Question

How do moss plants exhibit alternation of generations?

Answer 1

The distinct morphological and cytological stages through which the growth and development of a plant occurs is known as life cycle of the plant. When the life cycle of a plant consists of two morphological phases regularly alternating with each other, the phenomena is termed as alternation of generations

Complete answer:
The thallus is erect and differentiated into root stem and leaves. These parts are not true roots stem and leaves but rhizoids are root like organs, central axis system like part and leafy appendages are leaf like organs of gametophyte. The male and female sex organs are produced at the tip of branches in clusters on the same plant. Antheridia are male gametangia that produce male gametes antherozoids which swim in water with the help of flagella. Archegonia are female gametangia that produce female gametes or eggs.
Many antherozoids are present but only one fertilizers the egg and forms a zygote. The zygote develops into a sporophyte which is differentiated into foot, seta and capsule. Foot remains embedded in the gametophytic tissue whereas seta and capsule are raised above the gametophyte. Spores are haploid and are dispersed in dry weather.
The spores germinate and develop protonema which is an intermediate stage of gametophytic generation. The protonema bears vegetative buds which develop into leafy appendages. Thus from protonema gametophyte is produced. Presence of the protonema stage in the life cycle is characteristic of mosses. Protonema and gametophore together form the gametophytic phase in the life cycle. Thus distinct alternation of generation is seen in the life cycle of mosses.

Note: Depending upon the characters of the gametophyte the bryophytes are divided into two groups- liverworts and mosses. Mosses are mostly found in the damp moist habitat but you are also found in deserts, boxes and streams.