reproduction

• Main ways organisms can reproduce

  • Sexual reproduction
  • Asexual reproduction
• Some organisms like plants can reproduce through either sexual or asexual reproduction
• Most animals have to rely on sexual reproduction
• Bacteria all reproduce asexually
• Sexual reproduction


  Involves the fusion of male and female gametes (fertilization)
• Offspring from sexual reproduction contain a mixture of their parents' genes and are genetically different
• Gametes


  Cells like sperm and eggs in animals, or pollen and eggs in flowering plants
• Gametes only have half the normal number of chromosomes
• Meiosis


  The process that produces gametes with half the normal number of chromosomes
• Sexual reproduction does not have to involve sex or intercourse, it just refers to the fusion of male and female gametes
• Asexual reproduction


  Takes place with only one parent and does not involve the fusion of gametes
• Asexual reproduction results in offspring that are identical clones with no genetic variation
• Mitosis


  The process of asexual reproduction in eukaryotic organisms like plants and fungi
• Binary fission


  The process of asexual reproduction in prokaryotic organisms like bacteria
• Asexual reproduction


  Uses mitosis to form an identical clone of the parent organism
• Sexual reproduction


  Involves the fusion of two gametes like a sperm and an egg, leading to genetically different offspring
• Advantages of asexual reproduction

  • Only one parent is needed
  • The process is very quick
• Asexual reproduction allows a single organism to quickly colonize an entire new area
• Asexual reproduction can happen within just a couple of days in the right conditions
• Asexual reproduction can happen in some plants, where a single seed gets blown into a new habitat and then reproduces asexually to cover the whole area
• Disadvantage of asexual reproduction

  Because all the offspring are clones, there isn't any genetic variation
• If a new disease comes along and one of the asexual offspring is susceptible, then chances are that all of them will be susceptible and it could wipe out the whole population
• Asexual reproduction means the organisms will have less chance of adapting to new conditions like changes in the climate or the introduction of a new competitor
• Advantage of sexual reproduction

  It leads to loads of genetic variation within the population
• In the short term, the genetic variation from sexual reproduction means the population is less likely to get wiped out by a single event like a new disease, because some individuals will be more resistant to it than others
• In the longer term, the genetic variation from sexual reproduction allows for evolution to take place, as the most favorable traits are most likely to be passed on each generation
• Disadvantage of sexual reproduction

  It takes a lot more time and energy than asexual reproduction
• Animals have to first of all find their potential mates, which can be time-consuming, and they also need to impress their mate
• Some birds have colorful feathers just because they're useful for impressing their mates, even though they don't help the bird survive at all