Maharashtra State Board · Class 12 · Biology · Chapter 1

Reproduction in Lower and Higher Plants — Formula Sheet

Board Formulas

10 formulas

1.Double Fertilisation★
$Syngamy: male gamete + egg \to zygote (2n); Triple fusion: male gamete + 2 polar nuclei \to PEN (3n)$
Discovered by S.G. Nawaschin in Lilium and Fritillaria. Two male gametes take part; hence 'double'.
2.Types of Ovules (Placentation)
$Orthotropous, Anatropous, Campylotropous, Amphitropous, Hemitropous, Circinotropous$
Orientation of micropyle relative to funicle and chalaza. Anatropous is the commonest form (in most angiosperms).
3.Types of Pollination★
$Autogamy (same flower); Geitonogamy (same plant); Xenogamy (different plant)$
Autogamy and geitonogamy are genetically self-pollination; xenogamy is cross-pollination.
4.Pollen–Pistil Interaction
$Pollen germination \to tube growth \to entry into ovule \to fertilisation$
Regulated by chemical (γ-aminobutyric acid, Ca²⁺) and self-incompatibility genes.
5.Endosperm Development★
$PEN (3n) \to Nuclear \to Cellular \to Helobial$
Three types of endosperm development. Coconut water is nuclear endosperm.
6.Embryo Development in Dicot★
$Proembryo \to Globular \to Heart-shaped \to Torpedo \to Mature$
Follows Onagrad type in Capsella bursa-pastoris (Balbharati standard example).
7.Post-fertilisation Changes
$Ovule \to Seed; Ovary \to Fruit; Ovule wall \to Seed coat$
Petals, stamens, style, stigma wither. Sepals may persist (e.g. tomato).
8.Vegetative Propagation Structures★
$Runner, Sucker, Offset, Bulbil, Rhizome, Corm, Tuber, Leaf buds$
Balbharati lists 8 forms — memorise with one example each.
9.Apomixis
$Seed formation without fertilisation$
Diploid embryo from nucellus/integument. Example: Citrus, Mango. Used in hybrid crop production.
10.Polyembryony
$Two or more embryos in a single ovule/seed$
Example: Citrus, Mango. Common in gymnosperms too.