plant reproduction

• Plant reproduction


  The process in the life cycle of plants that allows them to reproduce and ensure the continuation of their species
• Plant reproduction


  • Involves the production of specialized structures like flowers that contain male and female reproductive parts
  • Facilitated by the transfer of pollen, either by wind, insects, or other agents, leading to the fertilization of the ovules and formation of seeds
  • Allows plants to thrive in various environments and contribute to the diversity of the plant kingdom
• Alternation of generations


  The process where plants alternate between two different life stages, or generations, in their life cycle: a haploid gametophyte stage and a diploid sporophyte stage
• Haploid


  Containing one set of chromosomes
• Diploid


  Containing two sets of chromosomes
• Meiosis


  The reductive cell division that produces haploid gametes
• Gametes


  The specialized reproductive cells that only have one set of chromosomes
• Sporophyte stage


  • The dominant, visible plant that is diploid
  • Produces haploid gametes
• Gametophyte stage


  • The haploid plant that produces gametes
  • Prominent in some plants like mosses
• The alternation of generations in plants is an alternation between the gametophyte stage and the sporophyte stage
• The alternation of generations is a prominent feature of the life cycle of mosses
• Alternation of generations in mosses

  1. Gametophyte stage

  2. Sporophyte stage
• Gametophyte stage


  The dominant stage in mosses, where the visible green moss plant is found
• Gametophyte


  • Haploid (n), meaning its cells have one set of chromosomes
  • Produces gametes (sperm and eggs)
• Fertilization


  1. Sperm from antheridia swim to archegonia and fertilize the eggs

  2. Zygote forms
• Sporophyte stage


  1. Zygote develops into the sporophyte

  2. Sporophyte consists of foot, seta, and capsule

  3. Capsule contains sporangia

  4. Sporocytes undergo meiosis to form haploid spores

  5. Spores are dispersed and develop into new gametophytes
• The sporophyte stage in mosses is short-lived and dependent on the gametophyte
• The alternation of generations completes when the dispersed spores develop into new gametophytes
• Alternation of Generation in Ferns

  Fundamental part of their life cycle
• Sporophyte stage in ferns

  • Dominant stage
  • Diploid (2n)
  • Result of fertilization
  • Consists of root system, stem, and leaves (fronds)
  • Sporangia on underside of fronds
  • Sporocytes undergo meiosis to produce haploid spores
• Spore production and dispersal

  1. Spores released from sporangia

  2. Spores dispersed by wind or other means

  3. Spore lands in suitable environment

  4. Spore germinates and develops into gametophyte
• Gametophyte


  • Haploid (n)
  • Small, flat, heart-shaped
  • Antheridia and archegonia formed on underside
  • Antheridia produce sperm cells
  • Archegonia produce egg cells
  • Water required for sperm to swim to archegonia for fertilization
• Fertilization


  1. Sperm fertilizes egg

  2. Diploid zygote formed

  3. Zygote develops into new sporophyte plant
• Alternation of Generation in Gymnosperms

  Sporophyte stage and gametophyte stage
• Gymnosperms


  • Includes conifers, cycads, ginkgoes, and others
• Life cycle of gymnosperms

  1. Sporophyte stage (diploid, 2n)

  2. Sporophyte produces cones

  3. Male cones produce pollen (haploid, n)

  4. Female cones contain ovules

  5. Fertilization of egg by sperm

  6. Zygote develops into seed with embryo
• Sporophyte


  Dominant stage, woody plant
• Gametophyte


  Haploid (n) generation
• Male cones


  • Produce pollen
• Female cones


  • Contain ovules
• Pollen lands on female cone


  Sperm fertilizes egg
• Seed


  Contains embryo, food supply, and protective layers
• Seed is dispersed and can germinate to grow into new sporophyte plant
• Sporophyte


  The dominant phase in flowering plants, such as trees, shrubs, or herbaceous plants. It is diploid (2n) and develops from a zygote formed by the fusion of male and female gametes during fertilization.
• Gametophyte


  The reduced stage in angiosperms compared to other plant groups. The male gametophyte is the pollen grain, and the female gametophyte is the embryo sac, which develops within the ovule.
• Reproduction in Angiosperms


  1. Sporophyte produces flowers

  2. Flowers contain male (stamens) and female (carpels) reproductive organs

  3. Pollen grains (male gametophyte) land on stigma

  4. Pollen tube grows, allowing sperm cells to reach egg cell

  5. Fertilization occurs, forming a diploid zygote

  6. Zygote develops into an embryo, and the ovule matures into a seed
• Flowers


  • Consist of petals, sepals, stamens, and carpels
  • Stamens contain microsporangia that produce pollen grains
  • Carpels contain ovules, which house the female gametophytes with egg cells
• Pollination


  • Pollen is transferred from the anther (part of the stamen) to the stigma
  • Can occur through wind, water, animals, or self-pollination
• Fertilization


  • Sperm cells from the pollen tube reach the egg cell within the ovule
  • Forms a diploid zygote
• Seed


  • Contains the embryo, a food supply (endosperm or cotyledons), and a protective seed coat