Name:							Period:		Date:					
Unit 4 Biochemistry Practice Test

____	1)	The element present in all organic molecules is
A)	hydrogen.	B)	oxygen.	C)	carbon.	D)	nitrogen.	E)	phosphorus.	

____	2)	A carbon atom is most likely to form what kind of bond(s) with other atoms?
A)	ionic	
B)	hydrogen	
C)	covalent	
D)	covalent bonds and hydrogen bonds	
E)	ionic bonds, covalent bonds, and hydrogen bonds	

____	3)	Which of the following statements best describes the carbon atoms present in a seed–eating bird?
A)	Inorganic carbon atoms in the seeds were incorporated into organic molecules by the bird.	
B)	The carbon atoms ultimately came from the soil.	
C)	The carbon atoms are ultimately derived from coal.	
D)	The carbon atoms ultimately came from carbon dioxide incorporated into sugars through photosynthesis.	
E)	The carbon atoms ultimately came from simple organic compounds that formed abiotically from inorganic carbon, hydrogen, oxygen, and nitrogen atoms.	

____	4)	In animal metabolism, most of the monomers released by digestion of food macromolecules are metabolized to provide energy. Only a small portion of these monomers are used for synthesis of new macromolecules. The net result is that
A)	water is generated by animal metabolism.	
B)	water is consumed by animal metabolism.	
C)	the water consumed is exactly balanced by the water generated, to maintain homeostasis.	
D)	water is consumed during homeostasis, but water is generated during periods of growth.	
E)	water is generated during homeostasis, but water is consumed during periods of growth.	

____	5)	Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
A)	as a pentose	D)	as a disaccharide	
B)	as a hexose	E)	as a polysaccharide	
C)	as a monosaccharide	

____	6)	The bonding of two amino acid molecules to form a larger molecule requires
A)	the release of a water molecule.	
B)	the release of a carbon dioxide molecule.	
C)	the addition of a nitrogen atom.	
D)	the addition of a water molecule.	
E)	the release of a nitrous oxide molecule.	

____	7)	There are 20 different amino acids. What makes one amino acid different from another?
A)	different side chains (R groups) attached to a carboxyl carbon	
B)	different side chains (R groups) attached to the amino groups	
C)	different side chains (R groups) attached to an α carbon	
D)	different structural and optical isomers	
E)	different asymmetric carbons	

____	8)	Polysaccharides, triacylglycerides, and proteins are similar in that they
A)	are synthesized from monomers by the process of hydrolysis.	
B)	are synthesized from subunits by dehydration reactions.	
C)	are synthesized as a result of peptide bond formation between monomers.	
D)	are decomposed into their subunits by dehydration reactions.	
E)	all contain nitrogen in their monomer building blocks.	

____	9)	What aspects of protein structure are stabilized or assisted by hydrogen bonds?
A)	primary structure	
B)	secondary structure	
C)	tertiary structure	
D)	quaternary structure	
E)	secondary, tertiary, and quaternary structures, but not primary structure	

____	10)	The tertiary structure of a protein is the
A)	bonding together of several polypeptide chains by weak bonds.	
B)	order in which amino acids are joined in a polypeptide chain.	
C)	unique three–dimensional shape of the fully folded polypeptide.	
D)	organization of a polypeptide chain into an α helix or b pleated sheet.	
E)	overall protein structure resulting from the aggregation of two or more polypeptide subunits.	

____	11)	If cells are grown in a medium containing radioactive 35S, which of these molecules will be labeled?
A)	phospholipids	D)	amylose	
B)	nucleic acids	E)	both proteins and nucleic acids	
C)	proteins	

____	12)	DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?
A)	The two strands of the double helix would separate.	
B)	The phosphodiester bonds between deoxyribose sugars would be broken.	
C)	The purines would be separated from the deoxyribose sugars.	
D)	The pyrimidines would be separated from the deoxyribose sugars.	
E)	All bases would be separated from the deoxyribose sugars.	

