The paper "The Origin of Plastids by Chan and Bhattacharya" is a good example of an article on biology. The article probes existing literature on the origin of plastids and makes a fairly informative overview of what plastids are, and how the debates on the origins of plastids impact our understanding of how they came to be constitutive of eukaryotic cells. The interest comes partly from the centrality of plastids to life on earth, chloroplasts, being primary plastids, being responsible for generating the primary food source for all life on the earth.
A proper understanding of the origins of plastids provides a solid foundation for future basic research into chloroplasts and other primary and secondary plastids. The review of the literature is well-ordered and hierarchical in this article, building upon primary plastids origins theories, which are relatively well-established and centers on endosymbiosis, to discussions on the origins of more complex secondary plastids, where the existing theories are unable to gain the same kind of certainty and acceptance as endosymbiosis. It is clear that the focus of the article is to be able to provide a detailed overview of the progress made in the science involved in tracing the origins of plastids.
In the process, it is able to glean several insights into the current debates. What is clear though from all the discussions is that competing theories on the origins of secondary plastids all rely on permutations of the endosymbiosis theory. The progression than in the literature review here is from what is known and established, namely endosymbiosis as the operative process in the development of primary plastids, to the less known and to the less-explored, namely secondary plastids, and among secondary plastids, those that are not in plantae nor in chromalveolata.
These latter group of secondary plastids includes Euglena as well as Rhizaria, The paper makes us understand that the theories are evolving and far from being etched in stone. The question is, are there other theories apart from endosymbiosis that can better explain and form the foundation of new theories relating to the development of plastids in eukaryotes? (Chan and Bhattacharya).