Which of the following help in soil formation? Justify. [3 MARKS]
(a) lichen (b) mosses (c) mango tree (d) cactus.
Identification: 1 Mark
Justification: 2 Marks
(a) Lichens and (b) Mosses.
Lichens and mosses release substances which break down the rocks 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 rocks to break and form a thin layer of soil. Other small plants mosses, are able to grow on this surface now and they cause the rocks to break further. The roots of big trees sometimes go into cracks in the rocks and as the roots grow bigger, the size of the cracks increase.