Chp - 14 Reproduction

• Asexual & sexual reproduction in Plants

  1. Pollination-Self &cross reproduction

  2. Insecta wind features

  3. Fertilisation
• Asexual Reproduction


  • Bacteria
  • Fungi
  • Potato tubers
• Advantages of Asexual Reproduction

  • Only one parent
  • Quick process
  • Genetically identical (parents & daughters)
  • No variation (unless environment affects)
  • No pollinators & can reproduce even if ucriety is sterile

  
• Disadvantages of Asexual Reproduction


  • Daughters are in the same place as the parents & Very little variation - gets affected by certain diseases
  • Genetically identical- If no resistance to a disease - may get wiped out
• Binary Fission


  Bacteria
• Sexual Reproduction


  Two parents, Not genetically identical, Variation, Allows daughters to evolve, Reduces the chance of extinction
• Advantages of Sexual Reproduction

  • Genetic variation (Diversity)
  • Mutation
  • Adaptation to environmental pressure
  • Evolution
  • Cross-pollination - occurs
  • Allows Seed Dispersal
  • Can colonize new areas
  • Less competition with parent plants
  • Can survive through harsh conditions
• Disadvantages of Sexual Reproduction

  • Finding a mate - valuable resources (time energy)
  • Difficult for an isolated individual to reproduce
• Asexual reproduction


  One parent, quick process, genetically identical to parent, no variation except from environment, no pollinators required
• Examples of asexual reproduction

  • Bacteria
  • Fungi
  • Potato tuber
• Disadvantages of asexual reproduction

  • New plants compete with parent for resources
  • Very little variation
  • Genetically identical, not resistant to disease, may all be killed
• Sexual reproduction


  Two parents, offspring not genetically identical to parents, brings about variation
• Advantages of sexual reproduction

  • Genetic variation/diversity
  • Allows adaptation to environmental pressure
  • Allows new species to evolve
  • Cross pollination
  • Seed dispersal
  • Colonise new areas
  • Less competition with parent plant
  • Survive through harsh conditions
• Disadvantages of sexual reproduction

  • Finding a mate uses valuable resources
  • Isolated individual cannot reproduce sexually
• Flowers


  Reproductive organs of plants, features that attract insects/birds: bright color petals, scent, nectar
• Pollen


  Contains male gametes
• Ovules


  Contain female gametes, inside ovaries
• Insect pollination


  Bees land on petals, feed on nectar
• Wind pollination


  1. Anthers hang outside flower, release pollen

  2. Stigmas are feathery, act as net to catch pollen
• Differences between insect-pollinated and wind-pollinated flowers

  • Insect-pollinated: Large, conspicuous petals, often scented, have nectaries, anthers/stigma inside flower
  • Wind-pollinated: Small/no petals, no scent, no nectaries, anthers/stigma hang outside flower
• Pollination


  Transfer of pollen grains from anther to stigma
• Self-pollination


  Pollen transferred within same flower or plant
• Cross-pollination


  Pollen transferred between different plants of same species
• Advantages of self-pollination


  • Only one plant needed
  • Greater chance of pollination
  • Reproduction successful if no other plants nearby
  • Less wastage of pollen
  • Not dependent on pollinators
• Disadvantages of self-pollination


  • Less variation
  • Increased competition between plants
  • All plants adapted to same environment
  • Less chance of surviving
  • Risk of extinction
  • Increased chance of genetic disease
  • Susceptible to same disease
• Advantages of cross-pollination


  • Allows variation/genetic diversity
  • Plants more likely to survive environmental pressure
  • Increased resistance to disease
• Fertilisation


  1. Pollen grain lands on stigma

  2. Pollen tube grows down to ovule

  3. Male gamete nucleus fuses with egg cell nucleus to form zygote

  4. Zygote divides to form embryo plant, ovule becomes seed, ovary becomes fruit