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51.

Bacteria have ____________(a) 70S ribosomes(b) 60S ribosomes(c) 50S ribosomes(d) 80S ribosomesI had been asked this question during an online exam.This key question is from Protein Synthesis in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct option is (a) 70S ribosomes

For explanation I WOULD say: Bacteria have 70S ribosomes, with a LARGE (50S) and a small (30S) subunit.

52.

Which position of a codon is said to wobble?(a) First(b) Second(c) Third(d) FourthI had been asked this question by my college professor while I was bunking the class.This intriguing question comes from The Genetic Code in portion DNA, RNA and Protein Metabolism of Biochemistry

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Right answer is (c) Third

To elaborate: The third position in each codon is MUCH LESS specific than the FIRST and second and is said to WOBBLE.

53.

How many t-RNAs are required to translate all 61 codons?(a) 31(b) 32(c) 30(d) 29The question was posed to me by my college director while I was bunking the class.The origin of the question is The Genetic Code in section DNA, RNA and Protein Metabolism of Biochemistry

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The correct option is (b) 32

To EXPLAIN: A minimum of 32 t-RNAs are REQUIRED to translate all 61 codons.

54.

Actinomycin D is an inhibitor of ____________(a) Transcription(b) Translation(c) Replication(d) None of the mentionedThis question was posed to me in homework.My question is based upon DNA-Dependent Synthesis of RNA in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct OPTION is (a) Transcription

To elaborate: The ELONGATION of RNA strands by RNA polymerase in both BACTERIA and eukaryotes is inhibited by the ANTIBIOTIC actinomycin D.

55.

Which of the following process occurs in regions where no large –scale sequence similarity is apparent?(a) Homologous genetic recombination(b) Site specific recombination(c) Non-homologous recombination(d) Replicative recombinationI have been asked this question in an online quiz.Origin of the question is DNA Recombination in chapter DNA, RNA and Protein Metabolism of Biochemistry

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Correct ANSWER is (c) Non-homologous recombination

Explanation: Site-specific recombination occurs between particular short sequences present on otherwise DISSIMILAR parental molecules.

Replicative recombination generates a new copy of the transposable ELEMENT at a new location of DNA.

Homologous genetic recombination occurs between DNA molecules of very SIMILAR sequences.

56.

In which of the following cases the first base of anticodon pairs with three codons?(a) When the first base of anticodon is A or C(b) When the first base of anticodon is A or G(c) When the first base of anticodon is inosine(d) When the first base of anticodon is G or UThe question was posed to me in final exam.Asked question is from The Genetic Code topic in section DNA, RNA and Protein Metabolism of Biochemistry

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The CORRECT OPTION is (c) When the first base of anticodon is INOSINE

To explain: When inosine is the first nucleotide of an anticodon, three DIFFERENT codons can be RECOGNIZED.

57.

Transcription is catalyzed by ____________(a) DNA-dependent RNA polymerases(b) RNA-dependent DNA polymerases(c) Reverse transcriptases(d) DNA ligasesThe question was asked in unit test.The origin of the question is DNA-Dependent Synthesis of RNA topic in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct ANSWER is (a) DNA-dependent RNA polymerases

For explanation I would say: Transcription is catalyzed by DNA-dependent RNA polymerases, which USE ribonucleotide 5’-triphosphates to SYNTHESIZE RNA COMPLEMENTARY to the template strand of duplex DNA.

58.

Which of the following occurs between particular short sequences present on otherwise dissimilar parental molecules?(a) Homologous genetic recombination(b) Site specific recombination(c) Non-homologous recombination(d) Replicative recombinationI had been asked this question in an internship interview.I would like to ask this question from DNA Recombination topic in portion DNA, RNA and Protein Metabolism of Biochemistry

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Correct CHOICE is (b) Site specific RECOMBINATION

The EXPLANATION: Homologous genetic recombination occurs between DNA molecules of very similar sequences.

Non-homologous recombination occurs in regions where no large –scale sequence similarity is apparent.

Replicative recombination generates a new COPY of the transposable element at a new location of DNA.

59.

A point mutation that replaces a purine with another purine, or a pyrimidine with another pyramidine ____________(a) Nonsense mutation(b) Silent mutation(c) Transition mutation(d) TransversionI got this question during an interview for a job.My enquiry is from DNA Repair topic in section DNA, RNA and Protein Metabolism of Biochemistry

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Correct answer is (c) Transition MUTATION

The BEST I can explain: Nonsense mutation (point mutation) results in a PREMATURE stop codon.

Transversion refers to substitution of a purine for a pyrimidine or vice-versa.

If the mutation has a negligible effect on the function of a gene, it is KNOWN as a SILENT mutation.

60.

