Essay on the Concept of Levels of Organism and Biosphere !
An evident unit of life in nature is the individual organism. Linguistically as well as biologically, the root of the word ‘organism’ is organisation: a characteristic structural order. Each kind of living organism possesses a certain degree of organisation which enables them to perform different life activities. In fact, close examination of the any aspect of the living world reveals that everything has a number of interrelated component parts.
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For example, a human being possesses in his body various organ systems such as digestive system, circulatory system, respiratory system, etc., for sustaining the life of an individual. Each organ system, in its turn, contains numerous different organs. For example, the digestive system is built up of such organs as mouth, buccal cavity, oesophagus, stomach, intestine, rectum, anus, liver, pancreas, etc.
Each organ too is made up of different kinds of tissues. ) Thus, stomach possesses epithelial tissues, muscles, glandular tissues and so on. Even each kind of tissue contains numerous cells, as muscles of stomach possess muscle cells.
Further, each cell contains different cellular organelles such as mitochondria, endoplasmic reticulum, Golgi bodies, lissome, and nucleus and so on. Each organelle is built up of different kinds of macroinolecules such as polypeptides, polysaccharides, lipids and nucleic acids (DNA and RNA).
Each kind of organic macromolecule is built up by several simple molecules (monomers), such as polypeptides contain many molecules of amino acids. Each molecule contains atoms of different elements, such as a molecule of amino acid consists of atoms of many elements like carbon, nitrogen, hydrogen.
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Lastly, each atom has its own structural components in the form of subatomic particles such as electrons, protons and neutrons. Thus, in the living world, there exist different separate levels of organisation. In non-living world too we may find different levels of structures of matter.