Growth

• Asexual reproduction


  A type of reproduction by which offspring are produced from a single parent and inherit the genes of that parent
• Sexual reproduction


  A new organism results from fusion of gametes (sex cells) which come from two parents
• Clone


  A group of organisms that are genetically identical
• Asexual reproduction in Amoeba (Binary fission)

  1. Amoeba divides

  2. 2 daughter cells are identical
• Asexual Reproduction in Hydra (Budding)

  1. Hydra produces a bud

  2. Bud develops into a new Hydra
• Asexual Reproduction in Bryophyllum (Wonder of the world)

  1. Bryophyllum produces plantlets on its leaves

  2. Plantlets develop into new plants
• Artificial methods of cloning

  • Cuttings
  • Grafting
  • Budding
  • Tissue culture
• Cuttings


  Parts of plants, for example stems, are cut into smaller pieces, each with a bud and planted to produce a new plant
• Plants propagated by cuttings

  • Sugar cane
  • African violet
  • Roses
• Grafting


  Part of a plant, for example the stem, is cut and the cut end is placed in contact with another plant so that the cambium of both are in contact, allowing the tissues to combine and grow as one plant
• Plants propagated by grafting

  • Citrus
  • Avocado
  • Grapes
  • Passion fruit
• Budding


  A form of grafting in which a bud from one plant is attached to the tissues of another plant so that the cambium of both are in contact, allowing them to combine and grow as one plant
• Plants propagated by budding

  • Peaches
  • Apples
• Tissue culture


  Individual cells from any part of a plant are cultured in special media containing hormones to stimulate growth, allowing a whole new plant to be produced from each cell
• Plants propagated by tissue culture

  • Bananas
  • Strawberries
  • Lilies
  • Orchids
• Advantages of Asexual reproduction


  • Production of new plants is sure (not dependent on pollination and dispersal)
  • Large food reserves are available for new plants
  • Very rapid growth and early maturity (no dormancy as seen in seeds)
  • Beneficial traits are preserved (all offspring genetically identical)
• Disadvantages of Asexual reproduction

  • Over crowding leads to intense competition for resources (all offspring grow up close to parents)
  • All offspring will have the same weaknesses as parents; e.g. vulnerable to same diseases, pests
  • Diseases can be passed on to offspring