Chapters 35-39 summary
Water transport in plants (7 min)
http://video.google.com/videoplay?docid=283386622038164
9782&q=water+transport+in+plnts&total=53&start=0&num=1
0&so=0&type=search&plindex=0 (start at 1:40)
Interesting…
76.8 Kg Willow tree
Seedling
Five years…
90.9 kg soil
Was it H20? Air?
90.84 Kg Soil!
No! it is C02!
• General
Sherman
Fig 37.2
Primary
xylem
Secondary
xylem
Primary
phloem
Secondary
phloem
NAIL?
Where is the
oldest ring?
Primary vs. Secondary
Primary
• Lengthen at
roots/shoots
• Apical Meristems
– “pinching back”
Secondary
• Growth in thickness
– Woody stems
– Lateral meristems
• Vascular cambium
• Cork cambium
• Fig 35.10
Apical dominance
“Source-to-sink”
• Translocation:
Phloem transport
• Mature leaves (source)
• Growing tissues, root stores & fruits (sink)
• Pressure Flow Hypothesis
Roots
• Mycorrhizae (fig 37.12)
• N fixation (figs 37.9, 37.11)
Nitrogen
• Is needed for proteins, nucleic
acids, other organic molecules
What is meant
by the
photosynthesis/
transpiration
compromise?
Fig 36.12 p.747
1. Which has more
water:
the air or the leaf?
2. Which is hypotonic?
3. Which has a greater
Ψ?
4. How does this relate
to the various environmental conditions in
lab 9?
Fig 36.13
Transpiration (lab 9)
• Cohesion
• Adhesion
• Tension
 (Osmotic Potential)
• > = >Potential Energy to do work/move
• Areas with more water usually have the
higher water potential ().
• =p+s
 Examples:
See Figs 36.5-36.6!
= 0 MPa
= (-) MPa
no solute
with solute
(High
H2O)
(LOW H2O)
Different ways to change : add solute (-)
add pressure (+)
tension pressure (-)
Xeriscaping
Xeriscaping
Chapter 39
Control Systems in Plants
Hormone—a chemical signal that
coordinates the different parts of an
organism.
Greek for “to excite”
- produced in a specific area
- travel to another specific area
- (target organ)
- used in minute concentrations
• Which hormone?
• How does it
work?
• This is what type
of -tropism?
Darwin and Darwin’s
experiments
Went’s
experiments
(All coleoptiles
have had their tips
cut off.)
Auxin’s effects: plant
elongation
• Similar to fig 39.8
Plant Movements
• TROPISMS: movement toward or away
from stimuli (-/+)
– Thigmotropism
– Gravitropism (geotropism)
– Phototropism
– (Chemotropism)
Thigmotropism
• Chemotropism