31 Years NEET Previous Year Questions: Biotechnology & Its Applications

Human insulin, which is used to treat diabetes, is now commonly produced using genetic engineering techniques. This process involves inserting the human insulin gene into a suitable organism, which then produces insulin identical to that produced in the human body.
Eli Lilly, a pharmaceutical company, was one of the pioneers in using genetically engineered organisms to manufacture human insulin. This marked a revolutionary advancement in biotechnology and medicine.
The genetically engineered organism used for this purpose by Eli Lilly was the bacterium Escherichia coli (E. coli).
E. coli, a common bacterium, was genetically modified to produce human insulin. Scientists introduced the human insulin gene into E. coli cells using recombinant DNA technology.
The modified bacteria then synthesized insulin, which was harvested, purified, and used for medical purposes.
This method replaced the earlier practice of extracting insulin from the pancreases of pigs or cows, which had limitations such as allergic reactions and a limited supply.
Using bacteria like E. coli for insulin production is cost-effective, scalable, and ensures the production of insulin that is identical to human insulin.
Other Options:
Yeast (Incorrect): While yeast cells, such as Saccharomyces cerevisiae, are also used in genetic engineering, they were not the organism initially used by Eli Lilly for insulin production. Yeast is sometimes used in modern biotechnology for producing proteins, but E. coli was the first organism used for this purpose in insulin production.
Virus (Incorrect): Viruses are used in genetic engineering for purposes such as gene therapy or as vectors to deliver genetic material into cells. However, viruses are not suitable for producing large quantities of insulin due to their biology and replication mechanisms.
Phage (Incorrect): Phages, or bacteriophages, are viruses that infect bacteria. They are often used in genetic research and as tools in biotechnology. They were not used by Eli Lilly for insulin production.

In somatic hybridization, the fusion of protoplasts from different plant varieties or species is a key technique. Protoplasts are plant cells that have had their cell walls enzymatically removed, exposing the cell membrane. This condition allows for the direct fusion of cellular contents including the nucleus and cytoplasm from different cells, facilitating recombination and the formation of a hybrid cell. The process of fusion typically involves techniques such as electrofusion or chemical treatments to encourage the protoplasts to merge.

Looking at the options provided:

• Option A: Callus – This is not correct. A callus is a mass of unorganized plant cells that are generally not involved in fusion during somatic hybridization but are rather a product of the culture of somatic cells.
• Option B: Somatic embryos – These are not the direct subjects of fusion in somatic hybridization. Somatic embryos can develop from hybrid cells, but they themselves are not fused; they are derived from somatic cells under appropriate conditions.
• Option C: Protoplasts – This is correct. Protoplasts are indeed what are fused in somatic hybridization to combine the genetic material from two different plants or varieties.
• Option D: Pollens – These do not fuse in somatic hybridization. Pollen fusion is more relevant to sexual reproduction and breeding, not somatic cell procedures.

Therefore, the correct answer is Option C: Protoplasts.

Statement I: Bt toxins are indeed insect group-specific and are coded by the cry gene family, including the cry IAc gene. This is true.
Statement II: While the Bt toxin is produced as an inactive protoxin, it is not the acidic pH of the insect gut but the alkaline pH that activates the protoxin into its toxic form. Therefore, Statement II is false.

Statement I: This statement is false because although Agrobacterium is often used in plant genetic engineering, it is not typically used to produce human insulin. Instead, Escherichia coli (E. coli) or yeast are commonly used to produce the insulin chains (A and B) by introducing the corresponding DNA sequences for each chain. Agrobacterium is more commonly used for plant transformation, not for human insulin production.
Statement II: This statement is true. After producing insulin chains A and B separately (often using bacteria or yeast), the two chains are extracted and combined by creating disulfide bonds to form human insulin. These disulfide bonds are crucial for the correct folding and functional activity of insulin.
Thus, Statement I is false, but Statement II is true.

One of the primary objectives of biotechnology in agriculture is to develop genetically modified (GM) crops that are resistant to pests, diseases, or environmental stresses. This can help reduce the need for chemical pesticides, improve crop yields, and ensure food security.
The other options:

• Increase nitrogen content in plants: While this can be beneficial (for example, through nitrogen-fixing bacteria), it is not the primary goal of agricultural biotechnology.
• Decrease seed number: This is not a common goal of biotechnology in agriculture, as increasing seed production is often preferred to improve crop yield.
• Increase plant weight: While improving plant growth is important, pest resistance (as mentioned in option a) is a more prominent application of biotechnology.

