question_answer 34)

  Comment on the life cycle and nature of a fern prothallus.

Answer:

                  The life cycle of fern (Dryopteris) clearly shows the alternation of generation. The gametophytic stage (n) alternates with the saprophytic stage (n) figure given shows its complete life cycle. Prothallus The prothallus of the fern is multicellular, free living, thalloid, haploid and autotrophic structure. It develops from the spores produced by saprophyte after reduction division, x       These spore germinate with a germ tube with an apical cell and forms a filament of 3-6 cells and one or two rhizoids at the base which later develops into gametophytic plant. Different stages in the germination of a spore and development of prothallus