Biotechnology MCQ Quiz - Objective Question with Answer for Biotechnology - Download Free PDF

The correct answer is option 3.

Key Points

• Human insulin was the first hormone to be produced using recombinant DNA technology. Hence, option 3 is correct.
• It was developed by Genentech and Eli Lilly in the early 1980s, marking a major breakthrough in biotechnology and medicine.
• This synthetic insulin is called "Humulin", and it is produced by inserting the human insulin gene into E. coli bacteria, which then synthesize insulin.

The correct answer is Statement I is incorrect but Statement II is correct

Concept:

• The differentiation between recombinant and non-recombinant colonies using blue-white screening is a widely used method in molecular biology.
• It is based on the insertional inactivation of the lacZ gene, which encodes the enzyme β-galactosidase.
• In this method, a chromogenic substrate such as X-gal is used. The β-galactosidase enzyme cleaves X-gal, producing a blue-colored product.
• Recombinant colonies are identified by the insertion of foreign DNA into the multiple cloning site of the plasmid, which disrupts the lacZ gene and prevents the production of β-galactosidase, resulting in white colonies.
• Non-recombinant colonies retain an intact lacZ gene and produce β-galactosidase, leading to blue-colored colonies.

Explanation:

Statement I: "The blue-colored colonies have DNA insert in the plasmid and they are identified as recombinant colonies."

• This statement is incorrect because the blue-colored colonies represent non-recombinant colonies.
• These colonies have an intact lacZ gene, which produces β-galactosidase, resulting in the cleavage of X-gal and the formation of blue color.
• No DNA insert is present in these colonies, and thus they are not recombinant.

Statement II: "The colonies without blue color have DNA insert in the plasmid and are identified as recombinant colonies."

• This statement is correct because the absence of blue color (white colonies) indicates the disruption of the lacZ gene by the insertion of foreign DNA.
• The lack of β-galactosidase activity results in no cleavage of X-gal, and thus no blue color is produced.
• These colonies are recombinant as they contain the inserted DNA fragment in the plasmid.

The correct answer is C and D only

Explanation:

• Gene cloning is a method used to create identical copies of a specific gene or DNA segment. It involves isolating a desired gene, inserting it into a vector, and introducing it into a host organism to amplify and express the gene.
• Enzymes play a crucial role in the various steps of gene cloning. However, not all enzymes are essential for the process.
• The most commonly used enzymes in gene cloning are restriction enzymes, DNA ligase, and DNA polymerase.
  • Restriction enzymes: These are essential enzymes for gene cloning. They recognize specific DNA sequences and cut the DNA at or near these sites, producing fragments that can be inserted into vectors.
  • DNA ligase: This enzyme is critical for gene cloning. It joins the DNA fragments (e.g., the insert DNA and the vector) by forming phosphodiester bonds, making a stable recombinant DNA molecule.
  • DNA polymerase: DNA polymerase is sometimes used in gene cloning for amplifying DNA through techniques like PCR (Polymerase Chain Reaction) or for filling in DNA overhangs after restriction digestion.
• DNA mutase: This enzyme is not essential for gene cloning. DNA mutase is involved in introducing mutations into DNA, which is not a requirement for cloning
• DNA recombinase: While recombinases facilitate site-specific recombination and have applications in advanced genetic engineering (e.g., CRISPR or recombineering), they are not essential for basic gene cloning processes.

The correct answer is It will be digested in the Gastro-Intestinal (GI) tract

Concept:

• Insulin is a peptide hormone produced by the pancreas and is crucial for regulating blood sugar levels in the body. It cannot be administered orally because of its structural composition, which makes it vulnerable to enzymatic degradation in the gastrointestinal (GI) tract.
• Insulin is commonly administered through subcutaneous injections to bypass the GI tract and directly enter the bloodstream for effective action.

