MCQ’s of microbiology (Genetics – Part 2)

Here we have prepared some of the mcq’s of microbiology that may be helpful to the students related to microbiology and microbiology related subjects. (Genetics)

1) Exons and Introns in mRNA synthesis was first identified by:

• Temin and Baltimore
• Sharp and R. Roberts
• Milstein and Kohler
• Luria and Delbruck

2) A segment of an eukaryotic gene that is not represented in the mature mRNA, is known as

• Exon
• TATA box
• Plasmid
• Intron

3) The messenger RNA molecule of eukaryotic microorganisms consists of a collection of

• Introns
• Exons
• Enzymes human cells:
• Protein fragments

4) Transcription of a gene in

• Requires a primer RNA
• Does not require local unwinding of two DNA-strands
• Always begins at an AUG codon
• Always reads the DNA template strand in the 3′ to 5′ direction

5) A process during which the anticodon aligns with the codon is:

• Recombination
• Transcription
• Translation
• None of these

6) The process involving both mRNA and tRNA is:

• Replication
• Transcription
• Translation
• None of these

7) Events likely to be found in a cell in lag phase of growth is/are:

• Transcription
• Translation
• Both a and b
• None of these

8) The instructions for building a protein from amino acids pass from the DNA to:

• An enzyme molecule containing FAD
• A molecule of RNA
• A series of protein enzymes
• The cell membrane where the protein is synthesized

9) The synthesis of proteins in a microorganism represents an aspect of

• Photosynthesis
• Anabolism
• Catabolism
• Chemiosmosis

10) In order to form proteins in the metabolizing cell, all the following factor are required except:

• Messenger RNA molecules
• ATP molecules
• Fatty acid molecules
• Enzymes

11) The promoter and terminator regions functioning in protein synthesis exist on the:

• Endoplasmic reticulum
• Ribosome
• DNA molecules
• Nuclear membrane

12) The starting amino acid in prokaryotic protein synthesis is:

• Methionine
• N-formyl methionine
• Cystiene
• Proline

13) Which one of the following molecules is not a component of the 30S initiation complex?

• Initiation factor 2(IF-2)
• ATP
• mRNA
• GTP

14) 5′ end of mRNA binds to the ribosome at its which sequence:

• Promoter
• Start codon
• Leader
• Operator

15) The aminoacyl or acceptor site (A-site) and peptidyl (p) sites are located on which subunit of prokaryotic ribosome?

• 50 S
• 30 S
• Both
• None

16)  Okazaki fragment is:

• DNA fragment
• DNA fragment with RNA head
• RNA fragment with DNA head
• RNA fragment

17) Okazaki pieces are involved in:

• Transcription
• Protein synthesis
• Translation
• DNA replication

18) DNA polymerase in E. coli was discovered by:

• Komberg
• Kossel
• Holley
• Okazaki

19) The function of DNA polymerase I (Pol l) is:

• Repair of DNA
• Proof reading and editing mismatched nucleotides
• 5’→ 3′ exonuclease activity
• All of these

20) 5’→ 3′ exonuclease activity is reported to be absent in:

• DNA Polymerase II
• DNA Polymerase III
• Both a and b
• None

21)  Which of the following DNA polymerase shows 3’→ 5’exonuclease activity?

• DNA polymerase I
• DNA polymerase III
• DNA polymerase II
• All of these

22) DNA Repair proof reading in prokaryotes are caused by:

• DNA Polymerase I
• DNA Polymerase II
• DNA polymerase III
• Gyrase

23) Which of the following is not found in eukaryotic DNA polymerase?

• γ polymerase
• β polymerase
• α polymerase
• Pol I

24) The model for replication of circular DNA is:

• Cairns model
• Yoshikawa model
• Rolling circle model
• All

25) The enzyme which cuts off DNA in specific sites besides terminal end is called:

• Endonuclease
• Exonuclease
• Protease
• Transferase

26) Replication and transcription are similar processes in mechanistic terms because both:

• Use RNA primers for initiation
• Use deoxyribonucleotides as precursors
• Are semi conserved events
• Involve phosphodiester bond formation with elongation occurring in the 5′-3′ direction

27) Transcription and translation are subdivisions of the general process of

• DNA replication
• Protein synthesis
• Glycolysis
• The electron transport chain

28) The sequential transfer of information from DNA to protein via. RNA is known

• Gene regulation
• Translation
• Transcriptional control
• Central Dogma

29) Which of the following is/are component(s) of transcription machinery?

• dsDNA
• Mg”, Mn”
• Ribonucleoside triphosphates
• All

30) The process which makes a mRNA copy of a segment of DNA is:

• Recombination
• Transcription
• Translation
• Replication

31) Which is not involved in transcription?

