Chapter 3 Flashcards
For every gram of organic matter
made by the plant, approximately ____of water is absorbed by the roots
500 g
Cell walls allow plant cells
to build up large internal hydrostatic pressures, called ___, which are a result of
their normal water balance
turgor pressure
cytoplasm makes up only ____ of the cell volume;
5 to 10%
Water typically constitutes ____ of the mass of growing plant tissues.
80 to 95%
____is the most abundant and arguably the best solvent known.
Water
water As a solvent, makes up the ____for the movement of molecules within
and between cells and greatly influences the ___of proteins, nucleic
acids, polysaccharides, and other cell constituents.
medium; structure
___forms the environment in which most of the biochemical reactions of
the cell occur, and it directly participates in many essential chemical reactions
Water
Most of the water lost by the plant evaporates from the leaf as the___needed
for photosynthesis is absorbed from the atmosphere.
CO2
On a warm, dry, sunny day a leaf will exchange up to ___ of its water in a
single ___.
100%; hour
During the plant’s lifetime, water equivalent to ___ times the fresh weight of
the plant may be lost through the leaf surfaces.
100
Such water loss in plants is called ___
transpiration
is an important means of dissipating the heat input from sunlight
Transpiration
Heat dissipates because the water molecules that escape into the atmosphere
have ____, which breaks the __holding them in the
liquid.
higher than-average energy; bonds
When these molecules escape, they leave behind a mass of molecules with
___and thus a cooler body of water.
lower-than-average energy
For a typical leaf, nearly half of the ____ from sunlight is dissipated
by ___
net heat input; transpiration
Of all the resources that plants need to grow and function, ___is the most abundant
and at the same time the most limiting for __
water; agricultural productivity
Properties of Water (5)
A. The Polarity of Water Molecules Gives Rise to Hydrogen Bonds
B. The Polarity of Water Makes It an Excellent Solvent
C. The Thermal Properties of Water Result from Hydrogen Bonding
D. The Cohesive and Adhesive Properties of Water Are Due to Hydrogen Bonding
E. Water Has a High Tensile Strength
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 ___of the water molecule.
polar structure
The two intramolecular hydrogen–oxygen bonds
form an angle of ___
105°
The opposite partial charges (δ– and δ+) on the water molecule lead to
the formation of ____with other water molecules.
intermolecular hydrogen bonds
Oxygen has __
electrons in the outer orbitals; each hydrogen has __.
six ; one
The water molecule consists of an oxygen atom ___bonded to __hydrogen
atoms.
covalently ; two
Because the oxygen atom is more ___than hydrogen, it tends to attract the ___of the ___bond
electronegative; electrons; covalent
– the weak electrostatic attraction between molecules; responsible
for many of the unusual properties of water.
Hydrogen Bond
The water’s versatility as a solvent is due in part to the
____ of the water molecule and in part to its ___nature
small size; polar
the ____ of water makes it a
particularly good solvent for ___ substances and for molecules such as sugars and proteins
that contain polar ___ or ___groups.
polar nature; ionic;
—OH or —NH2
extensive ___bonding between water molecules results in unusual ___
properties, such as (2)
hydrogen;
thermal;
high specific heat and high latent heat of vaporization
- the heat energy required to raise the temperature of a substance by a
specific amount.
Specific heat
___ – the energy needed to separate molecules from the
liquid phase and move them into the gas phase at constant ____ – a process
that occurs during ___[important component of temperature regulation in
plants].
Latent heat of vaporization;
temperature;
transpiration
The _____of water enables plants to cool themselves
by ____ water from leaf surfaces, which are prone to heat up because of
the radiant input from the sun.
high latent heat of vaporization;
evaporating
Water molecules at an ____ are more strongly attracted to neighboring
water molecules than to the ____ in contact with the water surface.
air–water interface; gas phase
an air–water interface minimizes its _____as a consequence of
such unequal attraction.
surface area
To increase the area
of an air–water interface, ___bonds must be broken, which requires an input of
___
hydrogen; energy
- the energy required to increase the surface area
Surface tension
not only influences the shape of the surface but also may
create a pressure in the rest of the liquid.
Surface tension
