Biology · Plant Kingdom · NEET
Meiosis is the reduction division that changes a diploid (2n) cell into haploid (n) cells. It can happen at only ONE point in a plant's life cycle, and that point defines the life-cycle type. It happens either (1) in the zygote right after fertilisation (zygotic meiosis), (2) during gamete formation (gametic meiosis), or (3) in spore mother cells to make spores (sporic meiosis). This is a favourite NEET topic because one small detail changes the whole answer.
In zygotic meiosis the zygote is the ONLY diploid cell in the whole life cycle. The zygote does not grow into a big plant; instead it divides by meiosis right when it germinates. This gives a haplontic life cycle where the haploid gametophyte is the main plant body. Most green algae like Chlamydomonas, Spirogyra and Volvox show zygotic meiosis. NEET 2017 asked exactly this: zygotic meiosis is characteristic of Chlamydomonas.
In gametic meiosis the plant body is diploid (2n) and meiosis happens only when it makes the gametes. So the gametes are the only haploid cells. This is the diplontic life cycle. The brown alga Fucus shows gametic meiosis. Careful: animals and Fucus show gametic meiosis, but seed plants (gymnosperms and angiosperms) do NOT. Seed plants make spores by meiosis first, then the spores make gametes by mitosis. So seed plants show sporic meiosis, not gametic.
In sporic meiosis, meiosis happens in spore mother cells inside the sporophyte to make haploid spores (not gametes). The spores grow into the gametophyte, and the gametophyte later makes gametes by mitosis. This gives an alternation of generations (haplo-diplontic pattern). Bryophytes (moss, Marchantia, Funaria), pteridophytes (ferns), gymnosperms (Cycas, Pinus) and angiosperms all show sporic meiosis. Remember: spore = product of meiosis in all land plants.
In bryophytes and pteridophytes, meiosis makes SPORES, never gametes directly. In a moss, the diploid sporophyte (the capsule) has spore mother cells that divide by meiosis to give haploid spores. In a fern, the sporangia on the sporophyte leaf have spore mother cells that undergo meiosis to make spores. Those spores then grow into a gametophyte (protonema in moss, prothallus in fern) which makes gametes by mitosis. NEET 2025 tested this fern sequence directly.
A gametophyte is already haploid (n). Meiosis needs a diploid (2n) starting cell, so a haploid gametophyte cannot do meiosis. The gametophyte makes gametes by MITOSIS. Only the diploid sporophyte (or a diploid zygote, or a diploid body in Fucus) can do meiosis. This is why students lose marks: they wrongly say the gametophyte does meiosis - it does not.
Use this shortcut. If it is a common green alga (Chlamydomonas, Spirogyra, Volvox) then zygotic meiosis (haplontic). If it is Fucus (brown alga) or an animal then gametic meiosis (diplontic). Everything else in the plant kingdom - Ectocarpus, all bryophytes, all pteridophytes, all gymnosperms, all angiosperms - shows sporic meiosis with alternation of generations. Note Ectocarpus is the special brown alga that is haplo-diplontic (sporic), unlike Fucus.
Zygotic meiosis is characteristic of
Life cycle of Ectocarpus and Fucus respectively are
Given below are the stages in the life cycle of pteridophytes. Arrange them in the correct sequence. A. Prothallus stage B. Meiosis in spore mother cells C. Fertilisation D. Formation of archegonia and antheridia in gametophyte E. Transfer of antherozoids to the archegonia in presence of water.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Haplontic life cycle = zygotic meiosis (e.g. Chlamydomonas, Spirogyra). Diplontic life cycle = gametic meiosis (e.g. Fucus and animals). Haplo-diplontic life cycle (alternation of generations) = sporic meiosis (bryophytes, pteridophytes, gymnosperms, angiosperms, and Ectocarpus).
No. Most green algae show zygotic meiosis (haplontic), but brown algae differ. Fucus shows gametic meiosis (diplontic) and Ectocarpus shows sporic meiosis (haplo-diplontic). NEET loves these two brown-alga exceptions, so remember Fucus = gametic and Ectocarpus = sporic.
In the anther (microsporangium) the microspore mother cells undergo meiosis to make microspores (pollen), and in the ovule (megasporangium) the megaspore mother cell undergoes meiosis to make megaspores. Both are spores, so angiosperms show sporic meiosis. The gametes are formed later by mitosis.
NEET repeatedly asks match-the-plant questions like 'zygotic meiosis is characteristic of' or 'life cycle of Ectocarpus and Fucus'. One word decides the answer. If you can instantly link a plant to zygotic, gametic or sporic meiosis, you save time and avoid the trap options.
Yes. The sporophyte is always 2n and forms after fertilisation from the zygote. The gametophyte is always n and forms from a spore. Meiosis is what converts the 2n line into the n line, so it must occur somewhere between the sporophyte and the gametophyte - which is why spore formation is where meiosis sits in land plants.
