CBSE Class 10 Science 2020 · Paper 31/4/1 · Question 20(a)

Evolution: the gradual change in living organisms over very long periods of time, since the beginning of life, which results in the formation of new species; it is the generation of diversity and the shaping of that diversity by environmental selection. Justification: evolution produces diversity, not progress. More and more complex body designs have emerged over time, but this does not mean that the older, simpler designs are inefficient. For example, bacteria, among the simplest organisms, still inhabit the most inhospitable habitats, such as hot springs, deep-sea thermal vents and the ice in Antarctica. A new species is not necessarily better than an older one, and human beings are not the pinnacle of evolution but one more species in the spectrum of evolving life.