____	13)	If cells are grown in a medium containing radioactive 15N, which of these molecules will be labeled?
A)	fatty acids only	D)	both fatty acids and proteins	
B)	nucleic acids only	E)	both proteins and nucleic acids	
C)	proteins only	

____	14)	Which of the following is not a monomer/polymer pairing?
A)	monosaccharide/polysaccharide	D)	deoxyribonucleotide/DNA	
B)	amino acid/protein	E)	ribonucleotide/RNA	
C)	triglyceride/phospholipid bilayer	

Figure 5.7

____	15)	The structure depicted in Figure 5.7 (to the right) shows the
A)	1–4 linkage of the a glucose monomers of starch.	
B)	1–4 linkage of the b glucose monomers of cellulose.	
C)	double–helical structure of a DNA molecule.	
D)	a helix secondary structure of a polypeptide.	
E)	b pleated sheet secondary structure of a polypeptide.	

____	16)	Which of the following categories includes all others in the list?
A)	monosaccharide	D)	carbohydrate	
B)	disaccharide	E)	polysaccharide	
C)	starch	

____	17)	The structural level of a protein least affected by a disruption in hydrogen bonding is the
A)	primary level.	D)	quaternary level.	
B) C)	secondary level.                          tertiary level.	E)	All structural levels are equally affected.	

____	18)	Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
A)	catalysis	B)	metabolism	C)	anabolism	D)	dehydration	E)	catabolism	

____	19)	For living organisms, which of the following is an important consequence of the first law of thermodynamics?
A)	The energy content of an organism is constant.	
B)	The organism ultimately must obtain all of the necessary energy for life from its environment.	
C)	The entropy of an organism decreases with time as the organism grows in complexity.	
D)	Organisms grow by converting energy into organic matter.	
E)	Life does not obey the first law of thermodynamics.	

____	20)	A system at chemical equilibrium
A)	consumes energy at a steady rate.	
B)	releases energy at a steady rate.	
C)	consumes or releases energy, depending on whether it is exergonic or endergonic.	
D)	has zero kinetic energy.	
E)	can do no work.	

____	21)	Which of the following is true for all exergonic reactions?
A)	The products have more total energy than the reactants.	
B)	The reaction proceeds with a net release of free energy.	
C)	The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.	
D)	A net input of energy from the surroundings is required for the reactions to proceed.	
E)	The reactions are rapid.	

____	22)	Why is ATP an important molecule in metabolism?
A)	Its hydrolysis provides an input of free energy for exergonic reactions.	
B)	It provides energy coupling between exergonic and endergonic reactions.	
C)	Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.	
D)	Its terminal phosphate bond has higher energy than the other two.	
E)	It is one of the four building blocks for DNA synthesis.	

____	23)	Which of the following statements is true concerning catabolic pathways?
A)	They combine molecules into more energy–rich molecules.	
B)	They supply energy, primarily in the form of ATP, for the cell's work.	
C)	They are endergonic.	
D)	They are spontaneous and do not need enzyme catalysis.	
E)	They build up complex molecules such as protein from simpler compounds.	

____	24)	When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?
A)	It is secreted as waste.	
B)	It is used only to regenerate more ATP.	
C)	It is added to water and excreted as a liquid.	
D)	It may be used to form a phosphorylated intermediate.	
E)	It enters the nucleus and affects gene expression.	

____	25)	Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
A)	entropy.	D)	equilibrium point.	
B)	activation energy.	E)	free–energy content.	
C)	endothermic level.	

____	26)	Which of the following statements regarding enzymes is true?
A)	Enzymes increase the rate of a reaction by making the reaction more exergonic.	
B)	Enzymes increase the rate of a reaction by lowering the activation energy barrier.	
C)	Enzymes increase the rate of a reaction by reducing the rate of reverse reactions.	
D)	Enzymes change the equilibrium point of the reactions they catalyze.	
E)	Enzymes make the rate of a reaction independent of substrate concentrations.	

____	27)	During a laboratory experiment, you discover that an enzyme–catalyzed reaction has a DG of –20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the DG for the new reaction?
A)	–40 kcal/mol 	B)	–20 kcal/mol	C)	0 kcal/mol	D)	+20 kcal/mol	E)	+40 kcal/mol	

____	28)	Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
A)	competitive inhibitor of the enzyme.	
B)	noncompetitive inhibitor of the enzyme.	
C)	allosteric activator of the enzyme.	
D)	cofactor necessary for enzyme activity.	
E)	coenzyme derived from a vitamin.	

