Ch 12

Question 1

Water Potential

Answer 1

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

Question 2

Pressure Potential

Answer 2

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

Question 3

Matric Potential

Answer 3

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

Question 4

Gravity Potential

Answer 4

.

Question 5

Symplastic Movement

Answer 5

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

Question 6

Apoplastic Movement

Answer 6

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

Question 7

Guard Cells function

Answer 7

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

Question 8

Motor Cells

Answer 8

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

Question 9

Transfer Cells

Answer 9

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

Question 10

Pressure flow hypothesis

Answer 10

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

Question 11

Sources

Answer 11

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

Question 12

Sinks

Answer 12

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

Question 13

Active transport

Answer 13

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

Question 14

Polymer trap mechanism for sugar loading

Answer 14

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

Question 15

STM/CC Complex

Answer 15

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

Question 16

P-protein plug

Answer 16

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

Question 17

Callose

Answer 17

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

Question 18

Cohesion-tension hypothesis

Answer 18

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

Question 19

Transstomatal transcription

Answer 19

water loss through stomatal pores

Question 20

Transcuticular transcription

Answer 20

water lost through the cuticle

Question 21

Cavitation

Answer 21

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

Question 22

Embolism

Answer 22

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