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ch.3
ch.3
66
Biology
Undergraduate 1
04/05/2008

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Term

what is the biological medium on earth?

Definition
water
Term
all living organism require ___ more than any other living substance
Definition
water
Term
most cells are surrounded by water and cells themselves are about __ water
Definition
70-95%
Term
The abundance of __is the main reason eath is habitable
Definition
water
Term
is water molecule polar or non-polar?
Definition
polar
Term
water is a polar molecule mearning?
Definition
the opposite ends have opposite charges
Term
__ allows water molecules to form hydrogen bonds with each other
Definition
Term
4 emergent properties of water that facilitate an environment for life are?
Definition

1. cohesive behavior

2. ability to moderate temperature

3.expansion upon freezing

4.versatility as a solvent

Term
vollectively hydrogen bonds hold water molecules together, a phemomenon called __
Definition
cohesion
Term

WHat helps the transport of water against gravity in plants?

Definition
cohesion and adhesion
Term
__ is a measure of how hard it is to break the surface of a liquid
Definition
surface tension
Term
how is surface tension related to cohesion
Definition

1. water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resis stretching or breaking the surface

2. water behaves as if covered by an invisible film

3. some animals can stand, walk, or run on water without breaking the surface

 

Term
how does water stabilize air temperatures?
Definition
water stabilizes air temperatures by absorbing heat from water airm and releasing heat to cooler air
Term

__ can absorb or release relatively large amounts of heat with only a slight change in its own temperature

Definition
water
Term
__ is the energy of motion
Definition
kinetic energy
Term
_ is a measure of the total amount of kinetic energy due to molecular motion
Definition

heat

Term

__ measures the intensity of heat due to the average kinetic energy of molecules

Definition
temperature
Term
the ___ of a substance is the amount of heat that must be absorbed or lost for 1 gram of that substabce to change its temperature by 1 degree celsius
Definition

the specific heat of a substance

Term
water's __ minimizes temperature fluctuations to within limits that permit life
Definition

water's high specific heat

Term
how does water's high specific heat minimize temperature fluctuations to within limits that permit life?
Definition

1. heat absorbed when hydrogen bonds break

2. heat is released when hydrogen bonds form

Term
__ is transformation of a substance from liquid to gas
Definition
evaporation
Term

_   is the heat a liquid must absorb for 1 gram to be converted to gas.

Definition
heat of vaporization
Term
as a liquid evaportates, its remaining surface cools, a process called
Definition
evaporation cooling
Term
___ helps stabilize temperatures in organisms and bodies of water
Definition
evaporation cooling of water
Term
why does ice float in liquid water?
Definition
because hydrogen bonds in ice are more "ordered," making ice less dense
Term
what would happen if ice sank?
Definition
if ice sank, all bodies of water would eventually freeze solid, making life impossible on earth
Term
instead, the surface water below which prevents what from happening?
Definition
instead, the surface layer of ice insulates liquid from below, preventing it from freezing and allowing life to exist under the frozen surface
Term
_ is a liquid that is homogenous miixture of substances
Definition
solution
Term
__ is the dissolving agent of a solution
Definition
solvent
Term
__ is a versatile solvent due to its polarity
Definition
water
Term

an __ solution is one which water is the solvent

Definition
aqueous solution
Term
why is water an effective solvent?
Definition
because it readily forms hydrogen bonds
Term
when an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a
Definition
hydration shell
Term
not only are ionic compounds dissolves in water, but water can also dissolve __ molecules
Definition
nonionic polar molecules
Term
even large molecules such as proteins can dissolve in water if they have?
Definition
ionic and polar regions
Term
a __ substance is one that has an affinity for water
Definition
hydrophilic
Term
a _ substance is one that does not have an affinity for water
Definition
hydrophobic
Term
most biochemical reactions occur in?
Definition
water
Term

___ depends on collisions of molecules and therfore on the concentration of solutes in an aqueous solution

Definition
chemical reactions
Term
_ is the sum of all masses of all atoms in a molecule
Definition
molecular mass
Term
numbers of molecules are usually measured in _
Definition
moles
Term
one mole is ___ molecules
Definition
6.02 x 10^23
Term
is the number of moles per solute per liter of solution
Definition

molarity

Term
a hydrogen atom in a hydrogen bond between two water molecules an shift from one to the other:
Definition

1. the hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H+).

2. the molecule wit the extra proton is now a hydronium ion (H30+).

3. the molecule that lost the proton is now a hydroxide ion (OH-)

Term

H20 + H20 → H30+ + OH-

this process can be described in a simplified way as?

Definition
the seperation of a water molecule into a hydrogen ion (H+) and a hydroxide ion (OH-)
Term
though statisically rare, the __ has a great effect on organisms
Definition
the dissociation of water molecules
Term

Changes in concentrations of _ and _can drastically affect the chemistry of a cell.

Definition
H+ and OH-
Term
concentration of H+ and OH- are equal in?
Definition
pure water
Term
adding solutes called acids and bases, modifies?
Definition

modifies the concentration of H+and OH-

Term
biologist use something called __, to describe how acidic or basic a solution is
Definition
pH scale
Term
an _ is any substance that increases the H+ concentration of a solution
Definition
acid
Term
_ is any substance that reduces the H+ concentration of a solution
Definition
base
Term
the pH of a solution is determined by?
Definition
the relative concentration of hydrogen ions
Term
acid solutions have pH values?
Definition
less than 7
Term

basic solutions have pH values of?

Definition
greater than 7
Term
most biological fluids have pH values in the range of?
Definition
6-8
Term

the internal pH of most living cells must remain close to pH of ?

 

Definition
7
Term
_ are substances tha minimize changes in concentrations of H+ and OH- in a solution
Definition
buffers
Term
most buffers consist of?
Definition
an acid-base pair that reversibly combines with H+
Term

one important buffer in human blood and other biological solutions is ?

Definition
cabronic acid
Term
the chemical equilibrium between carbonic acid and bicarbonate acts as a?
Definition
pH regulator
Term
how does the equilibrium shift?
Definition
the equilibrium shifts right or left as other metabolic processes add or remove H+ from the solution
Term

_ refers to rain, snow, or fog with a pH lower than 5.6

Definition
acid precipitation
Term
__ is caused mainly by the mixing of different pollutants with water in the air
Definition
acid precipitation
Term

_ can damage life in lakes and steams

Definition
acid precipitation
Term
effects of acid precipitation on soil chemistry are contributing to ?
Definition
the decline of some forests
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