Biology Notes - Plant Science

Topic 9 – Plant Science
First lesson
Without photosynthesis there would be no life.
Important words:
Plants have groups of stemcells that live throughout their lives = meristem.
Tissue – Many cells of the same type working together.
Organ – Two or more tissues working together with the same task.
Organ system – Several organs working together with a common task.
Angiospermophytes
Angio – container
Sperma – seed
Phytes – plant
= Plants producing seeds enclosed in a fruit
  Can be divided into two groups
      Monocotyledons/monocots
      Have on leaf when they germinate.
      Dicotyledons/dicots
      Have two leaves when they germinate.
    Cotyledon – Leaf formed in the embryo. The first leaves that appear when germinating.
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Monocots
Grasses, bananas, palm trees, gingers, lilies, irises, sedges.
Most woody plants and shrubs, many non-woody plants
The leaf of a dicot
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Plan diagram – Shows distribution of tissues, no individual cells.
27/08/09
Three tissues in leaf
  Mesophyll tissue
      Epidermal tissue
      Vascular tissue
      Filling out most space in the leaf
      Have chloroplasts
      Two major types
    The two main types of mesophyll
  Palisade mesophyll
      Spongy mesophyll
    Palisade mesophyll
  1-2 layers of regular “stacks”/tiers
      Many chloroplasts, since they are close to the leafs surface    highest light intensity.
    Spongy mesophyll
  Irregular (placed very randomly)
      Fewer chloroplasts
      Air spaces in-between the cells  gas exchange efficient within   the leaf
    Epidermis
  Single cell layer covering the surface
      Transparent, no chloroplasts
      Waxy layer  thick on upper epidermis, thin on lower epidermis
      Protects against transpiration and some insects
    In the lower epidermis there is stomata
  Consists of two guard cells that form a pore that...