Reproduction

• Development


  The process by which a multicellular organism, beginning with a single cell, goes through a series of changes, taking on the successive forms that characterize its life cycle
• Sexual reproduction


  The production of new organisms by the combination of genetic information of two individuals of different sexes
• In most species the genetic information is carried on chromosomes in the nucleus of reproductive cells called gametes, which then fuse to form a diploid zygote
• Sexual reproduction in animals


  • Typically requires a male and a female
  • Some hermaphroditic creatures switch sexes later in life or are born with both types of sexual organs
  • rnacles and clams
• Asexual reproduction


  A mode of reproduction in which a new offspring is produced by a single parent, without involving sex cells or gametes
• Vegetative propagation


  An asexual method of plant reproduction that occurs in its leaves, roots, and stem, through regeneration of specific vegetative parts of a parent plant
• Vegetative propagation


  • Garlic and onions reproduce through bulbs
  • Potato plants reproduce through tubers
  • Strawberry plants reproduce using stolons
• Fragmentation


  New plants growing from small parts of the parent plant that fall to the ground, e.g. stems or leaves broken off by animals or wind
• Fission


  Division of a body into two or more equal parts, e.g. in Amoeba and Paramecium
• Mechanisms of asexual reproduction in unicellular organisms


  • Mitosis
  • Showing the exact copy of the parent
• Parthenogenesis


  The female organism generates eggs without fertilization, and the offspring emerge from that. Seen in some lizards, insects, and fish, but not in mammals
• Most animals that procreate through parthenogenesis are small invertebrates such as bees, wasps, ants, and aphids, which can alternate between sexual and asexual reproduction
• Parthenogenesis has been observed in more than 80 vertebrate species, about half of which are fish or lizards
• Some hermaphroditic creatures switch sexes later in life or are born with both types of sexual organs
• Self-fertilization is more common in animals with limited mobility or that are not motile, such as barnacles and clams