Water Flashcards
what does water do
makes all life possible (biological medium of life)
– only common substance to
exist in the environment as
solid, gas and liquid
what is the source of oxygen in photosynthesis
water
what is the process involved in releasing O2 into the atmosphere
photosynthesis
which organisms are capable of this process
cyanobacteria
algae
plants
what does our body mostly consist of
water (60-65 % average)
– the water content
varies between different organs and tissues with brain, eyes and blood containing the higher proportion of water
how much water do our bones contain
~20% water
how much water does our brain contain
83%
how much water do our kidneys contain
83%
how much water do our lungs contain
85%
how much water do our eyes contain
95%
how much water do our muscles contain
75%
how much water does our heart contain
75%
how much water does our blood contain
94%
what is dehydration synthesis
removal of water to bind monomers together to form a polymer
what is hydrolysis
breaks the bonds of polymers by the addition of water
what happens when electrons of the molecule are more highly concentrated around oxygen
- each hydrogen is slightly positive
- each water molecule has 2 slightly positive ends and 1 slightly
negative end
is water polar or non polar
polar
what are the properties of water
solvent
cohesion, adhesion and tension
moderation of temp
density (h-bond)
what is solvation
process by which a solid
dissolves into solution
what is hydration
individual cations and anions separated from each other and the solid is dissolved (NaCl is not kept as a molecular unit)
what is water able to dissolve
substances that are polar or ionic
what is water not able to dissolve
nonpolar substances
why can’t water dissolve nonpolar substances
water doesn’t dissolve lipids because lipids aren’t chaged and it’s attracted towards other water mocules that are charged
partial + charge of the hydrogen atoms attracts…
anions (ex: Cl-)
partial – charge of the oxygen atom attracts…
cations (ex: Na+)
are compounds made up of non-ionic polar molecules (sugars) water soluble
yes
what makes glucose polar
it’s because oxygen makes it electronegative
what about sugars makes them polar
by forming hydrogen bonds with the molecules on the outer surface, water progressively removes individual
monosaccharides from the solid and eventually a homogenous aqueous solution results
when can large molecules such as
proteins dissolve in water
if they have ionic and/or polar
regions on their surface (like
polar functional groups)
what does the degree of polarity for a protein depend on
the types of amino acids that
make it up
in which organisms is water the solvent
inside all cells
in blood
in plant sap
what is cohesion
how well molecules of the same substance stay together (water molecules have a strong tendency to stick to each other b/c of H-bonding)
why do plants use cohesion
to get water from the roots to the leaves, against the force of gravity.
evaporation exerts pulling force on water within what tissue
this force is relayed all the way down to the roots
what is adhesion
is the clinging of one substance to another, particularly if they have charged groups of atoms on their surface
what is adhesion responsible for
- adhesion is responsible for creating the meniscus on the sides of a
graduated cylinder - explains why water makes things wet (water clings to things)
what is surface tension
is the measure of how difficult it is
to break or stretch the surface of a
liquid (due to cohesion)
what is cohesion and adhesion the basis of
is the basis for the process of CAPILLARY ACTION, the tendency of
water to move in narrow tubes, even against the force of gravity
why does water have a strong surface tension
due to the strong attraction
between water molecules
(hydrogen bonds)
what helps explain the way
water responds to temperature changes
the hydrogen bonds found in water molecules
what are the 3 states water exists in
solid
liquid
gas
– these different states differ in their degree of hydrogen bonding
what breaks hydrogen bonds
when heat energy is added to water, it serves to break hydrogen bonds
reducing the degree of cohesion between the molecules
what is heat
the total amount of energy associated with the movement of
atoms and molecules in a body of matter
what is temperature
the average speed of molecules (not the total amount of heat energy in a body of matter)
what is specific heat
the amount of heat that must be absorbed or lost for 1 g of a substance to change in temperature by 1oC
does what have a high specific heat
yes, it can absorb a relatively large
amount of heat before its temp increases
what is able to do because of its high specific heat
water has a better ability to resist
temperature changes (acts like a temperature buffer) than most other substances on Earth, keeping temps within the range needed for life
how can water allow oceans, lakes, rivers, to maintain constant temps
water’s ability to absorb and
release energy with little
temperature change allows
oceans, to maintain constant
temps, creating a stable
environment for aquatic life
how does water moderate temp
- when water cools, the molecules of water slow down which gives them the chance to form h-bonds
- heat energy is released to the around env. when h-bonds are formed which slows down the cooling process of the water
is cooling water a slow process
yes
what is the proper term for sweating
evaporative cooling
what is evaporative cooling
when water is heated certain water molecules are released from H
bonds faster than others and begin to absorb more energy
–these molecules are the ones most likely to escape the liquid phase and enter the gas phase (turn into water vapour).
what is the point of human perspiration
We have the ability to perspire which cools the surface
of the skin.
how can the more stable h bonds be found
ice contains more stable hydrogen bonds than those found in water
why do ice crystals have fewer molecules than an equal volume of liquid water
since water molecules in ice keep themselves at a greater distance
than in its liquid form
what is the purpose of ice sheets in the ocean
since ice is less dense, it floats on
the surface of a body of liquid water,
enabling the water below it to not
freeze and life can carry on but if ice were to sink, the oceans would freeze from the bottom up making life unsustainable
what is ionization
in aqueous solutions most water molecules are intact but some of the water molecules can break apart or dissociate (H+ and OH-)
what happens when you change the concentrations of H+ and OH-
it can drastically affect a cell’s
content (proteins and other molecules) and an entire organism’s
functioning (maintenance of homeostasis depends on stable pH)
what is an acid
a substance that increases the H+ concentration of a solution (conversely OH- concentration decreases)
what is a base
a substance that reduces the H+ concentration of a solution (conversely increasing OH- concentration).
what is the pH of human blood
about 7.4 (range between 7.35 and 7.45) and must be maintained
within a very narrow limit or else protein structures will be unstable
change in pH…
alter the shape of proteins
(denaturation) and consequently their effectiveness and function
how can a substance resist the changes in pH
- accepting H+ ions when they are in excess
- donating H + ions when they are depleted.
what acts a buffer in human blood
carbonic acid/bicarbonate and certain proteins act as buffers in
human blood to help keep blood pH within normal range
why would blood pH below normal range rise
May arise due to respiratory
disease as they are not able to rid their bodies of CO2 fast enough (↑ [CO2] in the blood causes an ↑ in [H+], acidosis)
why would blood pH above normal range rise
may arise from hyperventilation as the individual is expelling too much CO2 (↓ [CO2] in the blood causes
an ↓ in [H+], alkalosis)
why does your rate of respiration increase when you exercise?
need more oxygen and trying to get rid of the CO2 that our body is producing, there is lactic acid build up in our muscles, respiratory system kicks in to regulate O2 and CO2 concentrations
what is the response to increased CO2 (respiratory depression)
respiratory centers in the brain will trigger an increase in breathing rate to exhale excess CO2 and restore pH
what is the response to decreased CO2 (hyperventilation)
respiratory centers will slow
down breathing rate in order to
accumulate CO2 in blood and
tissues
what happens in cases of acidosis (low pH)
the kidney will tend to excrete excess H+ into the urine and reabsorb HCO3-
what happens in cases of alkalosis (high pH)
the kidney will do the opposite and excrete HCO3- and reabsorb H+ back into the blood
what is ocean acidification
excess carbon dioxide from the burning of fossil fuels is causing acidification of water bodies and affecting the health of aquatic living organisms
– organisms that require calcium carbonate to make shells such as
corals are most affected.
