Fertilisation in plants

• Where does the pollen grain first land?

  Stigma
• Only under what circumstance does the pollen grain start to germinate after landing?

  If the molecules on the surface of the pollen grain and the stigma recognise each other as being from different plants within the same species
• Where does the pollen grain grow from?

  Pollen nucleus
• Explain why the hydrolytic enzymes are beneficial to the movement of the pollen tube.

  They digest the tissue of the style so that the pollen tube can move through cells
• What nucleus divides into two male nuclei

  Generative nucleus
• Where does double fertilisation take place?

  Ovule
• How does double fertilisation work?

  • One male nucleus fuses with two polar bodies to form an endosperm nucleus (triploid)
  • One male nucleus fuses with the egg cell to form a zygote (diploid)
• Process of plant fertilisation

  • Pollen grain lands on surface of stigma
  • If molecules of pollen grain and stigma recognise each other as being from different plants within same species, pollen grain starts to germinate
  • Pollen grain grows from tube nucleus through stigma into style
  • Hydrolytic enzymes digest tissue of style
  • Generative cells (with a generative nucleus) travel down pollen tube as it grows towards ovary - generative nucleus divides by mitosis into two male nuclei
  • Tube enters micropyle of ovary and double fertilisation occurs
• Where are the hydrolytic enzymes produced from?

  Tip of the pollen tube
• Pollen germination


  The process by which a pollen tube starts to grow out of the pollen grain
• Double fertilisation


  The process occurring in plants whereby one male nucleus fuses with two polar bodies to form the endosperm nucleus and the other male nucleus fuses with the egg cell to form the zygote