Category: Biochemistry of Organisms

Quiz – Biochemistry

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Biochemistry Quiz
1. All of the following are carbohydrates EXCEPT:
starch
glycogen
chitin
cholesterol2. The structure contains which functional group
aldehyde
ketone
amino
carboxyl

3. Fatty acids that are unsaturated have:
an amino group
a double bond
an excess of protons
a carboxyl group

4. The structure below is a:


monosaccharide
disaccharide
lipid
polymer

5. Which of the following can have a quaternary structure?
fatty acid
protein
polysaccharide
DNA

6. An organic compound is one that:
contains carbon
is slightly acidic
forms long chains
is soluble in water

7. Which of the following elements is the LEAST abundant in living organisms?
oxygen
nitrogen
phosphorous
sodium

8. Which of the following is used in PET scans?
uranium
ions
isotopes
steroids

9. Carbon can form ___ separate bonds with other elements?
1
2
3
4

10. The cohesion of water is caused by:
ionic bonds
hydrophobic compounds
hydrogen bonds
covalent bonds

Score =
Correct answers:

 

 

 

PCC Biochemistry

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True/False
Indicate whether the statement is true or false. Write  + for true and  0 for false.
 1.
Atoms have a positive charge.
 2.
An element is made up of more than one kind of atom.
 3.
Hydrogen and oxygen atoms have an equal number of electrons.
 4.
A molecule is an atom that has gained or lost an electron.
 5.
An atom that gains or loses one or more electrons is called an ion.
 6.
An atom with more electrons than protons has a positive charge.
 7.
Ionic bonds form between two negatively charged particles.
 8.
A covalent bond forms between two atoms that share electrons to form a molecule.
 9.
Adhesion is an attraction between different substances.
 10.
The ability of water to retain heat helps cells maintain homeostasis.
 11.
Nonpolar molecules dissolve well in water.
 12.
Water molecules attract nonpolar molecules such as oil.
 13.
Organic compounds contain carbon atoms that are covalently bonded to other elements—typically hydrogen, oxygen, and other carbon atoms.
 14.
A nucleotide has four parts.
 15.
RNA is made up of a double strand of nucleotides.
 16.
DNA stores hereditary information that can be used to make proteins.
 17.
When cells break down food, the energy from the food is temporarily stored as ATP.
 18.
The amount of energy needed to cause a chemical reaction to start is called activation energy.
 19.
Without enzymes, chemical reactions necessary for life would not occur at a rate sufficient to sustain life.
 20.
Enzymes speed up a chemical reaction by increasing the activation energy of the reaction.
 21.
When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is increased.
 22.
Chemical reactions that occur in cells are called biochemical reactions.
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 23.
Atoms are composed of
a.
 protons.
c.
 electrons.
b.
 neutrons.
d.
 All of the above
 24.
The electrons of an atom
a.
 are found in the nucleus along with the protons.
b.
 occupy the space surrounding the nucleus.
c.
 have a positive charge.
d.
 are attached to the positive charge of neutrons.
 25.
The smallest particle of matter that can retain the chemical properties of carbon is a(n)
a.
 carbon molecule.
c.
 carbon atom.
b.
 carbon macromolecule.
d.
 element.
 26.
A substance that is composed of only one type of atom is called a(n)
a.
 nucleus.
c.
 element.
b.
 cell.
d.
 molecule.
 27.
All matter is composed of
a.
 cells.
c.
 atoms.
b.
 molecules.
d.
 carbon.
 28.
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.
 29.
A chemical formula shows the
a.
 kinds of bonds found in the molecule.
b.
 kinds of bonds found in the compound.
c.
 kinds of elements found in the compound.
d.
 arrangement of the elements found in the compound.
 30.
Ionic bonds form between molecules that have
a.
 opposite charges.
c.
 no charges.
b.
 the same charge.
d.
 neutral charges.
 31.
The bond formed when two atoms share a pair of electrons is called a(n)
a.
 hydrogen bond.
c.
 covalent bond.
b.
 ionic bond.
d.
 water bond.
 32.
Sharing of electrons in the outer energy levels of two atoms
a.
 results in ion formation.
b.
 occurs in covalent bonds.
c.
 only occurs if both are atoms of the same element.
d.
 is found only among carbon atoms.
 33.
Water is important to life because it
a.
 surrounds all cells.
b.
 is found inside cells.
c.
 influences the shape of the cell membrane.
d.
 All of the above
 34.
Nonpolar molecules have
a.
 no negative or positive poles.
c.
 only a negative pole.
b.
 both negative and positive poles.
d.
 only a positive pole.
 35.
When placed in the same container, oil and water do not mix because
a.
 they are both polar.
c.
 they are both nonpolar.
b.
 water is polar and oil is nonpolar.
d.
 water is nonpolar and oil is polar.
 36.
Due to the polarity of water, compounds that dissolve best in water contain
a.
 nonpolar bonds.
c.
 polar bonds.
b.
 ionic bonds.
d.
 Both (b) and (c)
 37.
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.
 38.
Acidic solutions have a pH that is
a.
 less than 7.
c.
 a negative number.
b.
 between 7 and 14.
d.
 more than 7.
 39.
Hydrogen ions, H+, react with hydroxide ions, OH-, to form
a.
 water.
c.
 a base.
b.
 an acid.
d.
 None of the above
 40.
Which of the following is not an organic macromolecule?
a.
 carbohydrate
c.
 lipid
b.
 ice
d.
 nucleic acid
 41.
All organic compounds contain the element
a.
 carbon.
c.
 calcium.
b.
 nitrogen.
d.
 sodium.
 42.
Which of the following organic molecules are classified as carbohydrates?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 43.
Polysaccharides are
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 unsaturated fats.
 44.
Lipids are
a.
 polar molecules.
c.
 water soluble.
b.
 similar to water molecules.
d.
 nonpolar molecules.
 45.
Which of the following organic molecules are most closely related to proteins?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 46.
Long chains of amino acids are found in
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 sugars.
 47.
All of the following are examples of lipids except
a.
 saturated fats.
c.
 cholesterol.
b.
 starch.
d.
 earwax.
 48.
Lipids are soluble in
a.
 water.
c.
 oil.
b.
 salt water.
d.
 All of the above
 49.
Which organic molecules below are most closely related to lipids?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 50.
Which of the following organic molecules are most closely related to nucleic acids?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 51.
Which of the following is a carbohydrate?
a.
 DNA
c.
 wax
b.
 insulin
d.
 sucrose
 52.
Carbohydrates and lipids have many carbon-hydrogen bonds; therefore, they both
a.
 store energy in these bonds.
c.
 dissolve only in vinegar.
b.
 are easily dissolved in water.
d.
 exist only in cells of plants.
nar001-1.jpg
nar001-2.jpg
Molecule A
Molecule B
 53.
Refer to the illustration above. Molecules like Molecule B are found in
a.
 carbohydrates.
c.
 nucleic acids.
b.
 lipids.
d.
 proteins.
 54.
Liquid fats called oils contain
a.
 mostly unsaturated fatty acids.
c.
 many glucose molecules.
b.
 mostly saturated fatty acids.
d.
 amino acids.
 55.
Animals store glucose in the form of
a.
 cellulose.
c.
 wax.
b.
 glycogen.
d.
 lipids.
 56.
The shape of a protein is primarily determined by
a.
 the type and sequence of its amino acids.
b.
 its size.
c.
 its cell location.
d.
 None of the above
 57.
The two types of nucleic acids are
a.
 chlorophyll and retinal.
c.
 lipids and sugars.
b.
 DNA and RNA.
d.
 glucose and glycogen.
 58.
DNA stores
a.
 fat.
c.
 protein.
b.
 carbohydrates.
d.
 heredity information.
 59.
The two strands of a DNA molecule are held together by
a.
 ionic bonds.
c.
 hydrogen bonds.
b.
 covalent bonds.
d.
 None of the above
 60.
A molecule shaped like a spiral staircase (double helix) is typical of
a.
 deoxyribonucleic acid.
c.
 lipids.
b.
 ribonucleic acid.
d.
 carbohydrates.
 61.
ATP (adenosine triphosphate) stores energy for cells to use in the bonds between its
a.
 amino acids.
c.
 nucleotides.
b.
 carbon atoms.
d.
 phosphates.
nar002-1.jpg
 62.
Refer to the illustration above. Which graph illustrates what happens during an energy-releasing reaction?
a.
 Graph A
b.
 Graph B
c.
 both graphs because they each show a different stage of an energy releasing reaction
d.
 None of the above
 63.
Refer to the illustration above. Which graph illustrates a reaction during which energy is released?
a.
 Graph A
b.
 Graph B
c.
 both graphs because all chemical reactions release energy
d.
 None of the above
nar003-1.jpg
 64.
Refer to the illustration above. Which of the following 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 between the graphs shown for Reaction 2 and Reaction 3 is because of a difference in the activation energy of these reactions.
c.
 Reactant A contains more energy at the beginning of the reaction than product C has after the reaction.
d.
 All of the above
 65.
Refer to the illustration above. Reaction 3 in the graph
a.
 probably occurred in the presence of a catalyst.
b.
 requires more activation energy than Reaction 2.
c.
 is the same as Reaction 1, but faster.
d.
 is slower than Reaction 2.
 66.
The molecule on which an enzyme acts is called a(n)
a.
 active site.
c.
 organic molecule.
b.
 inactive site.
d.
 substrate.
 67.
An enzyme
a.
 is not used up when catalyzing a reaction.
b.
 lowers the activation energy of a reaction.
c.
 bonds with a substrate molecule at the enzyme’s active site.
d.
 All of the above
 68.
Which of the following conditions affects the function of enzymes?
a.
 pH
c.
 enzyme concentration
b.
 heat
d.
 All of the above
 69.
Reducing 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.
 70.
Enzymes
a.
 are able to heat up molecules so that they can react.
b.
 always provide carbon dioxide for chemical reactions.
c.
 are biological catalysts.
d.
 absorb excess heat so that reactions occur at low temperatures.
 71.
A cell contains
a.
 thousands of different kinds of enzymes, each promoting a different chemical reaction.
b.
 one kind of enzyme that promotes thousands of different chemical reactions.
c.
 approximately 100 kinds of enzymes, each promoting a different chemical reaction.
d.
 one enzyme that promotes photosynthesis and one enzyme that promotes cellular respiration.
 72.
Amylase is a digestive enzyme that breaks down starch into
a.
 amino acids.
c.
 glycogen.
b.
 glucose.
d.
 cellulose.
 73.
The digestive enzyme pepsin works with hydrochloric acid to break down proteins in the stomach. Pepsin probably works best at a pH of
a.
 11.
c.
 3.
b.
 7.
d.
 Both (b) and (c).