Assertion (A): Ethical standards are indeed required to evaluate the morality of scientific activities, especially in areas like genetic engineering, where the manipulation of genes in living organisms can have both beneficial and harmful effects. This is true because scientific advancements, especially in biotechnology, can raise significant ethical concerns related to their potential impacts on health, environment, and society.
Reason (R): The Genetic Engineering Approval Committee (GEAC) is responsible for making decisions regarding the validity of genetically modified (GM) research and ensuring the safety of GM organisms before they are released into the environment or used for public services. This is also true as GEAC plays a critical role in overseeing the ethical and safety aspects of GM technology in India.
Although both statements are true, (R) does not directly explain (A). The requirement for ethical standards (A) is broader and pertains to evaluating the morality of various scientific activities, whereas (R) specifically talks about the function of the GEAC, which is more focused on regulatory aspects of GM organisms. Hence, (R) is not the correct explanation for (A).

Bt toxin (from Bacillus thuringiensis) is produced as a protoxin in an inactive form. When insects ingest it, the toxin is activated in their alkaline gut environment, where it is converted into its active form. This active toxin then binds to receptors in the insect’s gut, causing damage and ultimately killing the insect.
Bacillus thuringiensis itself is not harmed by the toxin because it is stored in an inactive form within the bacterial cells. The toxin does not activate inside the bacterium, and Bacillus has mechanisms that prevent the activated toxin from affecting itself. Therefore, the reason it doesn't harm the Bacillus is because the toxin is in an inactive form until ingested by an insect.

The other options are not entirely correct in this context:

• Option A: The acidic pH helps activate the toxin, but this is not the primary reason why it doesn't affect the bacterium.
• Option B: While Bacillus may have protective mechanisms, the key factor is the inactive form of the toxin inside the bacterium.
• Option C: The protoxin itself does not require a protein conjugate for activation; it is activated by the insect's digestive environment.

The incorrect statement among the provided options is: Option C.
Bio-reactors, also known as fermenters, are primarily utilized for scaling up microbial processes to industrial scales. They are designed to support the growth of a high density of cells and microbes under controlled conditions to produce large volumes of biochemical products such as enzymes, pharmaceuticals, and other biologically active compounds. While bio-reactors can technically be used for small-scale laboratory experiments, their main application and design focus is on large-scale production.
Other Options:
Option A: This statement is correct. Bio-reactors are specifically designed to provide optimal conditions such as temperature, pH, oxygen supply, and nutrients for the growth of microorganisms or cells, which helps in achieving a higher yield of the desired product.
Option B: This statement is also true. The most common type of bio-reactors used in industrial processes are of the stirred type, which have mechanical agitators to evenly distribute nutrients and maintain uniform conditions within the tank.
Option D: True, bio-reactors often include several essential systems: an agitator system for mixing, an oxygen delivery system to provide sufficient respiration for aerobic organisms, and a foam control system to prevent the formation of excessive foam, which could interfere with the operation of the reactor.
Thus, the incorrect statement about the typical scale and focus of bio-reactor use is Option C.

• A. Genetically engineered Human Insulin: Genetically engineered human insulin is produced using E. coli (II) through recombinant DNA technology. The gene for human insulin is inserted into E. coli, which then produces the insulin protein.
• B. GM Cotton: Genetically modified cotton is engineered using Bacillus thuringiensis (IV). The bacterium's Bt toxin gene is inserted into cotton plants to make them resistant to insect pests like bollworms.
• C. ADA Deficiency: ADA deficiency (Adenosine Deaminase deficiency) is treated through Gene therapy (I). Gene therapy involves inserting a normal copy of the ADA gene into the patient's cells to correct the genetic defect.
• D. ELISA: ELISA (Enzyme-Linked Immunosorbent Assay) is a technique used to detect antigen-antibody interaction (III). It is commonly used in diagnostic applications to detect the presence of specific antigens or antibodies in a sample.

Thus, the correct matching is A-II, B-IV, C-I, D-III.

