1Parts of a flower
Pollen is made in the anthers. For seeds to form, pollen must land on a stigma. Below it, the ovary holds the ovules. Many flowers also make sugary nectar.
anthersstigmaovarynectar
Lesson 25.3 notes
Pollination and food security
How insects carry pollen, from flower to fruit, insect or wind, the crops that need pollinators, and keeping our food secure.
2Insect pollination
A bee visits a flower to drink its nectar. Pollen from the anthers sticks to the bee's hairy body, and some rubs off on the sticky stigma of the next flower: pollination.
pollination
3From flower to fruit
After pollination, a pollen tube grows to an ovule and the pollen's nucleus fertilises the egg cell inside. The ovule becomes a seed and the ovary a fruit. No pollination, no fruit.
seedfruit
4Insects or wind?
Insect-pollinated flowers have big, bright, scented petals and nectar. Wind-pollinated flowers, like wheat, are small and dull, with dangling anthers, feathery stigmas and lots of light pollen.
5Crops that need insects
Apples, strawberries, tomatoes, almonds, coffee and cocoa need or benefit from insect pollination. Wheat, rice and maize are pollinated by the wind, but a diet of only those would lack many vitamins.
6Food security
Food security means everyone having enough safe, nutritious food. Three out of four kinds of food crop do better when animals, mostly insects, pollinate them, so losing pollinators means smaller harvests.
food security
7Helping pollinators
Bees and other pollinators are threatened by the loss of wild flowers and hedgerows, some pesticides, and disease. Strips of wild flowers beside fields, hedges and careful spraying all help them.
Explore: Orchard lab
Choose how many bees visit an apple orchard, add a wildflower strip or spray an insecticide while the trees flower, then run the season and count the apples.
Common mistake: Not every crop needs insects
Wheat, rice and maize, which give the world most of its food energy, are pollinated by the wind. But most fruits, many vegetables, nuts, coffee and cocoa need or benefit from insects, so losing pollinators would make food scarcer.
Remember
- Pollination is the transfer of pollen from an anther to a stigma. Without it, a flower can't make seeds or fruit.
- Insects visit flowers for nectar and carry pollen between them. Wind-pollinated flowers, like wheat, are small and dull, with feathery stigmas.
- Most fruits, many vegetables and nuts need or benefit from insect pollination, so pollinators matter for food security. Habitat loss, some pesticides and disease threaten them.
Going further at GCSE