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(4) ❌ Incorrect — removing nucleotides from 3′ or 5′ ends is the function of exonucleases, not restriction endonucleases (which cut within the DNA at specific sequences)
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Two core techniques that enabled birth of modern biotechnology are:
\(
\begin{array}{|l|l|}
\hline \text { A. } & \begin{array}{l}
\text { Techniques to alter the chemistry of genetic material, } \\
\text { to introduce these into host organisms and thus } \\
\text { change the phenotype of the host organism. }
\end{array} \\
\hline \text { B. } & \begin{array}{l}
\text { Maintenance of sterile ambience in chemical } \\
\text { engineering process to enable growth of only the } \\
\text { desired microbes/eukaryotic cell in large quantities } \\
\text { for the manufacture of biotechnological products. }
\end{array} \\
\hline
\end{array}
\)
(c)
What is true regarding A, B and C in the given diagrammatic representation of rDNA technology ?

\(
\begin{array}{|l|l|}
\hline \text { I: } & \text { At A, same restriction enzyme is used to cut both foreign and vector DNA } \\
\hline \text { II: } & \text { The enzyme used at B is DNA ligase } \\
\hline \text { III: } & \text { Step C can be called as transformation } \\
\hline
\end{array}
\)
(d)
The European Federation of Biotechnology [EFB] defines biotechnology as :
(d)
The construction of first rDNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid of:
(a)
The term ‘molecular scissors’ is used for :
(a)
Identify the correct statements :
\(
\begin{array}{|l|l|}
\hline \text { I: } & \begin{array}{l}
\text { In the Cohen and Boyer experiment, the linking of } \\
\text { antibiotic resistance gene with a plasmid vector } \\
\text { became possible with the enzyme DNA ligase. }
\end{array} \\
\hline \text { II: } & \begin{array}{l}
\text { Recombinant DNA molecules are DNA molecules } \\
\text { formed by laboratory methods of genetic } \\
\text { recombination that bring together genetic material } \\
\text { from multiple sources, creating sequences that would } \\
\text { not otherwise be found in the genome. }
\end{array} \\
\hline
\end{array}
\)
(c)
\(
A \text { and } B \text { in pBR322, shown in the diagram given below, respectively represent recognition sequences of: }
\)

(c)
In recombinant DNA experiments, a vector :
(a)
Identify the correct statements :
\(
\begin{array}{|l|l|}
\hline \text { Statement I: } & \begin{array}{l}
\text { In 1963, two enzymes responsible for } \\
\text { restricting the growth of bacteriophage in } \\
\text { E.coli were isolated. }
\end{array} \\
\hline \text { Statement II: } & \begin{array}{l}
\text { In 1968, the first restriction endonuclease, } \\
\text { that always cut DNA molecules by } \\
\text { recognising a specific sequence six base } \\
\text { pairs, was isolated and characterised. }
\end{array} \\
\hline
\end{array}
\)
(c)
The palindrome in DNA is a sequence of base pairs:
(a)
Identify the incorrect statement regarding restriction endonucleases :
(c)
They digest DNA by removing nucleotides from a free 3′ end.” ❌ Incorrect — that’s the function of exonucleases, not restriction endonucleases (which are endonucleases and cut within the DNA sequence).
The first type II restriction endonuclease whose functioning depended on a specific DNA nucleotide sequence was:
(b)
DNA fragments digested by restriction endonucleases separate on agar gel electrophoresis according to their size because :
(b)
Elution is :
(c)
The ability of plasmids and bacteriophage DNA to replicate within bacterial cells :
(d)
A cloning vector must :
(d)
What is true about the steps of PCR shown in the diagram given below ?

\(
\begin{array}{|l|l|}
\hline \text { I: } & \text { Step A occurs at the temperature of } 95-98^{\circ} \mathrm{C} \\
\hline \text { II: } & \text { Step B occurs at the temperature of } 55^{\circ} \mathrm{C} \\
\hline \text { III: } & \text { Step C occurs at the temperature of } 72^{\circ} \mathrm{C} \\
\hline
\end{array}
\)
(d)

