Sexual Reproduction in Plants

Parts and Stucture of the Flower
1. Carpel - female
  1. Stigma
    1. Where the pollen grain lands in pollenation
  2. Style
    1. Holds the stigma high and firm
  3. Ovary
    1. Holds ovules, becomes fruit after fertilisation
      1. Ovule contains female gamete
2. Stamen - male
  1. Anther
    1. Made up of pollen sacs, where pollen is made
      1. Pollen contains the male gamete
  2. Filament
    1. Holds up the anther
3. Other
  1. Petal
    1. Attracts insects for pollination (in insect pollinated plants)
  2. Sepal
    1. Protects the plant whilst it is in a bud
  3. Nectary
    1. Produces sugary nectar that attracts insects for pollination (in insect pollinated plants)
Pollination
1. Self pollination
  1. When pollen of the same plant begins fertilisation with the stigma of the same plant, this is avoided by different maturing times, or by position of the anther to the stigma
2. Cross pollination
  1. When pollen from one plant reaches the stigma of another plant, this is prefered as it increases variation
3. Insect Pollination
  1. Insect used to spread pollen for anther of one plant to stigma of another
    1. Large, bright flowers
    2. Scented
    3. Nectar
    4. Large, rough, but just a little amount of pollen
    5. Anther and stigma inside flower so that insect touches them
4. Wind Polination
  1. Wind used to disperse pollen from one anther to another stigma
    1. No nectar or scent
    2. Small, green petals
    3. Lots of light pollen
    4. Feathery anthers and stigmas out of the flower to catch and release pollen
Fertilisation
1. A pollen tube grows from the pollen landing onto the stigma and grows down the style, into the ovary
  1. There are 8 haploid nuclei in the ovary including the egg cell and 2 nuclei in the central cell
    1. One male nucleus fuses with the two nuclei from the central cell to form a triploid endosperm cell
      1. The endosperm develops into a food store for the seedling
    2. One male nucleus fuses with the egg cell to form a diploid zygote
      1. The ovule develops into a seed
        The zygote becomes the plant embryo
Seeds
1. Dispersal
  1. Animal
    1. Seeds dispersed in fruit eaten by animal, then planted elsewhere
  2. Wind
    1. Seeds have wings and glide elsewhere in the wind
  3. Mechanical
    1. Seeds in pods that burst open, sending the seed elsewhere
  4. Water
    1. Buoyant seeds travel on water
2. Germination
  1. When the conditons are correct, the seedling will begin to grow
    1. Oxygen
    2. Warmth
    3. Water

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Sexual Reproduction in Plants

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	Erstellt von Manraj Bhandal vor etwa 9 Jahre