All questions of February for NEET Exam

Methods for Creating Recombinant DNA
Recombinant DNA technology involves several techniques, each contributing to the creation and manipulation of DNA molecules. The options provided—gene cloning, DNA sequencing, and polymerase chain reaction (PCR)—are all integral to this process.
Gene Cloning
- Gene cloning is the primary method for creating recombinant DNA.
- It involves isolating a specific gene and inserting it into a vector (like a plasmid).
- The vector then replicates within host cells, producing multiple copies of the gene.
DNA Sequencing
- DNA sequencing is crucial for understanding the genetic makeup of the DNA being manipulated.
- It allows scientists to read the sequence of nucleotides in DNA, ensuring that the correct genes are being cloned.
- This technique helps verify that the recombinant DNA contains the desired genetic information.
Polymerase Chain Reaction (PCR)
- PCR is a powerful method used to amplify specific DNA sequences.
- It can generate millions of copies of a particular DNA segment, making it easier to work with.
- This amplification is often a preliminary step before cloning or sequencing, ensuring sufficient material for further experiments.
Conclusion
- All three methods—gene cloning, DNA sequencing, and PCR—play vital roles in recombinant DNA technology.
- Together, they enable scientists to manipulate genetic material effectively, paving the way for advancements in genetics, biotechnology, and medicine.
- Thus, the correct answer is indeed option 'D': all of the above methods are utilized in creating recombinant DNA.

The recombinant DNA is multiplied in the host organism, which replicates the DNA as part of its normal cell processes.

Common Selectable Marker in Genetic Transformation
In the context of genetic transformation, selectable markers are essential for identifying successfully modified cells. Among the options provided, antibiotic resistance genes are the most common and effective selectable markers.
Why Antibiotic Resistance Genes?
- Functionality: Antibiotic resistance genes provide a survival advantage to transformed cells in the presence of specific antibiotics. Only those cells that have successfully incorporated the resistance gene can survive.
- Examples: Common examples include the kanamycin resistance gene (nptII) and ampicillin resistance gene (bla). Cells that express these genes can grow in media containing the corresponding antibiotics, while untransformed cells will die.
Comparison with Other Options
- Green Fluorescent Protein (GFP): While GFP is a valuable marker for visualizing gene expression, it does not confer a survival advantage in selective media. Therefore, it's not a true selectable marker.
- Chlorophyll: This is not used as a selectable marker in genetic transformation. It is a pigment essential for photosynthesis but does not indicate successful transformation.
- Enzyme Activity Genes: Similar to GFP, these may indicate gene expression but do not provide a mechanism for selection under antibiotic pressure.
Conclusion
Using antibiotic resistance genes as selectable markers simplifies the identification of genetically transformed organisms, making them a cornerstone in genetic engineering and biotechnology. Their ability to enhance survival in selective environments is what sets them apart from other options.

Core Technique of Modern Biotechnology
Modern biotechnology is primarily driven by advancements in genetic engineering and bioprocess engineering. This combination has revolutionized how we manipulate biological systems for various applications, including medicine, agriculture, and environmental management.
Genetic Engineering
- Definition: Genetic engineering involves directly manipulating an organism's DNA to alter its genetic makeup.
- Applications: It allows for the creation of genetically modified organisms (GMOs), development of gene therapies, and production of recombinant proteins, like insulin.
- Techniques: Tools such as CRISPR-Cas9, cloning, and gene sequencing are employed to edit genes with precision.
Bioprocess Engineering
- Definition: Bioprocess engineering focuses on designing and optimizing processes that use living cells or their components.
- Applications: It is crucial in the production of biofuels, pharmaceuticals, and vaccines through fermentation and cell culture techniques.
- Optimization: Engineers work on scaling up lab processes to industrial levels, ensuring efficiency and cost-effectiveness.
Importance of Options A, C, and D
- Use of Microbial Fermentation (Option A): While important, it is a method rather than a core enabling technique of biotechnology.
- Use of Herbal Remedies (Option C): This is more traditional and does not involve the manipulation of genetic material.
- Fossil Fuel Extraction (Option D): This refers to a completely different field and is not a biotechnology technique.
In conclusion, genetic engineering and bioprocess engineering form the backbone of modern biotechnology, enabling innovations that significantly impact health, agriculture, and environmental sustainability.

