plant-water relations

Question 1

Biochemistry requires a highly hydrated environment

Answer 1

> -3 MPa

Question 2

The atmospheric environment provides CO2 and light but is dry

Answer 2

-100 MPa

Question 3

indispensable to plant life

Answer 3

water

Question 4

water accounts for ____ of the weight of the ____ tissues

Answer 4

90-95%, soft tissues

Question 5

serves several unique functions in plants

Answer 5

water

Question 6

water’s _____ makes it an excellent solvent

Answer 6

polarity

Question 7

water’s ability to form _____ bond gives it _____ properties that are important in plant processes

Answer 7

hydrogen; thermal, cohesive, and adhesive

Question 8

water has _________ under normal temperature and pressure, which minimizes water temperature variations in plant cells, tissues, and organs

Answer 8

high heat storage capacity

Question 9

water transmits ____ and absorbs ____ radiation more than short wave radiation

Answer 9

visible light; long wave

Question 10

is found in almost all parts of the cell and in all parts of the plant

Answer 10

water

Question 11

is the water found in cell structures

Answer 11

bound water

Question 12

utilized in the course of growth processes, especially during ____ where _____ is prerequisite

Answer 12

growth water; elongation; turgor

Question 13

utilized for photosynthesis and other reactions in the cell

Answer 13

metabolic water

Question 14

released by plants in the form of water vapor and cools the leaves

Answer 14

transpiration water

Question 15

along with ____, is transported from cell to cell for ____ distance and through _____ for long distances

Answer 15

transport water; solutes; short; vascular bundles

Question 16

released by ______, ______, and other organs into the atmosphere or released as part of __________

Answer 16

secretion/excretion water; glandular trichomes, nectaries; exudates

Question 17

amount of water required by plants DECREASES as follows

Answer 17

transpiration water - secretion water - growth water = transport water - metabolic water

Question 18

amount of water required by plants INCREASES as follows

Answer 18

metabolic - transport = growth - secretion - transpiration

Question 19

absorption and transport of water in various plant parts

Answer 19

water conduction/water transport

Question 20

water conduction can be:

Answer 20

fascicular (long distance) and extrafascicular (short distance)

Question 21

_____ water conduction only occurs at _____ axis via ______

Answer 21

fascicular (long distance); vertical; longitudinal; vascular bundles

Question 22

has a fast diffusion rate over short distances but an extremely low rate, by bulk flow, over long distances

Answer 22

fascicular (long distance)

Question 23

fascicular has a ___ diffusion rate over ____ distances but an extremely ____ rate, by _____, over _____ distances

Answer 23

fast; short; low; bulk flow; long

Question 24

water conduction within the cell itself (_____ transport) or from cells to neighboring cells or tissues (____ transport).

Answer 24

extrafascicular (short distance); cellular; radial

Question 25

in radial transport, movement by ____ or _____ may occur along the _____ or through the ______

Answer 25

diffusion or osmosis; symplast or apoplast

Question 26

_________ by osmosis from cell to cell (radial transport) takes place in ___ directions, driven by __________

Answer 26

water conduction; all; water potential gradient

Question 27

________ form a barrier to the apoplastic flux, forcing ions to pass through the selectively permeable plasma membrane into the cytoplasm, rather than move along the cell wall.

Answer 27

casparian strips

Question 28

casparian strips are found where?

Answer 28

endodermis

Question 29

Describes how tightly water is bound in the soil.

Answer 29

water potential

Question 30

Describes the availability of water for biological processes

Answer 30

water potential

Question 31

Defines the flow of water in all systems (including SPAC).

Answer 31

water potential

Question 32

water potential gradient hierarchy (highest to lowest):

Answer 32

soil > root > stems/trunks > leaves > outside air

Question 33

enumerate the water flow (high WP to low WP) in soil plant atmosphere continuum (SPAC)

Answer 33

1. root conductance to liquid water flow 2. stomatal conductance to water vapor flow 3. boundary layer conductance to water vapor flow

Question 34

the hydration capacity of the cell is determined, not by the absolute amount of water in the cell but by the chemical potential of water

Answer 34

water potential

Question 35

expresses the chemical activity of any substance in terms of free energy per mole of the substance.

Answer 35

chemical potential

Question 36

the free energy needed for the transport of water molecule in a system

Answer 36

water potential

Question 37

relative measurement in the sense that it is relative to the Ψ of pure water at ________ and _______

Answer 37

atmospheric pressure and temperature

Question 38

10 MPa is

Answer 38

1 bar = 1 atm

Question 39

useful parameter in evaluating the water status of plants

Answer 39

water potential

Question 40

water potential (Ψ) is ___ in chemically ____ water

Answer 40

zero; pure

Question 41

the maximum value of water potential

Answer 41

0

Question 42

water potential decreases in ______ where water is physically or chemically bound

Answer 42

aqueous solution

Question 43

the cell has ____ water potential since ____ molecules in all living cells lower free energy of water

Answer 43

negative; solute

Question 44

negative (-) sign indicates that dissolved solutes of the water potential (Ψ) of a solution _____ the concentration of water

Answer 44

reduce

Question 45

what are the forces that affect the entry of water in plant cell?

Answer 45

1) osmotic pressure 2) osmotic potential or solute potential 3) turgor pressure or pressure potential

Question 46

________ is the pressure exerted by the ____ obstructing the passage of _____ molecules, as water enters the cell freely

Answer 46

osmotic pressure (π); membrane; solute

Question 47

_________ same quantity as π but negative value

Answer 47

osmotic or solute potential (Ψπ or Ψs)

Question 48

_____ is the pressure exerted by the ____ equally but opposite to the pressured exerted by the cell wall

Answer 48

turgor pressure (P) or pressure potential (Ψp); protoplast

Question 49

_____ arises due to the ____ cell wall of the plant cell which restricts swelling upon entry of water

Answer 49

negative turgor pressure; rigid

Question 50

changes in water potential can be brought about by channges in what potentials?

Answer 50

pressure potential or solute potential

Question 51

plant cell water potential is dependent on what?

Answer 51

pressure potential

Question 52

give the formula for plant cell water potential

Answer 52

(Ψcell) = P – π (Ψcell) = Ψp + Ψs (Ψs is negative value for π)

Question 53

(Ψcell) = P – π the Ψ values are negative, π _____ the Ψ of the cell (makes ____ negative), while P _____ (makes _____ negative) it

Answer 53

decreases, more; increases, less

Question 54

________, cell volume is minimum, and protoplast barely touches the cell wall (Ψ = –π; P = 0).

Answer 54

incipient plasmolysis

Question 55

cells are ____, when Ψ is very low and P is negative the protoplast _____ from the wall

Answer 55

plasmolyzed; shrinks away

Question 56

occurs when air or gas is admitted into the vascular system of the plants

Answer 56

air embolism

Question 57

carbon dioxide enters the stomata, but when opening it loses water

Answer 57

trade-off