Biotechnology: Principles and Processes: NEET PYQ, 2018–2026

Q1 · Zoology · Biotechnology: Principles and Processes

The Ti plasmid of Agrobacterium tumefaciens is used in genetic engineering mainly for which purpose?

• ATransferring foreign genes into dicotyledonous plant cells
• BProducing insecticidal crystal proteins for pest control
• CProviding a heat-stable DNA polymerase for PCR
• DServing as a vector for cloning genes in E. coli bacteria

Q2 · Zoology · Biotechnology: Principles and Processes

Taq DNA polymerase is preferred over the E. coli DNA polymerase I in the polymerase chain reaction. What is the main reason for this preference?

• ATaq polymerase does not need a primer to start DNA synthesis
• BTaq polymerase is heat-stable and survives repeated high-temperature denaturation steps
• CTaq polymerase synthesises RNA from a DNA template, which PCR requires
• DTaq polymerase cuts DNA at palindromic sequences to generate sticky ends

Q3 · Zoology · Biotechnology: Principles and Processes

A foreign DNA fragment is ligated into the BamHI site located within the tetracycline-resistance gene (tetR) of plasmid pBR322, which also carries an intact ampicillin-resistance gene (ampR). The ligation mixture is used to transform E. coli, and the transformed cells are plated on ampicillin-containing medium. Colonies are then replica-plated onto tetracycline-containing medium. Which statement correctly describes the outcome?

• AColonies grow on ampicillin but fail to grow on tetracycline, so they are identified as recombinants.
• BColonies grow on tetracycline but fail to grow on ampicillin, so they are identified as recombinants.
• CColonies grow on both ampicillin and tetracycline, so the insert is confirmed by the presence of both resistance markers.
• DColonies grow on neither antibiotic, because the insert always kills the host cell regardless of which marker is disrupted.

Q4 · Zoology · Biotechnology: Principles and Processes

What is the natural biological role of restriction endonucleases in bacterial cells?

• AThey cut foreign DNA, such as that of invading bacteriophages, to protect the bacterium
• BThey join two DNA fragments together to form recombinant DNA inside the bacterium
• CThey copy the bacterial chromosome before cell division
• DThey degrade the bacterium's own DNA during programmed cell death

Q5 · Zoology · Biotechnology: Principles and Processes

Bacillus thuringiensis produces Cry protoxins that are crystalline and insecticidal. When a susceptible insect larva ingests the crystals, where is the protoxin converted into its active toxic form?

• AIn the alkaline midgut of the susceptible insect larva, where gut proteases cleave the protoxin.
• BIn the acidic stomach of a mammal that eats the Bt cotton, since acid is needed to activate the toxin.
• CInside the cytoplasm of the cotton plant cell, before the plant tissue is eaten.
• DIn the haemolymph of the insect, after the toxin is absorbed across the gut wall.

Q6 · Zoology · Biotechnology: Principles and Processes

A PCR run starts with 5 copies of a double-stranded target sequence in the reaction tube. Assume 100% efficiency at every cycle and no change in the number of cycles other than as stated. How many copies of the target sequence are present after 4 complete cycles of PCR?

• AAbout 80 copies
• BAbout 20 copies
• CAbout 160 copies
• DAbout 40 copies

Q7 · Zoology · Biotechnology: Principles and Processes

Restriction enzymes cleave DNA by hydrolysing which type of chemical bond?

• APhosphodiester bonds in the sugar-phosphate backbone
• BHydrogen bonds between complementary base pairs
• CPeptide bonds between amino acids
• DGlycosidic bonds between sugar and base

Q8 · Zoology · Biotechnology: Principles and Processes

When Agrobacterium tumefaciens is used to produce a transgenic dicot plant, which segment of its Ti plasmid is transferred into the plant cell and integrated into the plant genome?

• AThe entire Ti plasmid, including its origin of replication
• BThe vir gene region, which is copied into the plant chromosome
• CThe T-DNA region, which is integrated into the host genome
• DThe ampicillin-resistance gene carried over from the pBR322 cloning vector

Q9 · Zoology · Biotechnology: Principles and Processes

Two linear DNA fragments of 2 kb and 6 kb, obtained from a restriction digest, are run side by side on an agarose gel in the same buffer at the same voltage. Which statement about their migration is correct?

• AThe 2 kb fragment travels about three times as far as the 6 kb fragment, because migration distance is directly proportional to fragment size.
• BThe 6 kb fragment travels farther toward the anode because its larger mass gives it more negative charge.
• CThe 2 kb fragment travels farther toward the anode, and migration distance varies roughly with the logarithm of fragment size.
• DBoth fragments migrate toward the cathode because DNA is positively charged at neutral pH, and the larger fragment moves faster because of its greater mass.

Q10 · Zoology · Biotechnology: Principles and Processes

A cloning vector must be able to replicate independently inside a host bacterial cell. Which DNA element of the vector makes this possible?

• AOrigin of replication (ori)
• BRestriction site in the multiple cloning site
• CSelectable marker gene such as an antibiotic resistance gene
• DTranscription terminator sequence