00:00 Jan 01
Biology coursework deals with the various characteristics of mainly living things of this planet.
Our earthly environment is blessed with diverse kind of living things. We know them by their smell, sound, color, touch or even taste. Some of them are useful to mankind and some other causes illness or even death. Therefore, identifying the useful and being aware of the harmful living beings is basic human need and concern. Differentiating, grouping and giving names to living things in some form or other has been an ancient activity of every human culture.
The world is estimated to have species of living organisms anywhere between 5 to 30 million and probably over half of them are found in the yet unexplored tropical rain forests of the world. At present about 2.5 million species of living organisms have been given scientific names. Over 1.5 million of them are animal species and out of them 750000 belong to insect species.
Ever since life came into existence on the earth, existing species of living beings are also part of it. During this long period of existence innumerable species also became extinct, sometimes leaving behind fossils as evidence of their existence. It is estimated that the extinct species of animals may outnumber the living species of animals by 50 to 100 times.
Without proper classification it would be impossible to deal with the enormous diversity of life forms. Biological classification or taxonomy has two uses: to recognize as well as describe as completely as possible the basic taxonomic units (or species) and to device a method for grouping these units on the basis of their resemblances as well as relationship. Their arrangements are as follows- species, genus, family, order, class, phylum or division, and kingdom.
The life forms are broadly divided into two general groups on the basis of what is visible and obvious- the plant and the animals. Linnaeus classified all organisms into the Kingdom Plantae (plant kingdom) and Kingdom Animalia (animal kingdom). This arrangement proved unsatisfactory to many biologists. Thus a new five kingdom arrangement of organisms was proposed by Whittaker in 1969. The criteria of classification are complexity of cell structure, complexity of the organism’s body and mode of obtaining nutrition.
The five kingdoms are:
1) Monera: Kingdom of prokaryotes-microscopic, do not contain nucleus and have rigid cell wall. They are decomposers and mineralisers. Moneran cells are microscopic, about one to a few microns in length. They do not have a nucleus or other membrane bounded organelles. Most of them have a rigid cell wall.
2) Protista: They are mostly unicellular and primarily aquatic eukaryotes. They are found in various kinds and display diverse ways of life.
3) Plantae: Kingdom of multicellular producers- basically photosynthetic plants existing in heterotrophic forms on land, sea, lake and streams.
4) Fungi: Kingdom of multicellular decomposers- heterotrophic organisms and many of them parasitic in nature.
5) Animalia: Kingdom of multicellular consumers-comprise such groups as sponges, round worms, annelids, arthropods, mollusks, echinoderms and vertebrates.
Biology coursework will deal with many such wonderful information related with the living creatures of this planet.