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Biochemistry Practice

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

What is the approximate atomic mass of an atom with 16 neutrons, 15 protons, and 15 electrons?
A)
15 daltons
B)
16 daltons
C)
30 daltons
D)
31 daltons
E)
46 daltons
 

 2. 

Different atomic forms of an element contain the same number of protons but a different number of neutrons. What are these different atomic forms called?
A)
ions
B)
isotopes
C)
neutronic atoms
D)
isomers
E)
radioactive atoms
 

 3. 

How do isotopes of the same element differ from each other?
A)
number of protons
B)
number of electrons
C)
number of neutrons
D)
valence electron distribution
E)
amount of radioactivity
 
 
Use the figure below to answer the following questions.

biochempractice_files/i0050000.jpg
 

 4. 

Which drawing is of an atom with the atomic number of 6?
A)
Drawing A
B)
Drawing B
C)
Drawing C
D)
Drawing D
E)
Drawing E
 

 5. 

Atoms whose outer electron shells contain eight electrons tend to
A)
form ionic bonds in aqueous solutions.
B)
form covalent bonds in aqueous solutions.
C)
be stable and chemically nonreactive, or inert.
D)
be unstable and chemically very reactive.
E)
be isotopes and very radioactive.
 

 6. 

A covalent bond is likely to be polar when
A)
one of the atoms sharing electrons is much more electronegative than the other atom.
B)
the two atoms sharing electrons are equally electronegative.
C)
the two atoms sharing electrons are of the same element.
D)
it is between two atoms that are both very strong electron acceptors.
E)
the two atoms sharing electrons are different elements.
 
 
Use the figure below to answer the following questions. .

biochempractice_files/i0090000.jpg
 

 7. 

What is the atomic number of the cation formed in the reaction?
A)
1
B)
8
C)
10
D)
11
E)
16
 

 8. 

The ionic bond of sodium chloride is formed when
A)
chlorine gains an electron from sodium.
B)
sodium and chlorine share an electron pair.
C)
sodium and chlorine both lose electrons from their outer valence shells.
D)
sodium gains an electron from chlorine.
E)
chlorine gains a proton from sodium.
 

 9. 

The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride?
A)
MgCl
B)
MgCl2
C)
Mg2Cl
D)
Mg2Cl2
E)
MgCl3
 

 10. 

Explains most specifically the attraction of water molecules to one another.
A)
nonpolar covalent bond
B)
polar covalent bond
C)
ionic bond
D)
hydrogen bond
E)
hydrophobic interaction
 

 11. 

An example of a hydrogen bond is the bond between
A)
C and H in methane (CH4).
B)
the H of one water molecule and the O of another water molecule.
C)
Na+and Cl- in salt.
D)
the two hydrogen atoms in a molecule of hydrogen gas (H2).
E)
Mg+and Cl- in MgCl2.
 

 12. 

The molecular mass of glucose (C6H12O6) is 180 g. To make a 0.5 M solution of glucose, you should do which of the following?
A)
Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L.
B)
Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.
C)
Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.
D)
Dissolve 0.5 g of glucose in 1 L of water.
E)
Dissolve 180 g of glucose in 1 L of water.
 
 
Use the figure below to answer the following questions:

biochempractice_files/i0160000.jpg
 

 13. 

How many grams of the molecule in the figure above would be equal to 1 mol of the molecule?
(Carbon = 12, Oxygen = 16, Hydrogen = 1)
A)
29
B)
30
C)
60
D)
150
E)
342
 

 14. 

Which of the following statements is completely correct?
A)
H2CO3 is a weak acid, and NaOH is a weak base.
B)
H2CO3 is a strong acid, and NaOH is a strong base.
C)
NH3 is a weak base, and H2CO3 is a strong acid.
D)
NH3 is a weak base, and HCl is a strong acid.
E)
NH3 is a strong base, and HCl is a weak acid.
 

 15. 

What would be the pH of a solution with a hydroxide ion [OH-] concentration of 10-12 M?
A)
pH 2
B)
pH 4
C)
pH 10
D)
pH 12
E)
pH 14
 

 16. 

