Identify the type of life cycles represented by the following diagrams.
Identify the type of life cycles represented by the following diagrams.
The correct option is B 1⇒ Diplontic, 2⇒Haplontic, 3 ⇒ Haplo - Diplontic
1 is diplontic as life cycle has dominant diploid sporophyte stage. 2 is haplontic as life cycle has dominant haploid gametophyte stage. 3 is haplodiplontic as the life cycle is equally dominated by both the gametophyte and sporophyte stages.
The life cycles of all sexually reproducing plants follow a pattern of alternation between a haploid, sexual generation called gametophyte with a diploid, asexual generation called sporophyte. This phenomenon of alternation between gametophyte (n) and sporophyte (2n) in the life cycle of a plant is called alternation of generations. The haplontic life cycle is the primitive type of life cycle characterized by dominant gametophyte and zygotic meiosis. Here, free-living sporophyte is absent. The sporophyte generation is represented only by the one-celled zygote, sometimes called zygospore. The zygote undergoes meiosis to form haploid spores. Each spore germinates (divide mitotically) to form gametophyte. Diplontic life cycle characterized by gametic meiosis and diploid sporophyte this is dominant, photosynthetic and independent generation of the plant. The gametophyte generation is represented by the haploid gametes or few-celled haploid gametophyte. Here only sporophyte is conspicuous and gametophyte is inconspicuous. Haplo - diplontic type of life cycle involves the alternation of two vegetative individuals, the haploid gametophyte and diploid sporophyte. In this case, sporogenic meiosis occurs in sporophyte to produce spores (meiospores). Here both the generations are conspicuous.
1⇒ Diplontic, 2⇒Haplontic, 3 ⇒ Haplo - Diplontic
1 is diplontic as life cycle has dominant diploid sporophyte stage. 2 is haplontic as life cycle has dominant haploid gametophyte stage. 3 is haplodiplontic as the life cycle is equally dominated by both the gametophyte and sporophyte stages.
The life cycles of all sexually reproducing plants follow a pattern of alternation between a haploid, sexual generation called gametophyte with a diploid, asexual generation called sporophyte. This phenomenon of alternation between gametophyte (n) and sporophyte (2n) in the life cycle of a plant is called alternation of generations. The haplontic life cycle is the primitive type of life cycle characterized by dominant gametophyte and zygotic meiosis. Here, free-living sporophyte is absent. The sporophyte generation is represented only by the one-celled zygote, sometimes called zygospore. The zygote undergoes meiosis to form haploid spores. Each spore germinates (divide mitotically) to form gametophyte. Diplontic life cycle characterized by gametic meiosis and diploid sporophyte this is dominant, photosynthetic and independent generation of the plant. The gametophyte generation is represented by the haploid gametes or few-celled haploid gametophyte. Here only sporophyte is conspicuous and gametophyte is inconspicuous. Haplo - diplontic type of life cycle involves the alternation of two vegetative individuals, the haploid gametophyte and diploid sporophyte. In this case, sporogenic meiosis occurs in sporophyte to produce spores (meiospores). Here both the generations are conspicuous.
