Question

Question 43
Why do not lichens occur in Delhi whereas they commonly grow in Manali or Darjeeling?

Answer 1

Lichens are also called the bio-indicators of the pollution. They are found only in the non-polluted areas. Lichens are highly susceptible towards sulphur dioxide. A compound in them reacts with sulphur dioxide to form a poisonous chemical that kills the plant itself. This is because lichens grow in areas where sulphur dioxide pollution is very less, e.g., in Manali and Darjeeling. Delhi is a highly polluted place where lichens cannot grow and survive.