Which of the following process occurs between DNA molecules of very similar sequences?(a) Homologous genetic recombination(b) Site specific recombination(c) Non-homologous recombination(d) Replicative recombinationThe question was asked in final exam.Question is taken from DNA Recombination topic in portion DNA, RNA and Protein Metabolism of Biochemistry

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61.

An alteration in a nucleotide sequence that changes a triplet coding for an amino acid into a termination codon is ____________(a) Nonsense mutation(b) Mutagenesis(c) Mutation(d) MutagenThe question was posed to me during an interview.My enquiry is from DNA Repair topic in division DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT choice is (a) Nonsense mutation

Easiest explanation: Nonsense mutation (point mutation) results in a PREMATURE STOP CODON.
62.

Which of the following reactions is required for proofreading during DNA replication by DNA polymerase III?(a) 5’ to 3’ exonuclease activity(b) 3’ to 5’ exonuclease activity(c) 3’ to 5’ endonuclease activity(d) 5’ to 3’ endonuclease activityThe question was asked in semester exam.Enquiry is from DNA Replication in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct choice is (b) 3’ to 5EXONUCLEASE ACTIVITY

To EXPLAIN: The 3’ → 5’ exonuclease activity removes the mispaired nucleotide and the polymerase BEGINS again. This activity is known as proofreading.

63.

In which of the following cases the first base of anticodon pairs with only one codon?(a) When the first base of anticodon is A or C(b) When the first base of anticodon is A or G(c) When the first base of anticodon is inosine(d) When the first base of anticodon is G or UI have been asked this question in an online interview.This intriguing question comes from The Genetic Code in portion DNA, RNA and Protein Metabolism of Biochemistry

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Right option is (a) When the FIRST base of anticodon is A or C

The best I can explain: When the first base of the anticodon is C or A, base pairing is SPECIFIC and only one codon is RECOGNIZED by that t-RNA.

64.

The coated pits are coated on their cytosolic side with a lattice of ____________(a) Clathrin(b) Lipoprotein(c) Glycoprotein(d) TransferrinI had been asked this question in an online interview.Enquiry is from Protein Targeting and Degradation in section DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT option is (a) Clathrin

Best explanation: Clathrin is COATED on the CYTOSOLIC side of the coated PITS.
65.

The initiation codon is ____________(a) AUG(b) UAA(c) UAG(d) UGAThis question was addressed to me during an internship interview.I need to ask this question from The Genetic Code in section DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT option is (a) AUG

Easy explanation: UAA, UAG and UGA are termination CODONS.
66.

Which type of homing is DNA-based?(a) Group I intron(b) Group II intron(c) Group III intron(d) Group IV intronThe question was asked in an interview for job.I want to ask this question from RNA-Dependent Synthesis of RNA and DNA topic in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct CHOICE is (a) GROUP I intron

Easy explanation: Group II intron homing OCCURS through an RNA INTERMEDIATE.

67.

Which is the first nucleic acid synthesizing enzyme discovered?(a) Polynucleotide phosphorylase(b) DNA polymerase(c) RNA polymerase(d) DNA ligaseI got this question in an interview for internship.My doubt stems from RNA Processing in portion DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT choice is (a) Polynucleotide PHOSPHORYLASE

The best explanation: Polynucleotide phosphorylase is the first nucleic acid SYNTHESIZING enzyme DISCOVERED.
68.

What is the reaction in DNA replication catalyzed by DNA ligase?(a) Addition of new nucleotides to the leading strand(b) Addition of new nucleotide to the lagging strand(c) Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand(d) Base pairing of the template and the newly formed DNA strandI got this question in an interview for job.This interesting question is from DNA Replication in section DNA, RNA and Protein Metabolism of Biochemistry

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Correct option is (c) Formation of a phosphodiester BOND between the 3’-OH of one OKAZAKI fragment and the 5’-phosphate of the NEXT on the lagging strand

For explanation: DNA LIGASE catalyzes the formation of a phosphodiester bond between 3’-OH of one Okazaki fragment and 5’-phosphate of the next.

69.

How many amino acid residues are there in ubiquitin?(a) 72(b) 73(c) 75(d) 76This question was addressed to me by my school teacher while I was bunking the class.The doubt is from Protein Targeting and Degradation in portion DNA, RNA and Protein Metabolism of Biochemistry

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Correct choice is (d) 76

For EXPLANATION: ONE of the most HIGHLY CONSERVED proteins is known as ubiquitin (76 amino acid residues).

70.

Wobble hypothesis was first proposed by ____________(a) Nirenberg(b) Watson and Crick(c) Watson(d) CrickThis question was addressed to me in an interview for job.The question is from The Genetic Code in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct choice is (d) Crick

The BEST I can explain: Crick PROPOSED a set of FOUR RELATIONSHIPS CALLED the wobble hypothesis.

71.

