Module Part 6 Plant Water Relations

Question 1

Water typically comprises ____ - ____ of the biomass of nonwoody tissues such as leaves and roots.

At the cellular level, water is the major medium for transporting ____through the cell

water readily ____ large quantities of ions and polar organic metabolites like sugars, amino acids, and proteins that are critical to metabolism and life

water is the medium that transport the___ (carbohydrates and nutrients) as well as the ___ that are required for growth and development from one plant organ to another

Living cells must maintain a positive water pressure, or “____ “to grow and function properly. Like Tomato plants that pushes water against a wall

Answer 1

70—95%

metabolites

dissolves

raw materials, phytohormones

turgor

Question 2

Water concentration ranges for

Seeds

Wood (Heartwood, Sapwood)

Leafy Greens

Answer 2

10-15% Seed

30-35% Wood

95% Leafy Greens

Question 3

Evaporation from the interior of the leaves through the ___ is reffered to as ____

Water loss through ___
___ by leaves through transpiration
___ of the heat by sunlight is dissipated by transpiration
Latent heat of ____

Answer 3

Stomata
Transpiration

Leaf Surface
Heat Dissipation
Half
Vaporization

Question 4

Water passes easily through membranes due to ___ which are proteins embedded in cell membrane that regulate the flow of water

The opening and closing of ___ are based on short distance ___ transport

Answer 4

Aquaporins

Stomatal Pores
Intercellular

Question 5

Water Potential:

Combined effects of (2)

Water potential is in psi which is measured in MPa also known as ___ where one is 10 atmospheres of pressure

Water Potential = ___ + ___ + ___

Answer 5

Solute Concentration
Physical Pressure

megapascals (MPa)

Solute Potential + Pressure Potential + Gravitional Potential

Question 6

Physiological changes due to dehydration of well watered plants

Answer 6

Cell expansion

Question 7

Physiological changes due to dehydration of plants under mild water stress (4)

Answer 7

Wall Synthesis
Protein Synthesis
Stomal Conductance (CO2 travel)
Photosynthesis

Question 8

Physiological changes due to dehydration of plants in arid, desert climates

Answer 8

Abscisic acid accumulation
Solute accumulation

Question 9

____
Dissolved, it has an effect on water potential
Reduce Free Energy of Water

____
Hydrostatic (2) of the solution
Raises the water potential if positive
Positive (2) ____ and Negative (2) _____

____
Generally negligible
Overcomed by ____

Answer 9

Solute

Pressure
Turgor, Tension

Gravity
Transpirational Pull

Question 10

Water always moves from a ___ water potential to ____ water potential

Answer 10

higher

lower

Question 11

Water Dynamics in soil are governed by many factors that change ____ with depth, ___ across landforms, and ___ in response to climate

Answer 11

Vertically

Laterally

Temporally

Question 12

Water in soil:

____ Deep-rooted plants pull water upwards. The passive movement of water from roots into soil layers with low water potential while parts of the roots in moister soil layers absorb water

Allows survival of ____ during drought and in arid environments

Answer 12

Hydraulic Lift

Shallow Rooted Plants

Question 13

____Most active in the water absorption process.

Water enters the root most readily in the ____ part of the root

Answer 13

Root hairs

Apical

Question 14

Pathways water can go through (3)

____ At the ___, the apoplast pathway is blocked by the ___

____ Water moves across the plasma membranes with a short visit to the ___

____Water flows between cells through the ____ without crossing the plasma membrane. Water movement across the endodermis usually occurs here.

Usually this is through the ___

Answer 14

APOPLAST pathway, Casparian strip

TRANSMEMBRANE PATHWAY, Cell wall space

SYMPLAST PATHWAY, Plasmodesmata

Cortex

Question 15

Factors affecting water absorption (5)

A
C
S
S
T

Answer 15

Available Soil Water

Concentration of Soil Solution

Soil Temperature

Soil Aeration

Transpiration

Question 16

Factors affecting rate of transpiration (7)

H
T
W
L
A
C
R

Answer 16

Humidity of Air

Temperature

Wind Velocity

Light

Atmospheric Pressure

Carbon Dioxide Concentration

Root: Shoot ratio

Question 17

Significance of Transpiration (3)

Answer 17

Ascent of Sap

Absorption of Water and Minerals

Cooling Effects

Question 18

Accoding to ____ Transpiration is the main driver of water movement in the xylem which creates negative pressure ___ equivalent to __ at the leaf surface. THis also aids in drawing water from the soil

The Xylem also has thick walls lined with ___

The first to suggest this theory is ____

Answer 18

Cohesion-Tension Theory

Tension

-2 MPa

Lignin

Stephen Hales

Question 19

INJURY:

____ ice crystals can cut cell membranes which leads to cell and plant death

Symptoms include (4)

Answer 19

Freezing

Browning
Blackening
Wilting
Curling of Leaves and Stems

Question 20

INJURY:

___ Occurs at temperatures ___ to ___ plants from tropical origins are usually sensitive tot his while those in temperate zones are not

Answer 20

Chilling Injury

0 to 10C

Question 21

Coping mechanisms in the cold (2)

___ increase amount of sugar or salt to lower the ____ to require a much colder than normal temperature to freeze their cells

____ plants move water/sugar sap into ___ or ____ where it is less likely to freeze or cause damage

____ plants reduce or stop growing to conserve energy, food and reduce amount of water they need

____ Reduce surface area exposed to cold drying air to save water and return nutrients in the soil

Answer 21

Create anti-freeze
Freezing Point

Move Water Deeper
Roots/Spaces between cells

Enter Dormancy

Drop their leaves