Statement I: True. The Genetic Engineering Approval Committee (GEAC) is indeed set up by the Indian government to make decisions regarding the validity of genetically modified (GM) research and the safety of introducing GM organisms. GEAC is responsible for regulating genetically modified organisms (GMOs) in India, ensuring that they are safe for use in the environment and for public consumption.
Statement II: False. Biopiracy refers to the unauthorized use or patenting of biological resources, often by companies or individuals from developed countries, without proper compensation or recognition of the indigenous communities who have traditionally used these resources. It is not the term used for the use of bio-resources by native people themselves. Instead, biopiracy often involves the exploitation of traditional knowledge or natural resources without proper consent or benefit-sharing with local communities.
Thus, Statement I is True, but Statement II is False.

To provide the correct answer, let's evaluate each option by matching the items from List I with their corresponding descriptions from List II:
α-I antitrypsin - This is a protease inhibitor and its deficiency leads to emphysema due to the degradation of the lung tissue. Therefore, α-I antitrypsin corresponds to Emphysema (III).
Cry IAb - Part of a family of proteins from Bacillus thuringiensis used as a biological pesticide. Cry IAb is notably effective against certain types of Lepidoptera, including the European Corn Borer (IV).
Cry IAc - This is also a protein from Bacillus thuringiensis and is notably effective against Cotton Bollworm (I).
Enzyme replacement therapy - Typically used for treating deficiencies in certain enzymes; one prevalent example is Adenosine Deaminase (ADA) deficiency, which leads to immune deficiencies (II).
Let's match these back to the original options provided:
A-III (α -I antitrypsin matches with Emphysema)
B-IV (Cry IAb matches with Corn Borer)
C-I (Cry IAc matches with Cotton Bollworm)
D-II (Enzyme replacement therapy matches with ADA deficiency)
Based on these matches, the correct option would be: Option C: A-III, B-IV, C-I, D-II

Totipotency is defined as the capacity to generate a whole plant from any cell of the plant. 

• B: Bacillus thuringiensis produces crystals containing toxic insecticidal proteins. These proteins are produced by the bacterium as a defense mechanism.
• E: The toxin proteins exist as inactive protoxins in the bacteria. These protoxins are stored as crystalline proteins and are inactive in their native state.
• C: The alkaline pH in the insect’s gut solubilizes the crystals, which then allows the protoxin to be released.
• A: The inactive toxin is converted into its active form due to the alkaline pH of the insect’s gut. This conversion activates the toxin.
• D: The activated toxin binds to the surface of midgut cells, creating pores in the cells, leading to the death of the insect by disrupting the digestive system.

Thus, the correct sequence of steps is B → E → C → A → D.

The Bt toxin in genetically engineered Bt cotton kills pests, such as the cotton bollworm, by binding to the midgut cells of the insect. Once inside the gut, the toxin is activated by the alkaline pH and binds to receptors on the midgut cells, creating pores in the cell membranes. This disrupts the integrity of the gut cells, leading to the leakage of ions and eventually the death of the insect due to gut paralysis and nutrient absorption failure. This method of action is specific to insects, making Bt cotton effective in pest control without harming other organisms.

Statement I: RNA interference (RNAi) is not found in all eukaryotic organisms as a method of cellular defense. While RNAi is a well-known and widespread defense mechanism in many eukaryotes, including plants, animals, and fungi, it is not necessarily present in all eukaryotic organisms. Some organisms may lack the RNAi pathway or have a less pronounced RNAi mechanism. Therefore, Statement I is False.
Statement II: RNAi indeed involves the silencing of a specific mRNA. This is achieved through a complementary single-stranded RNA molecule (such as small interfering RNA or microRNA) that binds to the target mRNA and prevents its translation or induces its degradation. This process effectively silences the expression of specific genes. Therefore, Statement II is True.

• Option (A) is the correct answer as, during isolation of the genetic material, purified DNA ultimately precipitates out after the addition of chilled ethanol.
• Option (B) is not the answer as, proteins can be removed by treatment with proteases.
• Option (D) is not the answer as RNA can be removed by treatment with ribonuclease.

The correct answer is option (D) because recombinant DNA technology involves several steps in specific sequence such as isolation of DNA, fragmentation of DNA by restriction endonucleases, isolation of desired DNA fragment, ligation of the DNA fragment into a vector, transferring the recombinant DNA into the host, culturing the host cells in a medium at large scale and extraction of the desired product.

