WATER RELATIONS OF THE WHOLE PLANT

Question 1

defined as the loss of water from the plant in the form of water vapor

Answer 1

transpiration

Question 2

The outer surfaces of a typical vascular plant leaf are covered with a multilayered waxy deposit called

Answer 2

cuticle

Question 3

most of the water evaporates from the inner surfaces of epidermal cells in the immediate vicinity of the stomata

Answer 3

peristomal evaporation

Question 4

Diffusion of water vapor through the stomatal pores

Answer 4

stomatal transpiration

Question 5

weight loss method

Answer 5

lysimeter

Question 6

when a gas phase has reached equilibrium and is saturated with water vapor, the system will have achieved its

Answer 6

saturation vapor pressure

Question 7

The rate of transpiration will naturally be influenced by
factors such as _________ and _________, and ________

Answer 7

humidity, temperature, wind speed

Question 8

a layer of undisturbed air on the surface of the leaf

Answer 8

boundary layer

Question 9

is the actual water content of air

Answer 9

humidity

Question 10

the ratio of the actual water content of air to the maximum amount of water that can be held by air
at that temperature

Answer 10

relative humidity

Question 11

The distinguishing feature of vascular plants is the presence of

Answer 11

vascular tissues

Question 12

responsible for the transport of water, dissolved minerals, and, on occasion, small organic molecules upward
through the plant

Answer 12

xylem

Question 13

responsible primarily for the translocation of organic materials from sites of synthesis to storage sites or sites of metabolic demand

Answer 13

phloem

Question 14

are very elongated cells with thickened secondary walls. Their principal function is to provide structural support for the
plant.

Answer 14

fibers

Question 15

most highly specialized
of the xylem cells and are the principal water-conducting
cells

Answer 15

tracheary elements

Question 16

are single cells with diameters in the
range of 10 to 50 p,m. They are typically less than 1 cm
in length, although in some species they may reach
lengths up to 3 cm.

Answer 16

tracheids

Question 17

are very long tracheary elements made up
of individual units, known as vessel members, which are arranged end-to-end in longitudinal series

Answer 17

vessels

Question 18

At maturity, the end walls of the vessel members have dissolved away, leaving openings

Answer 18

perforation plates

Question 19

If the perforations are elongate and parallel

Answer 19

scalariform

Question 20

An irregular, net-like
pattern

Answer 20

reticulate

Question 21

Exudation of sap, which may persist for several hours, indicates the presence of a positive pressure in the xylem

Answer 21

root pressure

Question 22

central core of a root

Answer 22

stele

Question 23

In most roots,
the radial and transverse walls of the endodermal cells
develop characteristic thickenings

Answer 23

casparian strip

Question 24

the path in which the water is moving between the intercellular spaces

Answer 24

apoplast pathway

Question 25

the pathway in which the water molecules moves through the plasmodesmata region in the cells

Answer 25

symplast pathway

Question 26

cohesive forces between water molecules

Answer 26

surface tension

Question 27

If a glass capillary tube (that is, a tube ofsmall diameter)
is inserted into a volume of water, water will rise in the
tube to some level above the surface of the surrounding
bulk water

Answer 27

capillarity

Question 28

The most widely accepted theory for movement of water through plants

Answer 28

cohesion theory

Question 29

results from the attraction between fluid
molecules and a surface

Answer 29

adhesion

Question 30

Water lost by transpiration must be replenished by
the absorption of an equivalent amount of water from the soil through the root system. This establishes an integrated flow of water from the soil, through the plant, and into the atmosphere

Answer 30

soil-plant-atmosphere continuum

Question 31

a very complex medium, consisting of a solid
phase comprised ofinorganic rock particles and organic
material

Answer 31

soil

Question 32

refers to the interconnected channels between irregularly shaped soil particles

Answer 32

porosity

Question 33

If the roots of an actively transpiring plant are cut
off (under water, of course), there is an immediate increase in the rate of absorption into the xylem. In some species, absorption lag may cause a water deficit in the leaves sufficient to stimulate a temporary closure of the stomata

Answer 33

midday closure