Plant Reproduction

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This Weeks Quiz
This Friday Chapter 42
http//www.vcld.org/pages/newsletters/01_02_fall/t
esttaking.htm
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Chapter 43 Plant Reproduction
43.1 What Are the Basic Features of Plant Life
Cycles? 43.2 How Is Reproduction in Seed
Plants Adapted to Drier Environments? 43.3
What is the Function and Structure of the
Flower?
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Terms to Know

• Haploid having a single set of chromosomes in
  each cell.
• Diploid having two sets of chromosomes in each
  cell.
• Mitosis cell division, which produces two
  genetically identical cells.
• Meiosis reduction division, which produces four
  haploid reproductive cells.

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Plants and Animals
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Asexual Reproduction

• Natural cloning. Genetically Identical.
• Fast, no mate required.
• Beneficial for plants that must compete for
  scarce resources (Stable Environs).
• Part of a single plant divides by mitosis to give
  rise to a new plants.
• Spreading of runners (strawberries)
• Production of bulbs (daffodils)
• Sprouting of rhizomes (irises)

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Sexual Reproduction

• Fusion of egg and sperm cells (haploid), from
  meiosis, gamete formation and fertilization.
• May be limited to a certain season.
• Slower than asexual reproduction.
• Allows genetic mixing, increasing variability in
  a population. Two parents give rise to
  genetically variable offspring. Favored in
  variable environments.

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Alternate Generations

• All plant life cycles are characterized by
  alternating of portions (haploid-to-diploid-to-hap
  loid).
• Multicellular diploid plants (sporophytes) and
  multicellular haploid plants (gametophytes) take
  turns producing each other during the
  reproductive life cycle.
• Sporophyte diploid (2n), produce haploid spores
  by meiosis.
• Gametophyte haploid (n), produce gametes by
  mitosis.

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Life Cycle
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Life Cycle

• Diploid sporophyte (spore-forming plant) produces
  haploid spores by meiosis.

• Spore germinates (begins to grow and develop)
  divides repeatedly by mitosis forming a haploid
  gametophyte (gamete-forming plant).

• Gametophyte produces haploid sperm and eggs by
  mitosis (gametes are produced at different times
  to prevent self-fertilization).

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Life Cycle

• Sperm and egg fuse to form a diploid zygote
  (fertilized egg).
• Zygote undergoes repeated mitosis to form a new
  diploid sporophyte plant.

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Non-Flowering Plants

• Mosses, ferns, and related plants have motile,
  swimming sperm.
• Reproduction in these plants requires wet
  conditions, and requires having male and female
  parts close together.
• Living conditions, plant size, and genetic mixing
  is limited.

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Conifer Pollination

• Conifers (also non-flowering plants) have reduced
  gametophytes.
• Male gametophyte is contained in a dry pollen
  grain.
• Female gametophyte is a few cells inside of the
  structures that become the seed.

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Conifer Pollination

• Conifers are wind-pollinated plants.
• Chance allows some pollen to land on the scales
  of female cones.
• Pollen germinates, grows a pollen tube into the
  egg to allow sperm to fertilize the egg.
• Wind pollination is inefficient.

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Pollen In-between

• Showy flowers are the result of selection for
  more efficient pollination strategies.
• Flower parts are modified leaves. Those that were
  brightly colored attracted insects in search of
  pollen.
• Pollen itself is a protein-rich food for insects.
  Some plants offer other rewards, such as nectar.

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Seed Plant Reproduction

• 43.2 How Is Reproduction in Seed Plants Adapted
  to Drier Environments?
• Seed plants (gymnosperms and angiosperms).
• Gametophytes develop within sporophytes.
• Reproduction can occur in dry habitats.

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Seed Plant Reproduction

• Male gametophyte is surrounded by a protective
  coat called a pollen grain.
• The pollen grain encloses sperm cells in a
  watertight packet that can be easily transported
  to another plant.
• Egg-producing female gametophyte remains moist
  and protected within the sporophyte, and the
  pollen grain ensures that the sperm are delivered
  directly to the egg.

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Seed Plant Reproduction

• The fertilized egg becomes enclosed in a
  drought-resistant seed.
• Consists of an embryonic plant and a food reserve
  encased within a protective outer coating.
• May lie dormant up to years waiting for
  conditions favorable for germination and growth.

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Seed Plant Reproduction

• Non-flowering gymnosperms were the earliest seed
  plants.
• Gymnosperms bear male and female gametophytes on
  separate cones.
• Male cones release pollen grains that travel via
  wind to female cones.