Lesson 5 ·Class 9 · Pollination and Fertilization · Flow Lab
From Pollen Grain to Zygote
Double fertilisation, step by step.
Follow one pollen grain from the stigma all the way to the zygote.
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🌾 Step 1 of 6 · Pollen lands
A pollen grain lands on a receptive stigma and absorbs its sugary fluid.
Free play — step through the process at your own pace, and move the slider to see what changes. Switch to when you're ready to test yourself.
Two fusions happen in the same ovule — that is why it is called DOUBLE fertilisation.
What this lesson covers
Challenges to clear
- Advance until the pollen tube enters the ovule.
- Reach the fusion that makes the endosperm.
- Step through the whole process.
The task
Follow one pollen grain from the stigma all the way to the zygote.
What this lesson covers
- Pollen lands — A pollen grain lands on a receptive stigma and absorbs its sugary fluid.
- Pollen tube grows — The grain germinates: a pollen tube grows down through the style, carrying two male gametes.
- Tube enters the ovule — The tube reaches the ovary and enters the ovule through the micropyle.
- First fusion — One male gamete fuses with the egg cell to form the diploid zygote. This is syngamy.
- Second fusion — The other male gamete fuses with the two polar nuclei, forming the triploid primary endosperm nucleus.
- Seed and fruit begin — Two fusions in one ovule — double fertilisation. The zygote becomes the embryo and the endosperm feeds it.
Hint
Two fusions happen in the same ovule — that is why it is called DOUBLE fertilisation.