Transcript 6.L.2.2

Plant Survival
Changes in environmental
conditions can affect the
survival of individual organisms
and entire species.
Dormancy
…is a period of inactivity in
a mature seed prior to
germination (when the
seed begins to sprout or
grow).
 Dormancy
…the seed remains dormant until conditions are
favorable for growth and development of the new
plant. (i.e. when Spring occurs again with good
weather or when it’s planted in the ground with soil
and nutrients)
 A plants goal is to enhance it’s
survival rate given the environment
it’s in by responding to stimuli (things that cause the plant to
react).
Plant responses are:
Growth (Will it grow? How much?)
Reproduction (Will it reproduce?)
Shift in position of roots,
stems and leaves (Will it need to adapt? If
so how?)
 Conditions that may cause this are:
 Gravity…
 Sunlight
 Temperature…
 Day length
 Touch…
When a plant responds by
turning or bending toward or
away from an external
stimulus it is called
TROPISM.
This can be positive or
negative…
If the Tropism is positive the
plant will move, shift or grow
toward it.
If the Tropism is negative the
plant will move, shift or grow
away from it.
The roots have a
positive response
because they
grow down with
gravity.
The leaves have a
negative response
because they are
defying gravity
by growing up.
TAKE A LOOK! (STOP AT 1:17)
Plants in Action
OH YEAH!
http://www.youtube.
com/watch?v=zmxY
6aD7ltM