Plants Part 7: Reproduction

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Plants Part 7 Reproduction
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Asexual Reproduction

• Plants use many structures to reproduce
  asexually.
• Rhizomes are modified stems such as stolons, eyes
  on tubers, etc.
• Modified leaves or shoots that can grow into new
  plants
• Usually occurs by the mitosis of diploid cells
• Makes genetically identical individuals (clones)

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Asexual Benefits

• If plant is successful in its environment, all
  offspring will get the same traits.
• Plant does not need reproductive structures,
  which require a lot of energy
• Only one plant needed
• Higher survival rate

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Asexual Cost

• Environment selects only individuals with traits
  that are favoured.
• Lack of variation can be dangerous for survival
  in environments that are not ideal.

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Human Use of Asexual Reproduction

• Clone desirable plants by
• Stem cutting and place in water and once the
  roots grow, transfer to the soil
• Grafting cut a young branch of one plant and
  attach it to the stem of another plant of same or
  similar species

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Seed Plant Sexual Reproduction

• Seed functions protect and nourish the embryo
  and carry it to a new location.
• Seed dispersal by
• Wind
• Animals eating fruit
• Animals spreading from fur
• Increases chance of survival

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Seed Anatomy

• Monocots have one cotyledon with endosperm that
  feeds embryo.
• Dicots have two cotyledons that feed the embryo.

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Gymnosperm Sexual Reproduction

• Conifers produce both male cones and female
  cones.
• Haploid cells called microspores are made in
  meiosis in the male cones that develops into a
  pollen grain containing the male gametophyte.
• Meiosis in female cones make megaspores that make
  egg-producing female gametophytes.

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Seed Pollination and Fertilization

• Pollen grains have to move from the male cone to
  the female cone by pollination via the wind.
• The pollen grain grows a pollen tube that grows
  down to the ovule and releases two sperm nuclei.
  
• One fertilizes the egg, the other degrades
• Takes 13 months for the egg to be fertilized.
• Ovule then develops into a zygote, then an
  embryo.
• If the seed germinates, it becomes a sporophyte.

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Sexual Reproduction in Angiosperms

• The products are seeds inside of a fruit
• Fruit is a mature ovary
• Flowers are the key organs in sexual reproduction
• Animal pollinated flowers are usually dramatic in
  order to attract bees, birds, insects.
• Cross pollination is when pollen is transferred
  from one plant to another.
• Self pollination is when pollen goes from one
  flower to another flower on the same plant.

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Flower Anatomy
CARPEL
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Angiosperm Life Cycle