-Serum and Urine Analysis: This technique involves testing bodily fluids to detect abnormalities or diseases. While it can provide valuable information, it is generally not the primary method for early diagnosis of many diseases.
- Polymerase Chain Reaction (PCR): PCR is a molecular technique used to amplify DNA. It is highly sensitive and specific, making it an excellent tool for the early diagnosis of infectious diseases and genetic disorders.
- Enzyme-Linked Immunosorbent Assay (ELISA): ELISA is a widely used laboratory test to detect and quantify proteins, antibodies, and hormones. It is effective for early diagnosis of various diseases, including infections and autoimmune disorders.
- Recombinant DNA Technology: This technique involves manipulating DNA to study genes and produce proteins. It can be used for early diagnosis, particularly in genetic testing and identifying pathogens.

Thus, Serum and Urine analysis does not serve the primary purpose of early disease diagnosis as effectively as the other listed techniques.

• The mature insulin molecule consists of two polypeptide chains (A and B), not three. The C-peptide is a part of the proinsulin form and is removed during the conversion to mature insulin.
• Statement (b): Insulin is synthesized as a prohormone, known as proinsulin, which indeed contains an extra stretch called the C-peptide.
• Statement (c): C-peptide is not present in the mature insulin molecule. Once proinsulin is processed, the C-peptide is cleaved off, and only the A and B chains remain, linked by disulfide bridges.
• Statement (d): Polypeptide chains A and B are linked by disulfide bridges, which is true for the structure of mature insulin. These disulfide bridges stabilize the insulin molecule.

Thus, Statement (a) is incorrect because insulin consists of two chains (A and B), not three.

Option (B) is the correct answer because in gene gun method, microparticles of tungsten or gold are used. Gold or tungsten are inert in nature so they do not alter the chemical composition of cells.

(A) Gene therapy: Gene therapy involves the correction of a gene defect by introducing or altering a gene within a patient's cells, so it matches with (IV) Allows correction of a gene defect.

(B) RNA interference: RNA interference (RNAi) is a cellular defense mechanism where RNA molecules inhibit gene expression or translation, so it corresponds with (III) Cellular defense.
(C) ELISA: ELISA (Enzyme-Linked Immunosorbent Assay) is widely used as a diagnostic test for AIDS by detecting HIV antibodies or antigens, so it matches with (II) Diagnostic test for AIDS.
(D) Gel Electrophoresis: Gel electrophoresis is a technique used for separating DNA fragments based on size and charge, so it corresponds with (I) Separation of DNA fragments.
Thus, the correct matching is (A)IV, (B)III, (C)II, (D)I.

• Option (c) is the correct answer because the first transgenic cow Rosie produced human protein-enriched milk. The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow milk.
• Option (a) is not the correct answer because ADA deficiency in humans can be cured by gene therapy.
• Option (b) is not the correct answer because transgenic sheep produced human α-1-antitrypsin that is used to treat emphysema.
• Option (d) is not the correct answer because insulin-like growth factor was not present in Rosie’s milk.

• 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.
• 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 c.

• Option (b) is the correct answer as genetically engineered insulin has A-peptide and B-peptide chains of insulin which are produced separately in E.coli, then they are extracted and combined by creating disulphide bond between them.
• Statement (a) is incorrect as genetically engineered insulin does not have an extra stretch of C-peptide. Statement (c) is incorrect as insulin obtained from cattles and pigs is not genetically engineered insulin. Statement (d) is incorrect because conversion of pro-insulin to insulin is not required during production of insulin by genetic engineering as A-peptide and B-peptide chains are produced separately. Statement (e) is incorrect as allergic reactions to insulin are mostly seen when the insulin is obtained from animals.

However, very low concentration of a bacteria or virus (at a time when the symptoms of the disease are not yet visible) can be detected by amplification of their nucleic acid by PCR. It is being used to detect mutations in genes in suspected cancer patients too.

The functional insulin molecule has two chains A and chain B, that are linked together by disulphide bridges and not hydrogen bonds.

Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans and dipterans. B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein which exists as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals.

Retroviruses cause cancer in animals including humans. So modified retroviruses are used to transfer desirable genes into animal cells. It is used in gene therapy, in which lymphocytes from blood of patient are taken and grown in culture medium outside the body, a functional gene is introduced by using a retroviral vector into these lymphocytes which are again reintroduced into the patient body.

Gene therapy is a technique of genetic engineering which involves replacement of a faulty/disease causing gene by a normal healthy functional gene. The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is very important for the immune system to function. The deficiency of this enzyme can lead to severe combined immune deficiency (SCID).