Reproduction in Plants
Asexual reproduction needs one parent and produces genetically identical offspring (clones), e.g. runners, tubers, cuttings: fast, but no variation. Sexual reproduction involves the fusion of male and female gametes (fertilisation), giving variation. In flowers, pollen (male gametes) from the anther lands on the stigma (pollination). A pollen tube grows down to the ovule in the ovary, where fertilisation happens; the ovule becomes a seed and the ovary a fruit. Insect-pollinated flowers are colourful with nectar and sticky pollen; wind-pollinated flowers are small with feathery stigmas and light pollen. Germination needs water, oxygen and warmth.
Learning objectives
- Compare asexual and sexual reproduction.
- Describe flower structure and pollination.
- Describe fertilisation and seed formation.
- State the conditions for germination.
Strawberry plants send out runners that root and grow into new plants. Why do growers still plant seeds sometimes?
Core idea
Bright petals, sweet scent and nectar are all adverts aimed at insects. Grasses don't bother: they trust the wind.
Plants reproduce asexually (identical offspring) or sexually (pollination then fertilisation, giving variation). Flower structure matches the pollinator.
1. From pollen to seed
Pollination comes before fertilisation.
A flower has small green petals, long dangling anthers and large feathery stigmas.
- Goal
- Pollinated by?
- Strategy
- Match features.
- Doesn't need to attract insects.
- Release and catch pollen in the wind.
Why do gardeners take cuttings from their best rose bush rather than growing seeds?
Summary
- Asexual: clones; sexual: variation.
- Pollination → fertilisation.
- Water, oxygen, warmth for germination.
- Pollination
- Transfer of pollen from anther to stigma.
- Fertilisation
- Fusion of male and female gamete nuclei.
- Germination
- Start of growth of a seed.
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