 
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PCC Biochemistry 2011

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Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
The three particles that make up atoms are
a.
 protons, neutrons, and isotopes.
c.
 positives, negatives, and electrons.
b.
 neutrons, isotopes, and electrons.
d.
 protons, neutrons, and electrons.
 2.
The space surrounding the nucleus of an atom contains
a.
 protons.
c.
 neutrons.
b.
 electrons.
d.
 ions.
 3.
Democritus believed that atoms
a.
 were composed of electrons.
c.
 could be divided.
b.
 were composed of protons.
d.
 could not be divided.
 4.
If an atom contains 3 protons, 4 neutrons,  and 3 electrons, its mass number would be
a.
 3.
c.
 7.
b.
 4.
d.
 11.
 5.
If a chlorine atom had 17 protons and 18 neutrons, it would be called
a.
 chlorine-17.
c.
 chlorine-35.
b.
 chlorine-18.
d.
 chlorine-1.
 6.
Isotopes are atoms of the same element with the same number of protons and
a.
 a different number of electrons.
c.
 a different number of neutrons.
b.
 a different number of molecules.
d.
 the same number of neutrons.
 7.
Which of the following is a use of radioactive isotopes?
a.
 can determine the ages of rocks and fossils
b.
 can be used to treat cancer and kill bacteria that cause food to spoil
c.
 can be used as “tracers” to follow the movements of substances within organisms
d.
 all of the above
 8.
If an atom contains 11 protons and 12 neutrons, its atomic number is
a.
 1.
c.
 12.
b.
 11.
d.
 23.
 9.
Which of the following terms describes a substance formed by the combination of two or more elements in definite proportions?
a.
 compound
c.
 nucleus
b.
 isotope
d.
 enzyme
 10.
Which of the following makes up a molecule of water?
a.
 one atom of hydrogen and one atom of oxygen
b.
 one atom of sodium and one atom of chlorine
c.
 one atom of hydrogen and two atoms of oxygen
d.
 two atoms of hydrogen and one atom of oxygen
 11.
Which of the following is NOT true about chlorine?
a.
 It is a poisonous, greenish gas.
b.
 It combines with sodium to form table salt.
c.
 It was used to kill many soldiers in World War I.
d.
 It is not reactive.
 12.
Which of the following statements about a compound is true?
a.
 The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed.
b.
 Only the physical properties of a compound are usually the same as those of the elements from which it is formed.
c.
 Only the chemical properties of a compound are usually the same as those of the elements from which it is formed.
d.
 The physical and chemical properties of a compound are usually the same as those of the elements from which it is formed.
 13.
A covalent bond is formed as the result of
a.
 transferring electrons.
c.
 transferring protons.
b.
 sharing an electron pair.
d.
 sharing a proton pair.
 14.
Which term does NOT apply to sodium chloride?
a.
 molecule
c.
 compound
b.
 ionic bonding
d.
 crystal
 15.
What type of electron is available to form bonds?
a.
 valence
c.
 ionic
b.
 nucleus
d.
 covalent
 16.
What type of ion forms when an atom loses electrons?
a.
 neutral
c.
 negative
b.
 positive
d.
 possibly positive or negative
 17.
Ice floats on water because
a.
 of cohesion.
c.
 water shrinks when it freezes.
b.
 ice has a higher density than water.
d.
 water expands when it freezes.
 18.
The most abundant compound in most living things is
a.
 carbon dioxide.
c.
 sodium chloride.
b.
 water.
d.
 sugar.
 19.
Water molecules are polar, with the
a.
 oxygen side being slightly positive and the hydrogen side being slightly negative.
b.
 oxygen and hydrogen sides being slightly positive.
c.
 oxygen and hydrogen sides being slightly negative.
d.
 oxygen side being slightly negative and the hydrogen side being slightly positive.
 20.
In a water molecule, shared electrons spend more time around the oxygen atom than the hydrogen atoms.  As a result, the oxygen atom is
a.
 slightly negative.
c.
 slightly positive.
b.
 very negative.
d.
 very positive.
 21.
A solution is a(an)
a.
 combination of isotopes.
b.
 chemical reaction.
c.
 evenly distributed mixture of two or more substances.
d.
 combination of two or more liquids.
 22.
If you stir salt into boiling water, you produce a
a.
 mixture called a suspension.
c.
 solution and suspension.
b.
 mixture called a solution.
d.
 mixture only.
 23.
When salt is dissolved in water, water is the
a.
 reactant.
c.
 solute.
b.
 solution.
d.
 solvent.
 24.
While preparing a cell culture, a scientist places a colony of bacteria into distilled water and stirs it up.  This mixture of water and living cells would best be called a(an)
a.
 solution.
b.
 suspension.
c.
 buffer.
d.
 adhesion.
 25.
If the pH of stomach acid and of oven cleaner were measured,
a.
 both would be below 7.
b.
 both would be above 7.
c.
 the pH of stomach acid would be above 7, but the pH of oven cleaner would be below 7.
d.
 the pH of stomach acid would be below 7, but the pH of oven cleaner would be above 7.
 26.
A map of eastern North America, showing the pH of rainfall in the various states, indicates that the pH of rain in New York State varies from 4.22 to 4.40. According to these figures, the most acidic rainfall in New York State has a pH of
a.
 4.22.
c.
 4.35.
b.
 4.30.
d.
 4.40.
 27.
A substance with a pH of 6 is called
a.
 an acid.
c.
 both an acid and a base.
b.
 a base.
d.
 neither an acid nor a base.
 28.
Solutions that contain concentrations of H+ ions lower than pure water
a.
 have pH values below 7.
c.
 are bases.
b.
 are acids.
d.
 are enzymes.
 29.
Amino acid is to protein as
a.
 fat is to lipid.
c.
 sugar is to fat.
b.
 DNA is to RNA.
d.
 simple sugar is to starch.
 30.
A monosaccharide is a
a.
 carbohydrate.
c.
 nucleic acid.
b.
 lipid.
d.
 protein.
 31.
Which of the following is NOT a monomer?
a.
 a glucose molecule
c.
 a nucleotide
b.
 an amino acid
d.
 a protein
 32.
Which of the following is NOT a function of proteins?
a.
 store and transmit genetic information
b.
 help to fight disease
c.
 control the rate of reactions and regulate cell processes
d.
 build tissues such as bone and muscle
 33.
Which statement is true?
a.
 Simple sugars are made of polysaccharides.
b.
 Glycerol is made of fatty acids.
c.
 RNA molecules are made of nucleotides.
d.
 Amino acids are made of proteins.
 34.
In chemical reactions, atoms are
a.
 created.
c.
 rearranged.
b.
 destroyed.
d.
 neutralized.
 35.
When hydrogen and oxygen combine to form water, water is
a.
 a product.
c.
 both a product and a reactant.
b.
 a reactant.
d.
 neither a product nor a reactant.
 36.
Identify the reactant(s) in the chemical reaction, CO2 + H2O ® H2CO3.
a.
 CO2, H2O, and H2CO3
c.
 H2CO3
b.
 CO2 and H2O
d.
 CO2
 37.
What is the process that changes one set of chemicals into another set of chemicals?
a.
 cohesion
c.
 chemical reaction
b.
 adhesion
d.
 dissolving
 38.
What is the term used to describe the energy needed to get a reaction started?
a.
 adhesion energy
c.
 cohesion energy
b.
 activation energy
d.
 chemical energy
 39.
Chemical reactions that release energy
a.
 will not occur.
c.
 will always explode.
b.
 will never explode.
d.
 often occur spontaneously.
 40.
If a reaction in one direction releases energy, the reaction in the opposite direction
a.
 also releases energy.
c.
 destroys energy.
b.
 absorbs energy.
d.
 cannot occur.
 41.
Which of the following is a form of energy that may be released during a chemical reaction?
a.
 heat
c.
 light
b.
 sound
d.
 all of the above
 42.
Which of the following statements about enzymes is NOT true?
a.
 Enzymes work best at a specified pH.
b.
 All enzymes have the same shape as their substrates.
c.
 Enzymes are proteins.
d.
 The shape of an enzyme allows it to do its job.
 43.
Which of the following statements is true about catalysts?
a.
 Catalysts slow down the rate of chemical reactions.
b.
 All catalysts are enzymes.
c.
 Catalysts are used up during a chemical reaction.
d.
 Catalysts lower the activation energy of a chemical reaction.
 44.
A substance that accelerates the rate of a chemical reaction is called a(an)
a.
 catalyst.
c.
 molecule.
b.
 lipid.
d.
 element.
 45.
Enzymes affect the reactions in living cells by changing the
a.
 products of the reaction.
c.
 temperature of the reaction.
b.
 speed of the reaction.
d.
 pH of the reaction.
 

