Question

Question 36
Following are a few organisms

(a) lichen
(b) mosses
(c) mango tree
(d) cactus
Which among the above can grow on stones; and also help in formation of soil? Write the mode of their action for making soil.

Answer 1

(a) Lichens and (b) Mosses

Lichens and Mosses can grow on stones. Lichens and mosses release substances which break down the stones resulting in the formation of soil. The mode of action here is chemical.
Lichens grow on the surface of rocks. While growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil. Other small plants mosses are able to grow on this surface now and they cause the rock to break up further. The roots of big trees sometimes go into cracks in the rocks and as the roots grow bigger, the crack is forced bigger.