Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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Atoms are composed of
a. | protons with a positive charge. | b. | neutrons with no charge. | c. | electrons with a
negative charge. | d. | All of the above |
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2.
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The smallest particle of carbon that can retain the chemical properties of
carbon is
a. | a carbon molecule. | b. | a carbon macromolecule. | c. | a carbon
atom. | d. | the nucleus of a carbon atom. |
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3.
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A substance that is composed of only one type of atom is called a(n)
a. | nucleus. | c. | element. | b. | cell. | d. | molecule. |
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4.
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All matter in the universe is composed of
a. | cells. | c. | atoms. | b. | molecules. | d. | carbon. |
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5.
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The electrons of an atom
a. | are found in the nucleus along with the protons. | b. | orbit the nucleus in
various energy levels. | c. | have a positive charge. | d. | are attracted to the
positive charge of neutrons. |
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6.
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Atoms that have gained energy
a. | have protons and neutrons that move farther apart. | b. | lose neutrons from
the nucleus. | c. | have electrons that move to higher energy levels. | d. | absorb electrons
into the nucleus. |
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7.
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Which of the following states of matter contain(s) particles that are tightly
linked together in a definite shape?
a. | solid | c. | gas | b. | liquid | d. | solid and
liquid |
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8.
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Because carbon has four electrons in its outer energy level,
a. | it can form bonds with carbon atoms only. | b. | these atoms are
naturally chemically stable. | c. | it can react with up to four other atoms to
form covalent bonds. | d. | it cannot react with anything other than
organic molecules. |
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9.
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The bond formed when two atoms share a pair of electrons is called a
a. | hydrogen bond. | c. | covalent bond. | b. | nonpolar bond. | d. | water bond. |
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10.
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Sharing of electrons between atoms of two or more elements
a. | results in the formation of an ion. | b. | results in the formation of a
compound. | c. | results in the formation of noble gases. | d. | results in
destabilization of the atoms involved. |
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11.
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An atom that has gained or lost electrons is called a(n)
a. | molecule. | c. | ion. | b. | nucleon. | d. | element. |
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12.
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Which of the following statements most accurately describes the difference
between an ionic bond and a covalent bond?
a. | Atoms held together by ionic bonds separate when placed in water, while atoms held
together by covalent bonds do not separate in water. | b. | Ionic bonds hold together atoms of two
different types, while covalent bonds hold together atoms of the same type. | c. | Electrons are
exchanged between atoms held together by an ionic bond, but they are shared between atoms held
together by a covalent bond. | d. | Ionic bonds form between atoms that carry
opposite charges, while covalent bonds form between uncharged atoms. |
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13.
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Refer to the graph above. Reaction 1 in the graph
a. | is an energy-storing reaction. | b. | requires a greater activation energy than
reaction 2. | c. | may use the same initial reactant condition needed to form product
Y. | d. | All of the above |
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14.
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Refer to the graph above. Reaction 3 in the graph
a. | probably occurred in the presence of a catalyst. | b. | requires a greater
activation energy than reaction 2. | c. | is the same as reaction 1, but
faster. | d. | takes longer than reaction 2. |
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15.
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Refer to the graph above. Which of these statements regarding the graph is
true?
a. | Reaction 2 occurs faster than reaction 3 because reaction 2 requires more energy than
reaction 3. | b. | The difference in the graphs shown for reaction 2 and reaction 3 is due to a
difference in the activation energy needed for these reactions. | c. | Reactant X contains
more energy at the beginning of the reaction than product Z has after the
reaction. | d. | All of the above |
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16.
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Changing the course or pathway of a chemical reaction so that it requires less
activation energy
a. | is a violation of the laws of nature. | b. | requires higher temperatures than those found
within cells. | c. | occurs only when reactants are quickly added to the reaction
mixture. | d. | is accomplished by the action of catalysts on
reactants. |
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17.
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Enzymes
a. | are able to heat up molecules so that they can react. | b. | provide
CO2 for chemical reactions. | c. | are biological catalysts. | d. | absorb excess heat
so that reactions occur at low temperatures. |
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18.
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A single organism may contain
a. | thousands of different enzymes, each one specific to a different chemical
reaction. | b. | one enzyme that plays a role in thousands of different chemical
reactions. | c. | approximately 100 kinds of enzymes, each one specific to a different chemical
reaction. | d. | one enzyme that is specific to photosynthesis and one enzyme that is specific to
cellular respiration. |
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19.
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When a molecule gains an electron, it has been
a. | oxidized. | c. | digested. | b. | reduced. | d. | inactivated. |
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20.
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Oxidation-reduction reactions are important in organisms because they
a. | allow the passage of energy from molecule to molecule. | b. | prevent nuclear
reactions from occurring. | c. | allow the creation and destruction of
energy. | d. | None of the above; oxidation-reduction reactions do not occur in living
organisms. |
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21.
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The concentration of a solution is
a. | the number of particles of a substance in a solvent. | b. | the amount of a
solvent that is dissolved in a fixed amount of a solution. | c. | the amount of a
solute that is dissolved in a fixed amount of a solution. | d. | the ratio of solute
to solvent in a solution. |
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22.
