Solution

The thalli of lichens can adhere to the surface of the rock and absorb moisture from the atmosphere; therefore, these colonize the bare surfaces of rocks first. These lichens produce acids that corrode the rock and their thalli collect windblown soil particles among them that help in formation of a thin film of soil.
The adult plant body of bryophyte represents the gametophyte. A short-lived sporophyte occurs as a parasite on the gametophyte. In gymnosperms, a leafy green sporophyte generates cones containing male and female gametophytes; female cones are bigger than male cones and are located higher up in the tree.
The coralloid roots contain symbiotic cyanobacteria (blue-green algae), which fix nitrogen and, in association with root tissues, produce such beneficial amino acids as asparagine and citrulline.