Cheat sheet · Class 12 · CBSE · Science Biology
Sexual Reproduction in Flowering Plants cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 12 · Biology
Cheat sheet
Chapter 1Sexual Reproduction in Flowering Plants
Double fertilisation: one sperm + egg = zygote (2n); one sperm + 2 polar nuclei = endosperm (3n).
1. Male Gametophyte
- Anther: bilobed, tetrasporangiate; wall layers — epidermis, endothecium, middle layers, tapetum (nourishes).
- Microspore mother cell → meiosis → pollen tetrad.
- Pollen grain: exine of sporopollenin (germ pores), intine; vegetative + generative cell.
2. Female Gametophyte
- Ovule: funicle, hilum, integuments, micropyle, nucellus, chalaza.
- Megaspore mother cell → 4 megaspores; one functional (monosporic).
- Embryo sac: 7-celled, 8-nucleate (egg apparatus, 2 polar nuclei, 3 antipodals).
3. Pollination
| Type | Agent / feature |
|---|---|
| Autogamy | same flower; cleistogamous flowers ensure it |
| Geitonogamy | another flower of same plant |
| Xenogamy | flower of another plant (cross) |
| Wind | light pollen, feathery stigma (grasses) |
| Water | Vallisneria, Hydrilla, seagrasses |
| Insects/animals | colour, scent, nectar |
Outbreeding devices: unisexuality, dichogamy, self-incompatibility, different heights of style and anther.
4. After Fertilisation
- Endosperm first (free nuclear in coconut).
- Embryo: proembryo → globular → heart-shaped.
- Ovule → seed; ovary → fruit.
5. Special Cases
Apomixis
seed without fertilisation (Asteraceae, grasses).
Polyembryony
many embryos in one seed (citrus).
Parthenocarpy
seedless fruit (banana).
6. Key Points
- Pollen stored in liquid N₂ (−196 °C).
- Emasculation and bagging in breeding.
- Perisperm: persistent nucellus (black pepper).
- Scutellum is the monocot cotyledon.
Remember: Anther & ovule | pollination types | double fertilisation
Sexual Reproduction in Flowering Plants: questions and notes
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