Biology Medical Notes 22

  INTRODUCTION TO BIOLOGY   Now a days we find contributions of Aristotle, Socrates, Theophrastus and many other scholars of the past age in different fields of knowledge. This is not possible for the scholars of the present time. A question may arise in your mind as to why it is not possible today. The reason is that in ages long past the extent of knowledge was limited. People engaged in achieving knowledge were also small in number. Today the dimension of knowledge has been increased many times. To contribute in more than one field is quite difficult at the present time. For convenience to know and understand things we have divided our world of knowledge in many branches. In this way Science, Literature, Arts, Social Science and many other branches have been created. As a whole, knowledge of human beings is undivided. But it has been divided into various branches for easy learning and understanding.   You may have known that the knowledge of science is increasing rapid...

  PRINCIPAL BRANCHES OF BIOLOGY   Biology has been divided into Botany and Zoology on the basis of nature of living beings. Inspite of this, now-a-days extensive research has been done on Microorganism. They influence human life in various ways. So for discussion about them a new branch is made. This is known as  Microbiology.   Considering the subjects of living bodies on which discussion is made the whole range of Biology is divided into the following main branches.   1.          Morphology:  This branch deals with both the external and internalstructures of organism. The subject concerning internal . structures is also known as Anatomy.   2.    Cytology:  Each living organism consists of one or more cells. Structuresand functions of cells are treated in this branch of Biology.   3.          Histology:  In this branch discussion is made on structu...

  Biology is the result of research and thinking of some great scientists. This chapter introduces you with some of these scientists.   Aristotle (384-322 B.C):  The great Greek scientist, Aristotle is regarded as thefather of Zoology. He first established Zoology as a branch of Science. Aristotle was simultaneously a scientist, poet, thinker and philosopher. It is he who first mentioned about the basic similarities in the structure of plants and animals. He stayed in an island named Lesbos for five years continuously and made research on animals. He wrote a book on animals and named it "Historia animalium" which is full of information and knowledge. Theophrastus (370-285 B.C.):  Little amount of works of the Greekphilosopher Theophrastus is known to us. Of those available, nine volumes of "On the History of Plants" and six volumes of "On the causes of plants" are important. Theophrastus was the pupil of great philosopher Aristotle. He divided the plant co...

  CHARACTERISTICS OF PLANTS AND ANIMALS   Taking a few main characteristics from many we shall now compare plants with animals. 1.          Size and shape:  Plants have no definite size and shape while animals havedefinite size and shape.   2.          Life Time:  Life time is not limited for plants and under suitable conditionsthey live for a long period. But animals live up to a certain length of time under suitable conditions.   3.          Growth:  In suitable environment growth of many plants continue for a longperiod. Growth in animals takes place up to a certain stage of life and growth ceases after that.   4.          Movement:  Most land plants remain fixed in soil with the help of roots as aresult they cannot move. But some organs of plants may show some movement. A few anima...

  ROLE OF BIOLOGY IN SOCIAL, ECONOMIC AND ENVIRONMENTAL DEVELOPMENT   The two main branches of Biology are Botany and Zoology. In addition to these, there are other branches and sub-branches of Biology. You have come across some of those in the preceding parts of this chapter. Now let us discuss the importance of Biology on the basis of knowledge you have already attained. Agricultural science has many branches of which Agronomy, Horticulture, Plant breeding, plant pathology, Fishery, Animal husbandry, Poultry, Honeybee culture (Apiculture), Sericulture etc. are important. With the application of knowledge of these branches economic development is possible. Both plants and animals are the essential components of natural environment. It is known to you that plants and animals are interdependent in many ways. Ecology makes us alert about the importance of plants and animals and also the necessity of their presence in nature, Educated and conscious citizens can play important rol...

  NATURE AND ORIGIN OF LIFE   You know what nature is. We live in nature. We have soil, water, air different plants, animals, insects and worms etc. all around us. All these together constitute nature. Millions of years ago nature was not as we see it today. Nor will it remain the same after millions of years. This indicates that nature is always changing. Nature undergoes changes due to various natural forces such as river-currents, earthquakes, volcanic eruptions etc. Different human activities, such as destruction of forests, construction of dams etc. also bring about changes in nature. Scientists have been thinking about the origin of nature. There are different theories about the origin of the Earth. Among these the commonly acceptable theory explains that a part of the Sun or a similar star got detached as a result of the attraction of another star. The planets including the Earth and then satellites have been created from the detached part of the sun. According to this ...

  Structure and Nature of Living Cell Those who have life are living beings. Microorganisms, Plants and Animals have life, so they all are living beings. Living world is composed of microorganisms plants and animals. One or more cells make every living being. Cell is the structural and functional unit of living body. All sorts of reaction and anti- reaction in living body are cell centered. So to know about any living beings one should know about the living cell at first.   All living cells are not alike. As they are, different in structure, they are different in size, shape and functions. Different types of cell are described below in brief.   All the cells of Plants and Animals are eukaryotic but they have differences as well. Difference between Plant cell and Animal cell are shown in a tabular form at the end of this chapter. However the main difference between them is the Plant cells have a non-living cell wall, which is absent in the Animal cells. On the basis of Nuc...