Question

A location with luxuriant growth of lichens on the trees indicates that the
A. Trees are very healthy
B. Trees are heavily infested
C. Location is highly polluted
D. Location is not polluted

Answer 1

Hint:-Lichens are primarily just the algae (phycobiont) and fungi (mycobiont), which are symbiotically associated.
Both fungi and algae are mutually beneficial for each other, because the fungi serve as the shield/cover, and the algae synthesize the fungi’s carbohydrates, in return.

Complete step-by-step solution:-
Lichens basically are two units, which combinedly exist as one single and stable unit.
They are good bioindicators of (air) pollution. And they respond to any relevant environmental change.
The lichens are also Sulphur dioxide (SO2) pollution’s indicators, because they acquire the water and nutrients required, mainly from the atmosphere, and not from the soil. When the pollutant Sulfur dioxide (SO2) gets mixed with rainwater or air, it damages the lichens by not allowing them to grow. They are too delicate to handle pollution; so if they are present in large quantities, then it indicates pure and natural surroundings in that particular place.
Option a) Trees are very healthy - This is not relevant to the question, thus this option is incorrect.
Option b) Trees are heavily infested - This too is not related to the question, and is thus an incorrect option.
Option c) Location is highly polluted - This is absolutely wrong, because lichens are excellent indicators of pollution. And their presence can never mean that the respective location is polluted. Thus, this option is also incorrect.
Option d) Location is not polluted - As per the information mentioned above, this is the Correct option.

Note:-
Lichens exist in the following types of growths :-
- Squamulose.
- Foliose.
- Fruticose.
- Crustose.