Double fertilisation is a core Reproduction in Flowering Plants concept in Biology. This guide explains what it is, walks through a fully worked example, and lists the key equations you need — with a short quiz to test yourself.

Key equations and worked example

A typical flower: green sepals (calyx) protect the bud; colourful petals (corolla) attract pollinators; stamens (anther + filament) make pollen; the pistil (stigma + style + ovary) receives it. In double fertilisation, one sperm fuses with the egg (embryo) and another with two polar nuclei (endosperm).

• <code>Calyx = sepals (K), Corolla = petals (C)</code>
• <code>Androecium = stamens (A: anther + filament)</code>
• <code>Gynoecium = carpels (G: stigma + style + ovary)</code>
• <code>Double fertilisation: 1 sperm + egg → zygote; 1 sperm + 2 polar nuclei → endosperm</code>

Double fertilisation in detail

Double fertilisation is one of the central ideas in Reproduction in Flowering Plants, and it appears in Biology curricula under Sexual reproduction in flowering plants. It is worth learning deeply because it connects to so many other topics in this section.

The flower is the angiosperm&#39;s reproductive structure. Male gametophyte (pollen) lands on the stigma, germinates a pollen tube down the style, and delivers two sperm to the embryo sac. After fertilisation the ovary becomes the fruit and ovules become seeds. Highlight each whorl with the part selector.

For exams, the pattern is predictable: first a definition or statement of the result, then a direct numerical application of one of the equations above, then a "why" question — why the formula takes that form, or what changes when a variable is doubled or halved. The worked example and quiz below cover exactly that progression.

Quick self-check:

• Q: Which flower parts are male and which are female?<br />A: Stamens (anther + filament) are male; the pistil/carpel (stigma + style + ovary) is female.
• Q: What is double fertilisation?<br />A: Unique to flowering plants: one sperm forms the zygote with the egg, another forms triploid endosperm with the polar nuclei.
• Q: After fertilisation, what do the ovary and ovules become?<br />A: The ovary wall becomes the fruit (pericarp) and each ovule becomes a seed.