Explain briefly the following term with suitable examples 1)protonema 2)antheidium 3)archegonium 4)diplontic 5)sporophyll 6)isogamy
Answers
Answer:
spores of mosses germinate to form protonema which further form the main plant body.
Antheridium is the male reproductive organ
Archaegonium is the female reproductive organ where egg cell is produced
Answer:
i) Protonema is the haploid stage in the bryophyte lifecycle where thread-like chain of cells are formed Ex: In mosses protonema develops directly from a spore.
ii) Antheridium – The male sex organ, producing male gametes in bryophyte and pteridophytes is called antheridium. Ex: many fungi and algae have antheridia during their reproductive phases.
iii) Archegonium is a female reproductive organ of bryophytes which is flask-shaped and produces a single egg. Observed in pteridiophytes, gymnosperms, bryophytes, they are jacketed and multicellular, possessing a neck and a swollen venter.
iv) Diplontic – Life cycle in which dominant free living phase is diploid, generating haploid gametes. Ex: Sargassum
v) A leaf which bears sporangia is called as sporophyll, which may be microsporophyll or megasporophyll. These structures combine to form strobini(cones) Ex: Pinus
vi) Isogamy – Sexual reproduction that takes place through fusion of two gametes which can be flagellated and similar in size or non-flagellated (non-motile) but similar in size. Such reproduction is called isogamy. Ex: Ectocarpus