Read this essay to learn about the theories on the origin of angiosperms. Theories on the Origin of Angiosperms Essay Contents: Essay on the Isoetes-Monocotyledon Theory Essay on the Conifer-Amentiferae Theory Essay on the Gnetales-Angiosperm Theory Essay on the Bennettitalean Theory Essay on the Caytonialean Theory Essay on the Pteridosperm Theory Essay on the Pentoxylales Theory Essay # 1. Isoetes-Monocotyledon [...]
In this article we will discuss about the origin of cell wall in plants. Initially middle lamella creates a new boundary between the two-daughter nuclei of a dividing cell. The components of cell wall deposit on either side of middle lamella to form the cell wall. In a non-vacuolated cell, nucleus is usually present at the centre where it divides. [...]
There are three theories that have been put forward to explain the mode of evolution i.e., origin of species. 1. Lamarck's Theory of Evolution: Lamarck proposed that the evolution of life forms had occurred by the use and disuse of organs. He gave the example of Giraffe, which initially did not have long necks. But, in order to reach the [...]