Download turgor pressure - Net Start Class

Forces and Work in the Natural World
WORK
• Is force over a
distance
• If force is applied to
an object, and the
object moves work
has been done
• Plants can do work!
Osmosis in plant cells
• Osmosis – movement of water through the
semipermeable cell membrane
• When most plants are given water the roots
take up as much water as it needs which is
stored inside the cells (vacuoles) and the plant
looks normal
Osmosis in Plants
• When a plant does not receive enough water
there is a higher concentration of water inside
the plant cells than outside so the water
diffuses out of the cell
• This causes the plant to wilt
Turgor Pressure
• Pressure of
water
molecules
against the cell
wall that
allows plants
to stand up
straight.
Turgor Pressure
• Remember plant cells are surrounded by a
rigid (resists bending) cell wall. Just beneath
the cell wall is the cell membrane
Turgor Pressure
• Also remember the plant cell has a much
larger vacuole than an animal cell
• This vacuole is used to store food and water
for the plant cell
Turgor Pressure
• When a plant has the right amount of water
then the turgor pressure inside the cell will
help support the plant and the plant will stand
upright
• When a plant does not have enough water the
turgor pressure inside the cell is decreased
and the plant is not able to stand upright as
well
• If the plant does not get any water, it will wilt
completely and eventually die
No Turgor Pressure
Turgor Pressure
Tropism
• Tropism – a plant’s response that results in
plant growth toward or away from a
stimulus.
– Positive – growing TOWARD the stimulus
– Negative – growing AWAY from the
stimulus
Stimulus: Light
• Response:
Phototropism
• Tendency for plants to
grow towards sunlight
• Why is this beneficial
for the plant?
• 18 Sec Video
Stimulus: Gravity
• Response: Geotropism
(or Gravitropism)
• A plant’s growth in
response to gravity.
– Negative: Stems grow
away from gravity
– Positive: Roots grow
towards gravity
Seeds growing in response to gravity – select CORN
Stimulus: Touch
• Response:
Thigmotropism –
a plants growth in
response to touch
• Examples:
–Vines
–Carnivorous
Plants
–Roots avoiding
contact
Venus Fly
Trap Video