Herbert Boyer’s contribution was in discovering restriction enzymes and using them to modify DNA, which laid the foundation for recombinant DNA technology.

DNA ligase is used to join DNA molecules by forming phosphodiester bonds between them.

Main Principle of Biotechnology
Biotechnology is a field that merges biology with technology to manipulate living organisms for various applications. The core principle is primarily centered on genetic modification, making option 'B' the correct answer.
Genetic Modification Explained
- Genetic modification involves altering the genetic makeup of organisms to achieve desired traits.
- This can include introducing new genes, modifying existing ones, or knocking out undesirable genes.
Applications of Genetic Modification
- Agriculture: Crops can be engineered for pest resistance, drought tolerance, or enhanced nutritional value.
- Medicine: Genetically modified organisms (GMOs) are used to produce insulin, vaccines, and other therapeutic agents.
- Industry: Microorganisms can be modified to produce enzymes and biofuels efficiently.
Advantages of Genetic Modification
- Increased Yield: Modified crops can lead to higher food production to meet global demands.
- Environmental Benefits: Reduced need for chemical pesticides and fertilizers can lead to more sustainable farming practices.
- Health Improvements: Genetic engineering can help in creating crops with better nutritional profiles.
Conclusion
While biotechnology encompasses various methods, the genetic modification of organisms stands out as the primary principle. It allows for precise control over biological processes, leading to innovations that can significantly impact agriculture, medicine, and industry. Thus, option 'B' accurately represents the essence of biotechnology.

Plasmids act as vectors that carry foreign DNA into host cells, facilitating the creation of recombinant DNA.

Recombinant DNA technology is primarily used to insert foreign DNA into an organism to produce desired traits or products.

Introduction to Recombinant DNA in Plants
Recombinant DNA technology is essential for genetic engineering, allowing scientists to manipulate plant genomes. Among various methods, the gene gun is a prominent technique used to introduce recombinant DNA into plant cells.
What is a Gene Gun?
- The gene gun, or biolistic particle delivery system, uses high-velocity microprojectiles to deliver DNA into plant cells.
- It involves coating tiny gold or tungsten particles with DNA and accelerating them into the target plant tissue using high-pressure gas.
Advantages of Gene Gun Method
- High Efficiency: The gene gun can successfully transfer DNA into a broad range of plant species, including those that are typically difficult to transform.
- Direct Delivery: This method allows for direct delivery of DNA into the cell nucleus or cytoplasm, increasing the chances of stable integration into the plant genome.
Comparison with Other Methods
- Electroporation: While effective for some cells, it is less commonly used in plants due to the cell wall structure.
- Heat Shock: Typically used for bacterial transformation, it is not suitable for plant cells.
- Microinjection: Involves physically injecting DNA into cells, but is labor-intensive and not widely adopted for plant transformation.
Conclusion
Given its efficiency and versatility, the gene gun remains a favored method for introducing recombinant DNA into plant cells, paving the way for advancements in agricultural biotechnology and crop improvement.

Gel electrophoresis is used to separate DNA fragments based on size by applying an electric field to the DNA, which moves according to fragment size.

