Target Exam

CUET

Subject

Biology

Chapter

Evolution

Question:

Read the given passage and answer the following questions:

During post- industrialisation period, the tree trunks became dark due to industrial smoke and soots. Under this condition the white-winged moth did not survive due to predators, dark-winged or melanised moth survived. Before industrialisation set in, thick growth of almost white-coloured lichen covered the trees - in that background the white winged moth survived but the dark-coloured moth were picked out by predators. They will not grow in areas that are polluted. Hence, moths that were able to camouflage themselves, i.e., hide in the background, survived . This understanding is supported by the fact that in areas where industrialisation did not occur e.g., in rural areas, the count of melanic moths was low. This showed that in a mixed population, those that can better-adapt, survive and increase in population size. Remember that no variant is completely wiped out. Similarly, excess use of herbicides, pesticides, etc., has only resulted in selection of resistant varieties in a much lesser time scale. This is also true for microbes against which we employ antibiotics or drugs against eukaryotic organisms/cell. Hence, resistant organisms/cells are appearing in a time scale of months or years and not centuries. These are examples of evolution by anthropogenic action. This also tells us that evolution is not a directed process in the sense of determinism. It is a stochastic process based on chance events in nature and chance mutation in the organisms.

What happens to lichens in areas with high industrial pollution?

Options:

They grow rapidly

They change color

They die or do not grow

They become toxic

Correct Answer:

They die or do not grow

Explanation:

The correct answer is Option (3) -They die or do not grow

In areas with high industrial pollution, lichens die or do not grow. Lichens are sensitive to air pollutants, especially sulfur dioxide, which is commonly released by industrial activities. As a result, they struggle to survive in polluted environments. This sensitivity makes lichens useful as bio-indicators for air quality. When pollution levels are high, lichens either stop growing or die, signaling environmental degradation.