NEET Biology: Biotechnology: Principles and Processes questions with solutions

Q1. The sequence that controls the copy number of the linked DNA in the vector, is termed:

1. Ori site
2. Palindromic sequence
3. Recognition site
4. Selectable marker

Answer: Ori site

The ori (origin of replication) is the specific DNA sequence where replication begins, so it determines whether and how efficiently the vector is copied inside the host. Other options relate to restriction enzyme binding, symmetry, or selection, not replication control.

Q2. For transformation, micro-particles coated with DNA to be bombarded with gene gun are made up of:

1. Silver or Platinum
2. Platinum or Zinc
3. Silicon or Platinum
4. Gold or Tungsten

Answer: Gold or Tungsten

Gold and tungsten are used as microprojectiles because they are dense, inert, and can be coated with DNA for delivery into cells. Their physical properties make them suitable for being shot into tissues without easily reacting or degrading the genetic material.

Q3. Biolistics (gene-gun) is suitable for:

1. DNA finger printing
2. Disarming pathogen vectors
3. Transformation of plant cells
4. Constructing recombinant DNA by joining with vectors

Answer: Transformation of plant cells

Biolistics, or the gene gun method, propels DNA-coated particles into target cells. It is especially useful for transforming plant cells because their rigid cell wall makes other DNA delivery methods less effective.

Q4. PCR and Restriction Fragment Length Polymorphism are the methods for:

1. Study of enzymes
2. Genetic transformation
3. DNA sequencing
4. Genetic Fingerprinting

Answer: Genetic Fingerprinting

PCR makes many copies of specific DNA regions, and RFLP reveals variation in fragment lengths after restriction enzyme cutting. Together, these are classic tools for DNA profiling, also called genetic fingerprinting.

Q5. Which one is a true statement regarding DNA polymerase used in PCR

1. It is used to ligate introduced DNA in recipient cell
2. It serves as a selectable marker
3. It is isolated from a virus
4. It remains active at high temperature

Answer: It remains active at high temperature

PCR repeatedly heats the reaction to separate DNA strands, so the polymerase must not denature at those temperatures. Thermostable DNA polymerases, such as Taq polymerase, remain active after high-heat steps and can synthesize new DNA strands.

Q6. The separated DNA fragments can be visualised only after staining the DNA with Ethidium bromide followed by exposure to UV radiation.

1. The separated DNA fragments can be visualised only after staining the DNA with Ethidium bromide followed by exposure to UV radiation.
2. Bt cotton is resistant to cotton bollworm (Insect pest). cry I Ac and cry II Ab genes have been introduced in cotton to protect it from cotton bollworm. This makes Bt cotton as biopesticide.
3. Restriction endonucleases make cuts at specific positions within the DNA. They function by inspecting the length of a DNA sequence. Restriction endonuclease binds to the DNA and cut the two strands of double helix at specific points in their sugar-phosphate backbones. They are used in genetic engineering to form recombinant molecules of DNA. DNA ligases join the DNA fragments.
4. The restriction enzyme prevents replication of the phage DNA by cutting it into many pieces. Restriction enzymes were named for their ability to restrict, or limit, the number of strains of bacteriophage that can infect a bacterium.

Answer: The separated DNA fragments can be visualised only after staining the DNA with Ethidium bromide followed by exposure to UV radiation.

The correct statement is the one about visualizing separated DNA fragments: DNA is stained with ethidium bromide, which intercalates into DNA, and then viewed under UV light because the dye fluoresces. The other options describe Bt cotton or restriction enzymes, which are different concepts.

Q7. Given below are four statements pertaining to separation of DNA fragments using Gel electrophoresis. Identify the incorrect statements. (i) DNA is negatively charged molecule and so it is loaded on gel towards the Anode terminal. (ii) DNA fragments travel along the surface of the gel whose concentration does not affect movement of DNA. (iii) Smaller the size of DNA fragment, larger is the distance it travels through it. (iv) Pure DNA can be visualised directly by exposing to UV radiation. Choose correct answer from the options given below:

1. (a) (i), (ii) and (iv)
2. (b) (i), (iii) and (iv)
3. (c) (i), (ii) and (iii)
4. (d) (ii), (iii) and (iv)

Answer: (a) (i), (ii) and (iv)

DNA is negatively charged, so it migrates toward the anode, but it is loaded near the cathode, making (i) incorrect. DNA moves through the gel matrix and its movement depends on gel concentration, and pure DNA is not directly visible under UV without staining, so (ii) and (iv) are also incorrect.