Activity of various enzymes at various temperatures (a) and at various pH (b).

____	29)	Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?
A)	1 and 5	B)	2 and 4	C)	2 and 5	D)	3 and 4	E)	3 and 5	

Questions 30 – 33 are based on the reaction A + B « C + D shown in the graph to the right.

____	30)	Which of the following terms best describes the forward reaction in Figure 8.1?
A)	endergonic, DG > 0	D)	exergonic, DG > 0	
B)	exergonic, DG < 0	E)	chemical equilibrium, DG = 0	
C)	endergonic, DG < 0	

____	31)	Which of the following would be the same in either an enzyme–catalyzed or a noncatalyzed reaction?
A)	a	B)	b	C)	c	D)	d	E)	e	

____	32)	Which of the following represents the difference between the free–energy content of the reactants and the free–energy content of the products ?
A)	a	B)	b	C)	c	D)	d	E)	e	

____	33)	Which of the following represents the activation energy required for a noncatalyzed reaction?
A)	a	B)	b	C)	c	D)	d	E)	e	

____	34)	Which of the following is the most correct interpretation of the figure above?
A)	Inorganic phosphate is created from organic phosphate.	
B)	Energy from catabolism can be used directly for performing cellular work.	
C)	ADP + i are a set of molecules that store energy for catabolism.	
D)	ATP is a molecule that acts as an intermediary to store energy for cellular work.	
E)	i acts as a shuttle molecule to move energy from ATP to ADP.	

____	35)	Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _____ is to _____.
A)	exergonic; spontaneous	D)	work; energy	
B)	exergonic; endergonic	E)	entropy; enthalpy	
C)	free energy; entropy	

Unit 4 Biochemistry Practice Test
Answer Section

MULTIPLE CHOICE

	1)	ANS:	C	TOP:	Concept 4.1

	2)	ANS:	C	TOP:	Concept 4.2

	3)	ANS:	D	TOP:	Concept 4.2

	4)	ANS:	B	TOP:	Concept 5.1

	5)	ANS:	D	TOP:	Concept 5.2

	6)	ANS:	A	TOP:	Concept 5.4

	7)	ANS:	C	TOP:	Concept 5.4

	8)	ANS:	B	TOP:	Concept 5.1 | Concept 5.2 | Concept 5.3 | Concept 5.4

	9)	ANS:	E	TOP:	Concept 5.4

	10)	ANS:	C	TOP:	Concept 5.4

	11)	ANS:	C	TOP:	Concept 5.4

	12)	ANS:	B	TOP:	Concept 5.1 | Concept 5.5

	13)	ANS:	E	TOP:	Concept 5.2 | Concept 5.3 | Concept 5.4 | Concept 5.5

	14)	ANS:	C	TOP:	Concept 5.2 | Concept 5.3 | Concept 5.4 | Concept 5.5

	15)	ANS:	D	TOP:	Concept 5.4

	16)	ANS:	D	TOP:	Concept 5.4

	17)	ANS:	A	TOP:	Concept 5.2

	18)	ANS:	E	TOP:	Concept 8.1

	19)	ANS:	B	TOP:	Concept 8.1

	20)	ANS:	E	TOP:	Concept 8.2

	21)	ANS:	B	TOP:	Concept 8.2

	22)	ANS:	B	TOP:	Concept 8.3

	23)	ANS:	B	TOP:	Concept 8.3

	24)	ANS:	D	TOP:	Concept 8.3

	25)	ANS:	B	TOP:	Concept 8.4

	26)	ANS:	B	TOP:	Concept 8.4

	27)	ANS:	B	TOP:	Concept 8.4

	28)	ANS:	D	TOP:	Concept 8.4

	29)	ANS:	E	TOP:	Concept 8.4

	30)	ANS:	B	TOP:	Concept 8.4

	31)	ANS:	D	TOP:	Concept 8.4

	32)	ANS:	D	TOP:	Concept 8.4

	33)	ANS:	C	TOP:	Concept 8.4

	34)	ANS:	D	TOP:	Concept 8.3

	35)	ANS:	B	TOP:	Concept 8.1