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Stomata Density
By:By:Breana HullBreana Hull
Denzel DrennonDenzel Drennon
http://mrskingsbioweb.com/images/stomata.jpg
What Are Stomata?1
Are microscopic pores in the epidermis of plantsAre microscopic pores in the epidermis of plants
Surrounded by guard cells Surrounded by guard cells
In leaves and stems of plantsIn leaves and stems of plants
Allows gas exchange between the environment Allows gas exchange between the environment
and the interior of plantsand the interior of plants
Surrounded by guard cells which control the Surrounded by guard cells which control the
opening and closing of stomataopening and closing of stomata
What Are Stomata Cont.What Are Stomata Cont.11
There are three cues for There are three cues for Stomatal opening:Stomatal opening:
1.1.Depletion of carbon dioxide Depletion of carbon dioxide within plantswithin plants
2.2.Light at dawn triggers the guard Light at dawn triggers the guard cellscells
3.3.The internal clock of the guard The internal clock of the guard cells cells
Guard CellsGuard Cells11 Guard cells become turgid Guard cells become turgid
when swollen with water when swollen with water causing an opening in the causing an opening in the stomastoma
Water is stabilized in and out Water is stabilized in and out of the guard cells as of the guard cells as potassium ions are potassium ions are transported across the transported across the plasma membrane, plasma membrane, regulating the amount of regulating the amount of water and ions taken in.water and ions taken in.
When they lose water they When they lose water they become flaccid causing the become flaccid causing the stoma to closestoma to close
http://leavingbio.net/TRANSPORT%20OF%20MATERIALS%20IN%20A%20FLOWERING%20PLANT_files/image011.jpg
What do Stomata do?1
Main avenues of Main avenues of TRANSPIRATION:TRANSPIRATION:Transpiration is the evaporative loss of water through a Transpiration is the evaporative loss of water through a
plants leaves. plants leaves. Balance the requirement for water conservation for Balance the requirement for water conservation for
photosynthesisphotosynthesis Open during the day and close at night to prevent water Open during the day and close at night to prevent water
losslossEspecially in low water and high temperature Especially in low water and high temperature
conditionsconditions Regulate the carbon dioxide intake and oxygen output for Regulate the carbon dioxide intake and oxygen output for
photosynthesis.photosynthesis. Provides gas exchange for the plantProvides gas exchange for the plant
Why is it interesting to Why is it interesting to study stomata?study stomata?11
95% of a plant’s water loss is through 95% of a plant’s water loss is through these small pores.these small pores.
An internal clock in the guard cells open An internal clock in the guard cells open the stoma at dawn even if the plant is in the stoma at dawn even if the plant is in the dark. the dark.
HypothesisHypothesis
stomata density in leaves directly exposed to the sun will be greater then
those in the shade
In this environment the southern faced leaves are directly exposed to sunlight, where the northern faced leaves are low to the ground
with less sunlight exposure.
We think this has an We think this has an effect becauseeffect because44::
Increase gas exchange
Therefore more water released
Lowering plant temperature in times of
high sunlit conditions.
On the other hand…On the other hand…
If these plants were put under If these plants were put under conditions with limited water, they conditions with limited water, they
would be hypothesized to have less would be hypothesized to have less stomata in leaves of the sun.stomata in leaves of the sun.44
Area for sampling
HollyHolly
NORTH (shaded)NORTH (shaded)Found closest to Found closest to
the ground, under the ground, under the bushthe bush
Smaller leavesSmaller leavesLighter Lighter
yellow/greenyellow/green
HollyHolly
SOUTH (sun)SOUTH (sun)Found on top of Found on top of
bush, fully bush, fully exposedexposed
Bigger leavesBigger leavesDark greenDark green
MethodsMethodsGather leaf samples from site; 12 leaves from Gather leaf samples from site; 12 leaves from
shaded, north facing shaded, north facing ANDAND 12 leaves from direct 12 leaves from direct sun, south facingsun, south facing
Paint underside of leaves with clear nail polishPaint underside of leaves with clear nail polishPlace clear scotch tape on underside of leaf once Place clear scotch tape on underside of leaf once
drydryPlace tape on slide and labelPlace tape on slide and labelUnder microscope, count number of stomata for 3 Under microscope, count number of stomata for 3
fields of view on all 24 leavesfields of view on all 24 leavesMeasure field of view in millimeters under 400 xMeasure field of view in millimeters under 400 x
ResultsResults
The stomata density in leaves of the sun are greater than
those in the shade
YES!YES!
We accept our hypothesisWe accept our hypothesis
251.92
ConclusionConclusion
Looking at the t Critical and t Stat, we confirm that there is a significant difference between stomata density in leaves of the shade and sun areas
Sun Shade
Mean 251.92 186.50
Variance 1202.34 452.27
Standard Deviation 34.67 21.27
t Stat 5.57108
t Critical one-tail 1.73406
P(T<=t) one-tail 1.372 x 10-5
Looking at the Probability we can assure that we are 100% sure of our conclusion
StatisticsStatistics
Future StudyFuture Study
The shade of the leaf compared to the The shade of the leaf compared to the stomata densitystomata density
Hypothesis:Hypothesis:
Darker leaves have more stomata then Darker leaves have more stomata then lighterlighter
Because:Because:
The darker color of leaves attracts sunlightThe darker color of leaves attracts sunlight
References:References:
1.1. Campbell, Neil. 2010. Biology. Edition 8. Pearson Education, Inc.Campbell, Neil. 2010. Biology. Edition 8. Pearson Education, Inc.
2. http://mrskingsbioweb.com/images/stomata.jpg. mrskingsbioweb.com/images/stomata.jpg. “February 16, “February 16, 2011”2011”
3.3. http://leavingbio.net/TRANSPORT%20OF%20MATERIALS%20INhttp://leavingbio.net/TRANSPORT%20OF%20MATERIALS%20IN%20A%20FLOWERING%20PLANT_files/image011.jpg. %20A%20FLOWERING%20PLANT_files/image011.jpg. “February “February 16, 2011”16, 2011”
4.4. Bruce W. Grant, Itzick Vatnick, and the Ecological Society of Bruce W. Grant, Itzick Vatnick, and the Ecological Society of America. 2004.Environmental Correlates of Stomata Density. TIEE. America. 2004.Environmental Correlates of Stomata Density. TIEE. http://tiee.ecoed.net/vol/v1/experiments/stomata/stomata_descriptiohttp://tiee.ecoed.net/vol/v1/experiments/stomata/stomata_description.html. “n.html. “February16, 2011February16, 2011””