Lesson 1 GB

• Reproduction


  Biological process where offspring is produced by its parent(s)
• Purposes of reproduction

  • Procreation - sustains the species so it won't become extinct
  • Quality Improvement - allows mixing of genetic materials leading to variation among individuals in a species
• Types of reproduction

  • Sexual
  • Asexual
• Sexual reproduction


  Involves two parents who respectively contribute a specialized gamete which fuse to form a zygote, producing genetically unique offspring
• Types of sexual reproduction

  • External fertilization
  • Internal fertilization
• Asexual reproduction


  One parent copies itself to form genetically identical offspring, no gametes, but parts of a mature organism may develop into a new organism
• Mechanisms of asexual reproduction

  • Fission
  • Budding
  • Fragmentation
  • Regeneration
  • Vegetative Propagation
  • Spore Formation

  
• Fission


  Division of body into two (binary fission) or more (multiple fission) new bodies, common in single-celled organisms

  
• Binary fission


  • Divide into 2 equal halves called daughter cells (identical to each other and to the parent cell), Paramecium, Amoeba, Bacteria, Euglena

  
• Multiple fission


  • Divides into numerous daughter cells, Sporozoans, Algae, Plasmodium

  
• Budding


  New individual arises as outgrowth (bud) that develops organs like the parent's, then detaches itself, Hydra, Yeast, Corals

  
• Fragmentation


  Body breaks into two or more parts (with each fragment capable of becoming a complete individual), Worms, Acoel Flatworms/Planaria, Fungi, Lichens, Molds, Sea Stars, Sponges
• Regeneration


  Presence of specialized cells that differentiate and grow into new organism, can regrow lost or damaged body parts, leading to formation of a complete individual, Lizards
• Vegetative propagation


  Reproduce through vegetative parts like leaves, roots, stems, and buds, much faster than sexual reproduction in plants, Onion Bulbs, Tubers of Potato, Runners/Stolon
• Spore formation


  Specialized reproductive cells called spores are produced and released into the environment, where they germinate and develop into new individuals when conditions are favorable, Ferns, Aspergillus, Rhizopus, Moss

  
• Rhizome


  Ginger
• Tuber


  Potato
• leaf


  bryophyllum
• bulb


  onion
• runner


  oxalis
• sucker 


  mint
• root


  sweet potato