BCH 3025 Exam 2 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Which of the following is true about the difference between nucleotides and nucleosides?
•A. Nucleotides lack a nitrogenous base.
•B. Nucleosides lack a ribose sugar.
•C. Nucleotides lack a phosphate.
•D. Nucleosides lack a phosphate. - CORRECT ANSWER -D
The chemical synthesis of DNA
•A. occurs in a 5′ to 3′ direction.
•B. is carried out with the growing strand attached to a solid support.
•C. can add one or more nucleotides per chemical cycle.
D. requires a DNA template. - CORRECT ANSWER -B
Deoxyribonucleic acid (DNA) is different from ribonucleic acid (RNA) in that
•A. DNA contains a 3′ H, whereas RNA contains a 3′ OH.
•B. only DNA utilizes the base uracil.
•C. only RNA can be hydrolyzed by alkaline conditions.
D. only DNA contains a pentose sugar. - CORRECT ANSWER -C
Evidence that DNA stores the genetic information of the cell was provided by Avery-MacLeod-
McCarty experiment in which
•A. DNA from a heat-killed virulent strain of the bacterium Streptococcus pneumoniae could
genetically transform live non virulent strain into a virulent strain.
•B. DNA from a heat-killed nonvirulent strain of the bacterium Streptococcus pneumoniae could
transform live non virulent strain into a virulent strain.
,•C. a live nonvirulent strain of the bacterium Streptococcus pneumoniae could be transformed
into a virulent strain by heat treatment.
•D. DNA from a heat-killed virulent strain of the bacterium Streptococcus pneumoniae could
transform a live nonvirulent strain if the DNA was treated with deoxyribonucleases. -
CORRECT ANSWER -A
Which of the following is true about the denaturation of double-helical DNA?
•A. Denaturation increases with decreasing temperature.
•B. Denaturation is accompanied by an increase in the absorption of UV light by DNA.
•C. G-C rich DNA melts at lower temperature than A-T rich DNA.
•D. Once denatured, DNA strands cannot anneal. - CORRECT ANSWER -B
Which of the following is true about the structure of DNA as proposed by Watson and Crick (B-
form DNA)?
•A. DNA forms a left-handed double helix.
•B. The strands of DNA are parallel.
•C. The complementary base pairs are held together by hydrogen bonds.
•D. A complete turn of the double helix occurs after every base pair. - CORRECT
ANSWER -C
"Chargaff's rules" about the composition of bases in DNA dictates that
•A. the sum of purine residues must equal the sum of pyrimidine residues.
•B. the sum of A-T base pairs must equal the sum of G-C base pairs.
•C. the base composition of DNA is the same in all species.
•D. DNA specimens isolated from different tissues of the same species vary in base composition.
- CORRECT ANSWER -A
DNA can be sequenced by the Sanger method in which
•A. radioactively labeled DNA is subjected to four sets of base-specific cleavage reactions.
•B. automated sequencing can be done using different fluorescent-labeled 2′ deoxynucleotides.
, •C. the required DNA synthesis is performed via automated chemical synthesis.
•D. the sequence can be read by a laser beam. - CORRECT ANSWER -D
Which of the following is true about DNA sequence palindromes?
•A. A palindrome can form a cruciform structure involving one strand of DNA.
•B. Palindromes have two-fold symmetry over two strands of DNA.
•C. Palindromes are also known as mirror repeats.
•D. A palindrome is a sequence that is read the same way forward and backward on the same
strand. - CORRECT ANSWER -B
Which of the following is true about the bonds in DNA?
•A. Phosphomonoester bonds link successive nucleotides in nucleic acids.
•B. Phosphoanhydride bonds link successive nucleotides in nucleic acids.
•C. Single-stranded DNA or RNA does not form hydrogen bonds.
•D. Hydrogen bonding can occur in triplex DNA. - CORRECT ANSWER -D
Which of the following is true concerning a DNA double helix found inside cells?
• A. The backbone is positively charged.
•B. The bases are exposed through the major groove.
•C. Guanine forms two hydrogen bonds with cytosine.
•D. Adenine forms two hydrogen bonds with cytosine. - CORRECT ANSWER -B
Which of the following is true about mutations in DNA?
•A. Deamination and depurination are always caused by chemical agents.
•B. DNA damage caused by reactive chemicals and energy-rich radiation results in mutations
because cells have no DNA repair systems.
•C. Deamination occurs spontaneously under normal physiological conditions.
•D. Depurination results in the cleavage of the bond between the base and the phosphate. -
CORRECT ANSWER -C
Exam Questions and CORRECT Answers
Which of the following is true about the difference between nucleotides and nucleosides?
