Transcript Tropisms and Turgor Pressure Notes.ppt

Tropisms and Turgor
Pressure Notes:
Stimulus and Response in Plants
Stimulus = Light
Stimulus = Touch
INternal Stimuli in Plants
Turgor Pressure
 The outward pressure that occurs in a plant cell when
the cytoplasm and vacuoles fill up with water and the
cell membrane pushes against the cell wall.
KEY
Stimulus
Response
 Presence of water  turgid cell aka healthy plant cell
 Absence of water  flaccid (limp) cell aka dying plant cell
Draw this picture and label each
as turgid or flaccid.
Read Only
Turgor Pressure Animation
The PPT must be in
Slide Show Mode to
access the link.
Click HERE to view the animation
Click on the picture or hyperlink to watch
an animation that shows a plant cell gain
and lose Turgor Pressure. Watch it for
about 2 minutes in order to see the effect of
a full vacuole and a low-pressure vacuole.
EXternal Stimuli in Plants
Tropisms
 Tropisms: a plant’s growth in response to an
external stimulus.
 Positive (+) tropism: Plant growth toward a stimulus
(water, sunlight)
 Negative (-) tropism: Plant growth away from a
stimulus (spilled gas, toxins, too much sun or not
enough)
Light
Growth
Phototropism
 Growth of a plant in
response to light.
 The stalk displays
positive phototropism
growing towards the
light.
 The stalk displays
negative phototropism
growing away from the
light.
Earth
Growth
Gravity
Growth
Geotropism (Gravitropism)
 Growth of a plant in
response to earth / gravity.
 The roots display a
positive geotropism
growing towards earth
(with gravity.)
 The stalk displays a
negative geotropism
growing away from
gravity.
Negative
Positive
Water
Growth
Hydrotropism
 Growth of a plant in
response to water.
 The roots display a
positive hydrotropism
growing towards water.
 The roots display a
negative hydrotropism
growing away from
water.
Positive
Water
Touch
Growth
Thigmotropism
 Moves or grows in response
to touch or contact stimuli.
 A vine displays a
positive thigmotropism
growing towards touch
 Vine growing against a wall
 Venus Fly Trap closing
when touched
 A vine displays a
negative thigmotropism
growing away from
touch
Read Only
View the video below to hear a teacher
who created a song about tropisms.
Click HERE for the Tropisms Song
The PPT must be in Slide Show Mode to access the link.
Tropisms Notes Assignment
Assignment
 Draw a picture
of each tropism
showing its
positive
response to
each stimulus
listed.
 Label what is
happening in
each picture.
Color is optional.
Phototropism
Hydrotropism
Geotropism
Thigmotropism