Short Answer
 46.
Why are atoms considered neutral?
 47.
What is a molecule?
 

Other

USING SCIENCE SKILLS

 

pH Values of Some Common Substances
Substance pH
Hydrochloric acid
1.0
Sulfuric acid
1.2
Tomatoes
4.2
Rainwater
6.2
Pure water
7.0
Sea water
8.5
Ammonium chloride
11.1
Sodium hydroxide
13.0

Figure 2–2
 48.
Applying Concepts What is the strongest acid listed in Figure 2–2?
 49.
Applying Concepts What is the pH of the strongest base listed in Figure 2–2?
 50.
Applying Concepts Using your knowledge of the pH scale, which of the chemicals in Figure 2-2 has the lowest concentration of H+ ions?

 
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Chapter 3 Biochemistry Studyguide

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Modified True/False
Indicate whether the statement is true or false.  If false, change the identified word or phrase to make the statement true.
 1.
Atoms have a positive charge. _________________________
 2.
Electrons have very little mass. _________________________
 3.
Molecules are atoms that have gained or lost one or more electrons. _________________________
 4.
An atom with more electrons than protons has a positive charge. _________________________
 5.
A covalent bond forms between two atoms that share electrons to form a molecule. _________________________
 6.
Water molecules attract nonpolar molecules such as oil. _________________________
 7.
The ability of water to retain heat helps cells maintain a constant internal temperature. _________________________
 8.
The role of carbohydrates in cells is to supply energy. _________________________
 9.
RNA is made up of a double strand of nucleotides. _________________________
 10.
When cells break down food, the energy from the food is temporarily stored as ATP. _________________________
 11.
The amount of energy needed to cause a chemical reaction to start is called activation energy. _________________________
 12.
Without enzymes, chemical reactions necessary for life would not occur quickly or easily enough to sustain life. _________________________
 13.
When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is increased. _________________________
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 14.
Atoms are not composed of
a.
 protons.
c.
 electrons.
b.
 neutrons.
d.
 chemical bonds
 15.
The electrons of an atom
a.
 are found in the nucleus along with the protons.
b.
 occupy the space surrounding the nucleus.
c.
 have a positive charge.
d.
 are attached to the positive charge of neutrons.
 16.
The smallest particle of matter that can retain the chemical properties of carbon is a carbon
a.
 molecule.
c.
 atom.
b.
 macromolecule.
d.
 element.
 17.
A substance that is composed of only one type of atom is called a(n)
a.
 compound.
c.
 element.
b.
 cell.
d.
 molecule.
 18.
All matter is composed of
a.
 cells.
c.
 atoms.
b.
 molecules.
d.
 carbon.
 19.
Covalent bonds form when
a.
 two molecules of water share electrons.
b.
 a molecule of water becomes an ion.
c.
 two hydrogen atoms share electrons with one oxygen atom.
d.
 two hydronium ions are attracted to each other.
 20.
Ionic bonds form between particles that have
a.
 opposite charges.
c.
 no charges.
b.
 the same charge.
d.
 neutral charges.
 21.
The bond formed when two atoms share a pair of electrons is called a(n)
a.
 hydrogen bond.
c.
 covalent bond.
b.
 ionic bond.
d.
 water bond.
 22.
Sharing of electrons in the outer energy levels of two atoms
a.
 results in ion formation.
b.
 makes both atoms stable.
c.
 only occurs if both are atoms of the same element.
d.
 is found only among carbon atoms.
 23.
A molecule that has a partial positive charge on one side and a partial negative charge on the other side is called a(n)
a.
 nonpolar molecule.
c.
 charged molecule.
b.
 polar molecule.
d.
 ion.
 24.
Nonpolar molecules have
a.
 no negative or positive ends.
c.
 only a negative end.
b.
 both negative and positive ends.
d.
 only a positive end.
 25.
When placed in the same container, oil and water do not mix because
a.
 they are both polar.
c.
 they are both nonpolar.
b.
 water is polar and oil is nonpolar.
d.
 water is nonpolar and oil is polar.
 26.
Attractions between water molecules are called
a.
 covalent bonds.
c.
 polar bonds.
b.
 ionic bonds.
d.
 hydrogen bonds.
 27.
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.
 28.
Which is not a unique property of water?
a.
 Frozen water floats.
b.
 Water retains a large amount of heat.
c.
 Water molecules stick to each other.
d.
 Water cools rapidly.
 29.
Acidic solutions have a pH that is
a.
 less than 7.
c.
 a negative number.
b.
 between 7 and 14.
d.
 more than 7.
 30.
Hydronium ions, H+, react with hydroxide ions, OH-, to form
a.
 water.
c.
 a base.
b.
 an acid.
d.
 a buffer.
 31.
Which of the following is not a large biomolecule?
a.
 carbohydrate
c.
 lipid
b.
 ice
d.
 nucleic acid
 32.
The building blocks of most biomolecules contain the element
a.
 carbon.
c.
 calcium.
b.
 nitrogen.
d.
 sodium.
 33.
Which of the following molecules are classified as carbohydrates?
a.
 amino acids
c.
 nucleotides
b.
 fats
d.
 sugars
 34.
Polysaccharides are
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 nucleic acids.
nar001-1.jpg
nar001-2.jpg
Molecule A
Molecule B
 35.
Refer to the illustration above. Molecule A is a
a.
 carbohydrate.
c.
 nucleic acid.
b.
 lipid.
d.
 protein.
 36.
Plants store glucose in the form of
a.
 starch.
c.
 cellulose.
b.
 glycogen.
d.
 chitin.
 37.
Which of the following is a carbohydrate?
a.
 ATP
c.
 wax
b.
 steroid
d.
 sucrose
 38.
Lipids are
a.
 soluble in water.
b.
 made of chains of amino acids.
c.
 linked together with peptide bonds.
d.
 used by the body for storing energy.
 39.
All of the following are examples of lipids except
a.
 oil.
c.
 steroids.
b.
 starch.
d.
 candle wax.
 40.
Which molecules are most closely related to lipids?
a.
 amino acids
b.
 long chains of carbon and hydrogen
c.
 nucleotides
d.
 sugars
 41.
Which of the following molecules are most closely related to proteins?
a.
 amino acids
c.
 nucleotides
b.
 monosaccharides
d.
 sugars
 42.
Long chains of amino acids are found in
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 sugars.
 43.
The overall shape of a single chain of amino acids in a protein is that protein’s
a.
 primary structure.
c.
 tertiary structure.
b.
 secondary structure.
d.
 quaternary structure.
 44.
The amino group of one amino acid is linked to the carboxyl group of another amino acid in a protein. This link is a(n)
a.
 peptide bond.
c.
 ionic bond.
b.
 hydrogen bond.
d.
 polar bond.
 45.
What gives each amino acid its unique properties?
