Plant Physiology Flashcards
(90 cards)
what are the two types of transport?
- short
- long
what is short distance transport?
movement along the radial axis
what is long distance transport?
movement up and down a plant organ
how do short distance osmotic substances move?
osmotic substances move directly through cell membranes by diffusion
how do short distance symplastic substances move?
symplastic substances can only move from cell to cell by plasmodesmata through the cytoplasm
how do short distance apolplastic substances move?
not allowed in cell— move outside cells through continuum of cell walls
how do long distance substances move?
high to low pressure in the xylem/phloem
what are the 3 types of water movement?
- absorption of water
- roof pressure
- transpiration-cohesion-tension theory
how does the plant absorb water?
- absorbed by root hairs from soil to stele
- endodermal cells actively transport minerals/water to stele
what makes water go through the endodermal cells?
the casparian strip of the endodermis
what are the 3 types of water movement?
- absorption of water
- root pressure
- transpiration-cohesion-tension theory
how does water get absorbed by the plant?
- water goes from root hairs in soil to the stele (osmotically)
- endodermal cells actively transport minerals/water to stele
- xylem to leaf
what makes the water go through the endodermal cells?
the casparian strip of the endodermis
what is root pressure?
water pressure builds up in stele because of mucho concentration of dissolved substances in stele
how does root pressure work?
-pressure pushes water up stem (low success)
root pressure causes what in small plants?
guttation (dew)
what are the walls of xylem stiffened with and why?
lignin to prevent collapse under the negative pressure
what is the movement of water fueled by?
evaporation in leaves
what does the cohesion of water help?
water molecules stick together in xylem and can be pulled long distances (against gravity)
how does the T-C-T theory work?
- water vapor leaves stomata
- water in bundle sheath cells replace that
- water in xylem of vein replace that
what does the T-C-T theory cause?
a partial vacuum in the leaf vein and it pulls water up
what 3 things affect transpiration?
- temp (doubles every 10C increase)
- humidity (hindered if there’s already water in air)
- air currents (good if the air is blowing the humid air away)
where do plants not need gas?
xylem
what to guard cells do?
regulate stomata in leaves