Transcript Definition

Plant Responses
and Adaptations.
What is a tropism?
Tropism : a response of a
plant to an environmental
stimulus.
What is phototropism?
Phototropism: a
tendency of plants to
grow toward a source
of light.
What is thigmotropism?
Thigmotropism : the
response of plants to
touch.
Venus Fly Trap
Bean Plant
What is
gravitropism/geotropism?
Gravitropism/geotropism:
a tendency of a plant to
grow in a direction in
response to the force of
gravity.
What is negatively and
positively geotropic mean?
Negatively geotropic means
that the plant fights gravity and
grow upward.
Positively geotropic means that
the plants don’t fight against
gravity and grow downward.
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Turgor Pressure
• Definition: Turgor Pressure: also called turgidity,
is the main pressure of the cell contents against the
cell wall in plant cells. Turgid plant cells contain
more water than flaccid cells and exert a greater
pressure on its cell walls.
• Turgor is a force exerted outward on a plant cell
wall by the water contained in the cell. This force
gives the plant rigidity, and may help to keep it
erect. Turgor can result in the bursting of a cell.
When material such
as water, leaves the
cell the pressure on
the inside cell wall
decreases. This
means the turgor
pressure on the cell
wall is decreased.
When material such
as water leaves and
enters the cell at the
same rate, the
pressure on the
inside cell wall stays
the same. This
means the turgor
pressure on the cell
wall is not changed.
When material
such as water
enters the cell, the
pressure on the
inside cell wall
increases. This
means the turgor
pressure on the
cell wall is
increased.
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