Bio Lecture 4- chap 11 & 12.docx

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18 Apr 2012
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Plants physiological ecology 9/26/2011 6:49:00 AM
Lecture 4- Chapter 11 & 12
Plant ecophysiology of carbon balance
CO2+H20 carbohydrates + O2
photosynthetic structures embody adaptation to environmental studies
-lead size and shape is very important factor. To increase surface area, leaf
is perfect for letting oxygen out and absorbing everything. Only problem is
that there is a tradeoff when the leaf is being exposed to large amounts of
sun.
- it deals with the large amount of heat coming from the sun by evaporative
cooling. Does so by stomata opening and closing.
By closing the stomata, Co2 input:
-shuts down all gas exchange, including CO2 input, so photosynthesis and
plant stops growing.. risks overheating & tissue damage.
-tradeoff between water conservation and growth
- ADD MORE FROM SLIDE SHOW
KNOw PALO VERDE- green stick
-trunk has photosynthetic bark. overheating problems are less because
lesser SA/V. leaves are also very small. The term for small leaves is called
microphyllyl.
- plants have a hard time dealing w th stress because they cannot move.
The deal with stress by growth and development
-cactus family just got rid of leaves. Cacti are modified stem tissue. Cacti
can store water in sponge like tissue =succulents. They have extensive yet
shallow roots.
In Sonoran desert
- there is alot of water there for brief periods of time. rillito river. water
enters in episodic patterns. The cacti uses storage to water when its there.
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- saguaro cactus adapted to episodic rains. They have pleated form which
helps it absorb lots fo water without bursting unlike a cylindrical shape.
DECIDOUS HABIT
In dry seasons, plants with leaves get through dry season by dropping
leaves
-decidous habit
-reduces water stress. parts of tropics have pronounced dry season and they
drop there leaves
- takes a lot to make leave again
EVERGREEN
- do nto drop leaves on seasonal periods
- needle like leaves
many evergreen are not conifers
KIND OD LEAVES PLANTS MAKE
- mesophyll: maple leaf, high SA/V,flimsy fragile
-Scelrophyl: leves small, ADD MORE HERE
Leafshape influences gas exchange through laminar vs. turbulent flow fo
fluids over surfaces
- Laminar : far away from object, at high velocity. At area closer, velocity
slows bc of friction
- turbulent (bump in shape) : far away from object, at high velocity. At close
area, air flow get very much disrupted. Leaves get oxygen produced taken
away by different flow.something wrong here bc it is said that turbulence is
better. Check IT OUT
morpholical shaping
- top of tree there will be less SA/V where there is more sun
- as leaves appear at bottom, there is higer SA/V because of more shade at
bottom, it can have more SA/V
Sheltering
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