Biology Coursework

Biology coursework sample on species and palaeontology.This sample is posted here with the hope to introduce you to quality writing techniques and formats. Do not use this sample as your own coursework unless you want to be accused in plagiarism by your teacher. In addition, you may take a look at English coursework sample and health and social care coursework writing tips

Biology Coursework Excerpts

Variations in the species which populated the earth during past geological periods do not seem to corroborate such stability. Palaeontology shows that in ancient times species existed which have since disappeared, whilst conversely we now have species which were not formerly in existence, if we accept as evidence the absence of their remains among fossils. Fauna and flora have changed in the course of time, generally for the better. This led to the idea that species might have evolved by orthogeny, with variations accumulating from generation to generation and diverging thus ever increasingly from the primal type by a kind of differentiation which continuously made itself evident by setting in motion a "principle of perfection," or some "internal force" or "law of progress," that is to say a phylogenetic differentiation comparable to the differentiation which comes about during the development of the embryo, and which is similarly subject to internal forces intrinsic in the properties of organic matter, though itself lying totally outside our present knowledge.

It is not to be wondered at that phylogenetic development has many a time and oft been compared to that of the embryo. As far back as 1821, Meckel asserted that there was some similarity between the formation of an embryo and the various forms of species in the animal kingdom. Von Baer in 1828 noted that in ontogeny the higher vertebrates pass through stages at which the lower ones are arrested: "The embryos of mammals, birds, lizards and serpents are extraordinarily alike during the early stages of their development, in both the general and the particular, whence it is difficult to distinguish one from the other." Thus it is that Häckel in 1866 came to propound his fundamental law of biogenesis: "The organized individual repeats during the rapid course of its own development the more important phases through which its ancestors passed in the course of their long palaeontological evolution." In other words, "Ontogeny may be said to be a conspectus of phylogeny."

From the instant that orthogenetic evolution is not ascertainable and there is no further assurance that the species may tend to become differentiated by divergence, it is no longer feasible to make a comparison between phylogeny and ontogeny, where indeed there is a progressive multiplicative and differentiable evolution starting from the zygote. It must, however, be conceded that fossil plant and animal forms certainly show greater and greater complexity and a more evident differentiation in their organs the closer the period of their existence approaches the present time.