CHAPTER 3: Plant-Water Relations

Question 1

For every ___ of organic matter
made by the plant, approximately _____ of water is absorbed by the roots, transported through
the plant body and lost to the atmosphere.

Answer 1

gram

500 g

Question 2

A major difference between plant and animal cells that affects virtually all aspects of their relation with water is the existence in plants of the

Answer 2

cell wall

Question 3

___ is essential for many physiological processes,
including cell enlargement, gas exchange in the leaves, transport in the phloem, and various
transport processes across membranes.

Answer 3

Turgor pressure

Question 4

Turgor pressure also contributes to the rigidity and mechanical stability of

Answer 4

nonlignified plant tissues

Question 5

Each cell contains a large water
filled

Answer 5

vacuole

Question 6

In such cells the cytoplasm makes up only __ to ___ of the cell volume; the remainder is vacuole.

Answer 6

5 to 10%

Question 7

Water typically constitutes ___ to ___ of the mass of growing plant tissues.

Answer 7

80 to 95%

Question 8

most abundant and arguably the best solvent known

Answer 8

water

Question 9

____ as a solvent, it makes up the medium for the movement of molecules within and between cells and greatly influences the ____, ____, ____ and other cell constituents.

Answer 9

Water

structure of proteins, nucleic
acids, polysaccharides,

Question 10

Water forms the environment in which most of the _______ of the cell occur.

Answer 10

biochemical reactions

Question 11

Plants continuously ____ and ___ water.

Answer 11

absorb and lose

Question 12

Most of the water lost by the plant ____ from the leaf as the ____needed for photosynthesis is absorbed from the atmosphere

Answer 12

evaporates

CO2

Question 13

On a warm, dry, sunny day a leaf will exchange up to ____ of its water in a __ ____.

Answer 13

100%
single hour

Question 14

During the plant’s lifetime, water equivalent to ____ the fresh weight of the plant may be lost through the ____

Answer 14

100 times

leaf surfaces

Question 15

Such water loss is called

Answer 15

transpiration

Question 16

dissipating the heat input from sunlight

Answer 16

transpiration

Question 17

Heat dissipates because the water molecules that escape into the atmosphere have ________, which breaks the bonds holding them in the liquid.

When these molecules escape, they leave behind a mass of molecules with _____ and thus a ___ of water.

Answer 17

higher than-average energy

lower-than-average energy
cooler body

Question 18

For a typical leaf, nearly ___of the net heat input from sunlight is dissipated by transpiration.

Answer 18

half

Question 19

In addition, the stream of water taken up by the roots is an important means of bringing ___ ____ ____ to the root surface for absorption.

Answer 19

dissolved soil minerals

Question 20

Of all the resources that plants need to grow and function, ___ is the most abundant and at the same time the most ____ for agricultural productivity.

Answer 20

water

limiting

Question 21

Water has special properties that enable it to act as a ___ and to be readily transported through the body of the plant.

Answer 21

solvent

Question 22

Water has special properties that enable it to act as a solvent and to be readily transported through the body of the plant. These properties derive primarily from the

Answer 22

polar structure of the water molecule

Question 23

The two intramolecular hydrogen–oxygen bonds form an angle of

Answer 23

105°

Question 24

Oxygen has __ _____ in the outer orbitals; each hydrogen has one.

Answer 24

six electrons

Question 25

The opposite partial charges (δ– and δ+) on the water molecule lead to the formation of ___ ____ ____ with other water molecules.

Answer 25

intermolecular hydrogen bonds

Question 26

The water molecule consists of an

Answer 26

-oxygen atom covalently bonded to two hydrogen atoms

Question 27

Reason why two O—H bonds form an angle of 105°

Answer 27

oxygen atom is more electronegative than hydrogen

Question 28

the weak electrostatic attraction between molecules; responsible for many of the unusual properties of water

Answer 28

hydrogen bond

Question 29

responsible for many of the unusual properties of water

Question 30

Because the oxygen atom is more electronegative than hydrogen, it tends to attract the electrons of the covalent bond. This attraction results in a

Answer 30

-partial negative charge at the oxygen end -partial positive charge at each hydrogen.