a.
 its side group
c.
 its carboxyl group
b.
 its amino group
d.
 its sequence
 46.
The two types of nucleic acids are
a.
 RNA and ATP.
c.
 DNA and ATP.
b.
 DNA and RNA.
d.
 nucleotides and ATP.
 47.
Which of the following molecules are most closely related to nucleic acids?
a.
 amino acids
c.
 nucleotides
b.
 fats
d.
 sugars
 48.
DNA stores
a.
 fat.
c.
 energy.
b.
 carbohydrates.
d.
 hereditary information.
 49.
The two strands of a DNA molecule are held together by
a.
 ionic bonds.
c.
 hydrogen bonds.
b.
 covalent bonds.
d.
 peptide bonds.
 50.
Which of the following is not part of a nucleotide in a DNA molecule?
a.
 three phosphate groups
c.
 a base
b.
 a sugar
d.
 a phosphate group
 51.
ATP (adenosine triphosphate) stores energy in the bonds between its
a.
 hydrogen atoms.
c.
 nucleotides.
b.
 carbon atoms.
d.
 phosphate groups.
 52.
When paper burns, the paper combines with oxygen to form carbon dioxide and water vapor. How does the mass of carbon dioxide plus water vapor compare with the mass of the paper plus oxygen?
a.
 The mass of carbon dioxide plus water vapor is greater than that of paper plus oxygen.
b.
 The mass of carbon dioxide plus water vapor is less than that of paper plus oxygen.
c.
 It is impossible to tell.
d.
 The mass of carbon dioxide plus water vapor is identical to that of paper plus oxygen.
 53.
The law of conservation of energy states that energy cannot be
a.
 changed from one form to another.
b.
 taken from the surroundings in a reaction.
c.
 released into the surroundings in a reaction.
d.
 created or destroyed in a chemical reaction.
 54.
A chemical reaction will probably occur between two substrate molecules if they
a.
 are far apart.
b.
 are aligned in the wrong spatial orientation.
c.
 have large amounts of kinetic energy.
d.
 have little kinetic energy.
 55.
Reducing 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 enzymes on reactants.
nar002-1.jpg
 56.
Refer to the illustration above. Which of the following 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 between the graphs shown for Reaction 2 and Reaction 3 occurs because of a difference in the activation energy of these reactions.
c.
 Reactant A contains more energy at the beginning of the reaction than product C has at the end of the reaction.
d.
 Product B contains more energy at the end of the reaction than reactant A has at the beginning of the reaction.
 57.
Refer to the illustration above. Reaction 3 in the graph
a.
 probably occurred in the presence of an enzyme.
b.
 requires more activation energy than Reaction 2.
c.
 is the same as Reaction 1, but faster.
d.
 is slower than Reaction 2.
 58.
The molecule on which an enzyme acts is called a(n)
a.
 active site.
c.
 polar molecule.
b.
 inactive site.
d.
 substrate.
 59.
An enzyme
a.
 is used up in a reaction.
b.
 raises the activation energy of a reaction.
c.
 bonds with an active site on a substrate molecule.
d.
 lowers the activation energy of a reaction.
 60.
Enzymes
a.
 are able to heat up molecules so that they can react.
b.
 always provide carbon dioxide for chemical reactions.
c.
 hold substrate molecules in the correct alignment.
d.
 absorb excess heat so that reactions occur at low temperatures.
 61.
A cell contains
a.
 thousands of different kinds of enzymes, each assisting in a different chemical reaction.
b.
 one kind of enzyme that assists in thousands of different chemical reactions.
c.
 approximately 100 kinds of enzymes, each assisting in a different chemical reaction.
d.
 one enzyme that assists in reactions involving protein substrates and one enzyme that assists in reactions involving substrates that are not proteins.
 

Completion
Complete each statement.
 62.
The negatively charged particles in an atom are ____________________.
 63.
Protons and neutrons are found in the ____________________ of an atom.
 64.
A(n) ____________________ is a group of atoms held together by covalent bonds.
 65.
Sodium chloride, NaCl, is an example of a(n) _________________.
 66.
A(n) ____________________ bond forms between two atoms sharing electrons.
 67.
The attraction between oppositely charged ions results in the formation of a(n) ____________________.
 68.
Weak chemical attractions between polar molecules are ____________________ bonds.
 69.
Lipids are ____________________ molecules because they have no negative and positive poles.
 70.
Water heats and cools ____________________.
 71.
The attraction that causes water and other liquids to form drops and thin films is ____________________.
 72.
The medium in which most cellular events take place is ____________________.
 73.
Substances with a pH less than 7 are ____________________.
 74.
Substances with a pH greater than 7 are ____________________.
 75.
The pH scale measures the concentration of ____________________ ions in solutions.
 76.
A carbon atom can bond with four other atoms because it has ____________________ valence electrons.
 77.
A(n) ____________________ contains carbon, hydrogen, and oxygen in a ratio of 1:2:1.
 78.
Amino acids are the building blocks of __________________.
 79.
Most proteins consist of two or more ________________ that twist and fold around each other.
 80.
Long chains of nucleotides are called ____________________.
 81.
The ability to move or change matter is ____________________.
 82.
All living things require a source of ____________________ to carry out their life activities.
 83.
The starting materials for chemical reactions are called ____________________, while the new substances that are formed are called ____________________.
 84.
The energy needed to start a chemical reaction is called ____________________.
 85.
A biochemical reaction can be speeded up by adding a(n) ____________________, which lowers the amount of activation energy required to start the reaction.
 86.
The portion of an enzyme molecule into which a specific substrate can fit is called the ____________________.
 

Short Answer
 87.
How many different kinds of atoms are there in an element?
 88.
How does an atom become an ion?
 89.
An ionic bond forms between what two kinds of particles?
 90.
What makes a water molecule polar?
 91.
How well do nonpolar molecules dissolve in water?
 92.
What is an attraction between particles of different substances called?
 93.
What are the two most common elements found in large biomolecules?
 94.
What is the function of lipids in cells?
 95.
What determines the primary structure of a protein?
 96.
Where do your cells get most of the energy they need for metabolism?
 97.
How do enzymes speed up a chemical reaction?
 

Problem
 98.

