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Flashcards in Ch 12 Deck (22):
1

Water Potential

the chemical potential of water; measure of the ability of a substance to absorb or release water relative to another substance; Components: osmotic potential, pressure potential and matric potential

2

Pressure Potential

a component of water potential; a measure if the effect if pressure or tension on a substance's ability to absorb or release water

3

Matric Potential

a component of water potential; a measure of the effect of a matrix on a substance's ability to absorb or release water

4

Gravity Potential

.

5

Symplastic Movement

the protoplasm of all the cells in a plant are interconnected by plasmodesmata; the entire mass

6

Apoplastic Movement

the intercellular spaces and cell walls of a plant; all the volume of a plant that is not occupied by protoplasm;

7

Guard Cells function

opening and closing of stomatal pores based on short-distance intercellular transport; when guard cells open potassium ions are actively transported from surrounding cells into guard cells; when guard cells close potassium is pumped out of the cell and water follows

8

Motor Cells

cells that swell and shrink in plant organs capable of repeated, reversible movement, such as insect traps and petioles of leaves that undergo sleep movements

9

Transfer Cells

cells involved in rapid short-distance transfer of material; they have transfer (labrinthine) walls

10

Pressure flow hypothesis

the hypothesis that flow in phloem is due to active loading in sources and active unloading in sinks

11

Sources

in phloem transport, any organ or tissue that supplies material to be transported

12

Sinks

in phloem transport, any organ or tissue that receives material transported by the phloem

13

Active transport

the forced pumping of molecules from one side of a membrane to the other by means of molecular pumps located in the membrane; sugars actively transported into sieve elements

14

Polymer trap mechanism for sugar loading

conducting-cell plasma membranes are permeable to monosaccharides and disaccharides but not to polysaccharides; how phloem is loaded

15

STM/CC Complex

a functional unit consisting of a conducting cell and one or several companion cells

16

P-protein plug

phloem-protein or fibrillar protein that plugs sieve pores and prevents leakage if sieve elements are damaged

17

Callose

a long-chain carbohydrate polymer that seals certain regions ie damaged sieve elements or growing pollen tubes

18

Cohesion-tension hypothesis

hypothesis that as water is pulled upward by transpiration, its molecules cohere sufficiently to withstand the tension

19

Transstomatal transcription

water loss through stomatal pores

20

Transcuticular transcription

water lost through the cuticle

21

Cavitation

in xylem, the breaking of a water column when tension overcomes the cohesive nature of water; an embolism forms

22

Embolism

a packet of water vapor formed in the xylem when the water column cavitates (breaks); often called an air bubble