Q8. In genetic engineering, the antibiotics are used:

1. as selectable markers.
2. to select healthy vectors.
3. to keep the cultures free of infection.
4. as sequences from where replication starts.

Answer: as selectable markers.

Antibiotics are used with resistance genes to select only the cells that have successfully taken up the recombinant vector. Cells without the vector are killed, so the antibiotic acts as a selectable marker.

Q9. DNA fragments are negatively charged molecules. They are separated by forcing them to move towards positive electrode under an electric field through a medium/matrix.

1. DNA fragments are negatively charged molecules. They are separated by forcing them to move towards positive electrode under an electric field through a medium/matrix.
2. Increasing the concentration of agarose in the gel reduces the migration rate of DNA fragments. DNA fragment can not be visualised directly but can be visualised under UV light after staining with ethidium bromide.
3. Restriction enzymes belong to a larger class of enzymes called nucleases. Nucleases are of two different kinds: exonucleases (which remove nucleotides from the end of a DNA molecule) and endonucleases (which break internal phosphodiester bonds at palindromic sites that are highly specific).
4. DNA Polymerase I possesses a 3’→5’ exonuclease activity or "proofreading" function, which lowers the error rate during DNA replication, and also contains a 5’→3’ exonuclease activity, which enables the enzyme to replace nucleotides in the growing strand of DNA by nick translation.

Answer: DNA fragments are negatively charged molecules. They are separated by forcing them to move towards positive electrode under an electric field through a medium/matrix.

DNA has a negatively charged phosphate backbone, so in an electric field it migrates toward the positive electrode. A porous medium like agarose slows larger fragments more than smaller ones, allowing separation.

Q10. The name of DNA polymerase used in PCR is:

1. a) DNA polymerase I
2. b) RNA polymerase
3. c) Taq polymerase
4. d) DNA ligase

Answer: c) Taq polymerase

Taq polymerase is heat-stable, so it remains active after the repeated high-temperature denaturation steps in PCR. The other options do not function as the standard thermostable enzyme for DNA amplification.

Q11. Biolistic is a direct gene transfer method for constructing recombinant DNA. The gene gun was invented by:

1. a) Watson and Crick
2. b) John C. Sanford with Edward Wolf
3. c) Lederberg
4. d) T.H. Morgan

Answer: b) John C. Sanford with Edward Wolf

Biolistic gene transfer, also called particle bombardment, was developed by John C. Sanford and Edward Wolf. They are credited with inventing the gene gun used to introduce DNA directly into cells.

Q12. In gel electrophoresis, separated DNA fragments can be visualized with the help of

1. (a) Ethidium bromide in UV radiation
2. (b) Acetocarmine in UV radiation
3. (c) Ethidium bromide in infrared radiation
4. (d) Acetocarmine in bright blue light

Answer: (a) Ethidium bromide in UV radiation

Ethidium bromide binds between DNA bases and fluoresces when exposed to UV light, making DNA bands visible after gel electrophoresis. The other options do not match the standard DNA staining and detection method.

Q13. The correct option is (a) because ori sequence is responsible for controlling the copy number of the linked DNA in the vector. Ori i.e. origin of replication is responsible for initiation of replication.

1. The correct option is (a) because ori sequence is responsible for controlling the copy number of the linked DNA in the vector. Ori i.e. origin of replication is responsible for initiation of replication.
2. The high AT-content results in the low thermodynamic stability of the region which accounts for its role in the process of replication initiation. At the AT-rich regions, the initial DNA helix destabilization (opening) is induced by binding an initiator protein to its respective recognition sequences situated nearby.
3. Selectable marker is a gene introduced into a cell, especially a bacterium or to cells in culture that confers a trait suitable for artificial selection. Selectable markers help in identification and elimination of non-transformants whilst permitting selective growth of transformants.
4. Use of nptII in concert with the antibiotic kanamycin has become the most widely used selectable marker.