Which of the following solutions has the greatest concentration of hydroxide ions [OH-]?
A)
lemon juice at pH 2
B)
vinegar at pH 3
C)
tomato juice at pH 4
D)
urine at pH 6
E)
seawater at pH 8
 

 17. 

If the pH of a solution is decreased from 9 to 8, it means that the
A)
concentration of H+ has decreased 10 times what it was at pH 9.
B)
concentration of H+ has increased 10 times what it was at pH 9.
C)
concentration of OH- has increased 10 times what it was at pH 9.
D)
concentration of OH- has decreased 10 times what it was at pH 9.
E)
B and D are correct.
 

 18. 

If the pH of a solution is increased from pH 5 to pH 7, it means that the
A)
concentration of H+ is 2 times greater than what it was at pH 5.
B)
concentration of H+ is 2 times less than what it was at pH 5.
C)
concentration of OH- is 100 times greater than what it was at pH 5.
D)
concentration of OH- is 100 times less than what it was at pH 5.
E)
concentration of H+ is 100 times greater and the concentration of OH- is 100 times less than what they were at pH 5.
 

 19. 

One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6?
A)
4 times more
B)
400 times more
C)
4,000 times more
D)
10,000 times more
E)
100,000 times more
 

 20. 

Organic chemistry is a science based on the study of
A)
functional groups.
B)
vital forces interacting with matter.
C)
carbon compounds.
D)
water and its interaction with other kinds of molecules.
E)
inorganic compounds.
 

 21. 

Early 19th-century scientists believed that living organisms differed from nonliving things as a result of possessing a "life force" that could create organic molecules from inorganic matter. The term given to this belief is
A)
organic synthesis.
B)
vitalism.
C)
mechanism.
D)
organic evolution.
E)
inorganic synthesis.
 

 22. 

Which property of the carbon atom gives it compatibility with a greater number of different elements than any other type of atom?
A)
Carbon has 6 to 8 neutrons.
B)
Carbon has a valence of 4.
C)
Carbon forms ionic bonds.
D)
A and C only
E)
A, B, and C
 

 23. 

The two molecules shown in the following figure are best described as

biochempractice_files/i0270000.jpg
A)
enantiomers.
B)
radioactive isotopes.
C)
structural isomers.
D)
nonisotopic isomers.
E)
geometric isomers.
 

 24. 

Research suggests that side effects from Ritalin, the drug used to treat attention deficit disorder, may be caused by contamination of enantiomers, or molecules that
A)
have identical three-dimensional shapes.
B)
are mirror images of one another.
C)
lack an asymmetric carbon.
D)
differ in the location of their double bonds.
E)
differ in their electrical charge.
 

 25. 

Which is the best description of a carbonyl group?
A)
an oxygen joined to a carbon by a single covalent bond
B)
a nitrogen and two hydrogens joined to a carbon by covalent bonds
C)
a carbon joined to two hydrogens by single covalent bonds
D)
a sulfur and a hydrogen joined to a carbon by covalent bonds
E)
a carbon atom joined to an oxygen by a double covalent bond
 

 26. 

A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so?
A)
carboxyl
B)
sulfhydryl
C)
hydroxyl
D)
amino
E)
phosphate
 

 27. 

Which functional groups can act as acids?
A)
amine and sulfhydryl
B)
carbonyl and carboxyl
C)
carboxyl and phosphate
D)
hydroxyl and aldehyde
E)
ketone and amino
 
 
Use the figure below to answer the following questions.

biochempractice_files/i0320000.jpg
 

 28. 

Which is an amino functional group?
A)
Group A
B)
Group B
C)
Group C
D)
Group D
E)
Group E
 

 29. 

Which is a carboxyl functional group?
A)
Group A
B)
Group B
C)
Group C
D)
Group D
E)
Group E
 

 30. 

