Pollination and germination

• Structure of a flower

  • Sepals
  • Stamens
  • Anthers
  • Stigma
  • Ovary
• Sepals

  Protect the unopened flower
• Stamens

  The male parts of the flower (each consists of an anther held up on a filament)
• Anthers

  Produces pollen (male gametes)
• Stigma

  The top of the female part of the flower which collects pollen grains
• Ovary

  Produces the female sex cells contained in the ovule
• The flower is the reproductive organ of most plants
• The flower is involved in sexual reproduction as it allows for fusion of gametes (pollen and egg) to produce seeds
• Pollination

  Pollen from one flower needs to be transferred to the stigma of another flower
• Methods of pollen transfer

  • Insects
  • Wind
• Insect pollinated flowers


  • Petals may be brightly coloured and scented to attract insects
  • Nectary produces sugary solution called nectar which attracts insects
  • Pollen is sticky or spikey to attach to insects
• Wind pollinated flowers

  • Stamen has long filaments and loose anthers to release pollen into the wind
  • Stigma is outside of flower with feathery structure to catch passing pollen
  • Pollen is smooth and light to be easily carried by the wind
• Methods of seed dispersal


  • Wind
  • Roll or float
  • Animals (outside)
  • Animals (inside)
  • Self-propelled
• Wind dispersed seeds


  • Have lightweight parts, wings or parachutes
• Roll or float dispersed seeds


  • Have a round or buoyant structure to allow them to travel over land or water
• Animal (outside) dispersed seeds


  • Have hooks that attach them to the fur of passing animals
• Animal (inside) dispersed seeds


  • Are surrounded by brightly coloured and tasty fruits. These are eaten by animals, the seeds pass through undamaged and deposited far away
• Self-propelled dispersed seeds


  • Have pods that burst due to pressure or elasticity and send the seeds
• Plants compete for water, space, light, and minerals in the soil
• It is important for seeds to be dispersed far from both the parent as well as other seeds to reduce competition between plants of the same species and allow more growth
• Structure of a seed


  • Embryo
  • Food store
  • Seed coat
• Embryo


  The young root and shoot that will become the adult plant
• Food store


  Starch for the young plant to use until it can carry out photosynthesis
• Seed coat


  A tough protective outer covering
• Germination


  The seed begins to develop into a new young plant
• Factors needed for successful germination


  • Water
  • Oxygen
  • Warmth
• Germinating seeds use their food stores until the seedlings can produce their own food by photosynthesis
• Light is not needed for germination
• Dispersal


  • Plants compete for factors such as:
  • Water
  • Space
  • Light
  • Minerals in the soil
• Why plants compete for water


  For photosynthesis, to produce glucose eventually used for growth
• Why plants compete for space

  Grow as large as possible/more photosynthesis/higher chance of species survival
• Why plants compete for light

  Photosynthesis, to produce glucose eventually used for growth
• Why plants compete for minerals in the soil

  Used to make chlorophyll