Title: Bryophytes : Alternation of Generations
Headings: Bryophytes : Alternation of Generations
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Chapter: 11th 12th standard bio zoology Human Body higher secondary school
Bryophytes : Alternation of Generations
Bryophytes : Alternation of Generations

Content: Two types of organism, a haploid gametophyte generation and a diploid sporophyte generation, alternate in the life cycle. The cycle is summarized in the fig below. The haploid generation is called thegametophyte because it undergoes sexual reproduction to produce gametes. Production of gametes involves mitosis, so the gametes are also haploid. The gametes fuse to form a diploid zygote which grows into the next generation, the diploid sporophyte generation. It is called sporophyte because it undergoes asexual reproduction to produce spores. Production of spores involves meiosis, so that there is a return to the haploid condition. The haploid spores give rise to the gametophyte generation. One of the two generations is always more conspicuous and occupies a greater proportion of the life cycle. This generation is called as the dominant generation.