Download Plant Responses

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts
no text concepts found
Transcript
Plant Responses
How plants move
www.wou.edu/~bledsoek/103materials/.../Plant_responses.ppt
Early Inquiry
The houseplant observation
• For years, people
noticed that
houseplants tended to
lean toward a source of
light.
• Charles Darwin and his
son Francis, wondered
why. How does a plant
“know” where to lean?
Tropisms
• Tropisms are the growth of a plant
toward or away from a stimulus,
including:
• Phototropism: in response to light
• Gravitropism: in response to gravity
• Thigmotropism: in response to touch
Tropisms: cell elongation
• In general, tropisms
involve cell
elongation or
suppression of cell
elongation on one
side of a plant,
causing the plant to
grow in a particular
direction.
Phototropism
• Look at the sprouts
in the bottom
picture and the
explanatory
diagram at the top.
Explain why the
sprouts are all
leaning in the same
direction.
Gravitropism
• In this Impatiens plant,
shoots grow upwards
and roots grow
downwards in
response to gravity.
• On which side of the
shoot and root do you
think auxins are more
concentrated?
Thigmotropism
• In some plants,
vining stems or
tendrils will grow in
response to touch.
• Which side of the
tendril is
elongating? Where
might the auxin be?
(Remember, this is
the shoot system.)
Nastic
movement
in the
sensitive
plant
(Mimosa
pudica)
Other examples
• Sunflowers follow the sun during the day.
• Leaves of many plants turn to follow the
sun.