It is difficult to define life as there are no defining properties for life. The properties exhibited in the beginning are different from the properties we see today. This is because evolution has taken place.
In the same way, unexpected properties have emerged and are seen in different combinations today. So it is difficult to set down standard properties for "life".
Hence scientists have taken a few characteristics seen in almost all organisms and given them as the properties of "life".
Darwinism deals with the theories proposed by Charles Darwin, and Neo-Darwinism describes the modified theories of.
According to Darwinism, organisms are constructed to meet the demands of environment by natural selection which lacked the theory of heredity. On the other hand, Neo-Darwinism proposes that this natural selection of organisms is due to the genetic variation that passed from one generation to the next. It is known as the chromosomal theory of inheritance.
The essential elements of the Hypothetico-Deductive Method of Science are the following 6 steps:
• Empirical test
This method can be illustrated in the natural selection in British moth populations. The peppered moth Biston betularia is present as two variants- light and melanic.
Before the nineteenth century, the common variety of moth was the light color. This light coloration provided extremely effective camouflage against lichen-covered tree trunks. Also present, though less common, was a dark variety of the same species. While resting on lichen-covered trees, the dark, moths were more visible to birds and were therefore eaten more often. Thus in the end, the dark moths produced fewer offspring than the light moths.
By the end of the nineteenth century, the lichen covered trees were now covered in black soot. This was due to air pollution. This brought about a change in the variety of moths. Instead of light forms, the melanic forms dominated. This was because the melanic form was less visible on the black trees and was less eaten. The light forms on the other hand were quite visible against a dark background and was eaten more often.
In the late twentieth century, increasing control of pollutants allowed trees to return to their lighter, lichen-covered condition. As would be expected, the melanic moth is now replaced by the lighter moth.