Which molecule can increase the concentration of hydrogen ions in a solution and is therefore an organic acid?
A)
Molecule A
B)
Molecule B
C)
Molecule C
D)
Molecule D
E)
Molecule E
 
 
Use the molecules shown in the figure below to answer the following questions..

biochempractice_files/i0360000.jpg
 

 31. 

Which molecule is a thiol?
A)
Molecule A
B)
Molecule B
C)
Molecule C
D)
Molecule D
E)
Molecule E
 

 32. 

The molecule shown in the figure below is a

biochempractice_files/i0380000.jpg

A)
polysaccharide.
B)
polypeptide.
C)
saturated fatty acid.
D)
triacylglycerol.
E)
unsaturated fatty acid.
 

 33. 

What is the structure shown in the figure below?

biochempractice_files/i0390000.jpg
A)
starch molecule
B)
protein molecule
C)
steroid molecule
D)
cellulose molecule
E)
phospholipid molecule
 
 
Use the figure below to answer the following questions.

biochempractice_files/i0400000.jpg
 

 34. 

At which bond would water need to be added to achieve hydrolysis of the peptide, back to its component amino acid?
A)
Bond A
B)
Bond B
C)
Bond C
D)
Bond D
E)
Bond E
 

 35. 

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be comprised of
A)
120 adenine and 120 uracil molecules.
B)
120 thymine and 120 adenine molecules.
C)
120 cytosine and 120 thymine molecules.
D)
240 adenine and 240 cytosine molecules.
E)
240 guanine and 240 thymine molecules.
 

 36. 

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?
A)
a steroid
B)
cellulose
C)
DNA
D)
an enzyme
E)
a contractile protein
 
 
The following questions are based on the 15 molecules illustrated below. Each molecule may be used once, more than once, or not at all.

biochempractice_files/i0440000.jpg
 

 37. 

Which of the following molecules are structural isomers?
A)
1 and 4
B)
5 and 14
C)
6 and 12
D)
12 and 13
E)
14 and 15
 

 38. 

Which of the following molecules is a saturated fatty acid?
A)
1
B)
5
C)
6
D)
8
E)
9
 

 39. 

Which of the following molecules could be joined together by a phosphodiester type of covalent bond?
A)
3 and 4
B)
3 and 8
C)
6 and 15
D)
11 and 12
E)
11 and 13
 

 40. 

Which of the following statements is false?
A)
1 and 4 could be joined together by a glycosidic linkage to form a disaccharide.
B)
9 and 10 could be joined together by ester bonds to form a triacylglycerol.
C)
2 and 7 could be joined together to form a short peptide.
D)
2, 7, and 8 could be joined together to form a short peptide.
E)
14 and 15 could be joined together to form a polypeptide.
 
 
The following questions refer to the following simple metabolic pathway:

enzyme A
enzyme B
biochempractice_files/i0490000.jpg
biochempractice_files/i0490001.jpg
 

 41. 

According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?
A)
0
B)
1
C)
2
D)
3
E)
It cannot be determined from the pathway.
 

 42. 

Which of the following is true for both prokaryotic and eukaryotic gene expression?
A)
After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.
B)
Translation of mRNA can begin before transcription is complete.
C)
RNA polymerase binds to the promoter region to begin transcription.
D)
mRNA is synthesized in the 3' ? 5' direction.
E)
The mRNA transcript is the exact complement of the gene from which it was copied.
 

 43. 

Which of the following is not a part of the eukaryotic transcription initiation complex?
A)
promoter
B)
RNA polymerase
C)
transcription factors
D)
snRNP
E)
TATA box
 

 44. 

What are the coding segments of a stretch of eukaryotic DNA called?
A)
introns
B)
exons
C)
codons
D)
replicons
E)
transposons
 

 45. 

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that
A)
many noncoding nucleotides are present in mRNA.
B)
there is redundancy and ambiguity in the genetic code.
C)
many nucleotides are needed to code for each amino acid.
D)
nucleotides break off and are lost during the transcription process.
E)
there are termination exons near the beginning of mRNA.
 

 46. 