•A. Nucleotides lack a nitrogenous base.
•B. Nucleosides lack a ribose sugar.
•C. Nucleotides lack a phosphate.
•D. Nucleosides lack a phosphate. - CORRECT ANSWER -D
The chemical synthesis of DNA
•A. occurs in a 5′ to 3′ direction.
•B. is carried out with the growing strand attached to a solid support.
•C. can add one or more nucleotides per chemical cycle.
D. requires a DNA template. - CORRECT ANSWER -B
Deoxyribonucleic acid (DNA) is different from ribonucleic acid (RNA) in that
•A. DNA contains a 3′ H, whereas RNA contains a 3′ OH.
•B. only DNA utilizes the base uracil.
•C. only RNA can be hydrolyzed by alkaline conditions.
D. only DNA contains a pentose sugar. - CORRECT ANSWER -C
Evidence that DNA stores the genetic information of the cell was provided by Avery-MacLeod-
McCarty experiment in which
•A. DNA from a heat-killed virulent strain of the bacterium Streptococcus pneumoniae could
genetically transform live non virulent strain into a virulent strain.
•B. DNA from a heat-killed nonvirulent strain of the bacterium Streptococcus pneumoniae could
transform live non virulent strain into a virulent strain.
,•C. a live nonvirulent strain of the bacterium Streptococcus pneumoniae could be transformed
into a virulent strain by heat treatment.
•D. DNA from a heat-killed virulent strain of the bacterium Streptococcus pneumoniae could
transform a live nonvirulent strain if the DNA was treated with deoxyribonucleases. -
CORRECT ANSWER -A
Which of the following is true about the denaturation of double-helical DNA?
•A. Denaturation increases with decreasing temperature.
•B. Denaturation is accompanied by an increase in the absorption of UV light by DNA.
•C. G-C rich DNA melts at lower temperature than A-T rich DNA.
•D. Once denatured, DNA strands cannot anneal. - CORRECT ANSWER -B
Which of the following is true about the structure of DNA as proposed by Watson and Crick (B-
form DNA)?
•A. DNA forms a left-handed double helix.
•B. The strands of DNA are parallel.
•C. The complementary base pairs are held together by hydrogen bonds.
•D. A complete turn of the double helix occurs after every base pair. - CORRECT
ANSWER -C
"Chargaff's rules" about the composition of bases in DNA dictates that
•A. the sum of purine residues must equal the sum of pyrimidine residues.
•B. the sum of A-T base pairs must equal the sum of G-C base pairs.
•C. the base composition of DNA is the same in all species.
•D. DNA specimens isolated from different tissues of the same species vary in base composition.
- CORRECT ANSWER -A
DNA can be sequenced by the Sanger method in which
•A. radioactively labeled DNA is subjected to four sets of base-specific cleavage reactions.
•B. automated sequencing can be done using different fluorescent-labeled 2′ deoxynucleotides.
, •C. the required DNA synthesis is performed via automated chemical synthesis.
•D. the sequence can be read by a laser beam. - CORRECT ANSWER -D
Which of the following is true about DNA sequence palindromes?
•A. A palindrome can form a cruciform structure involving one strand of DNA.
•B. Palindromes have two-fold symmetry over two strands of DNA.
•C. Palindromes are also known as mirror repeats.
•D. A palindrome is a sequence that is read the same way forward and backward on the same
strand. - CORRECT ANSWER -B
Which of the following is true about the bonds in DNA?
•A. Phosphomonoester bonds link successive nucleotides in nucleic acids.
•B. Phosphoanhydride bonds link successive nucleotides in nucleic acids.
•C. Single-stranded DNA or RNA does not form hydrogen bonds.
•D. Hydrogen bonding can occur in triplex DNA. - CORRECT ANSWER -D
Which of the following is true concerning a DNA double helix found inside cells?
• A. The backbone is positively charged.
•B. The bases are exposed through the major groove.
•C. Guanine forms two hydrogen bonds with cytosine.
•D. Adenine forms two hydrogen bonds with cytosine. - CORRECT ANSWER -B
Which of the following is true about mutations in DNA?
•A. Deamination and depurination are always caused by chemical agents.
•B. DNA damage caused by reactive chemicals and energy-rich radiation results in mutations
because cells have no DNA repair systems.
•C. Deamination occurs spontaneously under normal physiological conditions.
•D. Depurination results in the cleavage of the bond between the base and the phosphate. -
CORRECT ANSWER -C
