Class 12 Biology Chapter 9 Biotechnology Principles and Processes Solutions. Explore Class 12 Biology Chapter 9 Biotechnology: Principles and Processes Solutions with clear answers, important questions, and exam-focused explanations to understand key concepts, strengthen your preparation, and score better in exams.
Class 12 Biology Chapter 9 Biotechnology Principles and Processes Solutions
A. Very Short-Answer Questions (1 mark each)
- What is biotechnology?
Answer: Biotechnology is the integration of natural science and engineering sciences with organisms, cells, parts of cells, and molecular analogues for the production of goods and services.
- What is a bioreactor?
Answer: A bioreactor is a vessel or device that provides suitable conditions for the growth and multiplication of microorganisms.
- What is meant by the origin of replication (ori)?
Answer: The origin of replication is a specific DNA sequence where replication begins. For a DNA fragment to be copied in a host, it must be associated with a replication origin that permits replication.
- What tools are required for genetic engineering or recombinant-DNA technology?
Answer: Restriction enzymes, DNA polymerase, DNA ligase, a suitable vector, and a host organism.
- What is a gene gun?
Answer: A gene gun is a method of introducing genes into cells by bombarding them with tiny particles coated with DNA.
- What is elution?
Answer: Elution is the process of recovering a desired DNA fragment from an agarose-gel band after separating DNA fragments by gel electrophoresis.
- Which method is used to introduce recombinant DNA into the nucleus of an animal cell?
Answer: Microinjection.
- How is restriction-enzyme digestion performed?
Answer: The DNA sample is incubated with the appropriate restriction enzyme under suitable conditions.
- What is a cloning vector?
Answer: A cloning vector is a DNA molecule, such as a plasmid or a viral vector, used to carry a desired DNA fragment or gene into a host cell so that it can be replicated.
- What is the full form of PCR?
Answer: Polymerase Chain Reaction.
Fill in the blanks (Biotechnology Principles and Processes Solutions)
- The method used to introduce recombinant DNA into a plant cell is called the ______ technique.
Answer: Gene-gun technique.
- The most commonly used bioreactors are ______-type bioreactors.
Answer: Stirring-type (stirred-tank) bioreactors.
- In fruits such as tomatoes, ______ reduces pectin and helps soften the fruit.
Answer: Polygalacturonase.
- The protein coat of a virus is called the ______.
Answer: Capsid.
- A human insulin preparation produced by recombinant technology is ______.
Answer: Humulin.
- Genetic engineering is also known as ______ DNA technology.
Answer: Recombinant-DNA technology.
- ______ is used to join DNA fragments.
Answer: DNA ligase.
- Bacteria protect their DNA from restriction endonucleases through ______.
Answer: Methylation.
B. Short-Answer Questions (Biotechnology Principles and Processes Solutions)
- Briefly describe the two basic principles of biotechnology.
Answer: (i) Genetic engineering: modifying genetic material and introducing it into an organism to create desired genetic combinations or traits. (ii) Maintaining sterile conditions for the large-scale growth and development of microorganisms or eukaryotic cells, along with suitable chemical and physical conditions, to produce useful products such as antibiotics, vaccines, and enzymes.
- What are transgenic plants? Give an example.
Answer: Transgenic plants are plants into which a gene from another organism has been introduced, giving them a trait that they did not previously possess. Example: Bt cotton.
- Briefly describe the isolation of genetic material in recombinant-DNA technology.
Answer: DNA must be isolated in a sufficiently pure form before it can be cut by restriction enzymes. Cells are broken open and DNA is separated from other macromolecules such as RNA, proteins, polysaccharides, and lipids. Enzymes are used to break down cell walls—for example, lysozyme for bacterial cells, cellulase for plant cells, and chitinase for fungal cells. After impurities are removed, chilled ethanol is used to precipitate the DNA.
- Briefly explain the introduction of recombinant DNA into an organism.
Answer: Competent host cells can take up DNA from their surroundings. For example, recombinant DNA carrying an ampicillin-resistance gene can be introduced into E. coli. When the cells are spread on a medium containing ampicillin, transformed cells carrying the resistance gene can grow, while non-transformed susceptible cells do not.
- Name the main steps involved in gene cloning.
Answer: The main steps are: (i) isolation of the desired DNA, (ii) insertion of the DNA fragment into a suitable vector, and (iii) cloning or amplification in a host cell.
- What is downstream processing? Describe it.
Answer: After biosynthesis is complete, the product must undergo several processes before it can be marketed as a finished product. These include separation and purification, collectively called downstream processing. Suitable preservatives may be added where appropriate. The exact downstream-processing steps and quality-control tests depend on the product.
- What are molecular scissors? Give two examples.
Answer: Restriction enzymes are called molecular scissors because they cut DNA at specific recognition sequences. Examples include HindII and EcoRI.
