reproduction

• Reproduction


  The process of making more of the same kind of organism
• Types of reproduction

  • Asexual reproduction
  • Sexual reproduction
• Asexual reproduction


  A process resulting in the production of genetically identical offspring from one parent
• Examples of asexual reproduction


  • Binary fission
  • New potato plants developing from buds or eyes of a potato tuber
• Advantages of asexual reproduction

  • Faster reproduction
  • Consistent offspring
  • Energy efficient
• Disadvantages of asexual reproduction

  • No genetic diversity
  • Vulnerable to disease
• Sexual reproduction


  A process involving the fusion of the nuclei of two gametes or sex cells to form a zygote and the production of offspring that are genetically different from each other
• Fertilization


  The fusion of the nuclei of gametes
• Gametes


  Sex cells (sperm and ovum in animals, pollen and ovum in plants)
• Haploid


  Having half the number of chromosomes as a normal body cell
• Diploid


  Having the full number of chromosomes as a normal body cell
• Advantages of sexual reproduction

  • Increased genetic diversity
  • More adaptable to changing environment
  • Less vulnerable to disease
• Disadvantages of sexual reproduction

  • Requires time and energy to find a mate
  • Slower process
• Flower


  • Contains male and female reproductive parts
• Parts of a flower

  • Sepal
  • Petal
  • Anther
  • Filament
  • Stigma
  • Style
  • Ovary
  • Ovule
• Stamen

  Anther and filament - the male reproductive part of the flower
• Carpel


  Stigma, style, and ovary - the female reproductive part of the flower
• Pollination


  The transfer of pollen grains from an anther to a stigma
• Structural adaptations of insect-pollinated flowers

  • Large, bright petals
  • Moderate amount of pollen
  • Large, heavy, sticky, spiky pollen grains
  • Presence of scent and nectar
  • Sticky stigma
  • Anther firmly attached inside the flower
• Structural adaptations of wind-pollinated flowers

  • Small, dull petals
  • Large amount of pollen
  • Small, smooth, light pollen grains
  • Absence of scent and nectar
  • Feathery stigma outside the flower
  • Anther loosely swinging outside the flower
• Self-pollination


  Transfer of pollen from anther to stigma of the same flower or a different flower on the same plant
• Cross-pollination


  Transfer of pollen from anther to stigma of a flower on a different plant of the same species
• Potential effects of self-pollination and cross-pollination

  • Self-pollination reduces genetic variation
  • Cross-pollination increases genetic variation but relies on pollinators
• Fertilization

  1. Pollen grain lands on stigma

  2. Pollen tube grows down style

  3. Pollen nucleus fuses with ovum nucleus
• Germination


  The beginning of seed growth
• Factors essential for successful germination

  • Water
  • Oxygen
  • Suitable temperature
• Investigating germination

  1. Set up 4 boiling tubes with Cress seeds on cotton wool

  2. Tube A has no water

  3. Tube B has all factors for germination

  4. Tube C has oxygen blocked

  5. Tube D is in a fridge at 4°C

  6. Compare results to see which tube has the most germinated seeds