Given below are the stages in the life cycle ofpteridophytes. Arrange the following stages in thecorrect sequence.A. Prothallus stageB. Meiosis in spore mother cellsC. FertilisationD. Formation of archegonia and antheridia ingametophyte.E. Transfer of antherozoids to the archegonia inpresence of water.Choose the correct answer from the options givenbelow:
Answer
Reproductive Cycle of Pteridophytes
In pteridophytes, the main plant body is a sporophyte, which is clearly differentiated into true roots, stems, and leaves. This sporophyte stage is the dominant and long-lived phase in their life cycle.
- Sporangia develop on specialized leaf-like structures called sporophylls.
- Inside sporangia, spores are produced by meiosis in spore mother cells.
- These haploid spores germinate into gametophytes which are:
- Small
- Multicellular
- Free-living
- Photosynthetic
- Thalloid in structure
- Called prothalli
Gametophyte Structure and Function
The prothallus (gametophyte) bears sex organs:
- Antheridia – Male sex organs
- Archegonia – Female sex organs
Water is essential for fertilization, as it facilitates the movement of motile male gametes (antherozoids) from the antheridia to the archegonia. Fertilization occurs with the fusion of a male gamete and an egg cell in the archegonium, leading to the formation of a zygote.
Formation of New Sporophyte
The zygote develops into a new multicellular sporophyte, which is well-differentiated and resumes the dominant phase of the plant. This cycle illustrates a clear alternation of generations between the haploid gametophyte and diploid sporophyte.