KS3 · Biology
Pollination and fertilisation in plants
A pollen grain is about 0.07 mm across. To help make a new plant, it must reach a stigma, then grow a tube right down to an ovum.
Follow one pollen grain
Tap each stage to look closer. Watch for the exact point where pollination stops and the journey to fertilisation begins.
Biology · Anatomy
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Layers
Explore
tap a part to read what it does
The whole flower: the plant's reproductive system.
Switch between the male and female parts, then tap any part to read what it does.
Half plus half
Reason it through
Why does a new plant resemble both of its parents?
First link · your turn
Start with the gametes. How much of the plant's DNA does each one carry?
WHAT YOU'VE LEARNED
A quick recap of today's lesson.
Two separate stages, in two different parts of the flower, and a plant needs both to reproduce sexually.
What you need to know
- The flower is a plant's reproductive system. The stamen (an anther on a filament) is the male part. The stigma, style, ovary and ovules make up the female part. Petals attract pollinators.
- Pollination is the transfer of pollen from an anther to a stigma. Pollen can be carried by wind, by water or by animals such as insects.
- Self-pollination moves pollen to the stigma of the same flower. Cross-pollination moves it to a flower on another plant of the same species, and increases variation.
- After pollination, a pollen tube grows down the style and the male gametes travel down it to the ovary.
- Fertilisation is the fusion of the nuclei of a male gamete and an ovum. In plants it takes place in the ovary and makes a zygote.
- Each gamete carries half a set of chromosomes, so the zygote has a full set. The new plant has half its DNA from each parent.
- The zygote develops into an embryo and then a seed. Germination, when the seed grows a stem, leaves and roots, is a separate, later process.
The big picture
Pollination and fertilisation are two separate stages of sexual reproduction in a flowering plant. Pollination is the transfer of pollen from an anther to a stigma, by wind, water or animals such as insects. Then a pollen tube grows down the style, and the male gametes travel down it to the ovary. Fertilisation happens there: a male gamete fuses with an ovum to make a zygote, which develops into an embryo and then a seed. Each gamete carries half a set of chromosomes, so the zygote has a full set and the new plant resembles both parents.
Key points
Worked example
Problem
A bee visits a flower on one plant and picks up pollen. It then flies to a flower on a different plant of the same species and leaves the pollen on that flower's stigma. Describe what must happen next for a zygote to form, and say what kind of pollination this was.
⚠ Watch out
Using 'pollination' and 'fertilisation' as if they mean the same thing. Pollination only moves pollen onto the stigma. Fertilisation comes later, in the ovary, when a male gamete fuses with an ovum.
Memory hook
P comes before F, in the alphabet and in the flower. Pollination happens up on the stigma, then Fertilisation happens down in the ovary. Pollination delivers; fertilisation fuses.
Check yourself
Cover the page. Where does pollination end, and where does fertilisation happen? What grows down the style, and what travels down it? Why does the zygote end up with a full set of chromosomes?
Flashcards
(15)What is pollination?
What is fertilisation in a flowering plant?
Where does fertilisation take place in a flower?
Which parts make up the stamen?
Which parts make up the female part of a flower?
What do the ovules in the ovary produce?
What happens straight after pollen lands on the stigma?
Is pollen a seed?
How much of the DNA does one pollen grain carry?
Self-pollination vs cross-pollination?
Why must the other plant in cross-pollination be the same species?
Which kind of pollination increases variation, and why?
What three ways can pollen be carried to another flower?
What does a zygote develop into?
What is germination?
Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.
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How this lesson was checked. This KS3 Biologylesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 29 September 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.