Name: ___KEY__________________________________ Period: __________
Study Guide: The Chemical Basis for Life
Part I: Water, Acids, and Bases
1. Vocabulary to know:
A. Acid
solution with a pH lower than 7; has more more H+
ions than OH- ions
B. Adhesion
Water also sticks to other substances because of its
unique bonding properties; When a molecule is
attracted to a different molecule
C. Base
solution with a pH higher than 7; has more more OHions than H+ ions
D. Capillarity
Because of their adhesive and cohesive properties
water molecules can move against gravity and stream
upwards in enclosed surroundings
E. Cohesion
If you drop a tiny amount of water onto a very
smooth surface, the water molecules will stick
together and form a droplet, rather than spread out
over the surface; Cohesion is the attraction of one
molecule to a similar molecule.
F. pH
scale that is used to measure acidity or alkalinity
G. Polarity
difference in electrical charge between different parts
of the same molecule
H. Solute
Substance that dissolves in a solution
I. Solution
mixture that has the same composition throughout
J. Solvent
Substance that causes a solute to dissolve in a
solution
2. What gives a water molecule polarity? Draw a water molecule below showing the properties that make a water
molecule polar.
The differences in electrical charges of the oxygen and hydrogen atoms; oxygen is slightly negative and the
hydrogen is slightly positive
3. Which of the following effects is produced by the high surface tension of water?
A. Lakes do not freeze solid in winter despite low temperatures.
B. A water strider can walk across the surface of a small pond.
C. Water can act as a solvent.
D. The pH of water remains exactly neutral.
4. If you mix sugar into water until it is totally dissolved, what is the solute? _sugar__________________________
The solvent? _water________________________ The solution? _sugar-water____________________________
REFRESHER: Know and understand the pH scale!!!!
In pure water there are an equal number of H+ ions and OH- ions. The amount or number of H+
ions to OH- ions determines the pH of a substance or whether the substance is acid, base or neutral. This
brings us to the pH scale. The pH scale ranges from 0 to 14, where 0 is the pH of very strong acids and 14
is the pH of very strong bases. Pure water has a pH of 7 and is a neutral solution, which means it is
neither acidic nor basic. The lower the pH of a solution the more acidic it is and the higher the pH of a
solution the more basic it is.
A solution of lemon juice or Coca-cola that has a pH of 2 is more acidic than Seven-up which has a
pH of 4. However, lemon juice is not twice as acidic as Coca-Cola! The lemon juice with a pH of 2 is
actually one hundred times more acidic than the Seven-up with a pH of 4 and has one hundred times
more H+ ions! The pH scale is based on an increase or decrease by a power of ten. Root beer is ten times
more acidic than pure water! Pure water has a pH of 7 and root beer has a pH of 6, the one unit difference
from 7 to 6 means that there is a ten times difference in strength and 10 times the number of H+ ions. A
solution of pH 5 has a 2 unit change with water (from 7 to 5), so it is 10x10 or one hundred times as
acidic as water.
pH Scale
Pure
Water
More acidic
More basic
1. Draw an arrow showing the direction in which substances become more acidic.
2. Draw an arrow showing the direction in which substances become more basic.
3. Complete the following problems, show your work.
a. Look at Orange juice and Coffee on the pH scale above. Which substance is more acidic? How much
more acidic is this substance than Pure Water?
OJ: pH = 3; Coffee: pH = 5
OJ more acidic four space difference = 10 X 10 X 10 X 10 = 10,000 X
b. Look at Bleach and Sea Water on the pH scale above. Which substance is more basic?
Bleach is more basic
c.
How much more basic is Sea Water than Pure Water?
One space = 10 X
Part II: Matter and Organic Compounds
1. Vocabulary to know:
K. Chemical bond
L. Chemical formula
M. Chemical reaction
N. Disaccharide
O. Element
P. Energy
Q. Isomers
R. Organic compound
S. Saturated fatty acids
T. States of matter
U. Unsaturated fatty acids
2. Where is energy stored in chemical compounds?
In chemical bonds; it is released when they are broken
force that holds molecules together; when these are
made energy is stored and when they are broken
energy is released
Scientific way of using chemical symbols with coefficients and subscripts to denote a chemical
compounds composition. Ex: H2O for water
process that changes some chemical substances into
others
Formed when two monosaccharides (two sugars)
combined
pure substance that cannot be broken down into
other types of substances
The ability to do work
Chemical compounds that have the same chemical
formula but are chemically structured differently
compound found in living things that contains mainly
carbon
Form straight chains; solid at room temperature
Gas, liquid, or solid…Temperature and pressure cause
changes in states of matter
Form bent chains; liquids at room temperature
3. List all four types of organic compounds and their monomers.
Carbohydrates monosaccharides
Lipids fatty acids & glycerol
Proteins amino acids
Nucleic acids nucleotides
4. What elements are found in all of the biological macromolecules shown above?
A. Carbon, Hydrogen, Phosphorous
B. Carbon, Hydrogen, Oxygen
C. Carbon, Hydrogen, Nitrogen
D. Carbon, Nitrogen, Sulfur
5. Which statement correctly describes how carbon’s ability to form four bonds makes it uniquely suited to form
macromolecules?