Explanation:

• Insulin is a protein-based molecule, and like other proteins consumed in food, it is broken down into amino acids by digestive enzymes in the stomach and intestines.
• This enzymatic breakdown prevents insulin from retaining its functional structure and biological activity, rendering it ineffective if taken orally.
• Since oral delivery is not feasible, insulin is typically given via injections (subcutaneous, intravenous, or intramuscular).
• Research is ongoing for alternative delivery methods, such as inhalable insulin, transdermal patches, and oral formulations with protective coatings or encapsulations.

Other Options:

• Human body will elicit a strong immune response:
  • The human immune system does not typically produce a strong immune response to insulin, especially if it is human recombinant insulin, which mimics the natural hormone produced in the body. Immune responses are more relevant in cases of non-human insulin or impurities in synthetic formulations, which are rare in modern medicine.
• Because of structural variation:
  • Insulin’s structure is not a limiting factor for its administration. Its molecular structure is well-suited for interaction with insulin receptors, and it performs its function effectively once in the bloodstream.
• Its bioavailability will be increased:
  • This statement is incorrect because oral administration of insulin would result in extremely low bioavailability due to enzymatic breakdown in the GI tract. Bioavailability refers to the proportion of a drug that enters circulation and can have an active effect. Oral insulin delivery significantly reduces this proportion.

The correct answer is Complementary dsRNA  

Explanation:

• Several nematodes parasitize a wide variety of plants and animals including human beings. A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield.
• A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).
• RNAi takes place in all eukaryotic organisms as a method of cellular defense.
• This method involves the silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing).
• The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.

Concept:

• Adenosine Deaminase (ADA) is an enzyme required for the proper functioning of the immune system.
• ADA deficiency is caused due to deletion of the gene for the enzyme adenosine deaminase.

Explanation:

• ADA deficiency can be treated through gene therapy. 
• In gene therapy, the lymphocytes from the patient are grown outside the body and a functional ADA cDNA is introduced (using a retroviral vector) into the lymphocytes.
• The genetically engineered lymphocytes are then introduced back into the patient.
• These genetically engineered lymphocytes are immortal hence, the patient has to be infused with such lymphocytes regularly.

So, the correct answer is option 1.

Additional Information:

• Introducing genes for ADA into the cells at early embryonic development can lead to a permanent cure for ADA deficiency.

Correct answer: 3)

Concept:

• Gel electrophoresis is a method of separation of a mixture of DNA samples based on their molecular size and charge.
• Generally, agarose gel is used to carry out gel electrophoresis.

Explanation:

• Gel electrophoresis is carried out in a series of steps- agarose gel is prepared, a sample of DNA is prepared, then the mixture of DNA sample is loaded into the wells in the gel, and then an electric field is applied.
• On applying electric field DNA fragments start to move towards the positive terminal as they are negatively charged.
• This separates the sample based on size and charge.
• Ethidium bromide (EtBr) is a fluorescent dye and an intercalation agent used in gel electrophoresis.
• EtBr inserts itself in between the stacked bases. When visualized under the UV lamp, it will appear as bright orange bands.

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So, the correct answer is option 3.

The correct answer is option 2.

Solution

Concept:

• Restriction enzymes act as molecular scissors.
• There are two kinds of restriction enzymes: endonucleases and exonucleases.
• Exonuclease helps in removing nucleotides from ends of DNA while endonuclease makes cuts at the specific sites in the DNA.

Explanation:

Let us understand the working of restriction endonuclease:

• Restriction endonuclease inspects the entire length of the DNA. 
• Upon finding a specific nucleotide sequence it will bind to it on the DNA and will slice the sequence from the DNA strand.
• It recognizes palindrome nucleotide sequences (the sequence of base pairs reads the same on the two strands of DNA when the reading orientation is kept the same).   
• They cut the DNA strand a little away from the centre of the palindrome nucleotide sequence but this occurs between the two same pairs on the opposite strands of DNA double helix.
• This leaves single-stranded portions at the ends. There are overhanging stretches called sticky ends on each strand.
• Sticky ends form hydrogen bonds with their complementary cut counterparts.

