Cambridge O Level Biology · Syllabus 5090 · Development of Organisms and Continuity of Life
Pollen Tube
What is Pollen Tube?
A tube that grows out of a germinating pollen grain, down through the style, and into an ovule. It carries a male nucleus from the stigma to the female nucleus so that fertilisation can occur; it is the link between pollination and fertilisation.
This definition is part of the Development of Organisms and Continuity of Life chapter in Cambridge O Level Biology.
Common mistakes with Pollen Tube
- “The style turns into the pollen tube.” Say instead The style is part of the flower and stays where it is. The pollen tube is a new structure, grown by the pollen grain, that travels through the style.
- “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 style becomes the pollen tube.” Why wrong The style is a permanent part of the flower. The tube is a new structure grown by the pollen grain. Say instead The pollen tube grows through the style.
Questions students ask about Pollen Tube
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.