Fertilization and Post-Fertilization Events in Flowering Plants – NEET Notes

🌸 Double Fertilization – A Unique Feature of Angiosperms

In angiosperms, fertilization occurs in two steps:

1️⃣ Syngamy

Fusion of one male gamete with the egg

Forms zygote (2n)

2️⃣ Triple Fusion

Fusion of the second male gamete with two polar nuclei

Forms Primary Endosperm Nucleus (3n)

🧠 Trick: “1 Egg + 2 Polar nuclei = 3N Endosperm”

📌 Double fertilization = Syngamy + Triple fusion

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🧫 Events After Fertilization (Post-Fertilization Events)

Structure Develops Into

Zygote Embryo

Primary Endosperm Nucleus Endosperm

Ovule Seed

Ovary Fruit

Ovary wall Pericarp (fruit wall)

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🌱 Development of Endosperm

The endosperm nourishes the developing embryo.

Types of Endosperm:

1. Nuclear – Most common (e.g., coconut water)

2. Cellular

3. Helobial

🧠 NEET Tip: “Endosperm forms before embryo in most plants”

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👶 Development of Embryo

Embryo arises from the zygote through mitosis.

In Dicots (e.g., bean):

Two cotyledons

Plumule (shoot tip)

Radicle (root tip)

Hypocotyl and epicotyl

In Monocots (e.g., maize):

One cotyledon (scutellum)

Coleoptile (shoot cover)

Coleorhiza (root cover)

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🌾 Seed and Fruit Formation

Seed: Fertilized ovule with seed coat (testa + tegmen)

Fruit: Ovary enlarges and ripens

Pericarp: Fruit wall (from ovary wall)

Types of fruits:

True fruit: Only ovary (e.g., mango)

False fruit: Includes other parts like thalamus (e.g., apple)