• This stickiness of the ends facilitates the action of the enzyme DNA ligase.

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Statement I: Restriction endonucleases recognise specific sequence to cut DNA known as palindromic nucleotide sequence; this is true. As restriction endonuclease recognizes palindrome sequence on the DNA.

Statement II: Restriction endonucleases cut the DNA strand a little away from the centre of the palindromic site; this is true. As restriction endonuclease cut the DNA strand a little away from the centre of the palindrome nucleotide sequence that occurs between the two same pairs on the DNA double helix.

So, the correct answer is option 2. 

Concept:

• PCR stands for Polymerase Chain Reaction.
• It is the process of amplifying or making multiple copies of a desired fragment of DNA.
• This technique was developed by Kary Mullis in 1983.
• PCR is a cyclical technique where each cycle consists of 3 basic steps - 
  • Denaturation
  • Annealing
  • Extension

Explanation:

• Option 1: Denaturation of template DNA
  • It is the process by which 2 strands of ds-DNA separates to form 2 single strands.
  • This is achieved by applying heat that helps in breaking the H-bonds between the 2 DNA strands.
  • This step does not require DNA polymerase and hence, this option is incorrect.
• Option 2: Annealing of primers to template DNA
  • In this process, 2 sets of primers bind to specific regions on the separated strands of DNA.
  • Primers - are small, chemically synthesized oligonucleotides that are complimentary to specific regions of DNA.
  • This option is also incorrect.
• Option 3: Extension of primer end on the template DNA
  • This step involves extension of the primers using Taq DNA polymerase in the presence of deoxynucleotides.
  • Taq polymerase is a thermostable DNA polymerase that is used for repeated amplification.
  • This enzyme remains active even in high temperatures because it is obtained from the bacteria Thermus aquaticus, which survives in extreme heat conditions like hot springs.
  • Hence, this option is correct.
• Option 4: All of the above
  • This option is incorrect as only one of the above options is correct.

Hence, the correct answer is option (3).

Concept:

• Recombinant DNA technology is the technique of introducing a desirable gene into the target organism. It alters the genetic composition of the organism.
• A DNA fragment with the desired sequence of the gene from varying sources is introduced via a vector into the host cell.
• A vector or a cloning vector are vehicles that are used for transferring DNA from one cell to another.
• A vector needs to possess the following properties:
  • Should be able to replicate.
  • Should be a small DNA molecule that allows for easy isolation and handling.
  • Should contain selectable marker genes that will help to identify and isolate the transformants.
  • Should possess a site for the insertion of the desired DNA molecule.

Explanation:

• A selectable marker is a characteristic feature of the ideal vector.
• It is a required component during recombinant DNA technology as it is used to identify transformed and non-transformed cells.
• The genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are considered useful selectable markers for E. coli.
• For example, if we insert a DNA fragment within the tetracycline resistance gene of E. coli plasmid, there will be insertional inactivation of that gene.
• So, the transformed cell with the recombinant DNA will have only ampicillin resistance and not tetracycline resistance.
• We first grow the cells in a medium containing ampicillin where both transformed and non-transformed cells will form colonies.
• These colonies are then transferred to a medium containing tetracycline, where only the non-transformed cells will grow.
• Thus we can select the transformed colonies from the ampicillin medium.
• The tetracycline resistance gene in this case is called a selectable marker. 

So from the above-given information, the correct answer is option 2.

Additional Information

Competent bacterial cell:

• Cell competence refers to a cell's ability to take up genetic material from its surroundings.
• A bacterial cell can be made competent by the heat-shock method, by which pores are created in the cell wall through which DNA can enter the bacterial cell.

Recombinant bacterial cell:

• A recombinant bacterial cell refers to a cell wherein its genetic constituent has undergone recombination.
• This genetic recombination is due to the DNA transfer that has taken place from a donor cell.
• The transfer of genetic material can take place either due to transformation, transduction or conjugation.