What is the role of sigma factor in bacterial RNA polymerase?(a) Catalyzing RNA synthesis(b) Positioning RNA polymerase correctly on the DNA template(c) Terminating RNA synthesis(d) Unwinding DNA templateI have been asked this question in an interview for internship.My doubt is from DNA-Dependent Synthesis of RNA in chapter DNA, RNA and Protein Metabolism of Biochemistry

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The CORRECT choice is (b) Positioning RNA polymerase correctly on the DNA template

To ELABORATE: Sigma factor enables specific BINDING of RNA polymerase to promoter.

72.

Repressors bind to ____________(a) Promoter(b) Enhancer(c) Operator(d) Hormone response elementThis question was addressed to me in quiz.I'd like to ask this question from DNA-Dependent Synthesis of RNA in portion DNA, RNA and Protein Metabolism of Biochemistry

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The correct answer is (C) OPERATOR

For explanation: A repressor MOLECULE BINDS to the operator.

73.

If the mutation has a negligible effect on the function of a gene, it is known as a ____________(a) Silent mutation(b) Frame shift mutation(c) Substitution mutation(d) Insertion mutationI had been asked this question by my college professor while I was bunking the class.Asked question is from DNA Repair in portion DNA, RNA and Protein Metabolism of Biochemistry

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Correct answer is (a) SILENT mutation

To EXPLAIN: Mutations can involve the REPLACEMENT of one BASE pair with another (substitution mutation) or the addition or deletion of one or more base PAIRS (insertion or deletion mutations).

74.

Which of the following does not code for an enzyme having both helicase and nuclease activity?(a) Rec-A(b) Rec-B(c) Rec-C(d) Rec-DThe question was asked in an internship interview.My question comes from DNA Recombination in division DNA, RNA and Protein Metabolism of Biochemistry

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Right answer is (a) Rec-A

Explanation: In E. COLI, rec-B, rec-C and rec-D genes encode the Rec-BCD enzyme, which has both HELICASE and nuclease ACTIVITIES.

75.

The genetic code translated the language of ____________(a) Proteins into that of RNA(b) Amino acids into that of RNA(c) RNA into that of proteins(d) RNA into that of DNAI got this question in my homework.My question is taken from The Genetic Code topic in section DNA, RNA and Protein Metabolism of Biochemistry

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The CORRECT choice is (c) RNA into that of proteins

The explanation: The overall PROCESS of mRNA-guided protein SYNTHESIS is often REFERRED to simply as translation.

76.

Which of the following inhibits initiation at higher concentrations?(a) Chloramphenicol(b) Streptomycin(c) Diphtheria toxin(d) RicinThis question was posed to me in semester exam.This interesting question is from Protein Synthesis in section DNA, RNA and Protein Metabolism of Biochemistry

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The CORRECT choice is (B) Streptomycin

To explain: Streptomycin, a BASIC tri-saccharide causes misreading of the genetic code at RELATIVELY low concentrations and inhibits initiation at HIGHER concentrations.

77.

Which of the following are not DNA viruses?(a) Hepatitis B virus(b) Influenza A virus(c) CMV virus(d) ParvovirusThis question was addressed to me by my college professor while I was bunking the class.The above asked question is from RNA-Dependent Synthesis of RNA and DNA in chapter DNA, RNA and Protein Metabolism of Biochemistry

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Right ANSWER is (B) Influenza A virus

Best explanation: Influenza A virus is RNA virus.

78.

Which of the following is true about RNA synthesis?(a) Synthesis of RNA is always in the 5’ to 3’ direction(b) RNA polymerase requires a primer for initiating transcription(c) U is inserted opposite T in transcription(d) New nucleotides are added on the 2’-OH of the ribose sugarThe question was asked during an online interview.The above asked question is from DNA-Dependent Synthesis of RNA topic in division DNA, RNA and Protein Metabolism of Biochemistry

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Correct answer is (a) SYNTHESIS of RNA is ALWAYS in the 5’ to 3’ direction

Explanation: Unlike DNA polymerase, RNA polymerase does not require a PRIMER to initiate transcription.

79.

Semi-conservative DNA replication was first demonstrated in ____________(a) Drosophila melanogaster(b) Escherichia coli(c) Streptococcus pneumonae(d) Drosophila melanogasterThe question was posed to me in a job interview.My question is based upon DNA Replication topic in section DNA, RNA and Protein Metabolism of Biochemistry

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Correct OPTION is (a) DROSOPHILA melanogaster

To explain: Semi-conservative DNA REPLICATION was FIRST demonstrated in E. coli.

80.

Which of the following mechanisms will remove uracil and incorporate the correct base?(a) Direct repair(b) Base excision repair(c) Mismatch repair(d) Nucleotide excision repairI have been asked this question during an internship interview.Question is taken from DNA Repair topic in chapter DNA, RNA and Protein Metabolism of Biochemistry

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The correct CHOICE is (b) Base excision repair

For explanation I would say: Base excision repair is RESPONSIBLE for removing small, non-helix-distorting base LESIONS from GENOME.