The most important feature in a plasmid to serve as a vector in gene cloning experiment is :
(a)
Some bacteria are resistant to antibiotics. This trait is normally due to :
(c)
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
\(
\begin{array}{|l|l|}
\hline \text { Assertion (A): } & \begin{array}{l}
\text { In order to link the alien DNA, the } \\
\text { vector needs to have very few, preferably } \\
\text { single, recognition sites for the } \\
\text { commonly used restriction enzymes: }
\end{array} \\
\hline \text { Reason: (R): } & \begin{array}{l}
\text { Presence of more than one recognition } \\
\text { sites within the vector will generate } \\
\text { several fragments, which will complicate } \\
\text { the gene cloning. }
\end{array} \\
\hline
\end{array}
\)
In the light of the above statements, choose the most appropriate answer from the options given below :
(a)
A cloning vector has two antibiotic resistance genes for tetracycline and ampicillin. A foreign DNA was inserted into the tetracycline gene. Non-recombinants transformants would survive on the medium containing:
(c)
In agarose gel electrophoresis, the DNA fragments produced by restriction enzyme digestion
(a)
What is true for the plasmids used as cloning vectors in recombinant procedures ?
(a)
A donor DNA and plasmid vector DNA of E. coli are cut by EcoR I. The plasmid contains genes for resistance to ampicillin and tetracycline. The ECoR I recognition sequence lies within the gene for tetracycline resistance. Ligase is used and the recombinant DNA is produced. The plasmids are transferred to E.coli with the help of electroporation. Samples of the bacterial colonies are then grown in four different media: nutrient medium plus ampicillin, nutrient medium plus tetracycline, nutrient medium plus ampicillin and tetracycline, and nutrient medium without antibiotics. Non recombinant transformants will grow on:
(d)
Let’s break it down carefully:
Plasmid: \(
\mathrm{Amp}^R
\) + \(
\operatorname{Tet}^R
\).
EcoRI cuts inside \(
\operatorname{Tet}^R
\) gene.
Recombinant → \(
\operatorname{Tet}^R
\) disrupted → \(
\mathrm{Amp}^R
\) intact.
Non-recombinant → \(
\operatorname{Tet}^R
\) intact + \(
\mathrm{Amp}^R
\) intact.
Growth patterns:
Non-recombinant: resistant to both ampicillin and tetracycline → grows on:
Nutrient + ampicillin ✅
Nutrient + tetracycline ✅
Nutrient + ampicillin + tetracycline ✅
Nutrient without antibiotics ✅
That means they grow on all four types of medium.
Correct answer: 4. on all four types of medium ✅
The bioreactor shown in the diagram is :

(c)
A host cell normally does not take up a foreign DNA until it has been made competent to do so. This is because :
(a)
The number of correct statements regarding cloning vectors amongst the given statements is:
I. Bacteriophages because of their high number per cell, have very high copy numbers of their genome within the bacterial cells.
II. If one wants to recover many copies of the target DNA, it should be cloned in a vector whose origin supports high copy number.
III. A selectable marker helps in identifying and eliminating non-transformants and selectively permits the growth of the transformants.
IV. Ti plasmid of Agrobacterium tumefaciens has now been modified into a cloning vector which is no more pathogenic to the plants but is still able to use mechanisms to deliver genes of our interest into a variety of plants.
V. Retroviruses in animals have the ability to transform normal cells into cancerous cells and hence can never be used as a cloning vector in rDNA procedures.
(c)
Retroviruses in animals have the ability to transform normal cells into cancerous cells and hence can never be used as a cloning vector in rDNA procedures.
❌ Incorrect — retroviruses can be modified to be non-oncogenic and are used in gene therapy.
In microinjection, the rDNA :
(d)
Primers used in PCR are :
(d)
Consider the following statements :-
I: Asexual reproduction preserves genetic information while sexual reproduction permits variations.
II: Traditional hybridization often leads to the inclusion and multiplication of undesirable genes along with the desired genes.
III: rDNA technology allows us to isolate and introduce only one or a set of desirable genes without introducing undesirable genes in the target organism.
Which of the above statements are true ?
(d)
The following palindrome is recognized by the restriction enzyme :

(b)
If we are able to link an alien piece of DNA with bacteriophage or plasmid DNA, we can multiply its number :
Which of the following statements is incorrect with respect to gene transfer ?
(a)
❌ Incorrect — after heat shock at 42∘42^\circ42∘C, bacterial cells are placed on ice (not in chilled ethanol). Chilled ethanol is used in DNA precipitation, not transformation.
Which of the given statements is correct in the context of visualizing DNA molecules separated by agarose gel electrophoresis ?
(d)
The trait ‘resistance to certain antibiotics’ is seen in some bacteria due to the presence in them of :
(c)
DNA fragments separated by gel electrophoresis are shown. Mark the correct statement :