The following statements are about the molecule ATP (adenosine triphosphate). For each statement, first determine whether it is true or false. Then, if it is false, rewrite the statement so that it is correct.

a. ATP is chemically similar to a carbohydrate.
b. Cells require ATP to function.
c. None of the energy in food molecules is stored in ATP.
d. ATP is the primary source of energy for chemical reactions occurring in all cells of all living organisms.

nar003-1.jpg
 99.

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.

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.

Enzymes catalyze a variety of biological reactions. The extent to which they can speed up the rate of a reaction is dependent on a number of factors. Draw a graph for the following condition(s), showing the effect of altering one factor on the relative rate of a reaction. Use “0” to indicate no activity, and “1” through “10” to indicate increasing rate of reaction from very low to very high. Include a label for your graph(s).
 100.
Refer to the paragraph above, and then draw your graph in the space below. Enzyme #1 is inactive between 0°C and 10°C. It is active above 10°C, with the rate increasing steadily until the temperature reaches 40°C. At 40°C, the rate of the reaction is very high. Above 40°C, the rate decreases steadily until the temperature reaches 60°C, at which point the enzyme is no longer active.
 101.
Refer to the paragraph above, and draw your graph. Enzyme #2 is inactive at a pH of 1–4. It is active above a pH of 4, with the rate increasing slowly until the pH reaches 6. Above a pH of 6, the rate increases sharply until the pH reaches 7. Above a pH of 7, the rate decreases sharply until the pH reaches 8. Above a pH of 8, the rate decreases gradually until the pH reaches 10, at which point the enzyme is no longer active.
 102.
Refer to the paragraph above, and draw your graph. Enzyme #3 is inactive when the concentration of the substrate it acts upon is zero. The enzyme is active when the substrate concentration is above zero, with the rate increasing only very slightly until the concentration reaches 30%. Above 30%, the rate increases very sharply to a high level, until the concentration reaches 60%. Above a concentration of 60%, the rate increases very little. The rate does not increase when the substrate concentration is above 80%.
 

Essay
 103.
Describe how an enzyme can function in speeding up a chemical reaction within a cell.

 
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Biochemistry PCC

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Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
At what temperature is water most dense?
a.
 0 degrees Celsius
b.
 1 degrees Celsius
c.
 4 degrees Celsius
d.
 10 degrees Celsius
e.
 100 degrees Celsius
 2.
Which property of water enables living things to survive in it?
a.
 high heat of vaporization
b.
 high specific heat
c.
 degree of surface tension
d.
 cohesion
e.
 density of ice
 3.
Which characteristic of water makes the existence of pH possible?
a.
 ionization
b.
 polarity
c.
 adhesion
d.
 cohesion
e.
 None of the above.
 4.
Which of the following types of biologist would need an understanding of chemistry?
a.
 molecular biologist
b.
 ecologist
c.
 evolutionary biologist
d.
 botanist
e.
 All of the above.
 5.
All of the following are inorganic compounds except:
a.
 glucose.
b.
 hydrochloric acid.
c.
 sodium chloride.
d.
 sodium hydroxide.
e.
 water.
 6.
An element is defined as a substance that:
a.
 is composed of more than one kind of atom.
b.
 is held together by covalent bonds.
c.
 cannot be broken into simpler substances by chemical reactions.
d.
 cannot burn.
e.
 is soluble in both acid and water.
 7.
Which of the following determines the type of element?
a.
 the number of electrons
b.
 the number of protons
c.
 the number of neutrons
d.
 the number of valence electrons
e.
 the number of energy levels
 8.
Which of the following elements is not responsible for a significant portion of the mass of living organisms?
a.
 O
b.
 S
c.
 N
d.
 H
e.
 C
 9.
An element found in minute quantities in living organisms is called:
a.
 a heavy element.
b.
 a vitamin.
c.
 an organic compound.
d.
 an isotope.
e.
 a trace element.
 10.
Select the incorrectly matched pair:
a.
 The 1st principal energy level contains 1 orbital.
b.
 The 2nd principal energy level contains 4 orbitals.
c.
 The 1st principal energy level contains a maximum of 2 electrons.
d.
 The 2nd energy level contains a maximum of 10 electrons.
e.
 All of the above are correctly matched.
 11.
Chlorine has seven electrons in its valence shell. The number of electrons it must gain to complete its valence shell is:
a.
 one.
b.
 two.
c.
 three.
d.
 seven.
e.
 eight.
 12.
An atom has six protons and eight neutrons. Its atomic mass is ____________ atomic mass units.
a.
 two
b.
 four
c.
 six
d.
 eight
e.
 fourteen
 13.
This determines the chemical properties of an element:
a.
 the atomic number.
b.
 the atomic weight.
c.
 the number of energy levels.
d.
 the number of valence electrons.
e.
 orbitals.
 14.
The difference between an electrically neutral atom and an ion is that:
a.
 an ion has an unequal number of protons and electrons, while an atom has an equal number.
b.
 an ion has an equal number of protons and electrons, while an atom has an unequal number.
c.
 an atom has an unequal number of neutrons and protons, while an ion has an equal number.
d.
 an atom has its electrons in orbitals, while an ion has its electrons in its nucleus.
e.
 an atom must have an equal number of neutrons and electrons, while an ion does not.
 15.
The difference between a stable isotope and a radioisotope is that:
a.
 the stable isotope emits radiation.
b.
 the radioisotope emits radiation.
c.
 the stable isotope emits light.
d.
 the stable isotope absorbs radiation.
e.
 the radioisotope has an unequal number of protons and electrons.
Figure 02-01
Use the figure below to answer the corresponding questions.nar001-1.jpg
 16.
Figure 02-01 represents:
a.
 two isotopes of the same element.
b.
 two different elements.
c.
 two different ions.
d.
 an acid and a base.
e.
 a cation and an anion.
 17.
The atomic mass of the atom identified as A in Figure 02-01 is:
a.
 2.
b.
 6.
c.
 8.
d.
 12.
e.
 18.
 18.
The difference between the two atoms in Figure 02-01 is:
a.
 pH.
b.
 the number of electrons.
c.
 the number of protons.
d.
 the number of neutrons.
e.
 electric charge.
 19.
Radioisotopes are used in all of the following scientific applications except:
a.
 dating fossils.
b.
 determining the sequence of genetic information in DNA.
c.
 localization of a drug, such as marijuana.
d.
 the treatment of cancer.
e.
 monitoring changes in the salinity of an estuary.
 20.
Isotopes differ from each other with respect to the number of:
a.
 protons.
b.
 electrons.
c.
 neutrons.
d.
 protons and electrons.
e.
 neutrons and protons.
 21.
When a chemical reaction is at equilibrium:
a.
 the forward reaction is going faster.
b.
 the reverse reaction is going faster.
c.
 the forward and reverse reactions are proceeding at equal rates.
d.
 the forward reaction stops.
e.
 the reverse reaction stops.
 22.
Any chemical interaction between atoms:
a.
 involves neutrons.
b.
 may potentially involve any electron.
c.
 involves protons.
d.
 involves only valence electrons.
e.
 involves only the nuclear subatomic particles.
 23.
The molecular mass of C6H12O6 is 180 amu. 0.25 moles of this substance contain:
a.
 180 daltons.
b.
 45 g.
c.
 1.8 g.
d.
 45 daltons.
e.
 180 g.
 24.
How many molecules are present in one mole of C6H12O6?
a.
 1.7 ´ 10-10 molecules
b.
 1.3 ´ 1010 molecules
c.
 5 molecules
d.
 1.7 ´ 1022 molecules
e.
 6.02 ´ 1023 molecules
Figure 02-02
Use the figure below to answer the corresponding questions.nar002-1.jpg
 25.
Figure 02-02 represents:
a.
 elemental helium.
b.
 molecular hydrogen.
c.
 molecular helium.
d.
 a water molecule.
e.
 molecular oxygen.
 26.
The type of bond illustrated in Figure 02-02 is:
a.
 an ionic bond.
b.
 a polar bond.
c.
 a single covalent bond.
d.
 a hydrogen bond.
e.
 a double covalent bond.
 27.
Select the covalent bond that involves 2 electrons:
a.
 single
b.
 double
c.
 triple
d.
 Both A and B.
e.
 Both A and C.
 28.
The representation H – O – H is known as:
a.
 a structural formula.
b.
 a simplest formula.
c.
 a molecular formula.
d.
 a Lewis structure.
e.
 an orbital diagram.
 29.
Which of the following choices correctly identifies a reactant in the following chemical equation? CO2 + H2O « H2CO3
a.
 carbonic acid
b.
 oxygen
c.
 water
d.
 sugar
e.
 carbon monoxide
 30.
In a chemical reaction, the product is:
a.
 generally written on the right side of the equation.
b.
 always in equilibrium with the reactants.
c.
 the substance that is generated by the reaction.
d.
 only joined by an ionic bond.
e.
 Both A and C.
 31.
A covalent bond:
a.
 can form only between identical atoms.
b.
 involves a sharing of only one pair of electrons.
c.
 is always polar.
d.
 may be polar or nonpolar depending on the atoms involved.
e.
 always forms between identical molecules.
 32.
In a water molecule, because oxygen is more electronegative than hydrogen, the shared electrons are more commonly found around the ____________ nucleus than the ____________ nucleus.
a.
 oxygen; hydrogen
b.
 hydrogen; oxygen
c.
 hydrogen; other hydrogen
d.
 oxygen; nitrogen
e.
 nitrogen; oxygen
 33.
The covalent bond between a hydrogen atom and the oxygen atom in water is formed when:
a.
 hydrogen gains an electron from oxygen.
b.
 hydrogen and oxygen share an electron pair.
c.
 hydrogen and oxygen both lose electrons from their outer shells.
d.
 hydrogen and oxygen both gain electrons in their outer shells.
e.
 hydrogen gains an electron from oxygen.
 34.
Covalently bonded atoms with similar electronic negativities are:
a.
 ionic.
b.
 polar.
c.
 nonpolar.
d.
 partially positive.
e.
 partially negative.
 35.
An atom becomes a cation if:
a.
 it gains one or more electron.
b.
 it loses one or more electron.
c.
 it shares electrons.
d.
 one or more of its electrons changes energy levels.
e.
 it emits radiation.
 36.
In the formation of common table salt, sodium and chlorine interact because:
a.
 sodium and chlorine share a pair of electrons.
b.
 sodium and chlorine share two pairs of electrons.
c.
 chlorine donates seven electrons to sodium.
d.
 there is no electron exchange.
e.
 sodium donates one electron to chlorine.
 37.
Table salt dissolves easily in water because:
a.
 water can form covalent linkages with salt molecules.
b.
 water can remove electrons from the chloride ion, which causes the latter to dissociate from the sodium and dissolve.
c.
 water can add electrons to the sodium ion.
d.
 water is polar and salt is nonpolar. Nonpolar compounds are more soluble in polar solvents because they are able to form strong covalent bonds that result in a breaking up of the molecule being dissolved.
e.
 the partial positive charge of the hydrogens in the water molecule can associate with the negative charge of the chloride ion, and the partial negative charge of the oxygen of the water molecule can associate with the positive charge of the sodium atom.
 38.
Which one of the following atoms would most likely be involved in an ionic bond?
a.
 hydrogen
b.
 oxygen
c.
 sodium
d.
 Both A and B.
e.
 Both A and C.
 39.
The process whereby water molecules surround ions during the process of dissolving is called:
a.
 reduction.
b.
 hydration.
c.
 buffering.
d.
 oxidation.
e.
 vaporization.
 40.
Which component becomes oxidized in the following chemical reaction?
4 Fe + 3 O2 ® 2 Fe2O3
a.
 water
b.
 iron
c.
 oxygen
d.
 rust
e.
 hydrogen
 41.
Which component is the oxidizing agent in the following chemical reaction?
4 Fe + 3 O2 ® 2 Fe2O3
a.
 water
b.
 iron
c.
 oxygen
d.
 rust
e.
 hydrogen
 42.
Which of the following statements is not correct?
a.
 Water heats up and cools down very quickly.
b.
 The amount of heat required to raise the temperature of 1 g of water 1 °C is one calorie.
c.
 Due to hydrogen bonds, water has a high surface tension.
d.
 Large bodies of water have relatively constant temperatures.
e.
 When one gram of water evaporates, it removes heat.
 43.
It takes one calorie of heat to raise the temperature of one gram of water one degree Celsius at sea level. This is referred to as the _______________________ of water.
a.
 heat of fusion
b.
 heat of vaporization
c.
 specific heat
d.
 heat of transformation
e.
 heat of homeostasis
 44.

