Cambridge O Level Biology · Syllabus 5090 · Development of Organisms and Continuity of Life
Ovule
What is Ovule?
A structure inside the ovary of a flower that contains the female gamete nucleus. After fertilisation each ovule develops into a seed, while the ovary that contained it develops into the fruit.
This definition is part of the Development of Organisms and Continuity of Life chapter in Cambridge O Level Biology.
Common mistakes with Ovule
- “Fertilisation happens on the stigma.” Say instead Fertilisation happens inside the ovule, at the far end of the journey. Only pollination happens on the stigma.
- “Any pollen will do.” Say instead The pollen must be compatible — from the same species. Incompatible pollen may land on the stigma but will not produce a tube that reaches an ovule.
- “A pollen grain is a sperm cell.” Why wrong The grain contains the male nucleus. The grain itself stays on the stigma; only the nucleus travels down the tube. Say instead The pollen grain contains a male nucleus, which passes down the pollen tube to the ovule.
- “Fertilisation happens on the stigma.” Why wrong The female nucleus is inside an ovule, at the far end of the style. Nothing can fuse with it on the stigma. Say instead Fertilisation happens inside the ovule, after the pollen tube has grown down the style and entered it.
- “The ovule becomes the fruit.” Why wrong The ovule is the small structure inside; it cannot become the large structure around it. Say instead Each fertilised ovule becomes a seed.
Questions students ask about Ovule
Is pollination the same as fertilisation?
No. Pollination is the transfer of pollen grains from an anther to a stigma. Fertilisation is the fusion of a male nucleus with the female nucleus, and it happens later and elsewhere — inside an ovule, after a pollen tube has grown down the style. A flower can be pollinated and never fertilised, for example if the pollen is from a different species.
Does the ovule become the fruit or the seed?
Each fertilised ovule becomes a seed. The ovary, which contained the ovules, becomes the fruit. The relationship is easiest to remember spatially: the ovules are inside the ovary, and the seeds end up inside the fruit, so what was inside stays inside. A pea pod is an ovary that became a fruit; each pea inside it is an ovule that became a seed.