The answer is that the criteria of classification change with the improved understanding of organisms around us. During the time of Aristotle, not much was known about the living organisms. So, he classified them as he observed. Plants were classified into herbs, shrubs and trees; very much like what’s taught to a second grade student. Animals as Enaima and Anaima based on the presence or absence of RBCs. After him, Carolus Linnaeus tried his hand over classification. He came up with the 2 kingdom classification: Plants and Animals. He considered only a set of morphological and physiological criteria to decide the kingdom to which an organism belongs. It includes presence of cell wall, mode of nutrition, contractile vacuole, locomotion and others. Based on these criteria, he included widely differing organisms into a single kingdom, for example, fungi, bacteria, algae, and higher plants were included into plant kingdom just because they have cell wall as a common aspect. Then came, Ernst Haeckel, who came with a third kingdom of Protista to include unicellular organisms. Copeland gave a 4 kingdom classification segregating unicellular organisms into 2 separate kingdoms based on their nuclear structure. R.H. Whittaker came next introducing the most accepted 5 kingdom classification system. You should understand one thing that man’s knowledge of classifying organisms improved with the improving technologies available to him, which he exploited to very effective extent. Carl Woese gave the 6 kingdom classification and 3 domain system based on the 16S rRNA sequence.
Our understanding of organisms around us is improving day by day and the system of classification will also change further in pace with the improvement in technology.
I hope this helps! :D]
~ Kana ^^
Beginning in the mid 1600's Earth entered into a mini-ice age. 1815 was known as the "year without a summer" and snow fell in many European countries during the summer months. The prolonged climate change is attributed to low sun spot activity, while the summer snow is believed to be the result of
A major volcanic eruption.
DNA gets compact only during cell division and are called chromosomes. On other conditons, it forms a network of thin threads called chromatin network.
One reason is because the short days and long nights prevent the earth from warming up, another reason could be because the sun's rays in winter are more spread out thus minimizing the amount of energy
They add nitrogen to the soul through their nodules !
