BCH 3025 EXAM 2 ACTUAL EXAM PRACTICE 2025|BRAND NEW VERIFIED EXAM QUESTIONS AND CORRECT ANSWERS ALL GRADED A+|LATEST UPDATE
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BCH 3025
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BCH 3025
BCH 3025 EXAM 2 ACTUAL EXAM PRACTICE 2025|BRAND NEW VERIFIED EXAM QUESTIONS AND CORRECT ANSWERS ALL GRADED A+|LATEST UPDATE
The compound that consists of ribose linked by an N-glycosidic bond to N-9 of adenine is:
A) a deoxyribonucleoside.
B) a purine nucleotide.
C) a pyrim...
BCH 3025 EXAM 2 ACTUAL EXAM
PRACTICE 2025|BRAND NEW VERIFIED
EXAM QUESTIONS AND CORRECT
ANSWERS ALL GRADED A+|LATEST
UPDATE 2024-2025
The compound that consists of ribose linked by an N-glycosidic bond to N-9 of
adenine is:
A) a deoxyribonucleoside.
B) a purine nucleotide.
C) a pyrimidine nucleotide.
D) adenosine monophosphate.
E) adenosine. - ANSWER-✅E) adenosine
A major component of RNA but not of DNA is:
A) adenine.
B) cytosine.
C) guanine.
D) thymine.
E) uracil. - ANSWER-✅E) uracil.
The difference between a ribonucleotide and a deoxyribonucleotide is:
A) a deoxyribonucleotide has an —H instead of an —OH at C-2.
B) a deoxyribonucleotide has configuration; ribonucleotide has the configuration at
C-1.
C) a ribonucleotide has an extra —OH at C-4.
D) a ribonucleotide has more structural flexibility than deoxyribonucleotide.
E) a ribonucleotide is a pyranose, deoxyribonucleotide is a furanose. - ANSWER-✅A)
a deoxyribonucleotide has an —H instead of an —OH at C-2.
,Which one of the following is true of the pentoses found in nucleic acids?
A) C-5 and C-1 of the pentose are joined to phosphate groups.
B) C-5 of the pentose is joined to a nitrogenous base, and C-1 to a phosphate group.
C) The bond that joins nitrogenous bases to pentoses is an O-glycosidic bond.
D) The pentoses are always in the beta-furanose forms.
E) The straight-chain and ring forms undergo constant interconversion. - ANSWER-
✅D) The pentoses are always in the beta-furanose forms
The phosphodiester bonds that link adjacent nucleotides in both RNA and DNA:
A) always link A with T and G with C.
B) are susceptible to alkaline hydrolysis.
C) are uncharged at neutral pH.
D) form between the planar rings of adjacent bases.
E) join the 3' hydroxyl of one nucleotide to the 5' hydroxyl of the next. - ANSWER-✅E)
join the 3' hydroxyl of one nucleotide to the 5' hydroxyl of the next.
The phosphodiester bond that joins adjacent nucleotides in DNA:
A) associates ionically with metal ions, polyamines, and proteins.
B) is positively charged.
C) is susceptible to alkaline hydrolysis.
D) Links C-2 of one base to C-3 of the next.
E) links C-3 of deoxyribose to N-1 of thymine or cytosine. - ANSWER-✅A) associates
ionically with metal ions, polyamines, and proteins.
The alkaline hydrolysis of RNA does not produce:
A) 2'- AMP.
B) 2',3'-cGMP.
C) 2'-CMP.
D) 3',5'-cAMP.
E) 3'-UMP. - ANSWER-✅D) 3',5'-cAMP
The DNA oligonucleotide abbreviated pATCGAC:
A) has 7 phosphate groups.
B) has a hydroxyl at its 3' end.
C) has a phosphate on its 3' end.
D) has an A at its 3' end.
E) violates Chargaff's rules. - ANSWER-✅B) has a hydroxyl at its 3' end
For the oligoribonucleotide pACGUAC:
A) the nucleotide at the 3' end has a phosphate at its 3' hydroxyl.