81.

What is DNA replication?(a) Conservative(b) Non-conservative(c) Semi-conservative(d) None of the mentionedThis question was addressed to me in an interview.My query is from DNA Replication in chapter DNA, RNA and Protein Metabolism of Biochemistry

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Correct ANSWER is (c) Semi-conservative

To elaborate: Each DNA strand serves as a template for the synthesis of a NEW strand, producing TWO new DNA molecules, each with one new strand and one old strand.

82.

The antibiotic aided in elucidating the steps of protein glycosylation is ____________(a) Streptomycin(b) Tunicamycin(c) Penicillin(d) CrocinThe question was asked during an interview.This key question is from Protein Targeting and Degradation topic in section DNA, RNA and Protein Metabolism of Biochemistry

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The correct ANSWER is (B) Tunicamycin

Easy explanation: It acts by interfering with one or more steps in this process.

83.

Which of the following is RNA-dependent RNA polymerase?(a) Reverse transcriptase(b) RNA polymerase I(c) RNA polymerase II(d) RNA replicaseI had been asked this question in unit test.Origin of the question is RNA-Dependent Synthesis of RNA and DNA topic in chapter DNA, RNA and Protein Metabolism of Biochemistry

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Correct choice is (d) RNA replicase

Easy EXPLANATION: RNA POLYMERASE I, RNA polymerase II are DNA DEPENDENT RNA POLYMERASES and reverse transcriptase is RNA-dependent DNA polymerase.

84.

Which is an example of RNA-dependent DNA polymerase?(a) Reverse transcriptase(b) DNA ligase(c) RNA polymerase I(d) RNA polymerase IIThis question was posed to me in homework.Question is from RNA-Dependent Synthesis of RNA and DNA topic in portion DNA, RNA and Protein Metabolism of Biochemistry

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The correct answer is (a) REVERSE transcriptase

Explanation: RNA polymerase I, RNA polymerase II are DNA DEPENDENT RNA POLYMERASES and DNA ligase is ATP-dependent.

85.

The sequences of the recombination sites recognized by site-specific recombinases are ____________(a) Partially asymmetric(b) Partially symmetric(c) Symmetric(d) PalindromicI have been asked this question in an interview.The doubt is from DNA Recombination topic in division DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT choice is (a) Partially ASYMMETRIC

The explanation: The sequences of the recombination sites recognized by site-specific recombinases are partially asymmetric (non-palindromic).
86.

RNA primer is removed from the Okazaki fragment by ____________(a) DNA polymerase I(b) DNA polymerase II(c) DNA polymerase III(d) RNA polymeraseI have been asked this question in exam.Query is from DNA-Dependent Synthesis of RNA topic in chapter DNA, RNA and Protein Metabolism of Biochemistry

Answer» CORRECT answer is (a) DNA polymerase I

To ELABORATE: DNA polymerase I remove RNA PRIMER from Okazaki FRAGMENT.
87.

What are the two subassemblies of 26S proteasome?(a) 20S core particle and 19S regulatory particle(b) 20S regulatory particle and 19S core particle(c) 18S core particle and 19S regulatory particle(d) 20S core particle and 18S regulatory particleThis question was posed to me in class test.Enquiry is from Protein Targeting and Degradation in portion DNA, RNA and Protein Metabolism of Biochemistry

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Correct CHOICE is (a) 20S core particle and 19S REGULATORY particle

For explanation: The TWO SUBASSEMBLIES are 20S core particle and 19S regulatory particle.

88.

What is the role of small nuclear RNAs in protein synthesis?(a) It translates genetic code to a specific amino acid(b) It modifies mRNA molecules prior to protein synthesis(c) It provides a genetic blueprint for the protein(d) It catalyzes the processI have been asked this question in homework.This interesting question is from Protein Synthesis in portion DNA, RNA and Protein Metabolism of Biochemistry

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Right option is (B) It modifies MRNA MOLECULES prior to protein synthesis

For explanation I would SAY: t-RNA translates genetic code to a specific amino acid.

r-RNA catalyzes the process.

mRNA provides a genetic blueprint for the protein.

89.

Which of the following contains only the sequences required for transposition and the genes for proteins that promote the process?(a) Insertion sequences(b) Complex transposons(c) Transposons(d) ChromosomesI have been asked this question in an international level competition.I'd like to ask this question from DNA Recombination topic in chapter DNA, RNA and Protein Metabolism of Biochemistry

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The correct choice is (a) Insertion sequences

The best I can EXPLAIN: Complex transposons CONTAIN one or more GENES in addition to those needed for transposition.