Question

Lichens are best indicators of
A. Water pollution
B. Soil pollution
C. Air pollution
D. Noise pollution

Answer 1

Hint: A symbiotic relationship exists between fungi and algae. Lichens are mutual collaborations of fungus and an alga/cyanobacterium. The algal partner is engaged in the process of photosynthesis while the fungal partner provides protection to the algae from the environment (mostly from moisture). They can be spotted as crusty patches or bushy growths on trees, rocks and bare ground. Lichens are known to have been very sensitive to sulphur dioxide concentration in the air. The main reason behind this is their efficient absorption system which results in rapid aggregation of sulphur when exposed to high levels of sulphur dioxide.

Complete Answer:
- Lichens are known to be able to live in wet and dry places. Whenever it rains, lichens turn into darker colours like black and green and start doing photosynthesis. But, when they are dry, they seem dormant. Their colour lightens and they look pale and dull. Thus, it can be said that lichens are not indicators of water pollution.
- Soil is a vital stratum for lichens. It provides them with nutrients, space to grow, moisture, and shelter, depending on the location.
- We have already stated that lichens are sensitive to concentration of sulphur dioxide in the air. Places with badly polluted air have a scarce population of lichens.
- But, when they are present in abundance, it means that the air is clean, thus supporting their presence.
- Thus, it has proven that lichens are the best indicators of air pollution since they can’t live in areas with concentration of sulphur dioxide in air.

Hence, we can say that Lichens are the best indicators of Air Pollution.

Note: Lichens are examples of symbiotic relationships in two species of the same or different families of any two organisms. They have a fungus and an alga living together and working for themselves. The algal partner is involved in the process of photosynthesis and production of food. On the other hand, the fungal partner provides protection against moisture.