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A neutral solution has an equal number of
a. | hydrogen and hydronium ions. | b. | hydroxide and hydronium
ions. | c. | hydrogen and hydroxide ions. | d. | oxygen and hydrogen
ions. |
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23.
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The terms base and alkaline refer to solutions that
a. | contain dissolved sodium hydroxide. | b. | contain more hydronium ions than hydroxide
ions. | c. | contain more hydroxide ions than hydronium ions. | d. | contain more
hydroxide ions than hydrogen ions. |
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24.
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A solution with a pH of 11 is
a. | acidic. | c. | neutral. | b. | alkaline. | d. | a buffer. |
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25.
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Acidic solutions have a pH that is
a. | less than 7. | c. | a negative number. | b. | between 0 and 14. | d. | more than 7. |
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26.
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Buffers
a. | are of relatively little importance in living things. | b. | are formed when a
large number of hydroxide ions are released in a solution. | c. | are formed when a
large number of hydronium ions are released in a solution. | d. | tend to prevent
great fluctuations in pH. |
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27.
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Atoms become more stable when they form compounds because
a. | they always lose electrons when they form compounds. | b. | their outer orbitals
become filled when they form compounds. | c. | they always gain electrons when they form
compounds. | d. | their nucleus loses extra protons when they form
compounds. |
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28.
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A water molecule is polar because its hydrogen and oxygen atoms
a. | both lose electrons. | b. | become ions. | c. | both gain
electrons. | d. | do not share the electrons equally. |
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29.
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Polar molecules such as water have
a. | no negative or positive poles. | b. | both negative and positive
poles. | c. | only a negative pole. | d. | only a positive
pole. |
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30.
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A molecule that has a partial positive charge on one side and a partial negative
charge on the other side is called a
a. | nonpolar molecule. | c. | charged molecule. | b. | polar molecule. | d. | bipolar
molecule. |
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31.
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Water is a polar molecule because
a. | it contains two hydrogen atoms for each oxygen atom. | b. | it has a
charge. | c. | different parts of the molecule have slightly different charges. | d. | it does not have a
charge. |
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32.
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Water molecules break up other polar substances
a. | such as salts. | b. | because of the uneven charge distribution that
exists in water molecules. | c. | thus freeing ions in these substances for use
by the body. | d. | All of the above |
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33.
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Which of the following characteristics of water is not a result of
hydrogen bonding?
a. | adhesive strength | b. | capillarity | c. | cohesive
strength | d. | All of the above are a result of hydrogen bonding. |
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Completion
Complete each
statement.
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34.
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Substances that are changed when they become involved in chemical reactions are
called ____________________, while the new substances that are formed are called
____________________.
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35.
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The energy needed to break existing chemical bonds during the initiation of a
chemical reaction is called ____________________.
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36.
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Chemical reactions in the body can be speeded up by adding a(n)
____________________, which lowers the amount of activation energy required to start the
reaction.
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37.
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The loss of electrons from a molecule is called ____________________, while the
gain of electrons by a molecule is called ____________________.
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38.
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A substance that dissolves in another is called a(n)
____________________.
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39.
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____________________ is the most common solvent in cells.
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40.
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____________________ and ____________________ ions form when water
dissociates.
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41.
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An acidic solution is one that has more ____________________ than
____________________ ions.
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42.
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A solution with a pH of 3 has ____________________ times more hydronium ions
than a solution with a pH of 6.
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43.
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Buffers are important because body fluids must be maintained within a relatively
narrow range of ____________________.
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44.
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Water is very effective at dissolving other polar substances because of its
____________________.
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45.
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Breaking of ____________________ bonds is the first thing that happens when
water is heated, which means that it takes a great deal of thermal energy to raise the temperature of
water.
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Problem
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46.
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Refer to the illustration above. The
graph depicts the relative energy levels of the products and reactants for the following chemical
reaction: A + B  C + D. Write your answers to the following in
the spaces below.
a. Which substances,
A, B, C, and/or D, are present at point 1 on the graph?
b. Which
substances, A, B, C, and/or D, are present at point 3 on the
graph?
c. Why is point 2 at a higher energy level than point
1?
d. Why is point 3 at a lower energy level than point
1?
e. Draw a dashed line on the graph indicating how the energy
level of this reaction over time would be different if the enzyme that catalyzes the reaction were
not present.
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Essay
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47.
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Plant growers often use sprinkler irrigation to protect crops they are growing
from frost damage. The water that lands on the leaves turns to ice. How does this protect the plants
from frost damage? Write your answer in the space below.
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48.
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Define enzyme, and describe how an enzyme can function in speeding up a
chemical reaction within a cell. Write your answer in the space below.
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49.
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How does water’s polar nature affect its ability to dissolve different
substances? Write your answer in the space below.
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50.
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Explain the relationship between hydrogen bonding and the observation that a
full sealed bottle of water breaks when it freezes. Write your answer in the space below.
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