Question

A. What is meant by the statement that plants undergo an alternation of generations?

B. In a typical multicellular plant, are the alternating generations equivalent or does one dominate over the other? Using mosses and angiosperms as examples, briefly describe how the dominant generation has changed during plant evolution.

Answer 1

A. Plants undergo alternation of generation, it means that plants alternate between two generations. One generation is haploid and other generation is diploid. In some generation, one is free and other is parasite on the other form. Plants undergo through haploid generation called as gametophye and diploid generation called as sporophyte.

B. In some plants, one generation is dominant and other is domparasitic on the dominat phase. In moss, which is a bryophyte, gametophyte is haploid stage that bear haploid germ cell whereas sporophyte is dominant phase that bear spores. In the moss, gametophyte is dominant and independent stage but sporophyte is dependent on the gametophyte for nutritive requirement. On the other hand, sporophyte is the dominant phase of stage in the angiosperm life cycle and gametoophyre is haploid stage.