Which characteristic of water molecules directly contributes to the remarkable “water walking” success of the aquatic insects pictured in the accompanying figure?

mc044-1.jpg

a.
 hydrogen bonds
b.
 capillary action
c.
 nonpolar covalent bonds
d.
 ionic bonds
e.
 adhesive forces
 45.
The cohesiveness between water molecules is due largely to:
a.
 hydrogen bonds.
b.
 polar covalent bonds.
c.
 nonpolar covalent bonds.
d.
 ionic bonds.
e.
 hydrophobic interactions.
 46.
A stalk of celery is placed in a solution of blue colored dye. After one hour, the leaves have blue fluid in their veins. Which property of water is being demonstrated?
a.
 adhesion and cohesion
b.
 evaporation and cooling
c.
 lower density as a solid than as a liquid
d.
 high specific heat
e.
 surface tension
 47.
Evaporative cooling is a process whereby ____________ moving ____________ molecules vaporize, thus ____________ large amounts of heat.
a.
 slow; water; adding
b.
 fast; water; removing
c.
 slow; oxygen; adding
d.
 fast; oxygen; removing
e.
 fast; carbon dioxide; removing
 48.
In a mixture, which one would be present in the least amount?
a.
 solvent
b.
 solute
c.
 water
d.
 Both A and B.
e.
 Both A and C.
 49.
This characteristic of a molecule determines the ability of hydrogen bonds to form between it and hydrogen:
a.
 A non polar atom
b.
 An atom with a partial positive charge
c.
 An atom with a partial negative charge
d.
 None of the above.
e.
 All of the above.
 50.
A pH of 4 is ____________ times more ____________ than a pH of 7.
a.
 3; basic
b.
 3; acidic
c.
 1000; neutral
d.
 1000; basic
e.
 1000; acidic
 51.
What is the OH- concentration of a solution having a pH of 2?
a.
 1 ´ 10-12
b.
 1 ´ 10-10
c.
 1 ´ 10-7
d.
 1 ´ 10-2
e.
 1 ´ 10-1
 52.
When a small amount of hydrochloric acid (HCl) is added to a solution of Na2HPO4, the pH of the solution does not change markedly. The pH also does not change drastically when a small amount of sodium hydroxide (NaOH) is added to this same solution. Based on these observations, the compound Na2HPO4 is:
a.
 able to donate hydrogen atoms to HCl.
b.
 able to remove hydrogen ions from the OH- of NaOH.
c.
 acting as a buffer.
d.
 an enzyme facilitating the reaction between HCl and NaOH.
e.
 All of the above.
 53.
A salt is a compound in which the hydrogen ion of _________________ is replaced by some other cation.
a.
 a base
b.
 an acid
c.
 an anion
d.
 a hydroxide ion
e.
 water
 54.
Which concentration(s) results in a pH of 7?
a.
 higher concentrations of hydrogen ions than hydroxide ions
b.
 higher concentrations of hydroxide ions than hydrogen ions
c.
 equal concentrations of hydroxide ions than hydrogen ions
d.
 Both A and B.
e.
 None of the above.
 55.
Identify the chemical(s) that act(s) as a buffer in human blood:
a.
 bicarbonate
b.
 hydrogen ions
c.
 carbon dioxide
d.
 water
e.
 None of the above.
 56.
Identify the hydrogen ion concentration that represents the lowest pH from the following list:
a.
 1 ´ 10-3
b.
 1 ´ 10-4
c.
 1 ´ 10-7
d.
 1 ´ 10-11
e.
 1 ´ 10-14
 57.
Which of the following has a pH closest to that of human blood?
a.
 beer
b.
 coffee
c.
 rain water
d.
 sea water
e.
 oven cleaner
 58.
Which of the following would most likely form electrolytes in water?
a.
 glucose
b.
 ethanol
c.
 An organic compound
d.
 An inorganic compound
e.
 None of the above.
 59.
Which of the following is not a property of carbon?
a.
 Carbon-to-carbon bonds are limited to single bonds.
b.
 Carbon has four valence electrons.
c.
 Carbon can form bonds to various other atoms.
d.
 Two carbon atoms can share three electron pairs with each other.
e.
 Carbon-to-carbon bonds are strong.
 60.
What aspect of long carbon chains makes them ideal for forming the backbones of long biomolecules?
a.
 The carbon atom itself is strong and hard to split.
b.
 Carbon can form a maximum of five covalent bonds with other atoms.
c.
 Carbons can form a maximum of three covalent bonds with other atoms.
d.
 Carbon-to-carbon covalent bonds are strong.
e.
 Carbon-to-carbon hydrogen bonds are weak and transitory.
 61.
The highly polarized nature of compounds containing carboxyl groups can be attributed to:
a.
 the presence of two highly electronegative carbon atoms.
b.
 the presence of two highly electropositive carbon atoms.
c.
 the presence of two highly electronegative oxygen atoms.
d.
 the presence of two highly electropositive oxygen atoms.
e.
 None of the above.
 62.

