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Introduction
Chapter 1
Biology
"It is a branch of natural science, which deals with the study of life, living things and related phenomenon."
Branches of Biology
Formally and classically, biology was classified into two main branches, namely:
Each branch is sub divided into following branches:
It is the study of external features and form of a living thing.
It is the study of internal structure of living things.
Study of vital activities and functions necessary for life is called Physiology.
Study of development of living beings from egg into an individual able to survive by its own is called Embryology.
Study of cell, its types, functions and functions is called Cytology.
It is the study of different types of tissues constituting a living body.
It is the study of inheritance of characters and their transmission from parents to off springs.
Art to produce variation and study of the events in the DNA is called Genetic engineering.
It is the study of effects and relationship of living things which each other and their environment
It is the study of disease, their causes and their effects on a living body.
Art of diagnosis and curing disease is called medicine.
It is the study of Bacteria, their types and effects on living things.
It is the study of different parasites and their effects on their hosts.
Study of living beings that lived in the past with the help of their fossils is called Paleontology.
It is the classification, identification and grouping of living beings.
Modern System of Classification
Robert Whithaker in 1969 contradicted old concept of "Animals and Plants" and proposed a new system of "Taxonomy". According to this system of classification, Living beings are classified into five Kingdoms, which are explained under:
In this kingdom, all living things having "Incapient Nucleus" (Nucleus not bounded in a nuclear membrane) are included. They are generally called Prokaryotes. Examples are Virus, Bacteria and Blue green Algae.
These are microscopic acellular or unicellular Eukaryotes (Living beings having complete nucleus). They may be single celled or colonial. Nutrition may be Autotropic or Holozoic. Examples are Protozoans like Amoeba, Paramecium and single celled Algae like Euglena and Chlamydomones.
These are unicelluar to multicellular Eukaryotic Thalloid, Heterotropic organisms. Multicellular fungi are filamentous, whole structure of them is called Mycellium made up of Hyphae. Reproduction is generally asexual by means of spores. Examples are Yeast, Moulds and Mashrooms.
These are Multicellular Eukaryotic Auttotropic (few heterotropic) living beings genrally having differentiated structures like root, stem and leaves. Examples are all phanerogams and Cryptogams.
These are all Eukaryotic, multicellular animals (Metazoa) which may be "sessile" or generally "motile". Examples are Man, Monkey, Ant, Star fish.
Biological Method
Like other subjects of science, Biology also has got definite way of investigation for the exploration and discovery of new facts. The scientific way of study and exploration of facts in biology is called Biological Method. Details are as follow:
The first logical statement given by scientist about work under study is the hypothesis. It is fairly reliable and simplified version of facts.
Hypothesis is then tested experimentally, results are recorded and certain additions or deductions are made accordingly.
After performing a number of experiments, the results are summarized and if majority of results and observations are in favour, a "theory" is established.
If a theory is tested and always found correct, it is accepted would over as a rule or law.
Study of Malaria as an Example
Malaria is an ancient known disease still present commonly in 3rd world nations. It was first recognized in Africa, according to the natives:
"This disease is caused by bad air from swamps and marshes."
Laveran, a French Physician discovered parasite of malaria in the Red Blood Cells of Malaria patients in the year 1878. He initially gave a hypothesis about his discovery that:
"Plasmodium (or malarial parasite) is the causative organism of Malaria."
Several experiments were performed on number of Malaria patients in different areas and the hypothesis was always found correct. Now it is a world over accepted truth.
From the Concept of ‘Bad Air from marshes and swamps’ scientists were convinced to search the reason for the spread of malaria. Hypothesis was made that "Malaria is associated with Marshes." On elimination of marshes, the rate of malaria out break was much reduced. Thus the hypothesis was found truth.
Relationship of malaria with marshes gave the concept of a "Vector" i.e. spreading organism having its link with the marshes. An American physician "King" in 1883 and later on "Manson" in 1887 A.D gave a hypothesis that:
Mosquitoes are responsible for the spread of Malaria."
Experiments were performed world over and a British Physician working in India Ronald Ross in 1887 confirmed the presence of Plasmodium in the stomach of Anopheles females mosquito. He also gave life cycle of Plasmodium when they bite a sufferer of Malaria. So the hypothesis was found true. Later on James in 1926 gave complete life cycle of Plasmodium in Man and Mosquitoes and therefore it is an accepted law that:
"Plasmodium is the causative organism and female Anopheles is the vector of malaria."
Life Cycle of Plasmodium
Plasmodium passes its life cycle in two hosts; female anopheles or primary host example human being or secondary host.
Life Cycle in Man
When an infected female anopheles bites a healthy person, plasmodium in the form of "Sporozoits" are transmitted from saliva of mosquito into the human body. Sporozoits pass through blood into the liver cells where they multiply by means of multiple fission. This process goes on for 12 to 14 days, as a result a large number of parasites are produced called Merozoits.
Merozoits then attack human blood and enter into the red blood cells. Here they start another cycle of multiple fission producing more and more Merozoits. Each newly formed merozoit when released enters and infects a new R.B.C, thus causing Anaemia. Release of merozoits in blood is the major event of the disease of Malaria causing fever and chills due to inflammation of brain tissue with toxins released.
After sometimes, Merozoits began to transform into Gamonts to start "Sexual Life Cycle." Male and female "gametocyts" are produced. They began to collect in the skin vessels of the Malaria patients to be transferred into Mosquito again.
Life Cycle in Mosquito
When a female Anopheles bites an infected malaria patient, the gametocytes are taken into the gut along with the blood. Here, Gametocytes develop into male and female gametes which fuse form "Zygote or Ookinete." The motile ookinete boves the gut wall of mosquito and enclosis itself in a cyst to form "Oocyst." Another event of multiple fission takes place by which "Sporozoits" are formed. They make their way into the salivary gland and again through saliva, enter into another healthy person.
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