A. It forms short, simple carbon chains.
B. It forms large, complex, diverse molecules.
C. It forms covalent bonds with other carbon atoms.
D. It forms covalent bonds that can exist in a single plane.
6. List the main function of each organic compound.
Carbohydrates energy storages
Lipids waterproofing; make up cell membranes
Proteins helps cells keep their shape, makes up muscles, speeds up chemical reactions (enzymes), carries
messages and materials
Nucleic acids Contains instructions for making proteins, passes instructions from parents to offspring, helps
make proteins
7. What are the three parts of an amino acid? Label them on the drawing below. What organic compound is this a
monomer for? _protein_____________________
Amino (amine)
group; NH2
O
O
Carboxyl
(carboxylic) acid
group; COOH
R group/
Radical group/
Side group
(chain)
8. What are the three parts of a nucleotide? Label them on the drawing below. What organic compound is this a
monomer for? _nucleic acid_____________________
Phosphate group
Nitrogenous base
5-C sugar/Pentose
9. What are the differences between a saturated fatty acid and an unsaturated fatty acid?
Saturated: Form straight chains b/c carbon atoms are bonded to as many H atoms as possible; store energy in
compact form; solid at room temperature; Animals use these to store energy
Unsaturated: Form bent chains b/c some C atoms (double bond) are not bonded to as many H atoms as
possible; store energy; liquid at room temperature; Plants use these to store energy
10. What are ‘essential’ amino acids?
Amino acids that the human body cannot make; must consume; 8 of them
HO—1—2—3—H + HO—4—H
HO—1—2—3—4—H + H2O
11. The diagram above shows a reaction that forms a polymer from two monomers. What is this type of reaction
called?
A. Glycolysis
B. Hydrolysis
C. Photosynthesis
D. Dehydration synthesis
Part II: Biochemical Reactions
1. Vocabulary to know:
2. Activation energy
3. Catalysts
4. Endothermic reaction
5. Enzyme
energy needed to start a chemical reaction
Speeds up a reaction; ex: enzymes
Chemical reaction that absorbs energy
protein that speeds up biochemical reactions
6. Exothermic reaction
7. Metabolism
Chemical reaction that releases energy
sum of all the biochemical reactions in an organism;
building up and breaking down of chemical
compounds
8. Product
substance that forms as the result of a chemical
reaction
9. Reactant
starting material in a chemical reaction
10. Substrates
The chemical molecule that has an active site for an
enzyme to bond with in a chemical reaction
2. What happens to the enzyme-substrate complex when it is denatured?
Enzyme changes shape and can no longer fit into the active site on the substrate. Denaturation caused by heat,
acid (pH), or force.
3. Explain what is happening in the graph below; which reaction is catalyzed, which reaction is not catalyzed, which
reaction needs more energy to get started, and which reaction needs less energy to get started?
Reaction A  not catalyzed (without enzyme); needs more
activation energy to get started; takes longer to happen
Reaction A
Reaction B
Reaction B catalyzed (with enzyme); needs less activation
energy to get started; happens more rapidly
4. List the characteristics of an enzyme.
Characteristics

Activation energy – enzymes reduce the amount of activation energy needed to start a reaction
For chemical reactions to take place, the reactants must collide with enough energy so that existing bonds will
be broken and new bonds will be formed.

Rate of reaction – is sped up with an enzyme present because less activation energy is needed; without them
some reactions would take days to happen not a split second as they do with enzymes
Works on – substrate (reactants of enzyme-catalyzed reactions)
Connects at – active site on the enzyme (which is complementary to a site on the substrate)
Sometimes named – catalysts; enzyme-substrate complex; lock-n-key model
Are made of – proteins by cells that act as biological catalysts
Are NOT – consumed by the reaction and can work over and over again
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5. How do enzymes help in metabolic processes?
They speed up the reaction rates by lowering the amount of activation energy needed