Question 31

Water is an excellent solvent: This versatility as a solvent is due in part to the ____ of the water molecule and in part to its ___

Answer 31

-small size -polar nature.

Question 32

The polar nature makes water a particularly good solvent for ionic substances and for molecules such (2)

Answer 32

-sugars -proteins

Question 33

The extensive hydrogen bonding between water molecules results in unusual thermal properties, such as

Answer 33

high specific heat and high latent heat of vaporization.

Question 34

the heat energy required to raise the temperature of a substance by a specific amount.

Answer 34

Specific heat

Question 35

the energy needed to separate molecules from the liquid phase and move them into the gas phase at constant temperature –

Answer 35

Latent heat of vaporization

Question 36

important component of temperature regulation in plants

Answer 36

transpiration

Question 37

Water molecules at an air–water interface are more strongly attracted to neighboring water molecules than to the____ in contact with the ____.

Answer 37

gas phase water surface

Question 38

the energy required to increase the surface area.

Answer 38

Surface tension

Question 39

not only influences the shape of the surface but also may create a pressure in the rest of the liquid

Answer 39

Surface tension

Question 40

at the evaporative surfaces of leaves generates the physical forces that pull water through the plant’s vascular system

Answer 40

Surface tension

Question 41

– the mutual attraction between molecules.

Answer 41

Cohesion –

Question 42

attraction of water to a solid phase such as cell wall or glass surface.

Answer 42

Adhesion

Question 43

movement of water along a capillary tube; result of cohesion, adhesion and surface tension.

Answer 43

Capillarity

Question 43

defined as the maximum force per unit area that a continuous column of water can withstand before breaking

Answer 43

tensile strength,

Question 44

tensile strength is such a property must exist for a water column to be pulled up a

Answer 44

capillary tube

Question 45

can be used to create positive and negative pressures in a fluid like water.

Answer 45

sealed syringe

Question 46

unit of measurement of pressure [more convenient is megapascals

Answer 46

Pascals (Pa)

Question 47

MPa = approximately

Answer 47

9.9 atmospheres

Question 48

Water is a constituent of

Answer 48

protoplasm

Question 49

Water acts as

Answer 49

solvent

Question 50

Water is used for _____ of nutrients from the soil to green plant tissues.

Answer 50

transpiration carrier

Question 51

Water, they are used for ____ and the end product is also conveyed through water to various plant parts.

Answer 51

photosynthesis

Question 52

Water forms over ___ of the plant body by green or fresh weight basis.

Answer 52

90%

Question 53

Water helps to maintain the ____ of cell walls. Water helps in ____

Answer 53

turgidity cell enlargement

Question 54

Water is essential for the (4)

Answer 54

germination of seeds, growth of plant roots, and nutrition and multiplication of soil organism.

Question 55

Water is essential in___in the plant. It helps in the conversion of starch to sugar.

Answer 55

hydraulic process

Question 56

Water is essential in hydraulic process in the plant. It helps in the conversion of ___

Answer 56

starch to sugar

Question 57

essential for maintaining the absorption of nutrient from the soil.

Answer 57

transpiration

Question 58

Water regulates the___and ___the plant

Answer 58

temperature cool

Question 59

Water helps in the___, ___ and ____reaction in soil.

Answer 59

chemical physical biological

Question 60

integral membrane proteins that form water-selective channels across the membrane;

Answer 60

aquaporins

Question 61

facilitate water movement into plant cells.

