Processes of Recombinant DNA Technology: NEET MCQs with Answers

15 free questions on Processes of Recombinant DNA Technology for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

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Question 1

Previous-year question
Identify the WRONG statement with regard to restriction enzymes. [NEET 2020]
  1. They cut the strand of DNA at palindromic sites.
  2. They are useful in genetic engineering.
  3. Sticky ends produced by them can be joined using DNA ligases.
  4. Each restriction enzyme functions by inspecting the length of a DNA sequence.
Show answer
Answer: (D) Each restriction enzyme functions by inspecting the length of a DNA sequence.
Explanation: A restriction enzyme inspects the base sequence, not the length, of the DNA; it binds only when it finds its specific palindromic recognition sequence.

Question 2

Previous-year question
In gel electrophoresis, separated DNA fragments can be visualised with the help of [NEET 2020]
  1. Ethidium bromide in UV radiation
  2. Acetocarmine in UV radiation
  3. Ethidium bromide in infrared radiation
  4. Acetocarmine in bright blue light
Show answer
Answer: (A) Ethidium bromide in UV radiation
Explanation: Ethidium-bromide-stained DNA bands fluoresce bright orange when the gel is exposed to ultraviolet light; without staining and UV, the fragments cannot be seen.

Question 3

Previous-year question
Choose the correct pair from the following. [NEET 2020]
  1. Polymerases — Break the DNA into fragments
  2. Nucleases — Separate the two strands of DNA
  3. Exonucleases — Make cuts at specific positions within DNA
  4. Ligases — Join the two DNA molecules
Show answer
Answer: (D) Ligases — Join the two DNA molecules
Explanation: Ligases join DNA fragments by forming phosphodiester bonds. Polymerases synthesise DNA, exonucleases remove nucleotides from the ends, and it is restriction endonucleases that cut at specific internal positions.

Question 4

Previous-year question
Which one of the following equipments is essentially required for growing microbes on a large scale, for the industrial production of enzymes? [NEET 2019]
  1. BOD incubator
  2. Sludge digester
  3. Industrial oven
  4. Bioreactor
Show answer
Answer: (D) Bioreactor
Explanation: A bioreactor provides the optimal temperature, pH, substrate, vitamins, salts and oxygen needed to convert raw materials into the desired product on a large (100–1000 litre) scale.

Question 5

Previous-year question
DNA precipitation out of a mixture of biomolecules can be achieved by treatment with [NEET 2019]
  1. Isopropanol
  2. Chilled ethanol
  3. Methanol at room temperature
  4. Chilled chloroform
Show answer
Answer: (B) Chilled ethanol
Explanation: Purified DNA is insoluble in chilled ethanol and separates out as fine white collections of threads that can be spooled out.

Question 6

Previous-year question
The correct order of steps in the polymerase chain reaction (PCR) is [NEET 2018]
  1. Extension, Denaturation, Annealing
  2. Annealing, Extension, Denaturation
  3. Denaturation, Annealing, Extension
  4. Denaturation, Extension, Annealing
Show answer
Answer: (C) Denaturation, Annealing, Extension
Explanation: Each cycle proceeds as denaturation (strand separation by heat), annealing (primers bind to the single strands) and extension (Taq polymerase synthesises the new strands).

Question 7

Previous-year question
The DNA fragments separated on an agarose gel can be visualised after staining with [NEET 2017]
  1. Acetocarmine
  2. Aniline blue
  3. Ethidium bromide
  4. Bromophenol blue
Show answer
Answer: (C) Ethidium bromide
Explanation: Ethidium bromide intercalates between the bases of DNA and fluoresces bright orange under UV light; bromophenol blue is only a tracking dye.
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Question 8

Previous-year question
What is the criterion for the movement of DNA fragments on an agarose gel during electrophoresis? [NEET 2017]
  1. The smaller the fragment size, the farther it moves.
  2. Positively charged fragments move to the farther end.
  3. Negatively charged fragments do not move.
  4. The larger the fragment size, the farther it moves.
Show answer
Answer: (A) The smaller the fragment size, the farther it moves.
Explanation: The agarose meshwork retards larger fragments more strongly, so the distance travelled towards the anode is inversely related to fragment size.

Question 9

Previous-year question
The process of separation and purification of an expressed protein before marketing is called [NEET 2017]
  1. Downstream processing
  2. Bioprocessing
  3. Post-production processing
  4. Upstream processing
Show answer
Answer: (A) Downstream processing
Explanation: All the steps carried out after the biosynthetic stage — separation, purification, formulation with preservatives, clinical trials and quality control — together form downstream processing.

Question 10

Previous-year question
The Taq polymerase enzyme is obtained from [NEET 2016]
  1. Thermus aquaticus
  2. Thiobacillus ferrooxidans
  3. Bacillus subtilis
  4. Pseudomonas putida
Show answer
Answer: (A) Thermus aquaticus
Explanation: Thermus aquaticus is a bacterium of hot springs, so its DNA polymerase is thermostable and remains active at the high temperature of the denaturation step of PCR.

Question 11

Previous-year question
An analysis of chromosomal DNA using the Southern hybridization technique does NOT use [AIPMT 2014]
  1. Electrophoresis
  2. Blotting
  3. Autoradiography
  4. PCR
Show answer
Answer: (D) PCR
Explanation: Southern hybridisation consists of gel electrophoresis, transfer (blotting) of the fragments to a membrane, hybridisation with a radiolabelled probe, and detection by autoradiography.

Question 12

Previous-year question
In vitro clonal propagation in plants is characterised by [AIPMT 2014]
  1. PCR and RAPD
  2. Northern blotting
  3. electrophoresis and HPLC
  4. microscopy
Show answer
Answer: (A) PCR and RAPD
Explanation: The clonal fidelity of tissue-culture-raised plants is confirmed by molecular markers analysed through PCR and RAPD.

Question 13

Previous-year question
Which one is a true statement regarding the DNA polymerase used in PCR? [AIPMT 2012]
  1. It is used to ligate the introduced DNA in recipient cells
  2. It serves as a selectable marker
  3. It is isolated from a virus
  4. It remains active at high temperature
Show answer
Answer: (D) It remains active at high temperature
Explanation: The DNA polymerase used in PCR is isolated from the bacterium Thermus aquaticus and remains active at high temperature. This allows it to survive the repeated high-temperature-induced denaturation of double-stranded DNA during the cycles.

Question 14

Previous-year question
Which of the following is NOT a component of downstream processing? [NEET 2016 Phase-II]
  1. Separation
  2. Purification
  3. Preservation
  4. Expression
Show answer
Answer: (D) Expression
Explanation: Downstream processing is the separation and purification of products synthesised in bioreactors, followed by formulation with suitable preservatives. Expression of the gene occurs earlier, during the biosynthetic stage, and is therefore not part of downstream processing.

Question 15

Previous-year question
The Taq polymerase enzyme is obtained from [NEET 2016 Phase-I]
  1. Thiobacillus ferroxidans
  2. Bacillus subtilis
  3. Pseudomonas subtilis
  4. Thermus aquaticus
Show answer
Answer: (D) Thermus aquaticus
Explanation: Taq polymerase is a thermostable DNA polymerase obtained from Thermus aquaticus, a bacterium that lives in hot springs and hydrothermal vents. It remains active during the high-temperature denaturation step of PCR.

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