Dr. N.L. Kachhara
According to biology living organism is qualitatively distinct from the non-living matter. Some unique biological laws govern functioning of the former. The essence of living organism is the set of principles determining the transmission of genetic information from one generation to next. Living organisms are composed of the same constituents as rest of earth, but it possess, besides free will, which is the characteristic of life, all of the following attributes; organization, excitability, conductivity, contractibility, metabolism, growth and reproduction. Non-living matter may possess one or more of these, but not all, also. In biology the life has been classified on the basis of origin and body structure processes etc. Biological sciences have broadly been divided into Botany dealing with plants, and Zoology dealing with animals. Animal life again has two divisions (i) protozoa, which are multi cellular organisms and (ii) metozoa which are single cellular organisms not visible to eye. On the basis of spinal column the animals are classified as (i) vertebrates like marine animals, amphibians, birds and mammals, and (ii) invertebrates like amoeba, hydra, insects, star fish, shells etc. The animals are also classified on the basis of body structures like, eumetazoa bilaleria, deuterostomia, chordata, echinodermata, protostomia, lophotrochozoa, lophophorates, nemertea, trochozoa, platyhelminthes, mollusea, ecdysozoa, arthropoda, nematoda, ctenophora, chidaria and porifera.
Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. Vertebrata contains most animals with which people are generally familiar (except insect). Fish, amphibians, reptiles, birds and mammals are vertebrates. Defining characteristics of a vertebrate are backbone or spinal cord, a brain case, and an internal skeleton. The skull is thought to have facilitated the development of intelligence as it protects vital organs such as the brain, the eyes and the ears. The central nervous system of a vertebrate consists of the brain and the spinal cord. Both of these are characterized by being hollow. In lower vertebrates the brain mostly controls the functioning of the sense organs. In higher vertebrates the size of the brain relative to the size of the body is greater. This larger brain enables more intensive exchange of information between different parts of the brain. Vertebrates are called samanaska beings in Jain philosophy.
Plants also form a large part of life in nature. On the basis of body structures the plants are of two types (1) flowering plants and (2) non flowering plants. The flowering plants called angiosperms form the largest section and make up around 80 percent of all the living plant species on Earth. They are divided in seventeen orders: apiales, asterales, ericales, fagales, hamamelidales, juglandales laurales, magnoliales, malvales, papaverales, piperales, primulales, ranunculales, rosales and salicales. The non-flowering plants fall in four groups:
- Mosses and Liverworts - These types of plants have no roots, leaves or stems.
- Tracheophytes - this group of plants has roots, stems and leaves.
- Ferns - Ferns do not have seeds. They have spores.
- Conifers and Cycads - These plants are gymnosperms. They have seeds, but no flowers.