Answer 61

aquaporins

Question 62

The molecules intermingle as a result of their random

Answer 62

thermal agitation

Question 63

The molecules intermingle as a result of their random thermal agitation. This random motion is called

Answer 63

diffusion

Question 64

causes the net movement of molecules from regions of high concentration to regions of low concentration

Answer 64

diffusion

Question 65

German scientist discovered that the rate of diffusion is directly proportional to the concentration gradient.

Answer 65

Adolf Fick

Question 66

– rate of transport; amount of substance crossing a unit area per unit time.

Answer 66

Flux density (Js)

Question 67

– proportionality constant that measures how easily substance moves through a particular medium;

Answer 67

Diffusion coefficient

Question 68

Diffusion is ___ over short ___ but __ over ___

Answer 68

Rapid Distances Extremely Slow Long Distances

Question 69

second process by which water moves; a concerted movement of groups of molecules en masse, most often in response to a pressure gradient

Answer 69

Bulk Flow or Mass Flow

Question 70

Bulk Flow or Mass Flow most often in response to a

Answer 70

pressure gradient

Question 71

is very sensitive to the radius of the tube.

Answer 71

pressure-driven bulk flow

Question 72

If the radius is doubled, the volume flow rate increases by a factor of

Answer 72

16 (24)

Question 73

responsible for long-distance transport of water in the xylem.

Answer 73

Pressure-driven bulk flow

Question 74

Osmosis is Driven by a

Answer 74

Water Potential Gradient

Question 75

___ is Driven by a Water Potential Gradient

Answer 75

Osmosis

Question 76

occurs spontaneously in response to a driving force.

Answer 76

osmosis

Question 77

substances move down a concentration gradient

Answer 77

simple diffusion

Question 78

substances move down a pressure gradient

Answer 78

pressure-driven bulk flow

Question 79

both types of gradients influence transport

Answer 79

osmosis

Question 80

- a quantitative expression of the free energy associated with water.

Answer 80

Chemical potential (of water)

Question 81

- a measure of the free energy of water per unit volume.

Answer 81

Water Potential

Question 82

represents the effect of dissolved solutes on water potential.

Answer 82

Solute potential or osmotic potential

Question 83

The major factors influencing the water potential in plants are (3)

Answer 83

concentration, pressure, and gravity

Question 84

Solutes reduce the free energy of water by .

Answer 84

diluting the water

Question 85

the mixing of solutes and water increases the disorder of the system and thereby lowers free energy.

Answer 85

entropy effect

Question 86

This means that the osmotic potential is ____ of the specific nature of the solute.

Answer 86

independent

Question 87

Hydrostatic pressure of the solution

Answer 87

pressure

Question 88

Pressure Sometimes called

Answer 88

pressure potential

Question 89

____ raise the water potential; ____ reduce it.

Answer 89

Positive pressures negative pressures

Question 90

The positive hydrostatic pressure within cells is the pressure referred to as

Answer 90

turgor pressure

Question 91

___ outside cells are very important in moving water long distances through the plant.

Answer 91

Negative pressures

Question 92

causes water to move downward unless the force of gravity is opposed by an equal and opposite force

Answer 92

gravity

Question 93

Water is important in the life of plants because it makes up the ___ and ___ in which most biochemical processes essential for life take place.

Answer 93

matrix and medium

Question 94

The structure and properties of water strongly influence the ___ and ___ of proteins, membranes, nucleic acids, and other cell constituents.

Answer 94

structure and properties

Question 95

The movement of water is driven by a reduction in free energy, and water may move by ____ of these fundamental transport mechanisms.

Answer 95

(3) diffusion, by bulk flow, or by a combination

Question 96

the movement of water across membranes, depends on a gradient in free energy of water across the membrane—a gradient commonly measured as a difference in water potential.

Answer 96

osmosis

Question 97

Water diffuses because molecules are in _____, which tends to even out concentration differences.

Answer 97

constant thermal agitation

Question 98

two major factors that affect water potential, although when large vertical distances are involved, gravity is also important.

Answer 98

Solute concentration and hydrostatic pressure