Question

Which one of the following is the best indicator of pollution?
A. Pinus
B. Fern
C. Lichen
D. Algae

Answer 1

Hint:-Pollution is the accumulation of unwanted and undesirable material that contaminates the natural environment. Pollution can be in the form of chemical substances or energies such as noise, heat and light. The major cause of pollution is release of harmful chemicals, toxic gases and non-useful particulate matters.

Complete step-by-step solution:-
Pollution can be described as the introduction of harmful materials known as pollutants in the normal environment. The accumulation of these pollutants causes changes that are harmful to the natural surroundings. Pollutants can be natural or anthropogenic in nature. The natural pollutants are the elements released from the natural calamities such as volcanic ash and forest fires. The other type of pollutants which enter the environment through the various activities of humans are known as anthropogenic pollutants or manmade pollutants. These include automobile emissions, industrial emissions, chlorofluorocarbons, nitrous oxide and volatile compounds. carbon dioxide, and sulphur dioxide are one of the major pollutants.
Sulphur dioxide is a toxic gas that releases the smell of burnt matches. It enters the atmosphere in two ways. It is released naturally during volcanic activity during the bioproduction of copper extraction and burning of fossil fuels containing sulphur compounds releases sulphur dioxide in the atmosphere. It is also produced during the manufacturing of sulfuric acid manufacturing processes. Burning and roasting of pyrite and other sulfide ores releases sulphur dioxide in the atmosphere.
Lichens are the best indicators of the concentration of the sulfuric dioxide in the atmosphere. The lichens are organisms that grow in exposed areas or substratum such as tree bars or rocks. They form a covering over the substratum. Lichens are very efficient at absorbing water and nutrients which helps them to survive. They require cleaner and pollution free air to survive. However, some leafy lichens can survive a small amount of pollution and crusty lichen can survive in more polluted areas. Sulphur dioxide dissolves in the rain water and causes damage to the lichen and prevents it from growing.
Lichens are hardy organisms which are useful indicators for sulphur dioxide pollution as they derive their water and nutrients mainly from the atmosphere and any change in the atmosphere affects them.
Pinus are bio indicators of sulphur and heavy metals in the atmosphere and soil as they show adaptive changes in response to pollution stress.

 Ferns are seedless vascular plants and are potent indicators of heavy metals are arsenic accumulation. They are directly affected by the alteration in the environment.
Algae are organisms that grow well in the organically polluted water, especially those rich in phosphorus and nitrogen and react rapidly to the disturbance related to the water.

Therefore, the correct option is option C.

Note:- An indicator species or a group of species are those whose function population or status indicate the quality of the environment. The indicator species reacts to any changes in the environment and serves as a monitoring mechanism of assessment of the environment. Lichens are good indicators of the sulphur dioxide pollution in the environment. They derive water and nutrients from the atmosphere and not from the soil.