Please Do Now: 1) What is the most important
environmental factor in determining when a seed
germinates?
2) Where is energy and resources stored within seeds?
Agenda
 Do Now
 Data Analysis
 Growth Notes
 Private Life of Plants: “Growing”
DATA ANALYSIS: Growth Hormones
 Background: IAA is a plant hormone, like testosterone,
insulin, and estrogen are hormones in animals
 What does IAA do? How does it do it? We will
discover!
DATA ANALYSIS: Growth Hormones
Leaf
 Chart 1.
1. What is
measured on
the X axis?
2. What is
measured on
the Y-axis?
3. What
happens
when you
apply IAA to
leaves?
4. How long
does it take
for IAA to
have an
effect?
DATA ANALYSIS: Growth Hormones
Suc = sucrose, a sugar
Leaf
 Chart 1.
1. What is measured
on the X axis?
2. What is measured
on the Y-axis?
3. What happens when
you apply IAA to
leaves?
4. What happens when
you apply sucrose to
leaves?
5. What happens when
you apply both?
DATA ANALYSIS: Growth Hormones
IAA conc. = 25 mM
 Chart 1.
IAA conc. = 3 mM
1. What is measured on
the X axis?
2. What is measured on
the Y-axis?
3. On what side of the
shoot is the
concentration of IAA
higher?
4. Would this make
plants grow towards
light or away from
light?
DATA ANALYSIS: Growth Hormones
IAA conc. = 25 mM
 Chart 1.
IAA conc. = 3 mM
1. What is measured on
the X axis?
2. What is measured on
the Y-axis?
3. On what side of the
shoot is the
concentration of IAA
higher?
4. Would this make
plants grow towards
light or away from
light?
DATA ANALYSIS: Growth Hormones
IAA conc. = 25 mM
 Chart 1.
IAA conc. = 3 mM
1. What is measured
on the X axis?
2. What is measured
on the Y-axis?
3. Does a given
concentration of
auxin have the
same effect in the
roots as it does in
shoots
(aboveground
parts)?
Unifying question
 If plants did not have auxin, how do you think they
would grow?
Use information from particular charts to support your
answer.
What part of the plant is growing?
 growth largely takes
place in the meristems
 Meristems are the places
in the plant with highly
active growth, where
cells are rapidly
dividing and
expanding
Meristems
 two main meristems
(and smaller side ones)
 shoot apical meristem =
aboveground growth
 root apical meristem =
belowground growth
Meristem
Meristems
 If the apical meristem is
damaged, it has to either
be replaced by a
secondary one or the
plant will cease to grow
vertically
 Meristems = stem cells
 Division and growth are
controlled by the signal
hormone auxin
Why do most plants grow upwards?
 A plant grows vertically
because only one bud is
getting lots of auxin
hormone
 This is the dominant bud
and is why plants grow
generally upward rather
than outward
Summarize
 Meristems _____________________________.
Summarize
 Meristems __are the parts of the plant where most of
the growth takes place_.
During the video
 On your data analysis looseleaf, please answer these
two questions:
 1. Why does the cheese plant grow the way it does?
 2. What does the narrator call the leaves of the
sycamore tree?