The number of electron pairs shared between carbon 2 and 3 in the accompanying figure is:

mc062-1.jpg

a.
 one.
b.
 one and a half.
c.
 two.
d.
 three.
e.
 None of the above.
 63.

The two molecules in the following figure represent:

mc063-1.jpg

a.
 ionized structures.
b.
 enantiomers.
c.
 secondary structures.
d.
 geometric isomers.
e.
 polymers.
 64.
This functional group is weakly basic because it can accept an H+ ion:
a.
 hydroxyl
b.
 carbonyl
c.
 amino
d.
 phosphate
e.
 sulfhydryl
 65.
This functional group forms cross bridges that help stabilize protein tertiary structure:
a.
 hydroxyl
b.
 carbonyl
c.
 amino
d.
 phosphate
e.
 sulfhydryl
 66.
The chemical interactions of large hydrocarbons are largely determined by:
a.
 their solubility in water.
b.
 their functional groups.
c.
 their polar nature.
d.
 isomerization of these hydrocarbons into other forms.
e.
 the hydrogens bonded to the carbon atoms.
 67.
Hydrocarbons are hydrophobic because:
a.
 the covalent bonds between hydrogen and carbon are nonpolar.
b.
 they contain functional groups.
c.
 they exist as isomers.
d.
 Both A and B.
e.
 Both A and C.
 68.
Which pair is mismatched?
a.
 monsaccharide:maltose
b.
 disaccharide:sucrose
c.
 polysaccharide:cellulose
d.
 None of these pairs are correctly matched.
e.
 All of these pairs are correctly matched.
 69.
Which of these terms is most inclusive?
a.
 monosaccharide
b.
 starch
c.
 polysaccharide
d.
 disaccharide
e.
 carbohydrate
 70.
Glucose dissolves in water because:
a.
 it ionizes.
b.
 it is a polysaccharide.
c.
 it has polar hydroxyl groups that interact with polar water molecules.
d.
 it has a very reactive primary structure.
e.
 it is hydrophobic.
 71.
Carbohydrate molecules:
a.
 serve as structural components of human cell walls.
b.
 form the regulatory compounds known as enzymes.
c.
 are a source of energy.
d.
 help protect vital organs from damage.
e.
 contain the genetic information of a cell.
 72.
A chemical reaction in which organic compounds are synthesized from their building blocks is called:
a.
 hydrolysis.
b.
 condensation.
c.
 oxidation.
d.
 reduction.
e.
 dissociation.
Figure 03-01
Use the figure below to answer the corresponding questions.nar003-1.jpg
 73.
The process illustrated in Figure 03-01 is called:
a.
 condensation.
b.
 protein synthesis.
c.
 hydrolysis.
d.
 dehydration synthesis.
e.
 denaturation.
 74.
The products of the process in Figure 03-01 are:
a.
 amino acids.
b.
 molecules of glycerol.
c.
 representative of a glycoside linkage.
d.
 enzymes.
e.
 monosaccharides.
 75.
Which one of the following carbohydrates is the most structurally complex?
a.
 sucrose
b.
 fructose
c.
 cellulose
d.
 glucose
e.
 a disaccharide
 76.
In which of the following reactions must the equivalent of a water molecule be added in order to break a bond?
a.
 fatty acids + glycerol ® fat
b.
 glucose + fructose ® sucrose
c.
 glycogen ® glucose
d.
 alanine + glycine ® dipeptide
e.
 glucose ® cellulose
 77.
Which of the following illustrates hydrolysis?
a.
 the reaction of two monosaccharides to form a disaccharide
b.
 the reaction of two amino acids to form a dipeptide
c.
 the reaction of a hydrogen atom and a hydroxide ion to form water
d.
 the reaction of a fat to form glycerol and fatty acids
e.
 the formation of ATP from ADP and inorganic phosphate
 78.
The difference between a hexose and a pentose is that:
a.
 a hexose is saturated, and a pentose is undersaturated.
b.
 a hexose is hydrophilic, and a pentose is hydrophobic.
c.
 a hexose always has six hydroxyl groups, and a pentose always has five.
d.
 a hexose always has six carbons, but a pentose always has five carbons.
e.
 a hexose can be polymerized, but a pentose cannot.
 79.
Monosaccharides are water soluble because:
a.
 they contain a large number of methyl groups.
b.
 they have a large number of polar hydroxyl groups.
c.
 they have at least one double bond between adjacent carbons.
d.
 they have large numbers of nonpolar carbons in their backbones.
e.
 they can form ring structures.
 80.
A carbohydrate energy storage molecule found in animal liver and muscle cells is:
a.
 starch.
b.
 glycogen.
c.
 cellulose.
d.
 fatty acids.
e.
 cholesterol.
 81.
Amyloplasts are organelles that store:
a.
 fat.
b.
 starch.
c.
 protein.
d.
 lipids.
e.
 DNA.
 82.
The major function(s) of lipids includes:
a.
 storing energy.
b.
 serving as structural components of cellular membranes.
c.
 serving as hormones.
d.
 Both A and B.
e.
 A, B, and C are correct.
 83.
The hydrolysis of triacylglycerol will yield:
a.
 three fatty acids and one glycerol.
b.
 three glycerols and one fatty acid.
c.
 two fatty acids and three glycerols.
d.
 one fatty acid, one amino acid, and one glucose.
e.
 one fatty acid, one phosphate, and one glycerol.
 84.
A molecule of a saturated triacylglycerol contains:
a.
 the maximum number of double bonds between carbons in the fatty acid chains.
b.
 the maximum number of triple bonds between carbons in the fatty acid chains.
c.
 the maximum number of hydrogen atoms in the fatty acid chains.
d.
 fatty acid chains with both amino and carboxyl groups.
e.
 alternating single and double bonds between carbons in the fatty acid chains.
 85.
Which of the following statements concerning unsaturated fats is correct?
a.
 They are more common in animals.
b.
 They have no double bonds in the carbon chains of their fatty acids.
c.
 They are generally liquids at room temperature.
d.
 They contain more hydrogen than do saturated fats having the same number of carbon atoms.
e.
 They have fewer fatty acids per fat molecule than do saturated fats.
 86.
The major difference between a structural lipid, such as those in cell membranes, and a storage fat is the fact that the structural lipid:
a.
 most commonly contains phosphate.
b.
 does not contain glycerol.
c.
 has four fatty acids attached to glucose.
d.
 is entirely hydrophobic.
e.
 is nonpolar.
 87.
An amphipathic molecule has:
a.
 two polar ends.
b.
 two hydrophobic ends.
c.
 a hydrophobic and a hydrophilic portion.
d.
 only one hydrophobic end.
e.
 only one hydrophilic end.
 88.