Concept:

• Biological control or biocontrol is the use of the naturally occurring enemies of insects, pests, and other disease-causing agents to control and eliminate them.
• Microbes like bacteria, fungi, viruses, etc. are used as biocontrol agents.
• Biocontrol agents have three modes of action - cause disease to the pest, compete with them or kill them.
• The biocontrol agents are multiplied on artificial media.
• These artificially grown agents are then released in large numbers to control the pest population naturally.
• This process is called augmentative biological control.

Explanation:

• Bacillus typhimurium - 
  • ​Salmonella typhimurium is a bacillus i.e. a rod-shaped bacteria.
  • It is a pathogenic bacteria found in the intestinal lumen.
  • It causes gastroenteritis in mammals including humans.
  • It is not used as a biocontrol agent.
• Bacillus taiwanensis - 
  • ​Bacillus taiwanensis is a Gram-positive bacteria. 
  • It was isolated first from a soil sample in Taiwan.
  • It is known to be a non-human pathogenic organism.
  • It is not used as a biocontrol agent.
• ​​Bacillus thuringiensis - 
  • ​Bacillus thuringiensis is a biocontrol agent.
  • It is used in agriculture to control the population of caterpillars and butterflies.
  • Bacillus thuringiensis controls the population of pests by killing them.
  • Bt crops such as cotton, brinjal,etc. are genetically engineered crops that contain the cry gene isolated from Bacillus thuringiensis. 
  • This gene encodes a toxin that is insecticidal in  property.
• Bacillus tropicus - 
  • ​Bacillus tropicus is a Gram-positive rod-shaped bacteria.
  • It was first isolated from the sediments of the South China Sea.
  • Studies have shown that Bacillus tropicus has the ability to biodegrade low density polyethylene (LDPE).
  • Polyethylene is the most commonly used plastic.
  • It is not used as a biocontrol agent.

So the correct answer is option 3 (Bacillus thuringiensis).​

Concept:

• Biotechnology is the branch of science that involves the manipulation of the genetic components of biological agents like microorganisms to produce commercially useful goods and services.
• Engineering and scientific principles are employed for this purpose.
• There are several applications of biotechnology which are as follows:
  • Plant biotechnology - production of GM crops
  • Animal biotechnology - gene therapy, tissue culture, etc.
  • Environmental biotechnology - bioremediation, pollution control, etc.
  • Microbial biotechnology - production of biopesticides, biofertilizers, etc.
  • Industrial biotechnology - protein engineering, production of enzymes, etc.

Important Points

​Bioprospecting - ​

• Bioprospecting involves the search for novel products from bioresources.
• These resources could be a plant, an animal, fungi, or even a microorganism.
• It explores the molecular, genetic, and species levels of diversity in search of these novel products.
• These products are useful to mankind and have economic value to them.
• Medicinal drugs and other commercially valuable products can be obtained through these products.
• E.g. - Poppy seeds contain many alkaloids which include morphine. Morphine is used as a pain reliever in the medicinal field. The knowledge of the presence of morphine in poppy seeds is due to bioprospecting.

Additional Information

Bioremediation - ​

• Bioremediation is a branch of biotechnology that uses microorganisms to clean the environment.
• Microorganisms are used to decontaminate affected soil, water, land, and other environments. It frees the affected area of the pollutants.
• Oil spills are a classic example of bioremediation. Oil spills are cleaned from a water body with the help of microorganisms.

Bioaccumulation - 

• ​Bioaccumulation is not a biotechnological process.
• It is a natural process in which chemicals get accumulated in an organism's body like that of a fish.
• This occurs when the intake rate of the chemicals exceeds that of its elimination rate.
• The chemicals can enter an organism's body through its surrounding environment like from the air, water, or soil.
• It can also enter through food intake.
• Chemicals like DDT, PCB, mercury, etc. get accumulated in an organism's body affecting its natural body functioning.