(c)
Let’s break this down step-by-step.
In gel electrophoresis for DNA, the negatively charged DNA migrates toward the positive (+) electrode.
Smaller DNA fragments move faster and travel farther down the gel, so the bottom bands correspond to shorter fragments.
Larger DNA fragments move more slowly and remain near the top.
From the image:
Band 1 (top) → longest DNA fragment
Band 2 (middle) → intermediate length
Band 3 (bottom) → shortest fragment
How does the bacterium protects its own DNA from the action of restriction endonucleases present in its cytoplasm ?
(c)
The correct answer is 3 ✅
Bacteria protect their own DNA from their restriction endonucleases by methylating specific bases within the recognition sequences.
This is done by DNA methyltransferases.
Methylation prevents the restriction enzyme from binding and cutting the bacterial DNA, while any unmethylated foreign DNA (like phage DNA) gets cleaved.
Which of the following is incorrect with respect to isolation of genetic material ?
(b)
(2) ❌ Incorrect — Alkaline phosphatase removes phosphate groups from DNA/RNA ends (used in cloning), not for removing RNA or proteins. For RNA removal, RNase is used; for protein removal, proteases are used.
Which of the following is incorrect for the techniques of gel electrophoresis ?
(c)
(3) ❌ Incorrect — ethidium bromide bound to DNA fluoresces orange (not blue) under UV light.
Which of the following statement is incorrect with respect to restriction enzyme ?
(d)
(4) ❌ Incorrect — removing nucleotides from 3′ or 5′ ends is the function of exonucleases, not restriction endonucleases (which cut within the DNA at specific sequences)
In agarose gel electrophoresis, DNA molecules are separated on the basis of their :
(b)
In the above diagram showing a typical agaro gel electrophoresis :

(a)
To isolate DNA in pure form from a bacterial cell, it should initially be treated with :
(b)
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
\(
\begin{array}{|l|l|}
\hline \text { Assertion (A): } & \begin{array}{l}
\text { It is possible to select a bacterial cell } \\
\text { transformed with a recombinant DNA } \\
\text { bearing gene for an antibiotic resistance } \\
\text { if the transformed cells are spread on } \\
\text { agar plates containing the antibiotic. }
\end{array} \\
\hline \text { Reason (R): } & \begin{array}{l}
\text { Due to insertional inactivation of the } \\
\text { gene for antibiotic resistance gene, only } \\
\text { the untransformed bacterial cells will } \\
\text { grow and the transformed bacterial cells } \\
\text { will die. }
\end{array} \\
\hline
\end{array}
\)
In the light of the above statements, choose the most appropriate answer from the options given below :
(c)
Assertion (A): True — Plating on an antibiotic selects transformants that carry an intact antibiotic-resistance gene (they survive; non-transformants die).
Reason (R): False — Insertional inactivation disrupts the resistance gene; such recombinants would not grow on that antibiotic. Hence R contradicts A and doesn’t explain it.
The underlying basis of the Polymerase Chain Rxn is:-
(d)
Following are the steps in the formation of recombinant DNA by action of a restriction endonuclease. Which one of the given option incorrectly identifies the steps, components labelled as A, B, C and D ?

(a)
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
\(
\begin{array}{|l|l|}
\hline \text { Assertion (A): } & \begin{array}{l}
\text { Bioreactors are important in } \\
\text { biotechnology procedures to obtain } \\
\text { desired products. }
\end{array} \\
\hline \text { Reason (R): } & \begin{array}{l}
\text { Bioreactor provides the optimal } \\
\text { conditions for achieving the desired } \\
\text { product by providing optimum growth } \\
\text { conditions }
\end{array} \\
\hline
\end{array}
\)
In the light of the above statements, choose the most appropriate answer from the options given below :
(b)
The significance of the ‘heat shock‘ method in bacterial transformation is to facilitate:
(c)
Which of the following statements does not hold true for restriction enzyme ?
(c)
“It is isolated from viruses” ❌ Incorrect — they are isolated from bacteria, not viruses.
Identify (a) and (b) bioreactors respectively in the given diagram :

(a)
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