Plant Physiology Exam quiz and
answers well graded A+
What percentage of water is absorbed and evaporated from the plant? - ANS✅✅Plants use huge
amounts of water, about 97% of the water absorbed by a plant's root is carried through the plant
and evaporates from the leaf surface
The constant water movement from root to atmosphere is called... - ANS✅✅transpiration
Only ~2% of the water absorbed by the roots remains in the plant to supply growth or to be used in
photosynthesis and ~1% for other metabolic processes. What is the reason the dramatic water loss
of the plant? - ANS✅✅The requirement of atmospheric CO2 for photosynthesis. As atmospheric
CO2 diffuses into the leaves, water vapor diffuses out.
Water vapor diffuses out of the plant leaves by what common pathway? - ANS✅✅The stomata
Furthermore... - ANS✅✅the driving gradient for water loss from leaves is much larger than that for
CO2 uptake (400 water molecules are lost per 1 CO2 molecule gained)
Due to water's hydrogen bonding capacity and its polar structure... - ANS✅✅It's is a wide-ranging
solvent that moves well through the body of the plant.
The oxygen atom of water is more ________ than the hydrogen - ANS✅✅Electronegative
Electrons of the covalent bonds with hydrogen tend to be _____ to the oxygen atom -
ANS✅✅Closer
Uneven distribution of the electrons results in a partial negative charge at the oxygen end of the
molecule and a partial positive charge at each hydrogen, making water a polar molecule - ANS✅✅
How many positive and negative poles do water molecules have? - ANS✅✅they have two positive
and two negative poles
, What energy is required to separate molecules from their liquid phase and move them to the gas
phase? - ANS✅✅The latent heat of evaporation
To break the hydrogen bonding of water molecules, what is required? - ANS✅✅a significant
amount of heat energy
Where does heat energy come from? - ANS✅✅It comes from the environment
What is the end result of energy being taken from the environment? - ANS✅✅the cooling of the
surrounding environment
How does the high latent heat evaporation of water help plants? - ANS✅✅It regulates the
temperature of transpiring leaves
What two properties of water result from its hydrogen bonding capacity? - ANS✅✅Cohesion and
adhesion
What is cohesion? - ANS✅✅the mutual attraction between molecules
What is adhesion? - ANS✅✅The attraction of water to a solid phase such as a cell wall or a glass
surface
What is surface tension? - ANS✅✅a force exerted by water molecules at the air-water interface.
This force minimizes the surface area of the air water interface
Cohesion and adhesion together with surface tension give rise to... - ANS✅✅the phenomenon
known as capillarity
Solid-plant-atmosphere continuum (SPAC) - ANS✅✅
If the concentration of solutes is higher within the cell than in the surrounding solution... -
ANS✅✅water will diffuse into the cell but the solutes are unable to diffuse out of the cell
What is osmosis? - ANS✅✅the net movement of water across a selectively permeable barrier
answers well graded A+
What percentage of water is absorbed and evaporated from the plant? - ANS✅✅Plants use huge
amounts of water, about 97% of the water absorbed by a plant's root is carried through the plant
and evaporates from the leaf surface
The constant water movement from root to atmosphere is called... - ANS✅✅transpiration
Only ~2% of the water absorbed by the roots remains in the plant to supply growth or to be used in
photosynthesis and ~1% for other metabolic processes. What is the reason the dramatic water loss
of the plant? - ANS✅✅The requirement of atmospheric CO2 for photosynthesis. As atmospheric
CO2 diffuses into the leaves, water vapor diffuses out.
Water vapor diffuses out of the plant leaves by what common pathway? - ANS✅✅The stomata
Furthermore... - ANS✅✅the driving gradient for water loss from leaves is much larger than that for
CO2 uptake (400 water molecules are lost per 1 CO2 molecule gained)
Due to water's hydrogen bonding capacity and its polar structure... - ANS✅✅It's is a wide-ranging
solvent that moves well through the body of the plant.
The oxygen atom of water is more ________ than the hydrogen - ANS✅✅Electronegative
Electrons of the covalent bonds with hydrogen tend to be _____ to the oxygen atom -
ANS✅✅Closer
Uneven distribution of the electrons results in a partial negative charge at the oxygen end of the
molecule and a partial positive charge at each hydrogen, making water a polar molecule - ANS✅✅
How many positive and negative poles do water molecules have? - ANS✅✅they have two positive
and two negative poles
, What energy is required to separate molecules from their liquid phase and move them to the gas
phase? - ANS✅✅The latent heat of evaporation
To break the hydrogen bonding of water molecules, what is required? - ANS✅✅a significant
amount of heat energy
Where does heat energy come from? - ANS✅✅It comes from the environment
What is the end result of energy being taken from the environment? - ANS✅✅the cooling of the
surrounding environment
How does the high latent heat evaporation of water help plants? - ANS✅✅It regulates the
temperature of transpiring leaves
What two properties of water result from its hydrogen bonding capacity? - ANS✅✅Cohesion and
adhesion
What is cohesion? - ANS✅✅the mutual attraction between molecules
What is adhesion? - ANS✅✅The attraction of water to a solid phase such as a cell wall or a glass
surface
What is surface tension? - ANS✅✅a force exerted by water molecules at the air-water interface.
This force minimizes the surface area of the air water interface
Cohesion and adhesion together with surface tension give rise to... - ANS✅✅the phenomenon
known as capillarity
Solid-plant-atmosphere continuum (SPAC) - ANS✅✅
If the concentration of solutes is higher within the cell than in the surrounding solution... -
ANS✅✅water will diffuse into the cell but the solutes are unable to diffuse out of the cell
What is osmosis? - ANS✅✅the net movement of water across a selectively permeable barrier
