TROPISMS!
TROPISMS AND OTHER RESPONSES AND
ADAPTATIONS HELP PLANTS SURVIVE.
DEFINITION
Tropism:
bending toward or away from a stimulus
“Trop”
the Greek word for turning
“ism”
means the act of
“trop”
turning
+
“ISM”
THE ACT OF
“trop”
“ism”
turning the act of
=
RESPONSE AND STIMULUS
Anything in the environment that produces a response
is called a stimulus.
Example:
A camera’s flash goes off…
Your eyes blink…
Flash = Stimulus
Blink = Response
THREE TYPES OF TROPISMS
HYDROTROPISM: response to water
Example: a plant’s roots grow towards a water
source
THREE TYPES OF TROPISMS
GRAVITROPISM: response to gravity
Example: a plant’s roots go down
THREE TYPES OF TROPISMS
PHOTOTROPISM: response to light
Example: a plant’s stem bends toward the sun
VIDEO OF TROPISMS
The following link is a YouTube video made by a third
grade student that shows and explain how phototropism
effects a plant
Tropism Video
AUXINS
• Plants chemicals that
help the plant grow
• Auxins cause the plant
to bend during all
kinds of tropisms
• When one side of the
plant is exposed to
light, the auxins move
to the other side and
down. Cells then grow,
which makes the plant
bend.
REVIEW QUESTIONS
What is a tropism?
Bending toward or away from a stimulus
What is a stimulus?
Anything in the environment that produces a response
What are the three types of tropisms?
gravitropism, phototropism, hydrotropism
REVIEW QUESTIONS
What is gravitropism?
response to gravity
What is phototropism?
response to light
What is hydrotropism?
response to water
What chemical causes plants to bend?
auxins
POWER POINT PRESENTATION PRODUCED
BY…
Mr. Reader Inc.
Where humor and looks meet education…