Understanding Recombinant DNA Technology
Recombinant DNA technology involves combining DNA from different sources to create new genetic combinations that are useful in medicine, agriculture, and research. One of the most significant applications of this technology is the production of insulin.
Why Insulin is a Product of Recombinant DNA Technology:
- Human Insulin Production:
- Previously, insulin was extracted from animal pancreases, which was less effective and could cause allergic reactions.
- With recombinant DNA technology, the gene responsible for human insulin production is inserted into bacteria, such as E. coli.
- Genetic Engineering Process:
- The human insulin gene is isolated and cut using specific enzymes.
- This gene is then inserted into a plasmid (a small circular DNA molecule) that can replicate within a bacterial cell.
- The modified bacteria are cultured, and they start producing insulin that is identical to human insulin.
- Benefits of Recombinant Insulin:
- Safety: It reduces the risk of allergic reactions compared to animal insulin.
- Consistency: It provides a reliable supply of insulin that can be mass-produced.
- Cost-Effectiveness: The production process is efficient and can be scaled up to meet global demands.
Comparison with Other Options:
- Vitamin C:
- Typically obtained from natural sources or through chemical synthesis, not recombinant DNA technology.
- Starch:
- A polysaccharide produced by plants, not involving recombinant DNA methods.
- Sodium Chloride:
- An inorganic salt, produced through traditional chemical processes, unrelated to genetic engineering.
In conclusion, insulin is a prime example of how recombinant DNA technology has revolutionized treatment for diabetes, showcasing the power of genetic engineering in modern medicine.

Role of Restriction Enzymes in Genetic Engineering
Restriction enzymes, also known as restriction endonucleases, are crucial tools in genetic engineering. Their primary function is to cut DNA at specific locations, facilitating various molecular biology applications.
Specificity in DNA Cutting
- Restriction enzymes recognize specific nucleotide sequences in DNA, known as recognition sites.
- They create double-stranded breaks at these sites, allowing scientists to manipulate DNA with precision.
Applications in Genetic Engineering
- Gene Cloning: By cutting DNA from one organism and inserting it into plasmids or vectors, researchers can clone genes of interest.
- DNA Fragment Analysis: The ability to cut DNA into fragments is essential for techniques like gel electrophoresis, which allows visualization and analysis of DNA.
Facilitating Recombinant DNA Technology
- Through the cutting and joining of DNA fragments, restriction enzymes enable the formation of recombinant DNA.
- This is critical for producing genetically modified organisms (GMOs), where genes from different species are combined.
Conclusion
In summary, the role of restriction enzymes in genetic engineering is to cut DNA at specific locations, making them indispensable for a wide range of genetic manipulation techniques. Their precision and specificity allow for the advancement of research and biotechnology applications.

Function of the Origin of Replication in Cloning Vectors
The origin of replication (ori) is a crucial component of cloning vectors, serving a specific and vital role in the process of DNA replication. Here’s a detailed explanation of its function:
Initiation of DNA Replication
- The primary role of the origin of replication is to initiate DNA replication.
- It is a specific sequence of nucleotides where the replication process begins, allowing the DNA to be copied within a host cell.
Mechanism of Action
- Once a cloning vector is introduced into a host cell (like bacteria), the origin of replication signals the cellular machinery to start the replication process.
- DNA polymerases and other associated proteins recognize the ori, unwind the DNA, and synthesize new strands.
Importance in Cloning
- By ensuring that the vector is replicated within the host, the ori allows for the amplification of the inserted DNA sequence.
- As a result, multiple copies of the desired gene or sequence can be produced, which is essential for various applications, including gene expression studies and protein production.
Conclusion
- In summary, the origin of replication is critical for the successful propagation of cloning vectors within host cells, ensuring that the desired genetic material is replicated and maintained for further use in research and biotechnology.
Understanding the function of the origin of replication is fundamental for anyone working with genetic engineering and molecular cloning techniques.

Restriction endonucleases are enzymes used to cut DNA at specific sequences, allowing for the manipulation of genes in recombinant DNA technology.

PCR is used to amplify a specific DNA sequence, making many copies of a targeted gene or region of DNA.

Gene cloning refers to the process of amplifying a gene, producing many copies of it for further study or application.

The main goal of recombinant DNA technology is to produce genetically modified organisms, which can produce desired traits or products.

Plasmids and bacteriophages are commonly used as vectors in recombinant DNA technology to deliver foreign DNA into host cells.

The selectable marker helps identify transformed cells by allowing them to survive in the presence of an antibiotic or other selective agent.