Plant biology 2
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what do amphistomatous and hypostomatous mean?
stomata on the upper AND lower leaf stomata on just the lower leaf
what are stomata sensitive to? (6 things)
light intensity temperature water deficit atmospheric CO2 air pollution touch
who said that stomatal opening was controlled by turgidity of guard cells relative to surrounding subsidiary cells?
von mohl - 1856
what does the diffusive capacity of leaves represent?
product of stomatal number and stomatal aperture
what is the endogenous circadian rhythm?
stomatal opening and closing over the course of the day under constant environmental conditions
what is triggered in soil water deficit?
abscisic acid (ABA)
what increases the opening of stomata?
guard cell turgor from active loading of guard cells with K+ (from the walls of surrounding epidermal cells) K+ uptake also drives the osmotic uptake of water
distortion of what what causes stomata to open?
guard cells
what 6 reasons make water good for sustaining life?
stable liquid in a range of temperatures good solvent transparent to visible light generates pressure (turgor) molecules show mutual attraction and are attracted to surfaces
what is the most active region of a plant?
root hair zone
what blocks the apoplast pathway?
casparian strip
how does water move through the symplast pathway?
between cytoplasm/vacuoles of adjacent cells
what are the two types of tracheary elements and which one is longer?
tracheids are < 3mm long vessel elements are 4 - 300cm in length
what is the direction of water movement determined by?
the value of water potential in the adjacent cell
which direction will water move?
to the area of decreasing water potential
what does it mean by cohesion and tension?
water molecules exhibit strong mutual attraction from hydrogen bonding leading to cohesion between molecules, this creates tension that pulls water in a column up the xylem
what 2 methods help pull water up the xylem?
capillary action root pressure - movement of water through root ‘pushes’ water up xylem aiding ‘pull’ created by cohesion-tension
what is cavitation?
tension on water column in xylem causes dissolved gases to come out of solution creating microscopic bubbles that coalesce and fill conduit
what is embolism?
cavitation bubbles obstruct passage of water in affected tracheids and vessels
when do stomata close to protect leaf against desiccation?
water stress
who said that ‘plants obtain a portion of their nutrition from the air when light is involved’?
stephen hales
what did julius mayer deduce?
that energy used by green plant tissue was derived form the sun and that plants were capable of of transforming radiant energy to chemical form
where does the light dependent reaction of photosynthesis take place and what are the products?
thylakoid membranes ATP and NADPH
where does the reactions of the calvin cycle take place?
in the stroma