Reproduction

• Asexual reproduction


  Reproduction that does not involve the union of sex cells
• Sexual reproduction


  Reproduction that involves the union of sex cells
• Asexual reproduction produces offspring that are genetically identical to the parent
• Sexual reproduction generally produces offspring that are hybrids of the parents
• Advantages of asexual reproduction

  • Maximizes reproductive success
• Disadvantages of asexual reproduction

  • Lacks genetic variation
• Vegetative reproduction in plants

  1. Reproduction from modified stems like runners, tubers, corms, rhizomes

  2. Produces offspring genetically identical to parent
• Artificial plant propagation


  1. Propagation of plants from stem cuttings

  2. Allows faster growth than from seeds
• Grafting in woody plants

  1. Attaching a stem from one plant to the root or root-bearing stem of another plant

  2. Forms a continuous vascular system to transport water and nutrients
• Angiosperms


  Flowering plants that reproduce sexually through their flowers
• Male reproductive parts of a flower

  • Stamen
  • Anther
  • Filament
• Female reproductive parts of a flower

  • Carpel
  • Stigma
  • Style
  • Ovary

  
• Pollination


  1. Transfer of pollen from anther to stigma

  2. Aided by insects, animals, wind
• Reproduction


  The process by which living organisms produce new individuals of the same species
• Flower


  • Sexual organ of the plant
  • Site of plant reproduction
• Asexual reproduction in plants


  • Rhizome
  • Tuber
  • Buds on leaf
  • Stolon
• Stamen


  Male reproductive part of a flower
• Anther


  Makes tiny grains called "pollen", which contains male sex cells
• Filament


  Holds up the anther
• Carpel


  Female reproductive part of a flower
• Stigma


  Top part of the carpel with sticky surface to trap the pollen
• Style


  Joins the stigma and the ovary
• Ovary


  Contains the female sex cells called ovules

  
• Pollination


  1. Pollen is transferred from the anther to the stigma

  2. Aided by insects, animals, and wind
• Double fertilization


  Seen in plants that bear fruits which may contain one or many seeds
• Fruit


  • Protects the seed from damage
  • Aids in seed dispersal
• Seed


  • Protects the future embryo from harm
  • Grows when favorable conditions exist
• Monocot


  Plant with one cotyledon inside its seed
• Dicot


  Plant with two cotyledons inside its seed
• Asexual reproduction in animals

  Reproduction without the fusion of gametes
• Fission


  Division of body into two or more equal parts
• Budding


  New individual arises as an outgrowth (bud) from its parent
• Fragmentation


  Body breaks into two or more parts, with each fragment capable of becoming a complete individual
• Parthenogenesis


  Modified process of sexual reproduction resulting in a complete offspring from unfertilized eggs

  
• Advantages of asexual reproduction

  • Organism can produce many offspring in a short period of time
  • No need to exert energy to produce gametes or find a mate
• Disadvantages of asexual reproduction

  • Lack of variation among individuals
  • Changing environment may wipe out a group of organisms that cannot easily adapt
• Sexual reproduction in animals

  New individuals are formed from sex cells or gametes produced by the parents
• Sexual reproduction in animals

  1. Gametogenesis: production of gametes

  2. Spawning or mating: bringing gametes together

  3. Fertilization: fusion of gametes
• Hermaphrodite


  Animal with both male and female reproductive organs
• Sequential hermaphroditism


  Animal can change its sex in response to social or environmental challenges