Biochemistry MCQ Quiz Hub

1. How many amino acid residues are there in ubiquitin?
70
72
74
75

2. Which of the following are the structural motifs that mediate protein-protein interactions?
Zinc finger
Helix-turn-helix
Homeodomain
Leucine zipper and basic helix-loop-helix

3. Which of the following are the structural motifs that mediate protein-protein interactions?
Zinc finger
Helix-turn-helix
Homeodomain
Leucine zipper and basic helix-loop-helix

4. Which of the following bacterial operon is not controlled by attenuation?
Histidine
Leucine
Arabinose
Tryptophan

5. Which of the following regulatory sequence allows transcription to continue?
Sequence 4
Sequence 1
Sequence 2
Sequence 3

6. Which of the following enzyme is secreted by the pancreas?
Myoglobin
Cytochrome c
Ribonuclease
Lysozyme

7. Which of the following is a hypertonic solution?
0.45% sodium chloride
Oceans
Red blood cells placed in fresh water
Freshwater habitats

8. Which of the following is not an example of housekeeping genes?
RNA polymerase
r-RNA genes
Beta galactosidase
Enzymes required for basic metabolic pathways common to most cells

9. Lactose utilization by E. coli requires ____________
Lac-Z
Lac-A
Lac-Y
Lac-l

10. The lactose repressor is encoded by ____________
Lac-l
Lac-A
Lac-Y
Lac-Z

11. Where does a repressor bind an operon?
Operator
Promoter
Inducer
Catabolite activator site

12. Lac repressor dissociates from its operator when the repressor binds to ____________
Heat shock module
Promoter
Inducer
Catabolite activator site

13. The lac repressor has which of the following DNA-binding motif?
Helix-turn-helix
Zinc finger
Homeodomain
Leucine zipper

14. Which of the following are the structural motifs that mediate protein-protein interactions?
Leucine zipper and basic helix-loop-helix
Homeodomain
Zinc finger
Helix-turn-helix

15. If lactose and glucose are provided in the growth medium of a culture of E. coli ____________
Lactose operon is not transcribed
Lactose metabolism is favored
Both lactose and glucose are metabolized at same rate
Adenylate cyclase is activated

16. Which of the following is not required for the expression of genes in the lactose operon?
lacl gene product
cAMP
Allolactose
Adenylate cyclase

17. Which out of the following is not an example of an inducible operon?
Lactose operon
Galactose operon
Maltose operon
Tryptophan operon

18. Which of the following statements is not correct?
Bacteria possess only one type of RNA polymerase
Attenuation is a regulatory process used by bacteria to control the initiation of transcription
Repressor binds to operator
Bacterial genes are polycistronic

19. Which of the following bacterial operon is not controlled by attenuation?
Arabinose
Tryptophan
Leucine
Histidine

20. Which of the following is the most appropriate definition of an operator?
A non-coding, regulatory DNA sequence that is bound by RNA polymerase
A non-coding, regulatory DNA sequence that is bound by a repressor protein
A DNA-binding protein that regulates gene expression
A cluster of genes that are regulated by a single promoter

21. To which class of transcription factor do nuclear receptors belong?
Zinc finger proteins
Leucine zipper proteins
Helix-turn-helix proteins
Helix-loop-helix proteins

22. Which of the following statements about lac operon in e.coli is true?
Promoter is the binding site for the lac repressor
Operon is only switched on in the absence of lactose in the growth medium
β-galactosidase is only produced in large quantities when the lac repressor is bound to the operator
Lac operon mRNA is a polycistronic mRNA

23. Which of the following statements regarding the regulation of trp operon expression by attenuation is correct?
Rapid translation of the leader peptide prevents completion of mRNA transcript
Rapid translation of the leader peptide allows completion of mRNA transcript
The leader peptide sequence encodes enzymes required for tryptophan synthesis
The leader peptide sequence contains no tryptophan residues

24. Which of the following increases gene expression as much as 200-fold?
TATA box
Insulator
Enhancer
CAAT box

25. The mechanism by which CBP activates transcription is?
CBP has DNA methyl transferase activity
CBP has histone acetyl transferase activity
CBP interacts with the basal transcription complex
CBP interacts with the basal transcription complex and has histone acetyl transferase activity