Which of the following is least related to the other items?
A)
snRNP
B)
triplet code
C)
wobble
D)
tRNA
E)
anticodon
 

 47. 

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that
A)
none of the proteins in the cell will contain phenylalanine.
B)
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
C)
the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.
D)
the ribosome will skip a codon every time a UUU is encountered.
E)
None of the above will occur; the cell will recognize the error and destroy the tRNA.
 

 48. 

During translation, chain elongation continues until what happens?
A)
No further amino acids are needed by the cell.
B)
All tRNAs are empty.
C)
The polypeptide is long enough.
D)
A stop codon is encountered.
E)
The ribosomes run off the end of mRNA.
 

 49. 

Which of the following does not occur during the termination phase of translation?
A)
A termination codon causes the A site to accept a release factor.
B)
The newly formed polypeptide is released.
C)
A tRNA with the next amino acid enters the P site.
D)
The two ribosomal subunits separate.
E)
Translation stops.
 

 50. 

Which of the following is least related to the other items?
A)
exons
B)
introns
C)
RNA splicing
D)
signal-recognition particles (SRPs)
E)
mRNA
 

 51. 

Which of the following is (are) true about RNA?
A)
snoRNA aids in processing pre-rRNA transcripts in the nucleolus.
B)
SRP RNA is an essential component of spliceosomes.
C)
It has functional groups that allow it to act as a catalyst (ribozyme).
D)
Only A and C are true.
E)
A, B, and C are true.
 

 52. 

Which of the following statements are true about protein synthesis in prokaryotes?
A)
Translation can begin while transcription is still in progress.
B)
Extensive RNA processing is required before prokaryotic transcripts can be translated.
C)
Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.
D)
Only A and B are true.
E)
A, B, and C are true.
 

 53. 

Of the following types of mutations, which one is likely to be the most common?
A)
point mutation
B)
missense mutation
C)
base-pair substitution
D)
nonsense mutation
E)
frameshift mutation
 

 54. 

A frameshift mutation could result from
A)
a base insertion only.
B)
a base deletion only.
C)
a base substitution only.
D)
deletion of three consecutive bases.
E)
either an insertion or a deletion of a base.
 

 55. 

Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?
A)
a base substitution
B)
a base deletion near the start of a gene
C)
a base deletion near the end of the coding sequence, but not in the terminator codon
D)
deletion of three bases near the start of the coding sequence, but not in the initiator codon
E)
a base insertion near the end of the coding sequence, but not in the terminator codon
 

 56. 

Which enzyme was used to produce the molecule in the figure below?

biochempractice_files/i0650000.jpg

A)
ligase
B)
transcriptase
C)
a restriction enzyme
D)
RNA polymerase
E)
DNA polymerase
 
 
Use the following information to answer the questions below.

A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics.
 

 57. 

Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in
A)
the nutrient broth only.
B)
the nutrient broth and the tetracycline broth only.
C)
the nutrient broth, the ampicillin broth, and the tetracycline broth.
D)
all four types of broth.
E)
the ampicillin broth and the nutrient broth.
 

 58. 

Which of the following is least related to the others?
A)
Southern blotting
B)
denaturation
C)
nucleic acid probe
D)
RNA interference
E)
nucleic acid hybridization
 

 59. 

The major advantage of using artificial chromosomes such as YACs and BACs instead of plasmids for cloning genes is that
A)
plasmids are unable to replicate in cells.
B)
only one copy of a plasmid can be present in any given cell, whereas many copies of a YAC or BAC can coexist in a single cell.
C)
YACs and BACs can carry much larger DNA fragments than plasmids can.
D)
YACs and BACs can be used to express proteins encoded by inserted genes, but plasmids cannot.
E)
all of the above
 

 60. 

The "shotgun" approach used by Craig Venter to sequence the human genome skipped which of the following steps that were used by the Human Genome Project?
A)
genetic mapping
B)
physical mapping
C)
DNA sequencing
D)
A and B only
E)
A, B, and C
 



 
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