Plant and Animal Reproduction

• the main advantage of asexual reproduction, in addition to its speed, is that it permits the propagation of advantageous genetic makeups since the offspring are genetically identical with the parent
• sexual reproduction, on the other hand, permits new combination of traits to arise from the contributions of multiple different ancestors
• certain plants produce body parts specialized for breakaway and dispersal that are known as propagules
• in grafting, the plant that is to be asexually proparagated is known as the stock; this is atteched to the scion, which may be little more than a root. It is important that the two have their cambium layers in contact with each other
• the production of pollen by the seed plants largely circumvents the requirement found in ferns, mosses, and the like for water as a requirement for fertilization
• the type of reproduction in which an animal divides into several pieces and then each piece develops into an entire new animal is called fragmentation
• in metagenesis there is an alternation of asexual and sexual generation
• parthenogenesis is a type of reproduction in which an unfertilized egg develop into a new individual
• an individual that can produce both eggs and sperm is described as hermaphroditic
• a sex cell (either egg or sperm) is properly called a gamete; a fertilized egg is a zygote
• reproduction - biological process by which "offspring" are produced from their parent or parents
• two main types of reproduction

  1. sexual
  2. asexual
• asexual reproduction - also called vegetative reproduction
• asexual reproduction - usually involves only the plant's vegetative structure like roots, stem, and leaves
• sexual reproduction - use of sex cells (gametes)
• sexual reproduction - involves the fusion of male and female gametes to form zygote
• sexual reproduction - genetic variability
• sexual reproduction - two parents
• sexual reproduction - fusion of gametes
• sexual reproduction - parent and offspring are not identical
• sexual reproduction - variation is present in the same species
• asexual reproduction - one parent only
• asexual reproduction - no gametes are produced
• asexual reproduction - parent and offspring are identical
• asexual reproduction - no variation
• types of asexual reproduction

  1. binary fission
  2. budding
  3. fragmentation
  4. parthenogenesis
  5. metagenesis
  6. vegetative reproduction
  7. sporogenesis
• binary fission - separation of the body into two new bodies
• binary fission - common in single celled organisms
• budding - a new organism develops from as an outgrowth from the parent body known as bud
• budding - once grown, the new organism detaches from the parent body
• fragmentation - the parent body breaks into several pieces where each piece grows into a new individual
• parthenogenesis - the female gamete develops into the offspring without being fertilized by a male gamete
• metagenesis - reproduction characterized by the alternation of a sexual generation and a generation that reproduces asexually
• metagenesis - alternation of generations
• vegetative reproduction - a plant such as stems, leaves, roots or turions are used to reproduce new plants
• sporogenesis - formation of spores from sporangia, which themselves are reproductive cells
• flower - reproductive shoots of the angiosperm sporophyte
• flower is composed of four whorls of highly modified leaves called flower organs:

  1. sepals
  2. petals
  3. stamens
  4. carpels
• a stamen consists of a stalk called the filament and the terminal structure called the anther; within the anther are chambers called pollen sacs, in which pollen is produced
• a carpel has an ovary at its base and a long, slender neck called the style. At the top of the style is the sticky structure called the stigma that serves as a landing platform for pollen.