26. RNAi stands for ____________
RNA inducer
RNA interference
RNA intron
RNA insertion

27. Which of the following about mRNA stability is not correct?
Regulation of mRNA stability is a way of regulating gene expression b) c) d)
Prokaryotic mRNAs have a half-life of only a few minutes
Histone mRNAs have especially long poly-A tails and are stable
It is thought that poly-A tails stabilize eukaryotic mRNAs

28. Which of the following about mRNA stability is not correct?
Regulation of mRNA stability is a way of regulating gene expression
Prokaryotic mRNAs have a half-life of only a few minutes
Histone mRNAs have especially long poly-A tails and are stable
It is thought that poly-A tails stabilize eukaryotic mRNAs

29. CAP is ____________
Catabolite gene activator protein
Catabolite gene repressor protein
Anabolite gene activator protein
Anabolite gene repressor protein

30. Trp repressor is a ____________
Homodimer
Homotrimer
Heterodimer
Heterotrimer

31. Attenuator sequences base-pair to form a stem-and-loop structure rich in ____________
A = T
G ≡ C
A = C
G = C

32. Formation of the attenuator stem-and-loop structure depends on the events that occur during translation of ____________
Sequence 1
Regulatory sequence 2
Regulatory sequence 3
Regulatory sequence 4

33. Which of the following takes place when tryptophan levels are low?
Ribosomes quickly translates sequence 1
Sequence 2 is blocked before sequence 3 is transcribed
Ribosomes pauses at the Try codons in sequence 1
Attenuation at the attenuator structure formed by sequences of 3 and 4

34. Which of the following takes place when tryptophan levels are high?
Attenuation at the attenuator structure formed by sequences of 3 and 4
Ribosomes pauses at the Try codons in sequence 1
Formation of paired structure between 2 and 3 sequences prevents attenuation
2:3 structures, unlike the 3:4 attenuator, does not prevent transcription

35. Whose interaction with Lex-A facilitates the repressor’s self-cleavage reaction?
Rec-A
Rec-B
Rec-C
Rec-D

36. When DNA segment is in one orientation ____________
The gene for FljB and gene encoding FljA are expressed
The gene for FliC are expressed
The gene for FljB and gene encoding FljA are not expressed
The gene for FljB and gene encoding FljC are not expressed

37. When DNA segment is in one orientation ____________
The gene for FljB and gene encoding FljA are expressed
The gene for FliC are expressed
The gene for FljB and gene encoding FljA are not expressed
The gene for FljB and gene encoding FljC are not expressed

38. When DNA segment is in one orientation ____________
The gene for FljB and gene encoding FljA are expressed
The gene for FliC are expressed
The gene for FljB and gene encoding FljA are not expressed
The gene for FljB and gene encoding FljC are not expressed

39. Which of the following encodes recombinase?
fliC
fljB
hin
fljA

40. Which of the following is not true about secondary protein structure?
The hydrophilic/hydrophobic character of amino acid residues is important to secondary structure
The ability of peptide bonds to form intramolecular hydrogen bonds is important to secondary structure
The alpha helix, beta pleated sheet and beta turns are examples of protein secondary structure
The steric influence of amino acid residues is important to secondary structure

41. A structure that has hydrogen bonds between polypeptide chains arranged side by side is ____________
Primary structure
α-helix
β-pleated sheets
Tertiary structure

42. The enzyme of E.coli is a nuclease that initiates the repair of double stranded DNA breaks by homologous recombination is?
DNA glycosylase
DNA ligase
DNA polymerase
RNA polymerase

43. Which of the statements is false about multiple sequence alignment?
Both protein and nucleic acid secondary structures can be used
More useful in RNA
These alignments can be made more accurate by the inclusion of secondary structure information
A significant increase in accuracy

44. Which of the statements is false about multiple sequence alignment?
Both protein and nucleic acid secondary structures can be used
More useful in RNA
These alignments can be made more accurate by the inclusion of secondary structure information
A significant increase in accuracy

