1Inside a flower
A flower holds a plant's sex organs. The stamens are male: each anther makes pollen. The carpel is female: the stigma catches pollen, and the ovary holds ovules, each with an egg cell.
Lesson 10.4 notes
Take a flower apart, see how insects and the wind carry pollen, follow fertilisation, and investigate how seeds are spread.
A flower holds a plant's sex organs. The stamens are male: each anther makes pollen. The carpel is female: the stigma catches pollen, and the ovary holds ovules, each with an egg cell.
Pollination is the transfer of pollen from an anther to a stigma. Plants can't move, so insects or the wind carry the pollen, often to a flower on another plant.
Insect-pollinated flowers have bright petals, a scent and sweet nectar to attract insects. Sticky pollen clings to a visiting bee and rubs off on the next flower's stigma.
Grasses are pollinated by the wind. Their flowers are small and green, with no scent or nectar. Dangling anthers shed huge amounts of light pollen, and feathery stigmas catch it.
A pollen grain on a stigma grows a pollen tube down through the style to an ovule. The male nucleus travels down the tube and joins the egg cell's nucleus: fertilisation.
After fertilisation, each ovule becomes a seed, holding a tiny plant and a food store. The ovary grows into a fruit around the seeds, and the petals wither and fall.
Seed dispersal spreads seeds away from the parent plant, so the new plants don't compete with it for light, water and space. Seeds travel by wind, animals, water or bursting pods.
Drop paper 'sycamore seeds' with different wing lengths in front of a fan. Measure how far each one travels, and work out the means.
Pollination is pollen landing on a stigma. Fertilisation comes afterwards, when a pollen tube grows down to an ovule and the male nucleus joins the egg cell's nucleus.