Question

Haplo-diplontic life cycle is found in------.
A.Bryophytes
B.Pteridophytes
C.Fungi
D.Both (a) and (b)

Answer 1

In haplo-diplontic life cycles, In meiotic division gametes are not the direct result . Diploid sporophyte cells undergo meiosis to produce haploid spores, different from our own diplontic life cycle, in which only the gametes are in the haploid state.

Complete answer: Haplontic life cycle - when sporophytic generation is represented by the only single-celled zygote and gametophyte is in dominant nature. Haplo-diplontic - This is An intermediate condition between the haplontic and diplontic life cycle where both the sporophyte and gametophyte are free-living and multicellular but have different dominant phases in life cycles.
The Haplo-Diplontic life cycle is observed in 8 following plants. This life cycle is present only in Bryophytes and pteridophytes.
So, sphagnum, Polytrichum , Marchantia and Riccia are in direct relation with Bryophyta and Selaginella , Pteris , Dryopteris , and Polysiphonia belong to Pteridophyta.
In pteridophytes, the diploid sporophyte remains dominant, independent, photosynthetic, and vascular plant body. In an alternative with a multicellular, saprophytic, independent, and short-living haploid gametophyte. Ectocarpus , Polysiphonia , and kelps are haplodiplontic. Bryophytes are having life cycles with alternation of generations. In every cycle, a haploid gametophyte, each of whose cells contains a fixed number of unpaired chromosomes, alternates with a diploid sporophyte, whose cells contain two sets of paired chromosomes.
The correct answer is option "D" that is Both (a) and (b).

Note: 1. Haplontic life cycle — the haploid stage is multicellular and the diploid stage is a single cell stage, meiosis is "zygotic".
2. Diplontic life cycle — the diploid stage is a multicellular process and haploid gametes are formed in this, meiosis is "gametic".
3. Haplo diplontic life cycle (also referred to as diplohaplontic, diplobiontic life cycle) — multicellular diploid and haploid stages occur, meiosis is "sporic".