Answer: The correct option is (a) because ori sequence is responsible for controlling the copy number of the linked DNA in the vector. Ori i.e. origin of replication is responsible for initiation of replication.

The ori is the origin of replication, so it is the DNA sequence that allows replication to begin in the host cell. Because replication starts there and its properties affect how often the plasmid is copied, option (a) is the best match.

Q14. For gene transfer into the host cell without using vector microparticles made of tungsten and gold coated with foreign DNA are bombarded into target cells at a very high velocity. This method is called:

1. a) Microinjection
2. b) Electroporation
3. c) Biolistics
4. d) Liposome-mediated gene transfer

Answer: c) Biolistics

Biolistics is the particle bombardment method in which DNA-coated gold or tungsten microprojectiles are shot into cells. It is specifically used for gene transfer without a biological vector.

Q15. PCR is a technique for enzymatically replicating DNA without using a living organism such as E. coli or yeast. The correct steps shown in the above figure are:

1. a) Denaturation at 94°C, Annealing at 50°–65°C, Extension at 72°C
2. b) Denaturation at 50°–65°C, Annealing at 94°C, Extension at 72°C
3. c) Denaturation at 94°C, Annealing at 72°C, Extension at 50°–65°C
4. d) Denaturation at 72°C, Annealing at 50°–65°C, Extension at 94°C

Answer: a) Denaturation at 94°C, Annealing at 50°–65°C, Extension at 72°C

PCR cycles through three temperature-dependent steps. High heat (~94°C) denatures DNA strands, moderate cooling (50°–65°C) allows primers to anneal, and 72°C is ideal for Taq polymerase to extend new DNA strands.

Q16. Which of the following is not correctly matched for the organism and its cell wall degrading enzyme?

1. Plant cells-Cellulase
2. Algae-Methylase
3. Fungi-Chitinase
4. Bacteria-Lysozyme

Answer: Algae-Methylase

Plant cell walls are digested by cellulase, fungal walls by chitinase, and bacterial walls by lysozyme. The algae pair is incorrect because methylase is not a cell wall degrading enzyme for algae.

Q17. The introduction of t-DNA into plants involves:

1. Altering the pH of the soil, then heat shocking the plants
2. Exposing the plants to cold for a brief period
3. Allowing the plant roots to stand in water
4. Infection of the plant by Agrobacterium tumefaciens

Answer: Infection of the plant by Agrobacterium tumefaciens

t-DNA is the segment of the Ti plasmid from Agrobacterium tumefaciens that naturally integrates into plant genomes during infection. This bacterium is widely used as a vector for plant genetic transformation.

Q18. Endonucleases hydrolyse internal phosphodiester bonds in a polynucleotide chain (DNA). While exonucleases hydrolyse terminal phosphodiester bonds in a polynucleotide chain (DNA).

1. Endonucleases hydrolyse terminal bonds.
2. Exonucleases hydrolyse internal bonds.
3. Endonucleases hydrolyse internal bonds.
4. Exonucleases hydrolyse both internal and terminal bonds.

Answer: Endonucleases hydrolyse internal bonds.

Endonucleases cleave phosphodiester bonds within a nucleic acid chain, not at the ends. Exonucleases act on terminal bonds, removing nucleotides from the 5' or 3' end.

Q19. Reproducing new plants by cells instead of seeds is known as

1. mutation
2. tissue culture
3. antibiotics
4. biofertilizer

Answer: tissue culture

Tissue culture is the technique of producing new plants from cells or tissues grown on a nutrient medium. It allows rapid cloning of plants without seeds.

Q20. Which of the following enhances or induces fusion of protoplasts?

1. Polyethylene glycol and sodium nitrate
2. IAA and kinetin
3. IAA and gibberellins
4. Sodium chloride and potassium chloride

Answer: Polyethylene glycol and sodium nitrate

Polyethylene glycol (PEG) is a standard fusogen used to induce protoplast fusion by promoting close membrane contact. Sodium nitrate can also aid fusion conditions, whereas the other options are plant growth regulators or simple salts not used for this purpose.