Plant Reproduction

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Flower Structure: reproductive parts

Female part- CARPEL

  • OVARY males female ovules
  • STIGMA recieves male pollen grains
  • STYLE- links the two

Male part- STAMEN

  • ANTHER-produces male pollen grains
  • FILAMENT- thin stalk holding anther, with vascular tissue.
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Flower structure: other

  • SEPAL- small grene leaves which protect flower in bud
  • PETALS- colourful and scented to attract insects
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Ovule development

  • The mother cell undergoes meiosis
  • to make a haploid embryo sac
  • with 8 haploid nuclei later made by mitosis.
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Pollen grains

  • Undergoes meiosis to make haploid pollen grains
  • Haploud nuclei udnergoes mitosis to make a generative nucleus and tube nucleus.

Pollen grains:

  • Have a hard coat shell to avoid dessication
  • Released when four pollen sacs dry out and split
  • This is called dehiscence.
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Fertilisation 8 POINTS

The fusion of male and female gametes to make a zygote.

  • The pollen grain lands on a complemntary stigma.
  • Pollen rain germinates in a sugary solution produced by the stigma.
  • The tube nucelus release proteases which digests the stigma, creating a pollen tube.
  • Tube nucelus leads growth of tube.
  • Proteases may be used for pollen grain nutrients.
  • The pollen tube grows down the stigma and up through the micropyle, past integuments.
  • Tube nucelus disintegrates when reaching the ovule sac, and the pollen tube burts, releasing the  2 generative nuclei.
  • DOUBLE FERTILSATION- one nuclei combines with female nucleus to ake zygote, and other nucleus combines with polar bodie sto make the triploid endosperm.
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Seed and fruit development

  • Integuments become seed coat or testa.
  • Zygote divides by mitosis to make the seed, with a radicle and plumule, and two cotelydons (seed leaves.)
  • Ovary becomes the fruit.
  • Ovule sac becomes seed.
  • Triploid endosperm becomes sa food source for the devloping seed.
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Pollination: Cross v Self


When the pollen grain from one flower is transferred to teh stigma of a differnet flower on a different plant of the same species.

Self pollination

When the pollen grain is transferred to teh stigam of teh same flower on the same plant.

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Pollination: Pros/Cons of self pollination

Pros and Cons of Self pollination


  • preserves good genomes


  • Harmful recessive alleles are expressed
  • Low resistance to diseases
  • Relies on crossing over and independent assortment for variation.
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Pollination Insect v Wind Characteristics


  • Brightly coloured and scented
  • Nectar
  • small amounts of sticky pollen
  • anther inside the plant


  • Small green and inconspicuous
  • no nectar
  • large amounts of light smooth pollen
  • antehrs are large and feathery to increase surface area
  • anther and stigma hang outside plant.
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Insect v Wind mechanisms


  • relies on isnects such as bees
  • they feed on nectar at base of flower
  • brush past anther, and pollen grains stick to them
  • they then transfer this pollen to another plant.


  • Wind picks up pollen grains from the feathery anthers.
  • transfers them to a stigma of another plant.
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