,B) the nucleotide at the 3' end is a purine.
C) the nucleotide at the 5' end has a 5' hydroxyl.
D) the nucleotide at the 5' end has a phosphate on its 5' hydroxyl.
E) the nucleotide at the 5' end is a pyrimidine. - ANSWER-✅D) the nucleotide at the
5' end has a phosphate on its 5' hydroxyl.
The nucleic acid bases:
A) absorb ultraviolet light maximally at 280 nm.
B) are all about the same size.
C) are relatively hydrophilic.
D) are roughly planar.
E) can all stably base-pair with one another. - ANSWER-✅D) are roughly planar.
Which of the following statements concerning the tautomeric forms of bases such
as uracil is correct?
A) The all-lactim form contains a ketone group.
B) The lactam form contains an alcohol group.
C) The lactam form predominates at neutral pH.
D) They are geometric isomers.
E) They are stereoisomers. - ANSWER-✅C) The lactam form predominates at neutral
pH.
In a double-stranded nucleic acid, cytosine typically base-pairs with:
A) adenosine.
B) guanine.
C) inosine.
D) thymine.
E) uracil. - ANSWER-✅B) guanine.
In the Watson-Crick model for the DNA double helix (B form) the A-T and G-C base
pairs share which one of the following properties?
A) The distance between the two glycosidic (base-sugar) bonds is the same in both
base pairs, within a few tenths of an angstrom.
B) The molecular weights of the two base pairs are identical.
C) The number of hydrogen bonds formed between the two bases of the base pair is
the same.
D) The plane of neither base pair is perpendicular to the axis of the helix.
E) The proton-binding groups in both base pairs are in their charged or ionized form.
- ANSWER-✅A) The distance between the two glycosidic (base-sugar) bonds is the
same in both base pairs, within a few tenths of an angstrom.
The experiment of Avery, MacLeod, and McCarty in which nonvirulent bacteria were
made virulent by transformation was significant because it showed that:
, A) bacteria can undergo transformation.
B) genes are composed of DNA only.
C) mice are more susceptible to pneumonia than are humans.
D) pneumonia can be cured by transformation.
E) virulence is determine genetically. - ANSWER-✅B) genes are composed of DNA
only.
Chargaff's rules state that in typical DNA:
A) A = G.
B) A = C.
C) A = U.
D) A + T = G + C.
E) A + G = T + C. - ANSWER-✅E) A + G = T + C.
In the Watson-Crick structure of DNA, the:
A) absence of 2'-hydroxyl groups allows bases to lie perpendicular to the helical axis.
B) adenine content of one strand must equal the thymine content of the same strand.
C) nucleotides are arranged in the A-form.
D) purine content (fraction of bases that are purines) must be the same in both
strands.
E) two strands are parallel. - ANSWER-✅A) absence of 2'-hydroxyl groups allows
bases to lie perpendicular to the helical axis.
In the Watson-Crick model of DNA structure:
A) both strands run in the same direction, 3' 5'; they are parallel.
B) phosphate groups project toward the middle of the helix, where they are
protected from interaction with water.
C) T can form three hydrogen bonds with either G or C in the opposite strand.
D) the distance between the sugar backbone of the two strands is just large enough
to accommodate either two purines or two pyrimidines.
E) the distance between two adjacent bases in one strand is about 3.4 Å. - ANSWER-
✅E) the distance between two adjacent bases in one strand is about 3.4 Å.
Which of the following is not true of all naturally occurring DNA?
A) Deoxyribose units are connected by 3',5'-phosphodiester bonds.
B) The amount of A always equals the amount of T.
C) The ratio A+T/G+C is constant for all natural DNAs.
D) The two complementary strands are antiparallel.
E) Two hydrogen bonds form between A and T. - ANSWER-✅C) The ratio A+T/G+C is
constant for all natural DNAs.
In the Watson-Crick model of DNA structure (now called B-form DNA):
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