• mRNA
• rRNA
• Charged tRNA
• DNA

32) Which of the following is not a component of entire RNA polymerase of prokaryote?

• ω
• α, α, β, β’
• Sigma (σ) factor
• Rho (ρ) factor

33) Sigma (σ) subunit of prokaryotic RNA polymerase:

• Is inhibited by a-amanitin
• Is the part of co-enzyme
• Binds the antibiotic rifampicin
• Specifically recognize the promoter site

34) All the following statements are true regarding transcription in prokaryotes except:

• Do not require primers
• Prokaryotic mRNAs are polycistronic
• RNA chain start with pppG or pppA
• Requires primers

35) A single amino acid is encoded by a group of:

• Three enzymes
• Three nucleotides
• Three molecules of ATP
• Three anticodons

36) Codon consists of:

• Single base
• Two bases
• Single nucleotide
• Three nucleotides

37) What is the maximum number of different amino acids in a polypeptide chain coded by the synthetic polyribonucleotide (UCAG)₅?

• 3
• 4
• 2
• 5

38) Amber codon is

• Terminator codon
• Alter protein structures
• Initiator codon
• None

39)  Which one of the following codons is not the terminal codon?

• UAG
• UAA
• UGA
• AUG

40) All of the following are termination codon except:

• UAA
• UGG
• UAG
• UGA

41) Which one of the following is not the nonsense codon?

• UUA
• UGA
• UAG
• UAA

42) Which of the following process makes a double-stranded copy of DNA?

• Replication
• Recombination
• Transcription
• Translation

43) Replication of DNA takes place during:

• Prophase
• Interphase
• Anaphase
• Telophase

44) During the replication of DNA molecule, one of the original DNA strands:

• Combines with the other original DNA strand
• Combines with one of the new strands of DNA
• Is broken down for nucleotide units
• Is converted into carbohydrate molecules for energy metabolism

45) Which of the following scientists conclusively demonstrated the semi-conservative manner of DNA replication?

• Jacob & Monod
• Watson & Crick
• Meselson- Stahl
• Hershey & Chase

46) In E. coli, the locus for the origin of replication is at………minutes and that for termination

of replication is at…… minutes on the chromosome map.

• 5, 75
• 74, 25
• 79, 65
• 5, 2.5

47) All the followings are needed for replication of DNA except:

• Charged tRNA
• DNA template
• RNA primer
• dNTPs, MG ^{+ +}

48) DNA template required to synthesize new DNA is:

• ssDNA
• dsDNA
• Both a and b
• Fragmented DNA

49) RNA primer required to initiate DNA replication is synthesized from:

• tRNA
• mRNA
• Template DNA
• rRNA

50)  The following enzymes are needed for DNA synthesis EXCEPT:

• DNA polymerase
• Restriction endonuclease
• Ligase
• None

51) Principal enzyme for DNA synthesis:

• RNA dependent DNA polymerase
• 50 S ribosomal subunit
• DNA polymerase-III
• 30 S ribosomal subunit

52) Unwinding of DNA double helix is brought about by:

• Topoisomerase
• Reverse transcriptase
• DNAse
• Ligase

53) Which is true for DNA replication?

• DNA synthesis takes place in 5 to 3′ direction
• dNTPs are added at the 3′ end of RNA primer
• Complementary DNA strand is synthesized by DNA polymerase III
• All of the above

54) RNA primer is hydrolyzed and replaced from the replication site by 5′-3′ exonuclease activity of:

• DNA polymerase II
• DNA polymerase III
• DNA polymerase I
• None

55) A mutation in which there is deletion or insertion of one or a few nucleotides is called:

• Base-pair mutation
• Switches mutation
• Frameshift mutation
• None of above

56) Any mutation resulting in the alteration of a codon specifying an amino acid to

• Missense mutation
• Nonsense mutation
• Silent mutation
• None

57) The mutation which results in the replacement of one amino acid in a polypeptide chain by

another is called as:

• Missense mutation
• Nonsense mutation
• Silent mutation
• None

58) A missense mutation can be caused by:

• Deletion
• Insertion
• Substitution
• All of these

59) Any gene mutation which does not result in phenotypic expression is called:

• Nonsense mutation
• Missense mutation
• Silent mutation
• None

60) The first chemical mutagen discovered was:

• HNO₂
• 2-aminopurine
• Mustard gas
• Dimethyl sulphate

71) Chemical mutagens donot include:

• Bromouracil
• Nitrous acid
• Intercalating agents
• Thymine dimmers

 

72) Certain fluorescent acridine dyes like proflavine and acridine orange cause mutation by:

