Question

Given alongside are two figures (A and B) showing a phenomenon that was first observed in Manchester before and after the year 1850.

Answer the following:

1. What name has been given to this phenomenon?
2. Give the common name and the scientific name of the insect involved in this phenomenon.
3. Briefly mention why the changes shown in the two figures appeared.
4. The following phenomenon provides a classical explanation of a scientific theory given by a certain scientist.
   1. Name and explain the said theory.
   2. Give the name of the scientist who gave this theory.

Answer 1

1. Industrial melanism.
2. 1. Common name: peppered moth.
   2. Scientific name: Biston betularia.
3. The changes shown in the figure appear because:
   1. Before the Industrial Revolution in England, white-winged moths were more common than dark-winged moths. Lower pollution levels resulted in lighter tree trunks due to lichen.
   2. On light backgrounds, white-winged moths were not noticeable, but predators could easily eat dark-winged moths.
   3. Following industrialisation, dark-winged moths became more prevalent than white-winged moths.
   4. During industrialisation, air pollution caused darkened tree trunks to have white lichens, making white-winged moths more visible.
   5. White-winged moths lack camouflage, making them vulnerable to predators. Nature selected the most suitable moths. However, none were exterminated.
4. 1. Natural selection: During the struggle for existence, only those with favourable variations survive, while those without these variations are wiped off. Nature chooses just the variants that are suitable for existence. This process is known as natural selection.
   2. Charles Darwin proposed the idea of natural selection.