Monday 28 December 2015

ALTERNATION OF GENERATION IN PLANTS

Different plant group complete their life cycle in different patterns, e.g.- angiosperm complete their life cycle in two phases- a diploid sporophyte  plant body and the other haploid gametophyte, the two follow each other rigidly. this phenomenon is called alternation of generation.
   
     Life cycle of other plant group can be of following patterns-
1. Haplontic- there is a single vegetative individual or somatic phase. it is haplod and it is often called gametophyte. the haploid plant body may be unicellular, colonial or multicellular.

2. Diplontic- there is a single somatic  phase or vegetative individual. it is diploid  and is often called sporophyte though it produces gametes in its body or sex organ.

3.this type of life history involves the  sequential recurrence of two well developed somatic phase or vegetative individuals, gametophyte and sporophyte. the sporophyte. the sporophyte possess  diploid chromosome number(2n). meiosis takes place in it at the time of formation of  meiospors. the haploid meiospores germinate to produce haploid gametophyte. the gametophyte produces gametes.fusion of gametes produces zygote which develops in sporophyte. this is called alternation of generation.

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