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Principles and processes of biotechnology: NEET MCQs with answers

122 questions on this topic of Biotechnology and Its Applications (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. Starting from one double-stranded DNA molecule, the number of copies of the target sequence after 28 PCR cycles (ideal amplification) is:

  1. 2.68 × 10⁸
  2. 784
  3. 56
  4. 1.34 × 10⁸
Show answer and explanation

Answer: (A) 2.68 × 10⁸

Each cycle doubles the DNA: 2²⁸ = 2.68 × 10⁸ copies.

medium

2. Given below are two statements: Statement I: Exonucleases remove nucleotides from the ends of the DNA, whereas endonucleases make cuts at specific positions within the DNA. Statement II: Presence of more than one recognition site for a single restriction enzyme within a cloning vector is highly desirable as it generates multiple cloning sites. In the light of the above statements, choose the correct answer:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
Show answer and explanation

Answer: (B) Statement I is correct but Statement II is incorrect

Statement I is correct as exonucleases hydrolyse terminal nucleotides, while endonucleases cleave internal phosphodiester bonds. Statement II is incorrect because having more than one recognition site for an enzyme generates several fragments, which complicates gene cloning rather than facilitating it.

hard

3. In the alternative selectable marker system based on β-galactosidase, recombinant colonies:

  1. Do not produce colour, because the insert inactivates the β-galactosidase gene
  2. Produce blue colour
  3. Grow only on ampicillin
  4. Cannot grow
Show answer and explanation

Answer: (A) Do not produce colour, because the insert inactivates the β-galactosidase gene

Without an insert, β-galactosidase acts on a chromogenic substrate and colonies turn blue; an insert causes insertional inactivation, so recombinant colonies are colourless.

medium

4. Match Column-I with Column-II. Column-I: (A) Lysozyme (B) Cellulase (C) Chitinase (D) Taq polymerase Column-II: (i) Fungal cell wall (ii) PCR (iii) Bacterial cell wall (iv) Plant cell wall

  1. A-(iii), B-(i), C-(iv), D-(ii)
  2. A-(iv), B-(iii), C-(i), D-(ii)
  3. A-(iii), B-(iv), C-(i), D-(ii)
  4. A-(i), B-(iv), C-(iii), D-(ii)
Show answer and explanation

Answer: (C) A-(iii), B-(iv), C-(i), D-(ii)

Lysozyme breaks bacterial walls, cellulase plant walls, chitinase fungal walls; Taq polymerase is used in PCR.

easy

5. Starting from one double-stranded DNA molecule, the number of copies of the target sequence after 14 PCR cycles (ideal amplification) is:

  1. 8192
  2. 28
  3. 196
  4. 16384
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Answer: (D) 16384

Each cycle doubles the DNA: 2¹⁴ = 16384 copies.

hard

6. In pBR322, a foreign DNA ligated at the BamHI site of the tetracycline resistance gene results in recombinant plasmids that:

  1. Gain kanamycin resistance
  2. Cannot replicate
  3. Lose tetracycline resistance but keep ampicillin resistance
  4. Lose ampicillin resistance
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Answer: (C) Lose tetracycline resistance but keep ampicillin resistance

Inserting DNA into tetR causes insertional inactivation. Transformants grow on ampicillin, but recombinants do not grow on tetracycline, allowing them to be identified.

NCERT Class 12

easy

7. Starting from one double-stranded DNA molecule, the number of copies of the target sequence after 19 PCR cycles (ideal amplification) is:

  1. 361
  2. 2.62 × 10⁵
  3. 5.24 × 10⁵
  4. 38
Show answer and explanation

Answer: (C) 5.24 × 10⁵

Each cycle doubles the DNA: 2¹⁹ = 5.24 × 10⁵ copies.

medium

8. A restriction enzyme has 3 recognition sites in a linear DNA molecule. Complete digestion gives how many fragments?

  1. 4
  2. 5
  3. 6
  4. 3
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Answer: (A) 4

Cutting a linear molecule at 3 sites gives 3 + 1 = 4 fragments.

medium

9. Which vector among the following is disarmed and commonly utilized to transfer functional genes into cultured animal cells?

  1. Retrovirus
  2. Agrobacterium tumefaciens Ti plasmid
  3. Bacteriophage M13
  4. Baculovirus
Show answer and explanation

Answer: (A) Retrovirus

Retroviruses in animals have the ability to transform normal cells into cancerous cells. Disarmed retroviruses are engineered and used as vectors to deliver desirable genes into cultured animal cells.

easy

10. Starting from one double-stranded DNA molecule, the number of copies of the target sequence after 5 PCR cycles (ideal amplification) is:

  1. 16
  2. 25
  3. 32
  4. 10
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Answer: (C) 32

Each cycle doubles the DNA: 2⁵ = 32 copies.

medium

11. In agarose gel electrophoresis, DNA fragments move towards the:

  1. Cathode, with larger fragments moving farther
  2. Anode, with larger fragments moving farther
  3. Cathode only when stained
  4. Anode, with smaller fragments moving farther
Show answer and explanation

Answer: (D) Anode, with smaller fragments moving farther

DNA is negatively charged and moves towards the anode. The agarose matrix sieves the fragments, so smaller ones move farther. Stained with ethidium bromide, bands appear orange under UV.

NCERT Class 12

easy

12. Starting from one double-stranded DNA molecule, the number of copies of the target sequence after 12 PCR cycles (ideal amplification) is:

  1. 2048
  2. 144
  3. 24
  4. 4096
Show answer and explanation

Answer: (D) 4096

Each cycle doubles the DNA: 2¹² = 4096 copies.

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