Biotechnology: Principles and Processes – Daily Practice Problem (DPP)

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🎯 NEET 2026 Daily Practice Problem (DPP)

Class 12 | Unit 4: Biotechnology | Topic: Principles and Processes

Q1. The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid of:

  1. Escherichia coli
  2. Salmonella typhimurium
  3. Bacillus thuringiensis
  4. Agrobacterium tumefaciens
✅ View Answer & Explanation

Correct Answer: (2) Salmonella typhimurium
Explanation: Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene and linking it with the plasmid of Salmonella typhimurium.

Q2. Restriction endonucleases are enzymes which:

  1. Make cuts at specific positions within the DNA molecule
  2. Recognize a specific nucleotide sequence for binding of DNA ligase
  3. Restrict the action of the enzyme DNA polymerase
  4. Remove nucleotides from the ends of the DNA molecule
✅ View Answer & Explanation

Correct Answer: (1) Make cuts at specific positions within the DNA molecule
Explanation: They inspect the length of a DNA sequence and cut both strands at specific points in the sugar-phosphate backbone. Exonucleases remove nucleotides from the ends.

Q3. The specific DNA sequence recognized by EcoRI is:

  1. 5′ – GAATTC – 3′
  2. 5′ – GGATCC – 3′
  3. 5′ – AAGCTT – 3′
  4. 5′ – CTTAAG – 3′
✅ View Answer & Explanation

Correct Answer: (1) 5′ – GAATTC – 3′
Explanation: EcoRI recognizes the palindromic sequence GAATTC and cuts between G and A on both strands.

Q4. In Gel Electrophoresis, DNA fragments separate according to their:

  1. Size only
  2. Charge only
  3. Shape only
  4. Both size and charge
✅ View Answer & Explanation

Correct Answer: (1) Size only
Explanation: Since DNA is negatively charged, it moves towards the anode. The separation is based on size (sieving effect of agarose gel); smaller fragments move farther.

Q5. The separated DNA fragments can be visualized only after staining with:

  1. Acetocarmine
  2. Aniline Blue
  3. Ethidium Bromide
  4. Bromophenol Blue
✅ View Answer & Explanation

Correct Answer: (3) Ethidium Bromide
Explanation: DNA fragments stained with Ethidium bromide appear as bright orange bands under UV radiation.

Q6. ‘Elution’ is the process of:

  1. Separating DNA fragments on gel
  2. Staining DNA with Ethidium bromide
  3. Cutting out DNA bands from agarose gel and extracting them
  4. Joining DNA fragments with ligase
✅ View Answer & Explanation

Correct Answer: (3) Cutting out DNA bands from agarose gel and extracting them
Explanation: The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is known as elution.

Q7. In the vector pBR322, the ‘rop’ codes for:

  1. Proteins involved in the replication of the plasmid
  2. Antibiotic resistance proteins
  3. Restriction enzymes
  4. Selectable markers
✅ View Answer & Explanation

Correct Answer: (1) Proteins involved in the replication of the plasmid
Explanation: ‘rop’ stands for Repressor of Primer. It codes for proteins involved in the replication of the plasmid.

Q8. Insertional inactivation of the beta-galactosidase gene results in:

  1. Blue coloured colonies
  2. Colourless colonies
  3. Red coloured colonies
  4. Fluorescent colonies
✅ View Answer & Explanation

Correct Answer: (2) Colourless colonies
Explanation: If the plasmid has an insert, the beta-galactosidase gene is inactivated. The colonies do not produce any colour with the chromogenic substrate (X-gal). Non-recombinants produce blue colonies.

Q9. The tumor-inducing (Ti) plasmid used as a cloning vector is obtained from:

  1. Bacillus thuringiensis
  2. Thermus aquaticus
  3. Agrobacterium tumefaciens
  4. Escherichia coli
✅ View Answer & Explanation

Correct Answer: (3) Agrobacterium tumefaciens
Explanation: It is a pathogen of several dicot plants. It delivers a piece of DNA (T-DNA) to transform normal plant cells into tumor cells.

Q10. DNA precipitation from a mixture of biomolecules can be achieved by treatment with:

  1. Isopropanol
  2. Chilled ethanol
  3. Methanol at room temperature
  4. Hot ethanol
✅ View Answer & Explanation

Correct Answer: (2) Chilled ethanol
Explanation: Addition of chilled ethanol causes the DNA to precipitate out as fine threads, which can be spooled out.

