Questions and answers for exam Preparation

MCQs

Total Questions : 232 | Page 8 of 24 pages

Question 71. The recognition sequence of Sau3A is 5’ |GATC 3’ and that for DpnI is 5’ GA|TC 3’. Which of the statements is true?

The ends created by both the enzymes are compatible
The ends created by both the enzymes are not-compatible
The ends created by DpnI are single stranded
The ends created by Sau3A are single stranded

Discuss Question

Answer: Option B. -> The ends created by both the enzymes are not-compatible
Answer: (b).The ends created by both the enzymes are not-compatible

Question 72. If all the nucleotides are present with equal frequencies and at random, what are the chances of having a particular four nucleotide long motif?

1/256
1/64
1/16
1/8

Discuss Question

Answer: Option A. -> 1/256
Answer: (a).1/256

Question 73. Which of the following is the correct nomenclature of a restriction enzyme obtained from the first activity of strain R of Escherichia coli?

EcoR1
EscRI
EcorI
EcoRI

Discuss Question

Answer: Option D. -> EcoRI
Answer: (d).EcoRI

Question 74. The ends created by use of DNase have unique single stranded sequences.

True
False
May be True or False
Can't say

Discuss Question

Answer: Option B. -> False
Answer: (b).False

Question 75. Why is DNase preferred over restriction endonuclease in some cases?

DNase is preferred over restriction endonuclease in some cases because the latter are not able to recognize some of the restriction sites
DNase is more specific as restriction endonuclease, so the required fragment is obtained
DNase is less specific as compared to restriction endonuclease, hence there are more chances of representation of all the possible fragments
DNase is abundant in comparison the restriction endonuclease

Discuss Question

Answer: Option C. -> DNase is less specific as compared to restriction endonuclease, hence there are more chances of representation of all the possible fragments
Answer: (c).DNase is less specific as compared to restriction endonuclease, hence there are more chances of representation of all the possible fragments

Question 76. Besides enzymatic means, physical stress can also be used for cleaving the DNA. Which of the following statements is true?

Sonication, needles, syringes, etc all come under the category of physical stress
In physical stress, there are no chances of contamination
The ends obtained have unique sequences
They are less effective than DNase treatment

Discuss Question

Answer: Option A. -> Sonication, needles, syringes, etc all come under the category of physical stress
Answer: (a).Sonication, needles, syringes, etc all come under the category of physical stress

Question 77. Phosphatases refer to __________

the enzymes which add phosphate group at the end of the DNA molecule in the place of hydroxyl group
the enzymes which hydrolytically remove phosphate group from the DNA molecules and replace them with hydroxyl group
the enzymes responsible for removal of phosphate group from the DNA molecules and replace them with hydrogen
the enzymes responsible for replacing hydrogen in the DNA molecules with the phosphate group

Discuss Question

Answer: Option B. -> the enzymes which hydrolytically remove phosphate group from the DNA molecules and replace them with hydroxyl group
Answer: (b).the enzymes which hydrolytically remove phosphate group from the DNA molecules and replace them with hydroxyl group

Question 78. How is phosphatase related to the ligation reactions?

Phosphate group is not required for the ligation reaction to take place, thus phosphatase is helpful
It is helpful in ceasing the unwanted ligation
Phosphatases are not at all related to ligation reactions
They act as a catalyst in case of the ligation reaction

Discuss Question

Answer: Option B. -> It is helpful in ceasing the unwanted ligation
Answer: (b).It is helpful in ceasing the unwanted ligation

Question 79. How can phosphatase activity terminated prior to a ligation reaction?

By heating
By cooling
By creating vibrations
By alternatively cooling and heating

Discuss Question

Answer: Option A. -> By heating
Answer: (a).By heating

Question 80. Polymerase can be defined as ______________

an enzyme used to synthesize a new DNA or RNA strand on the basis of pre-existing strand or at times without a pre-existing strand
an enzyme used for removal of nucleotides from the DNA or RNA strand
an enzyme which can synthesize only a new DNA strand, not an RNA strand
an enzyme which can synthesize either a new DNA or an RNA strand but only when a strand is there

Discuss Question

Answer: Option A. -> an enzyme used to synthesize a new DNA or RNA strand on the basis of pre-existing strand or at times without a pre-existing strand
Answer: (a).an enzyme used to synthesize a new DNA or RNA strand on the basis of pre-existing strand or at times without a pre-existing strand