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Class 12th Biology 2015 Set1 Delhi Board Paper Solution

Question 3

State a reason for the increased population of dark coloured moths coinciding with the loss of lichens (on tree barks) during industrialization period in England.


Industrial melanism was the reason behind the increase in the population of dark-coloured moths along with the loss of lichens during industrialisation in England.

The tree trunks became darker (after industrialisation) with deposits of soot and smoke; hence, the number of dark moths increased as they were not easily visible to their predators while the white-winged ones were easily picked up by the predators. Thus, dark ones were selected by nature (natural selection) and light ones fail to survive.