.
It can be divided into two parts:
1. The study of fossils of plants is called Palaeobotany.
2. The study of fossils of animals is called Palaeozoology.
The study of metabolic reactions taking place in living organisms is called biochemistry. These reactions may be constructive or destructive. The assimilation of food is a constructive process and respiration is a destructive process.
It is the branch of biology which deals with the practical application of organisms and their components for the welfare of human beings e.g. disinfections and preservations of food, preservations of insulin and biogas from bacteria etc.
******************************TOPIC NO 2*******************************
Relationship of Biology with other Sciences
In ancient times, there was no distinction of biology and other sciences. Different fields of sciences like biology, chemistry, physics and mathematics are met together in the writings of ancient scientists. In ancient times, these subjects were studied under one head "science", but with the passage of time, the science developed very much and the huge scientific knowledge was then divided into different branches.
However even today the interrelationship of these branches cannot be denied.
The study of various biological phenomena according to principles of physics is called biophysics. For example, movement of muscles and bones based on principles of physics.
The study of different biochemical like carbohydrates, proteins and nucleic acids etc found in cells of living organisms and hundreds of the underlying chemical reactions in cells of organisms is called biochemistry.
The data obtained from observations and experiments on living organism is analyzed by various statistical methods. This is called Biometry.
The study of plants and animals and the basis of geographical distribution is called Biogeography.]
The study of living organisms from economic point of view is called Bio-Economics. It includes the study of cost effectiveness and viability of biological projects from commercial point of view.
******************************TOPIC NO 3*******************************Biological Method of Study or Method Used to Solve the Problem of Malaria
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:
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.
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 plasmodim 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.