Plant Science

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Plant Science

• 9.3 Reproduction in angiospermophytes

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Flower structure
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Functions of flower parts
Structure Function
Sepal Protect other floral parts when in bud
Petal Brightly coloured to attract insects
Anther Contains pollen grains (male nuclei)
Filament Holds anthers up high
Stigma Receives pollen. May be sticky.
Style Supports stigma holding it high
Ovary Contains ovules (eggs) with female nuclei
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Structure of a seed
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Conditions for germination

• Water needed to rehydrate the dry tissues of
  the seed.
• Oxygen needed for aerobic respiration.
• Suitable temperature needed for the enzymes
  involved in the process.

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Metabolism of germination

• Absorption of water via the micropyle. This
  rehydrates the living cells.
• The hormone GIBBERELLIN is produced in the
  cotyledons.
• Gibberellin stimulates the production of amylase
  which catalyses the breakdown of starch to
  maltose.

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Metabolism contd.

• Maltose is transported from the food stores to
  the meristems of the embryo root and shoot.
• Maltose is converted to glucose for use in
  aerobic respiration as a source of energy, or
  used to synthesize cellulose etc.
• Once the first green leaves appear, the plant can
  begin to photosynthesize.

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