Correct Answer - Option 2 : A and C only
Concept:
- The term ''Lichen'' was given by Theophrastus.
- Study of Lichens - Lichenology.
- Father of Lichenology - Erik acharius
Explanation:
Lichen:
- Lichen is a composite thalloid structure of algae & fungi.
- The algal part of Lichen is called phycobiont and the fungal part is called mycobiont.
- Both algae & fungi remain in symbiotic association i.e. they are beneficial for each other.
- The algal component prepares the food by photosynthesis while the fungal component helps in the absorption of minerals and nutrition from the soil
- Lichens are good indicators of air pollution.
- Lichens are sensitive towards SO2 (sulphur dioxide).
- They die in more concentrations of SO2.
- Therefore they are not found in those areas (polluted areas) where the concentration of SO2 is high.
- Lichens do not help in nitrogen fixation.
- Legumes and certain bacteria like Rhizobium help in nitrogen fixation.
Thus,
A. They show symbiotic relationships: Correct
B. They are made up of algae and bacteria: Incorrect
C. They are natural indicators of SO2: Correct
D. They also help in nitrogen fixation: Incorrect
Other ecological importance of Lichen:
- Many Lichens are used as food and fodder. Eg –Parmelia, used as food in South India. It is known as Rock Flower.
- It is also used as dyes. Eg – Litmus(Acid-base indicator) is obtained from many members of lichens like Roccella tinctoria.
- The crustose and foliose lichens grow on rocks and secrete different types of acids. These acids break the rocks. In this way, these lichens help in soil formation.
