Question

Indicator plants which can be used to indicate atmospheric pollution by $S{O}_2$ are

• A. Lichens like Usnea
• B. Grassland like Deschampsia
• C. Moss like Sphagnum
• D. Climbers like Cucurbita

Answer 1

The correct option is A Lichens like Usnea

Sulphur dioxide is produced during combustion of fossil fuels, refining of petroleum and smelting of sulphur containing ores. Sulphur dioxide produces smog and acid rain. Sulphur dioxide causes membrane damage, destruction of chlorophyll, necrosis and water soaked appearance. Lichens are the most sensitive organisms to sulphur dioxide pollution and do not grow in areas with high levels of sulphur dioxides. Hence Lichens like Usnea are used as indicators of level of sulphur dioxide pollution.