Which one of the following organisms can be used as industrial pollution indicator?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Lichens
A pollution indicator is an organism whose presence or absence tells us how clean the air or water is. Lichens are very sensitive to air pollution, especially to the gases given out by industries, and they do not grow in polluted areas. This is why the tree trunks in industrial areas of England lost their white lichen cover. The dark (melanised) moths then survived better there, which is the story of industrial melanism.
(1) Lichens — Correct. Their absence shows that the air is polluted.
(2) Mycorrhiza — Incorrect. Mycorrhiza is an association of a fungus with the roots of a plant. The fungus absorbs phosphorus from the soil for the plant. It is used as a biofertiliser, not as a pollution indicator.
(3) Cyanobacteria — Incorrect. Cyanobacteria fix atmospheric nitrogen and are used as biofertilisers, for example in paddy fields.
(4) Algae — Incorrect. Algae are not the organisms used to indicate industrial air pollution.
Note: A similar question was also asked in CUET (UG) 2023 on 15-06-2023 (Slot 1).
NCERT Extract:
What Are the Evidences for Evolution? – “… 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. Do you know that lichens can be used as industrial pollution indicators? They will not grow in areas that are polluted.”