Question

Which of the following are most suitable indicators of SO₂ pollution in environment?
1. Algae
2. Fungi
3. Lichen
4. Conifers

Answer 1

Correct Answer - Option 3 : Lichen

Explanation:

Lichen as Bio-indicators:

• Lichens are widely used as environmental indicators or bio-indicators.
• If air is very badly polluted with sulfur dioxide there may be no lichens present, just green algae may be found.
• If the air is clean, shrubby, hairy, and leafy lichens become abundant.
• A few lichen species can tolerate quite high levels of pollution and are commonly found on pavements, walls, and tree bark in urban areas.
• The most sensitive lichens are shrubby and leafy while the most tolerant lichens are all crusty in appearance.
• Since industrialization many of the shrubby and leafy lichens such as Ramalina, Usnea, and Lobaria species have very limited ranges, often being confined to the parts of Britain with the purest air such as northern and western Scotland and Devon and Cornwall.​