• Deletion of bases
• Insertion of bases
• Both a and b
• None of these

73) Ames test is used

• To evaluate mutagenicity of a chemical
• To identify transferring substances
• To study physical nature of plasmids
• To evaluate antigenicity of chemical

74)  The Ames test for mutagenicity exposes bacteria to a substance and then assesses:

• Degree of carcinogenic activity
• Number of cancer-forming cells
• Rate of mutation-from wild type
• Rate of reversion to wild type

75) Replica plating technique is used to detect:

• Complements
• Conjugation
• Toxin
• Mutants

76) Ultraviolet light causes mutations in bacteria:

• By breaking the chromosome
• By causing a frame shift
• By binding together adjacent thymine bases
• By reversing a segment of DNA

77) Mutants that can no longer synthesize à particular essential metabolites and are unable to grow in medium that does not content the essential amino acid are called:

• Auxotrophs
• Autotrophs
• Prototrophs
• None

78) Small pieces of DNA that can insert themselves into chromosomes at numerous locations and cause mutations are called:

• Carcinogens
• Transposons
• Replica genes
• Frameshift genes

79) Transposable elements in bacteria is:

• Transposons
• Insertion sequence
• Mu phage
• All of these

80) Which is true for transposable elements?

• Can cause mutations during insertion
• Mobile genetic sequences
• Jumping genes
• All of these

81) Discovery of the genetic codes for amino-acids by:

• Holley, Khorana and Niremberg
• Delbruck, Luria and Hershey
• Smith, Arber and Nathans
• Temin, Baltimore and Dulbecco

82) All are true of the genetic code except:

• Non-overlapping
• Degenerate
• Universal
• Punctuation

83) Choose the incorrect one. The genetic code:

• Is universal
• Is degenerate
• Is read in the direction of 3″-5″
• None

84) Degeneracy of the genetic code means that:

• A given base triplet can code for more than one amino acid
• There is no punctuation in the code sequences
• The third base in the codon is not important in coding
• A given amino acid can be coded for by more than one base triplet

85) Horizontal transmission of ‘R’ factor is by:

• Transformation
• Transduction
• Conjugation
• Fusion

87) An F⁺ strain and Hfr strain of E. coli shares all of the following characteristic except

• Overall growth rate
• Sensitivity of male specific bacteriophage
• Physical state of the F factor DNA
• Ability to mobilize non conjugative plasmids

88) Fertility factor proposing chromosomal genesis known as:

• F prime factor
• F-factor
• Hfr
• R-factor

89) Phage mediated of genetic recombination in bacteria is called:

• Transformation
• Transduction
• Conjugation
• Sexduction

90) Which of the following process involves recombination of homologous pairs of DNA?

• Conjugation
• Sexduction
• Transduction
• Transformation

91) Transduction phage contains:

• Single stranded DNA
• Double stranded DNA
• Single stranded RNA
• Double Stranded RNA

92) A bacterium that has been transduced contains:

• An enhanced supply of ATP
• Numerous new plasmids
• Fewer DNA segments than it originally had
• New DNA segments

93) Which of the following characteristics is associated with specialized transduction?

• The virus fails to replicate within the host bacteria
• The virus attaches to the bacterial chromosomes
• A virus immediately replicates within a host bacteria
• The viral DNA is destroyed immediately on entering the bacterium

94) The mechanism of genetic transfer where a phage serves as a vehicle is:

• Transformation
• Conjugation
• Transition
• Lysogeny

95) When a virus remains with the chromosome of a host bacterium for a long period of time, the viral DNA is called

• Adenovirus
• Provirus
• Baculovirus
• Enterovirus

96) Bacterial recombinations are essential feature of the process of:

• Chemiosmosis
• Photosynthesis
• Genetic engineering
• Anaerobic fermentation

97) All the following are mechanisms by which prokaryotes acquire eukaryotic gene sequence except:

• Transformation
• Transduction
• Conjugation
• rDNA technology

98) Genetic variation is accomplished in prokaryotes by all except:

• Mutation
• Sexual reproduction
• Conjugation
• Transformation

99) The source of genetic variability in prokaryotes is:

• Recombination
• Transcription
• Translation
• All of these

100) The processes when mutation in the genotype are most likely to occur is/are:

• Replication
• Recombination
• Both a and b
• None of these

REFERENCES:

i) https://www.sanfoundry.com/1000-microbiology-questions-answers/

ii) https://www.nursingofficer.net/2021/03/microbiology-mcqs-online-test.html

iii) https://engineeringinterviewquestions.com/microbiology-objective-questions-and-answers/

MCQ’s of microbiology (Genetics – Part 2)