Sexual + Asexual Reproduction

• Chromosomes


  Genetic material found in the nucleus of cells
• Human cells


  • Contain 23 pairs of chromosomes
• Mitosis


  One cell is copied into two identical cells
• Gametes


  Cells where the chromosomes are not paired
• Human gametes


  • Sperm cells and egg cells
  • Contain 23 single chromosomes
• Meiosis


  • The type of cell division that produces gametes
  • Produces non-identical cells
• Sexual reproduction


  • Involves the fusion of male and female gametes
  • Mixing of genetic information from both parents
  • Leads to variation in offspring
• Asexual reproduction


  • Aphids
  • Plants forming tiny buds
• Asexual reproduction


  • Involves only one parent
  • No mixing of genetic information
  • Offspring are genetically identical (clones)
  • Only involves mitosis, not meiosis
• Sexual reproduction


  Offspring receive a mixture of genetic information from two parents
• Sexual reproduction


  • Produces variation in the offspring
  • Gives a species survival advantage by natural selection
  • Allows for selective breeding
• Asexual reproduction


  • Only one parent is needed
  • More efficient in time and energy than sexual reproduction
  • Allows an organism to produce many genetically identical offspring rapidly
• Asexual reproduction


  • Risky because all offspring are genetically identical and could all die if conditions become unfavourable
• Organisms that can use both sexual and asexual reproduction

  • Malaria parasite
  • Fungi
  • Flowering plants (e.g. strawberry)
  • Daffodils
• Asexual reproduction in strawberry plants

  1. Parent plant sends out runners

  2. Runner touches soil and develops into new plant genetically identical to parent
• Asexual reproduction in daffodils

  1. Parent plant has underground bulb

  2. Bulb produces buds

  3. Buds form new offspring plants genetically identical to parent