Biology
HS/Science
Unit: 12 Lesson: 02
Plant Responses KEY
I. Much like hormones help to regulate your body, plants have hormones
that help them regulate their functions. Using the research material
available at your station, fill in the chart below to explain about the
function of plant hormones.
Hormone
Function
auxins
Promote cell elongation
gibberellins
Cause plants to grow taller;
stimulate cell elongation
cytokinins
Stimulate mitosis and cell division
ethylene
©2012, TESCCC
Speeds ripening of fruits and
promotes breakdown of complex
carbohydrates to simple sugars
05/31/13
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Biology
HS/Science
Unit: 12 Lesson: 02
II. Plants also have the ability to respond to external stimuli. This is tropism.
Using the research material available to you, fill in the definition for each
type of plant response.
Term
Definition
phototropism
The growth of a plant towards
light
gravitropism
©2012, TESCCC
Plant growth in response to
gravity (Stems grow upward, and
roots grow downward.)
thigmotropism
The growth of a plant in response
to touch
nastic movement
A responsive movement of a plant
that is not dependent on the
direction of the stimulus. These
movements can be reversible if
they do not involve growth.
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