1. Reproductive Structures: Stamen vs Pistil
| Feature | Stamen (male) | Pistil / carpel (female) |
|---|---|---|
| Main parts | Anther and filament | Stigma, style and ovary |
| Produces / contains | Pollen grains in pollen sacs (microsporangia) | Ovules inside the ovary |
| Gametophyte | Pollen grain - male gametophyte | Embryo sac - female gametophyte |
| Gametes | Two male gametes are released from the pollen tube | Egg cell and two polar nuclei occur in the embryo sac |
| Fate after fertilisation | Usually withers | Ovary becomes fruit; ovules become seeds |
NCERT cueEach typical angiosperm anther is bilobed, dithecous and has four microsporangia arranged tetrahedrally.
2. Microsporogenesis vs Megasporogenesis
| Point | Microsporogenesis | Megasporogenesis |
|---|---|---|
| Site | Microsporangium / pollen sac of anther | Nucellus of ovule |
| Mother cell | Pollen / microspore mother cell (PMC) | Megaspore mother cell (MMC) |
| Division | Meiosis | Meiosis |
| Products | Four haploid microspores, usually in a tetrad | Four haploid megaspores |
| Functional product | All four usually separate and form pollen grains | Usually one functional megaspore; the other three degenerate |
| Gametophyte development | Microspore develops into pollen grain | Functional megaspore develops into embryo sac |
3. Self-pollination vs Cross-pollination
| Type | Definition | Genetic outcome / key point |
|---|---|---|
| Autogamy | Transfer of pollen from anther to stigma of the same flower. | True autogamy needs anther and stigma to mature together and be close; cleistogamous flowers guarantee it. |
| Geitonogamy | Transfer of pollen between different flowers of the same plant. | Genetically self-pollination, but functionally cross-pollination because an agent is needed. |
| Xenogamy | Transfer of pollen to a flower on a different plant of the same species. | True cross-pollination; brings genetically different pollen. |
| Cleistogamy | Flowers do not open; anthers and stigma remain enclosed. | Assured seed set even without pollinating agents; examples: Viola, Oxalis, Commelina. |
Exam distinctionGeitonogamy is genetically self, but ecologically/functionally cross-pollination.
4. Abiotic vs Biotic Pollination
| Feature | Abiotic: wind / water | Biotic: insects, birds, bats and others |
|---|---|---|
| Frequency | Relatively uncommon in flowering plants; wind is more common than water. | Most common mode in angiosperms. |
| Flowers | Small, inconspicuous; often without colour, nectar or fragrance. | Often large, colourful, fragrant and nectar-producing. |
| Pollen | Very large quantity; light and non-sticky in wind-pollinated plants. Water-pollinated pollen may have mucilaginous coating. | Usually sticky so it adheres to the animal body. |
| Stigma | Large and feathery in wind pollination to trap pollen. | Positioned to receive pollen from the visitor. |
| Examples | Maize: wind. Vallisneria and Zostera: water. | Yucca and its moth show a specific mutualism. |
5. Double Fertilisation: Two Fusions
| Event | Fusion | Product | Ploidy |
|---|---|---|---|
| Syngamy | One male gamete + egg cell | Zygote | 2n |
| Triple fusion | Second male gamete + two polar nuclei / secondary nucleus | Primary endosperm nucleus (PEN) | 3n |
| Double fertilisation | Syngamy + triple fusion in the same embryo sac | Zygote and PEN | Characteristic of angiosperms |
| Post-fertilisation growth | Zygote develops into embryo; PEN develops into endosperm. | Embryo is nourished by endosperm. | - |
Pollen tube enters embryo sac→2 male gametes released→Syngamy + triple fusion
6. Dicot Embryo vs Monocot Embryo
| Feature | Dicot embryo | Monocot embryo (e.g. maize) |
|---|---|---|
| Cotyledons | Two cotyledons | One cotyledon, called scutellum |
| Embryonal axis | Epicotyl above cotyledons; hypocotyl below them and ending in radicle. | Embryonal axis has plumule and radicle at its ends. |
| Protective sheaths | Not named as coleoptile / coleorhiza in NCERT diagram. | Plumule is enclosed in coleoptile; radicle and root cap are enclosed in coleorhiza. |
| Food reserve | May be stored in cotyledons in non-albuminous seeds. | Usually endospermic; scutellum absorbs nutrients from endosperm. |
7. Seed, Fruit and Special Reproductive Terms
| Term | Meaning | Examples / NCERT cue |
|---|---|---|
| Albuminous seed | Endosperm persists in mature seed. | Wheat, maize, castor, coconut. |
| Non-albuminous seed | Endosperm is completely used up during embryo development. | Pea, groundnut, bean. |
| Perisperm | Persistent residual nucellus. | Black pepper, beet. |
| True fruit | Develops only from the ovary. | Mango, tomato. |
| False fruit | Thalamus also contributes to fruit formation. | Apple, strawberry, cashew. |
| Apomixis | Seed formation without fertilisation. | Common in some Asteraceae and grasses; useful in hybrid seed production. |
| Polyembryony | More than one embryo in a seed. | Common in Citrus and mango. |