Biosensoring - 

• Biosensors are devices that comprise a biological component and a physiochemical component.
• Biosensors have a wide range of applications ranging from the detection of disease to the detection of pollutants.
• It is also used in drug discovery and detection of disease-causing germs in bodily fluids.
• Biosensors help measure biological or chemical reactions in an analyte.
• It does so by measuring the electrical signal that is generated during the reaction which corresponds to the concentration of the analyte.
• The biological component of the biosensor detects the analyte whereas the physiochemical component produces the signal.

So the correct answer is option 4 (Bioprospecting).

Explanation:

Therefore option 4 is correct.

Concept:

• Agarose gel electrophoresis separates DNA molecules based on their size.
• The basic principle of this process is based on the fact that DNA is a negatively charged molecule.
• DNA molecules move towards an anode through the medium under an electric field.
• Agarose is a natural polymer obtained from algae and is commonly used as the medium in gel electrophoresis process.
• This medium provides a sieving effect by which DNA fragments move and get separated.
• Wells are made in the medium tray, where DNA is put.
• These wells are away from the anode end.
• The smaller fragments are lighter molecules and hence move faster towards the anode when electric field is applied.
• The larger molecules move slowly and remain away from the anode end.

Explanation:

• Option 1: DNA can be seen in visible light
  • Pure DNA cannot be seen in visible light.
  • Hence, this option is incorrect.
• Option 2: DNA can be seen without staining in visible light
  • DNA can only be seen after staining.
  • Hence, this option is incorrect.
• Option 3: Ethidium bromide stained DNA can be seen in visible light
  • Ethidium bromide is a fluorescent dye that can be viewed only under UV light.
  • Hence, this option is incorrect.
• Option 4: Ethidium bromide stained DNA can be seen under exposure to UV light
  • Pure DNA is stained with Ethidium bromide and then viewed under UV light.
  • The DNA fragments are visible as orange-coloured bands in the agarose gel under UV light.
  • Hence, this option is correct.

Hence, the correct answer is option (4).

Concept:

• PCR stands for Polymerase Chain Reaction.
• It is the process of amplifying or making multiple copies of a desired fragment of DNA.
• It has wide applications in various fields involving genetic studies.

Important Points

Option 1: Paternity testing - CORRECT

• PCR is commonly used in paternity testing to compare DNA profiles between individuals and determine biological parentage.
• It allows for the amplification of specific regions of DNA for comparison and analysis.

Option 2: Detection of mutations of genes in suspected cancer patients - CORRECT

• PCR is frequently used in genetic testing to detect mutations in specific genes associated with cancer.
• By amplifying and analyzing DNA samples, PCR enables the identification of genetic alterations that may contribute to the development or progression of cancer.

Option 3: Powerful technique to identify genetic disorders - CORRECT

• PCR is extensively employed in genetic diagnosis to identify various genetic disorders.
• It allows for the detection of specific genetic mutations associated with inherited diseases, providing valuable information for clinical management and genetic counseling.

Option 4: To cure ADA (adenosine deaminase) deficiency - INCORRECT

• PCR is not directly involved in the cure or treatment of genetic disorders such as ADA deficiency.
• ADA deficiency is a rare genetic disorder that affects the immune system and requires specialized medical interventions such as enzyme replacement therapy or bone marrow transplantation.

Hence, option 4 is NOT an application of PCR.

Additional Information

• PCR is carried out by a thermostable DNA polymerase called Taq polymerase.
• This enzyme remains active at high temperatures because it is obtained from Thermus aquaticus which thrives in extreme conditions of hot springs.
• PCR involves 3 basic steps which are repeated in cycles such that we get about a billion copies of the DNA in 30 cycles.
• The steps are:
  • DNA Denaturation
  • Primer Annealing
  • Primer Extension