2 ... 12 - Water relations

Question 1

Modes of water movement?

Answer 1

Bulk flow
Diffusion
Osmosis

Question 2

Define bulk flow

Answer 2

overall movement of water driven by differences in potential energy. (pressure gradient)

Major mechanism of long-distance water transport via xylem

Question 3

Define diffusion

Answer 3

net movement of a substance from a more concentrated region to a less concentrated one… towards equilibrium

Rapid over short distances, extremely slow over long distances

Question 4

Define osmosis

Answer 4

movement of water across selectively permeable membrane
FROM:
high water potential, lower solute concentration, higher osmotic potential
TO:
lower water potential, higher solute concentration, lower osmotic potential

Question 5

Define turgor pressure

Answer 5

hydrostatic pressure in plant cells that keeps the plant rigid

Question 6

Define plasmolysis

Answer 6

separation of protoplast from cell wall due to removal of water from protoplast by osmosis

Question 7

Modes of solute transport across membrane?

Answer 7

Simple diffusion (passive, no energy req)
Facilitated diffusion (passive, no energy req)
Active transport (high energy req)

Question 8

Uniporter?

Answer 8

one solute moved directly across in one direction

Question 9

symporter?

Answer 9

two different solutes moved simultaneously in same direction

Question 10

antiporter?

Answer 10

two different solutes moved simultaneously in different directions

Question 11

Describe primary active transport

Answer 11

directly energy requiring… proton pump against gradient

Question 12

Describe secondary active transport

Answer 12

driven indirectly by primary pumps…

Question 13

Define plasmodesmata

Answer 13

narrow strands of cytoplasm that interconnect the protoplasts of adjoining plant cells.

Question 14

Function of plasmodesmata

Answer 14

Cell to cell communication

Question 15

Define transpiration and describe the process

Answer 15

Loss of water vapor in plants

Water -> roots -> xylem -> leaves -> stomata -> evaporation

Question 16

Water uptake occurs in

Answer 16

roots

Question 17

Capillary pressure

Answer 17

water climbs inside small tube… height determined by radius of tube.

smaller tube = higher height

Question 18

Define cohesion

Answer 18

water attracted to water

Question 19

Define adhesion

Answer 19

water attracted to other substances

Question 20

Factors affected stomata movement?

Answer 20

[CO2]
light (open bright, close dark)
temperature (close high)
circadian rhythms

Question 21

Cohesion-tension theory

Answer 21

Water pulled to top via water tension and its cohesion… water evaporates, tension in cohesive water column pulls water from roots

Question 22

Define cavitation

Answer 22

rupture of water column that breaks water connections … stops transpiration if water column network not rerouted

Question 23

Define source

Answer 23

organ (ie. mature leaf, storage root) that produces more sugars than it requires.

Question 24

Define sink

Answer 24

organ (ie. root, flower, dev fruit) that consumes sugars

Question 25

assimilates, aka

Answer 25

sugars