Adaptations of Plants for Survival on Land - BEST LIBRARY

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					Adaptations of Plants for
Survival on Land
  Problem # 1: Need a constant supply of
   water and nutrients → but water and
   nutrients are available in soil

  Solution: ROOTS – transport
   nutrients/water from soil to plant & help
   anchor plant
Adaptations of Plants for
Survival on Land
  Problem # 2: Need to obtain as much
   energy from sun as possible (to make
   food) so need a structure with a large
   enough surface area to capture sunlight
Adaptations of Plants for
Survival on Land
 Solution = LEAVES – large
  surface area to capture sun
  energy needed for
  photosynthesis, but must
  exchange O2 and CO2 with air
  without losing too much water.
  On land, get O2/CO2 via dry air
  which results in water loss by
  plant
Adaptations of Plants for
Survival on Land
  - Cuticle = wax covering to prevent drying out
   (desiccation) of plant tissues by evaporation
   (algae do not possess this as they are adapted
   to living in an aquatic environment)

  Photosynthesis (p/s) must still occur which
   creates problem since the cuticle makes
   exchanges of gases between the plant and
   atmosphere impossible – problem overcome
   by tiny openings in the surface tissue of plants
   called stoma (permits gas exchange)
Adaptations of Plants for
Survival on Land
  Problem # 3: Photosynthetic tissues (ie
   leaves) need to be exposed to as much
   sunlight as possible so need to be held
   upright to obtain sunlight and need rigid
   structures to hold up leaves

  Solution = STEMS
Adaptations of Plants for
Survival on Land
  Problem # 4: Land plants get
   water/nutrients from roots in soil but
   make food in leaves which then must be
   taken into other parts of the plant – must
   deliver water upward to all cells (even
   those that grow above ground in dry air)
   AND transport products of
   photosynthesis down
Adaptations of Plants for
Survival on Land
  Solution = XYLEM & PHLOEM

  XYLEM: conducts (transports) water and
   nutrients from roots up through stem & to
   leaves
  PHLOEM: transports products of
   photosynthesis (sugar) = food) from
   leaves down to rest of plant for use and
   storage
Adaptations of Plants for
Survival on Land
   Problem # 5: Reproduction must occur without
    water

   Solution = SEEDS (some land plants use
    SPORES or use sperm/egg but these plants
    need to be close to water so are limited to
    where on land they can live & can not live in
    any land environment)
   Seeds provide a protective outer covering
    which protects the growing embryo
Seeds are reproductively
superior to spores for the
following reasons:
  1. Seeds contain a tiny, well developed
   young plant with embryonic root, stem &
   leaves already formed whereas plant
   spores are composed of a single cell
  2. Seeds contain a food supply. After
   germination, the plant embryo within the
   seed is nourished by food stored in the
   seed until it becomes self-sufficient
Seeds
  3. Seeds are protected by a resistant
   seed coat. Like spores, seeds can live for
   extended periods of time at reduced
   rates of metabolism and germinate when
   conditions become favourable
Reproduction

  Possess male gametophyte containes
   inside pollens grains
  Female gametophyte inside the flowers
   or cones.
  Pollination: The carrying of pollen to the
   female gametophyte is called pollination.

				
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