Sexual reproduction in plants — Cambridge IGCSE Biology
Flower structure and function, insect and wind pollination, pollination and fertilisation, self and cross-pollination, and germination.
Revision notes
5 short notes, in the order of the specification. Each one in short:
An insect-pollinated flower has a male part, the stamen, and a female part, the carpel. The anther in the stamen produces pollen grains containing the male gametes, and the filament holds it up. The stigma receives pollen, the style holds it up, and the ovary contains ovules, which develop into seeds after fertilisation. Petals attract insects.
Insect-pollinated and wind-pollinated flowers are adapted to different ways of carrying pollen. Insect-pollinated flowers have large, brightly coloured petals, nectar and larger, sticky or spiky pollen. Wind-pollinated flowers, such as grasses, have small dull petals, anthers and feathery stigmas hanging outside the flower, and very large numbers of small, light, smooth pollen grains.
Pollination is the transfer of pollen grains from an anther to a stigma, and fertilisation occurs when a pollen nucleus fuses with a nucleus in an ovule. Pollination must happen first. A pollen tube then grows from the pollen grain down through the style into an ovule, carrying the pollen nucleus to fuse with the egg cell nucleus.
Self-pollination and cross-pollination
SupplementSelf-pollination is the transfer of pollen grains from an anther to the stigma of the same flower or another flower on the same plant. Cross-pollination transfers pollen to a flower on a different plant of the same species. Cross-pollination gives more variation, so a population can respond better to change, but it relies more on pollinators.
Germination
PracticalGermination is when a seed begins to grow into a new plant, and it needs water, oxygen and a suitable temperature. Water makes the seed swell and activates its enzymes, oxygen is needed for aerobic respiration, and enzymes work best at a suitable temperature. Light is not needed for most seeds, so investigation tubes are kept in the dark.
Exam questions
7 exam-style questions (26 marks), each with its mark scheme.
Answer the questionsFlashcards
15 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of reproduction on one page, so you can see where this subtopic fits.
Open the mind mapPractical sheet
Method, variables, risks and a results table, with questions to answer.
Print it
Free PDFs to print or save.
Quick check questions
Which part of a flower makes pollen?
Show answer
The anther.
Define pollination.
Show answer
The transfer of pollen grains from an anther to a stigma.
Give two features of wind-pollinated pollen grains.
Show answer
Small and light; smooth surface.
What three conditions does a seed need to germinate?
Show answer
Water, oxygen and a suitable temperature.
Supplement Define cross-pollination.
Show answer
The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species.
Frequently asked questions
What is the difference between pollination and fertilisation?
Pollination is the transfer of pollen grains from an anther to a stigma, while fertilisation is the fusion of a pollen nucleus with a nucleus in an ovule. Pollination happens first. Only after pollen reaches the stigma can a pollen tube grow down to the ovule, so that the nuclei can fuse.
How are wind-pollinated flowers adapted?
Wind-pollinated flowers have anthers hanging outside the flower on long filaments, so the wind can blow the pollen away. Their stigmas are large and feathery and hang outside, to catch pollen from the air. Petals are small, dull or absent, with no nectar, and they make very large numbers of small, light, smooth pollen grains.
How does a pollen tube grow?
Supplement A pollen tube grows out of a pollen grain after it lands on the stigma of a flower of the same species. The tube grows down through the style towards the ovary and enters an ovule. The pollen nucleus passes down the tube and fuses with the nucleus of the egg cell, which is fertilisation.
What conditions are needed for germination?
Seeds need water, oxygen and a suitable temperature to germinate; light is not needed for most seeds. Water makes the seed swell and activates enzymes that break down stored food. Oxygen is needed for aerobic respiration, which releases energy for growth. If it is too cold, the enzyme reactions are too slow.
Why is cross-pollination better than self-pollination?
Supplement Cross-pollination gives more variation, because the offspring get genetic information from two different plants. So some offspring may be suited to new conditions, such as a new disease, and the population is more likely to survive. However, it relies on insects or wind to carry pollen, whereas self-pollination is less reliant on pollinators.
Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026