Question

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

Answer 1

Hint: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".