Q11. The correct order of steps in Polymerase Chain Reaction (PCR) is:

  1. Extension, Denaturation, Annealing
  2. Annealing, Extension, Denaturation
  3. Denaturation, Annealing, Extension
  4. Denaturation, Extension, Annealing
✅ View Answer & Explanation

Correct Answer: (3) Denaturation, Annealing, Extension
Explanation: (1) Denaturation of dsDNA (94°C), (2) Annealing of primers (50-60°C), (3) Extension by Taq polymerase (72°C).

[Image of Steps in PCR]

Q12. The thermostable DNA polymerase used in PCR is isolated from:

  1. Thermus aquaticus
  2. Agrobacterium tumefaciens
  3. Bacillus thuringiensis
  4. Escherichia coli
✅ View Answer & Explanation

Correct Answer: (1) Thermus aquaticus
Explanation: Taq polymerase is a thermostable enzyme isolated from the bacterium Thermus aquaticus, which survives in hot springs.

Q13. In the context of biotechnology, ‘Biolistics’ or ‘Gene gun’ is suitable for:

  1. Disarming pathogen vectors
  2. Transformation of plant cells
  3. Constructing recombinant DNA by joining with vectors
  4. DNA fingerprinting
✅ View Answer & Explanation

Correct Answer: (2) Transformation of plant cells
Explanation: Cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA. This method is suitable for plants.

Q14. The most commonly used bioreactor is:

  1. Simple stirred tank bioreactor
  2. Sparged stirred tank bioreactor
  3. Airlift bioreactor
  4. Fluidized bed bioreactor
✅ View Answer & Explanation

Correct Answer: (1) Simple stirred tank bioreactor
Explanation: A stirred-tank reactor is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents.

Q15. Downstream processing includes:

  1. Separation and Purification
  2. Biosynthesis and Separation
  3. Purification and Preservation
  4. Separation, Purification, and Preservation
✅ View Answer & Explanation

Correct Answer: (1) Separation and Purification
Explanation: After the biosynthetic stage, the product involves separation and purification before it is marketed as a finished product. Preservation is also part of formulation.

Q16. To isolate DNA from fungal cells, the cell wall is treated with:

  1. Lysozyme
  2. Cellulase
  3. Chitinase
  4. Protease
✅ View Answer & Explanation

Correct Answer: (3) Chitinase
Explanation: Fungal cell walls are made of chitin. Lysozyme is for bacteria, and Cellulase is for plant cells.

Q17. Which of the following is a selectable marker in pBR322?

  1. Ampicillin resistance gene ($amp^R$)
  2. Tetracycline resistance gene ($tet^R$)
  3. Both 1 and 2
  4. Ori (Origin of replication)
✅ View Answer & Explanation

Correct Answer: (3) Both 1 and 2
Explanation: pBR322 carries two antibiotic resistance genes, ampicillin and tetracycline, which act as selectable markers to identify transformants.

Q18. The process of making the host cell competent by treating with divalent cations like calcium:

  1. Increases the efficiency with which DNA enters the bacterium through pores in its cell wall
  2. Destroys the cell wall
  3. Activates the DNA ligase
  4. Makes the DNA hydrophilic
✅ View Answer & Explanation

Correct Answer: (1) Increases the efficiency with which DNA enters the bacterium
Explanation: Divalent calcium ions increase the permeability of the cell membrane to DNA.

Q19. Which restriction site is present in the Ampicillin resistance gene of pBR322?

  1. BamHI
  2. SalI
  3. PstI
  4. EcoRI
✅ View Answer & Explanation

Correct Answer: (3) PstI
Explanation: The $amp^R$ gene contains restriction sites for PstI and PvuI. The $tet^R$ gene contains sites for BamHI and SalI.

Q20. Stirred-tank bioreactors have been designed for:

  1. Purification of product
  2. Addition of preservatives to the product
  3. Availability of oxygen throughout the process
  4. Ensuring anaerobic conditions in the culture vessel
✅ View Answer & Explanation

Correct Answer: (3) Availability of oxygen throughout the process
Explanation: The stirrer facilitates even mixing and oxygen availability throughout the bioreactor.

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