Question

Lichens are important in the studies on
atmospheric pollution because they
(a) can grow in polluted atmosphere
(b) can readily multiply in polluted atmosphere
(c) efficiently purify the atmosphere
(d) are very sensitive to pollutants like sulphur
dioxide

Answer 1

Lichens are the symbiotic association of algae and fungi and they are very important in the environmental study as they are the indicators of air pollution. They are plants that grow in exposed places such as tree bark and rocks. They need water and nutrients to grow. Rainwater contains just enough nutrients to keep them alive. Air pollutants dissolved in rainwater, especially SO_22 (sulphur dioxide) can damage lichens, and check them from growing. In places where lichens are not growing, it indicates a good sign that the air is heavily polluted with sulfur dioxide. 

So, the correct answer is option D

Answer 2

The correct option is option d.) are sensitive to pollutants like sulphur dioxide.

Explanation:

• The symbiotic association of Fungi and algae is called as lichens.
• Lichens are very sensitive to sulphur dioxide because it effects it's absorption capacity, they can accumulate large amounts of sulphur dioxide and due to this the chlorophyll is destroyed, which affects the process of photosynthesis and ultimately they die.
• Because of this unique property lichens are used as bio indicators.
• If the air has high levels of sulphur dioxide, lichens would not be found in that area.
• They are also very sensitive to acid rains, which again is related to the high levels of sulphur dioxide in the air.