Reproduction in plants

• Asexual reproduction


  The process resulting in the production of genetically identical offspring from one parent, without the fusion of gametes
• Sexual reproduction


  The process involving the fusion of two nuclei to form a zygote, resulting in the production of genetically dissimilar offspring
• Reproduction is the process of producing new organisms
• Reproduction ensures the continuity of a species
• Organisms can reproduce via

  • Asexual reproduction
  • Sexual reproduction
• Asexual reproduction


  1. Cell divides to produce two identical daughter cells through mitosis

  2. Each daughter cell has the same number of chromosomes as the parent cell
• Clones


  Offspring produced through asexual reproduction, genetically identical to the parent
• Sexual reproduction


  1. Gametes are formed when a cell divides to produce four daughter cells through meiosis

  2. Each daughter cell has half the number of chromosomes as the parent cell

  3. Fusion of male and female gametes to form a zygote
• Sexual reproduction produces genetically dissimilar offspring
• Flower


  May occur singly or in clusters called inflorescences
• Parts of a flower

  • Sepals
  • Petals
  • Receptacle
  • Pedicel
  • Stamens
  • Carpels

  
• Sepal


  A modified leaf that protects the flower in the bud stage
• Petal


  A modified leaf that forms the most obvious part of a flower, brightly coloured to attract insects for pollination and provide a landing platform

  
• Receptacle


  The enlarged end of the flower stalk that bears parts of the flower
• Pedicel


  The flower stalk
• Sessile flower


  Flowers without a pedicel, attached directly to the plant at the base
• Stamen


  The male part of the flower, consisting of an anther and a filament
• Filament


  Holds the anther in a suitable position to disperse pollen grains
• Anther


  Produces pollen grains, made up of two lobes each containing two pollen sacs
• Pollen grain


  Has a haploid set of chromosomes and two nuclei (generative and pollen tube/vegetative)
• Carpel


  The female part of the flower, consisting of an ovary, style and stigma
• Stigma


  A swollen structure that receives pollen grains, secretes sugary fluid to stimulate pollen germination
• Style


  Connects the stigma to the ovary, holds the stigma in a suitable position to trap pollen grains
• Ovary


  Contains one or more ovules, each with an ovum and definitive nucleus
• Ovule


  Attached to the placenta by a stalk called the funicle, contains the ovum with a haploid set of chromosomes
• Pollination


  The transfer of pollen grains from the anther to the stigma
• Types of pollination


  • Self-pollination
  • Cross-pollination
• Self-pollination


  The transfer of pollen grains from the anther to the stigma of the same flower or a different flower on the same plant
• Advantages of self-pollination


  • Only one parent is required
  • Less pollen and energy is wasted
  • More likely to take place since stigmas are closer to anthers
  • Not dependent on external factors for pollination
  • Beneficial qualities are passed down from parent plant to offspring
• Disadvantages of self-pollination


  • Offspring produced are genetically similar to parents causing fewer varieties
  • Higher probability of harmful recessive alleles being expressed
• Cross-pollination


  The transfer of pollen grains to the flower of another plant of the same species