Tag: alternation of generation in angiosperms

Answer is option C i.e. "Bryophytes"
The zygote does not undergo meiosis immediately in bryophytes to form the sporophyte (a multi-cellular body). Some cells of the sporophyte undergo meiosis to form haploid spores. Spores further germinate to produce the gametophyte.

Bryophytes are known as amphibians of the plant kingdom because they require water for the movement of male gametes to the archegonia. Option B is wrong because sex organs in bryophytes are multicellular. Option C is wrong because the plant body is a thallus, not differentiated into true roots, stems, or leaves. Option D is wrong because Polytrichum is a moss, not a liverwort.

In pteridophytes, the spore germinates to form a small, inconspicuous, multicellular, free-living, photosynthetic thallus called a prothallus. This structure represents the reduced gametophyte stage of the plant.

The opening of floral buds is a growth-related movement that occurs independently of external stimuli, making it an autonomic movement of growth (specifically a nastic movement).

Statement (A) is wrong because the sporophyte in mosses is more elaborate than in liverworts. Statement (D) is wrong because Pinus is monoecious, meaning male and female cones are borne on the same tree. Statements (B) and (C) are correct.

In bryophytes, the main plant body is the gametophyte (n), which produces gametes through mitotic division since the cells are already haploid and do not need to undergo reduction division.

In gametophytic self-incompatibility, the pollen is typically 2-celled at the time of shedding, whereas in sporophytic self-incompatibility, the pollen is often 3-celled.

Apospory is the development of a gametophyte directly from the vegetative cells of a sporophyte without meiosis. Since the sporophyte is diploid (2n), the resulting aposporously formed gametophyte is also diploid, and therefore its gametes will be diploid.