45. Which of the following serves as a bactericidal agent?
Ribonuclease
Lysozyme
Cytochrome c
Myoglobin

46. Which of the following enzyme is secreted by the pancreas?
Ribonuclease
Lysozyme
Cytochrome c
Myoglobin

47. Which of the following statement is false?
Lysozyme has S-S linkage
Ribonuclease has S-S linkage
Heme group in cytochrome c is covalently linked to the protein on two sides
Ribonuclease has SH-SH linkage

48. Which of the following is first determined as oligomer?
Myoglobin
Collagen
Keratin
Hemoglobin

49. Which of the following is abundantly found in collagen?
Glycine
Serine
Alanine
Tryptophan

50. Which of the following are important for white blood cell recognition?
Glycosaminoglycans
Proteoglycans
Glycoproteins
Glycolipids

51. Which of the following is a hypertonic solution?
Oceans
Freshwater habitats
0.45% sodium chloride
Red blood cells placed in fresh water

52. If pH of solution of NaOH is 12.0 the pH of H2SO4 solution of same molarity will be ____________
a) 2.0
12.0
1.7
10.0387

53. 1M NaCl and 1M HCl are present in an aqueous solution. What is the solution?
Not a buffer solution with pH < 7
Not a buffer solution with pH > 7
A buffer solution with pH < 7
A buffer solution with pH > 7

54. What does it mean when we say that water acts as a “heat buffer”?
It keeps the temperature of an organism relatively constant as the temperature of the surroundings fluctuates
It increases the temperature of an organism as the temperature of the surroundings increases
It decreases the temperature of an organism as the temperature of the surroundings increases
It increases the temperature of an organism as the temperature of the surroundings decreases

55. What trend does the reactivity of group II elements follow with water?
Increases down the group
Decreases down the group
Does not follow any particular trend
No reaction

56. Which of the following is not the classified form of conjugated proteins?
Lipoproteins
Glycoproteins
Metalloproteins
Complete proteins

57. Tertiary conformation of proteins is maintained by 3 types of bonds namely ionic, hydrogen and ____________
Sulfide
Disulfide
Covalent
Peptide

58. Which of the following is true?
The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine destabilize protein tertiary structure c) d)
The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine destabilize protein tertiary structure

59. In 3° structure of proteins, folding and shaping is done by ____________
Hydrophobic interactions
Polar interactions
Hydrogen bonding
None of the mentioned

60. Which of the following glycoprotein functions as a lubricant and protective agent?
Collagens
Mucins
Transferrins
Immunoglobulins

61. Which of the following is a hydroxyl fatty acid?
Linoleic acid
Palmitic acid
Linolenic acid
Cerebronic acid

62. Which of the following is false about fatty acids?
Melting point of fatty acids decreases with increase in the degree of saturation
Lipids in tissues that are subjected to cooling are more unsaturated
Naturally occurring unsaturated long-chain fatty acids are nearly Trans-configuration
The membrane lipids contain mostly unsaturated fatty acids

63. The binding of ligands to many GPCRs leads to ____________
Decrease in concentration of second messengers
Increase in concentration of second messengers
Decrease in concentration of first messengers
Increase in concentration of first messengers

64. Which of the following are included in the types of glycolipids?
N-acetylgalactosamine
N-acetylglucosamine
Xylose
Cerebrosides

65. Which of the following catalyzes the cutting of PIP2 into 2 moles of IP3 and diacylglycerol in cell signaling?
Phosphokinase C
Phospholipase C
Lipokinase
Phosphodiesterase C

66. Site directed mutagenesis facilitated research on ____________
Carbohydrates
Proteins
Lipids
Fats

67. Which product formed in the isomerization of mannose 6-phosphate?
Fructose 6-phosphate
Glucose 6-phosphate
2-phosphoglycerate
3-phosphoglycerate

68. Which is the first reaction of the pentose phosphate pathway?
Oxidation of glucose 6-phosphate to 6-phosphoglucono-δ-lactone
Oxidation of 6-phosphogluconate to ketopentose ribulose 5-phosphate
Reduction of 6-phosphoglucono-δ-lactone to glucose 6-phosphate d)
Reduction of ketopentose ribulose 5-phosphate to 6-phosphogluconate