Question

Indicator plants which can be used to indicate atmospheric pollution by $SO_2$ are
A)Lichens like Usnea
B)Grassland like Deschampsia
C)Moss like Sphagnum
D)Climbers like Cucurbita

Answer 1

Hint: Indicators plants are the plants which help in indicating the soil, water or air pollution. They are useful as they point to certain deficiencies and diseases. These plants are specific to a certain area.

Complete answer:
The pollution is the adding of unwanted particles in soil, water, air. These unwanted particles are called the pollutants. One of the major air pollutants is sulphur dioxide. It is produced by the industrial or domestic fuel combustion, power plants etc. It causes severe effects on health, and leads to acid rain. It can also harm plants on higher concentrations.

The sulphur dioxide pollution is indicated by a plant called lichens. The lichen is the symbiotic relation of algae and fungi. They are called bioindicators. When the air is polluted with sulphur dioxide, the fungal partner of the lichen does not exist. Only the algae or the cyanobacteria is found. Usnea is a leafless fruticose lichen which grows as small shrubs. It is found all over the world.

1.Deschampsia- This plant is a perennial herb found in grassland. It is used as a fertility indicator.
2.Sphagnum- This is a moss which is used as an indicator of dust and ultra violet rays. The higher wavelength of UV rays inhibits the growth of Sphagnum.
3.Cucurbita-It is the indicator of the taxonomic group.

Hence, the correct answer is option (A)

Note: Lichen is the association between the algae and fungi where algae provide food and fungi provide shelter. In the industrial zone, the lichens are not able to absorb the nutrients properly and die. It is also used as a medicine.