C. Descriptive Questions (Biotechnology Principles and Processes Solutions)
- What are restriction enzymes? Explain in detail.
Answer: In 1963, two enzymes involved in restricting the growth of bacteriophages in Escherichia coli were identified. One enzyme methylates DNA, while the other cuts DNA. Restriction enzymes belong to the broader group of nucleases. Exonucleases remove nucleotides from the ends of DNA molecules, whereas endonucleases cut DNA at specific internal sites. A restriction endonuclease scans a DNA molecule and cuts it when it recognizes its specific recognition sequence. Many restriction enzymes cut the two DNA strands at positions that are not directly opposite one another, creating short single-stranded overhangs called sticky ends. Complementary sticky ends can pair by hydrogen bonding. In genetic engineering, DNA fragments cut with the same restriction enzyme can be joined with DNA ligase to form recombinant DNA.
- State the principle of gel electrophoresis and give two uses in biotechnology.
Answer: DNA fragments are negatively charged because of their phosphate backbone, so they move towards the positive electrode (anode) in an electric field. The gel matrix acts as a molecular sieve: smaller DNA fragments generally move through it more quickly and travel farther than larger fragments. Uses include (i) separating and isolating DNA fragments for recombinant-DNA construction and cloning, and (ii) DNA profiling/fingerprinting.
- Discuss the cutting of DNA at specific sites.
Answer: The DNA sample is incubated with a suitable restriction enzyme under the required conditions. The resulting DNA fragments can be separated by agarose-gel electrophoresis. Because DNA is negatively charged, it migrates towards the positive electrode. The desired DNA fragment is identified and recovered from the gel by elution. The vector DNA is cut with the same restriction enzyme, and the desired DNA fragment is mixed with the cut vector. DNA ligase joins the DNA ends to produce recombinant DNA.
- What is biotechnology? Briefly describe its basic principles.
Answer: Biotechnology is the integration of natural science and engineering sciences with organisms, cells, parts of cells, and molecular analogues to produce goods and services. Its two basic principles are: (i) genetic engineering—the modification of genetic material and its introduction into an organism to create desired genetic combinations; and (ii) providing sterile conditions and suitable growth environments for the large-scale cultivation of microorganisms or eukaryotic cells to manufacture useful products such as antibiotics, vaccines, and enzymes.
- What is PCR? Explain.
Answer: Polymerase chain reaction (PCR) is a technique used to amplify a selected DNA sequence in vitro. It uses primers, DNA polymerase, nucleotides, and template DNA. Repeated cycles of denaturation, primer annealing, and DNA extension produce many copies of the target sequence. A thermostable DNA polymerase is used so that the enzyme remains active through repeated heating cycles. The amplified DNA may then be used for further analysis or inserted into a vector for cloning.
- What is the role of bioreactors in producing food products on a large scale?
Answer: Bioreactors are needed for large-scale cultivation and production. They are large vessels in which raw materials are converted into desired products, such as food ingredients or enzymes, by microorganisms or plant, animal, or human cells. A bioreactor controls and supplies suitable conditions, including temperature, pH, nutrients, salts, vitamins, and oxygen. Stirred-tank bioreactors are commonly used. Their stirring system mixes the contents and helps distribute oxygen evenly. They also have arrangements for adding air and withdrawing samples or culture at intervals.
D. Additional Questions and Answers (Biotechnology Principles and Processes Solutions)
- Name the two types of enzymes that restrict the growth of bacteriophages in Escherichia coli.
Answer: A DNA methylase and a restriction endonuclease.
- What is a plasmid used for?
Answer: A plasmid can be used as a vector to introduce a foreign DNA fragment into a host cell.
- Which enzyme is known as molecular scissors?
Answer: A restriction enzyme.
- What is a bacteriophage?
Answer: A bacteriophage is a virus that infects and reproduces within bacterial cells.
- How can DNA be eluted?
Answer: DNA fragments separated on an agarose gel are identified, the desired band is excised, and the DNA is recovered from the gel. This recovery process is called elution.
- Do eukaryotic cells have restriction enzymes? Explain.
Answer: The source states that eukaryotic cells do not have restriction endonucleases of the bacterial restriction-modification type. In bacteria, methylation protects the cell’s own DNA from its restriction enzymes, which can otherwise cut foreign DNA such as viral DNA.
- Are enzymes larger in molecular size than DNA? Explain.
Answer: The source answer says that enzymes are smaller than DNA molecules and explains that DNA carries genetic information and instructions for protein synthesis, whereas enzymes are proteins made of polypeptide chains. However, molecular size varies widely: some DNA fragments are much larger than most enzymes, but it is not universally true that every enzyme is smaller than every DNA molecule. 0 0 0
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