The most abundant molecules in this structure are:

mc088-1.jpg

a.
 structural proteins.
b.
 polysaccharides.
c.
 triacylglycerols.
d.
 phospholipids.
e.
 polypeptides.
 89.
Which of the following molecules is not grouped with the lipids?
a.
 prostaglandins
b.
 steroids
c.
 cholesterol
d.
 carotenoids
e.
 None of the above, all are lipids.
 90.
The hydrogenation process used to make margarine from cooking oil produces fatty acids that:
a.
 are known to increase the risk of cardiovascular disease.
b.
 contain fewer double bonds.
c.
 can contain rearrange double bonds to the cis configuration.
d.
 Both A and B are correct.
e.
 A, B, and C are correct.
 91.
Which statement is false?
a.
 Trans fatty acids are unsaturated.
b.
 Trans fatty acids are more solid at room temperature than cis fatty acids.
c.
 Unsaturated fatty acids are liquid at room temperature.
d.
 Saturated fatty acids are solid at room temperature.
e.
 All of these statements are true.
 92.
The major function(s) of proteins includes:
a.
 catalyzing chemical reactions.
b.
 controlling the expression of genes.
c.
 strengthening and protecting cells and tissues.
d.
 Both A and B.
e.
 A, B, and C are correct.
 93.
There are 20 different amino acids in the proteins that make up the tissues of living organisms. The primary difference between these amino acids is in their:
a.
 R or variable groups.
b.
 number of potassium groups.
c.
 number of phosphate groups.
d.
 number of carbonyl groups.
e.
 number of asymmetric carbons.
Figure 03-02
Use the figure below to answer the corresponding questions.nar004-1.jpg
 94.
In Figure 03-02, ionic attractions would form between the R groups of which amino acids?
a.
 1 and 3
b.
 2 and 4
c.
 3 and 5
d.
 4 and 6
e.
 None of the above.
 95.
Hydrophobic interactions would occur between the R groups of which two amino acids in Figure 03-02?
a.
 1 and 4
b.
 2 and 5
c.
 3 and 6
d.
 2 and 4
e.
 3 and 5
 96.
Which of the following is responsible for the alpha-helical structure of proteins?
a.
 hydrophobic interactions
b.
 nonpolar covalent bonds
c.
 ionic interactions
d.
 hydrogen bonds
e.
 polar covalent bonds
 97.
At which level of protein structure are peptide bonds most important?
a.
 primary
b.
 secondary
c.
 tertiary
d.
 quaternary
e.
 globular
 98.
Proteins with alpha helical forms exhibit this property:
a.
 strength
b.
 elasticity
c.
 heat stability
d.
 rigidity
e.
 All of the above.
 99.
Which of the following would help stabilize a protein the most?
a.
 alpha helix
b.
 beta pleated sheet
c.
 hydrogen bonds
d.
 hydrophobic interactions
e.
 disulfide bonds
 100.
Some proteins are important biological buffers because:
a.
 they react with water to produce carbon dioxide, which neutralizes acids.
b.
 they contain weakly acidic and weakly basic groups.
c.
 they are able to absorb great amounts of carbon dioxide during condensation reactions.
d.
 they produce carbonic acid upon hydrolysis.
e.
 All of the above.
 101.
The tertiary structure of proteins is typified by the:
a.
 association of several polypeptide chains by weak bonds.
b.
 order in which amino acids are joined in a peptide chain.
c.
 bonding of two amino acids to form a dipeptide.
d.
 folding of a peptide chain to form an alpha helix.
e.
 three-dimensional shape of an individual polypeptide chain.
 102.

All of the following types of chemical bonds are responsible for maintaining the tertiary structure of this polypeptide except:

mc102-1.jpg

a.
 ionic bonds.
b.
 hydrogen bonds.
c.
 hydrophobic interactions.
d.
 disulfide bonds.
e.
 peptide bonds.
 103.
Regulatory proteins:
a.
 defend against foreign invaders.
b.
 store nutrients.
c.
 catalyze a specific chemical reaction.
d.
 control the expression of specific genes.
e.
 strengthen and protect cells and tissues.
 104.
Molecular chaperones are proteins that mediate the folding process of:
a.
 other proteins.
b.
 amino acids.
c.
 lipids.
d.
 DNA.
e.
 sugars.
 105.

The following amino acid would be characterized as __________ based on the chemical properties of its side chain.

mc105-1.jpg

a.
 nonpolar
b.
 acidic
c.
 basic
d.
 hydrophilic
e.
 electrically charged
 106.
Which of the following statements is true of proteins?
a.
 Proteins lose some or all of their normal activity if their three-dimensional structure is disrupted.
b.
 Proteins are composed of ribose, phosphate, and a nitrogen-containing base.
c.
 The activity of proteins is independent of temperature and pH.
d.
 Denaturation is usually reversible.
e.
 All proteins are enzymes.
 107.

If the differently shaded portions of this molecule represent different polypeptide chains, then this figure is representative of:

mc107-1.jpg

a.
 an amino acid.
b.
 the quaternary structure of a protein.
c.
 a steroid hormone.
d.
 cellulose.
e.
 a carotenoid.
 108.
Which of the following statements is false?
a.
 DNA is usually composed of two nucleotide strands.
b.
 DNA contains deoxyribose.
c.
 DNA does not normally contain uracil.
d.
 The nucleotides of DNA are linked by phosphodiester linkages.
e.
 DNA does not normally contain a phosphate group.
 109.
ATP is important in living organisms because:
a.
 like all other nucleic acids, it stores hereditary information.
b.
 like RNA, it acts as a source code for the formation of proteins.
c.
 it can transfer some of its energy to other chemicals.
d.
 it is an important structural component of cell membranes.
e.
 it is easily converted to starch for long-term storage.
 110.
Which of the following statements best summarizes the differences between RNA and DNA?
a.
 RNA is a protein and DNA is a nucleic acid.
b.
 DNA is a polymer and RNA is a monomer.
c.
 DNA comprises the genes, while RNA is a direct participant in the process of protein synthesis.
d.
 RNA is a single-stranded form of DNA.
e.
 DNA is the primary energy currency of all cells.
 111.
Analysis of a certain complex compound shows that it contains phosphate groups, ribose groups, and pyrimidines. Based on this information, which of the following is the best description of this compound?
a.
 It is most likely ribonucleic acid.
b.
 It is DNA.
c.
 It is an inorganic compound.
d.
 It contains thymine.
e.
 It is a polypeptide.
 112.
Which of the following are most directly arranged from DNA structure?
a.
 polysaccharides
b.
 polypeptides
c.
 nucleotides
d.
 triglycerides
e.
 fatty acids
 113.
This molecule transmits heredity information:
a.
 cholesterol
b.
 adenosine triphosphate
c.
 nucleic acid
d.
 fatty acid
e.
 polysaccharide
Figure 03-03
Use the figure to answer the corresponding questions.
nar005-1.jpg
 114.
The molecular fragment represented in Figure 03-03 is:
a.
 ATP.
b.
 RNA.
c.
 a protein.
d.
 a nucleotide.
e.
 a polysaccharide.
 115.
The type of connection between the atoms at the point labeled 1 in Figure 03-03 is:
a.
 a peptide bond.
b.
 a glycoside linkage.
c.
 a disulfide bond.
d.
 a phosphodiester linkage.
e.
 a hydrogen bond.
 116.

Which portion of the following molecule is easily transferred and therefore responsible for the energy transfer property of this molecule?

mc116-1.jpg

a.
 1
b.
 2
c.
 3
d.
 1 and 2
e.
 None of the above.
 117.
Ester linkages would not be formed during condensation reactions that produce:
a.
 polysaccahrides.
b.
 triacylglycerols.
c.
 polypeptides.
d.
 nucleic acids.
e.
 All of the above contain ester linkages that are formed during condensation reactions.
 118.
Which monomer is incorrectly matched with the corresponding polymer?
a.
 Amino acids are used to build proteins.
b.
 Monosaccharides are used to build polysaccharides.
c.
 Fatty acids are used to build nucleic acids.
d.
 Glucose molecules are used to build starches.
e.
 All of these monomers are correctly matched with the corresponding polymer.

 
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