CBSE Class 12 Biology Bio Technology Principles and Processes Question Bank

CBSE Class 12 Biology Bio Technology Principles and Processes Question Bank. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

BIO TECHNOLOGY PRINCIPLES AND PROCESSES 

1. What are the two core techniques that enabled the birth of Biotechnology? [1 Mark]

Answer:
1. Genetic engineering: techniques to alter the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism.
2. Bioprocess engineering: maintenance of sterile (contamination - free) ambience in chemical engineering processes to enable growth of only the desired microbe or eukaryotic cell in large quantities for the manufacture of biotechnological products like antibiotics, vaccines, enzymes, etc.

Teacher's Note:
a) These two techniques form the foundation of modern biotechnology.
b) Genetic engineering allows the creation of recombinant DNA, while bioprocess engineering enables large - scale production.

2. How does genetic engineering help in overcoming the limitations of traditional hybridization procedures used in plants & animals? [2 Marks]

Answer:
1. Traditional hybridization often leads to inclusion and multiplication of undesirable genes along with the desired genes.
2. Genetic engineering allows isolation and introduction of only one or a few desirable genes without introducing undesirable genes into the target organism.

Teacher's Note:
a) Traditional breeding methods are often time-consuming and unpredictable.
b) Genetic engineering provides precise control over the genetic makeup of the organism.

3. How does the stickiness of cut ends of DNA help? [1 Mark]

Answer:
1. The stickiness of the cut ends facilitates action of the enzyme DNA ligase.
2. They form hydrogen bonds with their complementary cut counterparts, holding them together for ligation.

Teacher's Note:
a) Sticky ends are generated when restriction enzymes cut DNA a little away from the centre of the palindrome sites.
b) Overhanging stretches facilitate end-to-end joining by DNA ligase.

4. How can an alien piece of DNA made to multiply in a host cell? [2 Marks]

Answer:
1. By linking the alien piece of DNA with a bacteriophage or plasmid vector which acts as a vehicle to transfer the DNA into a host cell.
2. The alien DNA gets integrated into the genetic material of the vector, where it can replicate using the host cell's replication machinery.

Teacher's Note:
a) The vector must possess an origin of replication (ori) site.
b) Multiple copies of the alien DNA are produced along with the vector.

5. What are the 'molecular scissors' in rDNA technology. What are they used for in rDNA technology? [2 Marks]

Answer:
1. Restriction endonucleases are known as the 'molecular scissors'.
2. They are used to cut DNA molecules at specific recognition sequences, creating fragments with sticky or blunt ends for recombinant DNA technology.

Teacher's Note:
a) They belong to a larger class of enzymes called nucleases.
b) Each restriction endonuclease inspects the length of a DNA sequence for a specific palindromic sequence.

6. List the major techniques in Genetic Engineering? Who was the first to construct an rDNA? [2 Marks]

Answer:
1. Major techniques include creation of recombinant DNA, gene cloning, and gene transfer.
2. Stanley Cohen and Herbert Boyer were the first to construct the first recombinant DNA in 1972.

Teacher's Note:
a) Recombinant DNA technology relies heavily on restriction enzymes and DNA ligases.
b) Cohen and Boyer accomplished this by isolating an antibiotic resistance gene and linking it with a plasmid vector.

7. What are the three basic steps in genetically modifying an organism? [2 Marks]

Answer:
1. Identification of DNA with desirable genes.
2. Introduction of the identified DNA into the host.
3. Maintenance of introduced DNA in the host and transfer of the DNA to its progeny.

Teacher's Note:
a) These steps outline the entire workflow of genetic engineering.
b) Careful screening is required at each step to ensure successful modification.

8. What are recognition sequences of endonucleases? Name the five key tools in rDNA technology. [2 Marks]

Answer:
1. Recognition sequences are specific base pair sequences on DNA recognized by restriction endonucleases where they bind and cut.
2. The five key tools are restriction enzymes, cloning vectors, host organisms, DNA ligase, and the gene of interest.

Teacher's Note:
a) Recognition sequences are usually palindromes read the same way forward and backward on opposite strands.
b) All these tools are essential for the successful execution of recombinant DNA experiments.

9. What are nucleases. What are the two types ? [2 Marks]

Answer:
1. Nucleases are enzymes that cleave the phosphodiester bonds between nucleotide subunits of nucleic acids.
2. The two types are exonucleases (which remove nucleotides from the ends of DNA) and endonucleases (which make cuts at specific positions within the DNA).

Teacher's Note:
a) Exonucleases cut nucleotides singly from 5' or 3' ends of DNA strands.
b) Endonucleases make cuts within the DNA strands at specific recognition sites.

10. Show diagrammatically how endonucleases work? [3 Marks]

Answer:
1. The restriction enzyme recognizes a specific palindromic nucleotide sequence in the DNA duplex.
2. It binds to the DNA and cuts both strands at specific points a little away from the center of the palindrome sites.
3. This creates single-stranded overhanging stretches called sticky ends on each resulting DNA fragment.

Teacher's Note:
a) Mention the specific palindrome sequence like 5'-GAATTC-3' for EcoRI.
b) Clearly illustrate the action of the enzyme cutting between G and A on both strands.

Fig 11.1 (Action of the endonuclease EcoRI):

11. How can the fragments of DNA be separated? Explain [2 Marks]

Answer:
1. DNA fragments are negatively charged molecules and can be separated by forcing them to move towards the anode under an electric field through a medium.
2. Agarose gel electrophoresis is commonly used, where smaller fragments move faster and further through the pores of the gel matrix compared to larger fragments.

Teacher's Note:
a) Separated DNA fragments can be visualized by staining with ethidium bromide followed by exposure to UV radiation.
b) The cutting of DNA by restriction endonucleases results in fragments of varying lengths.

12. Explain the features required for a cloning vector [3 Marks]

Answer:
1. Origin of replication (ori): A sequence from where replication starts, responsible for controlling the copy number of the linked DNA.
2. Selectable marker: Genes (like resistance to antibiotics) that help in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.
3. Cloning sites: Single or few recognition sites for commonly used restriction enzymes to link the foreign DNA.

Teacher's Note:
a) Vectors must also be small in size for easy uptake.
b) Vectors like plasmids and bacteriophages have high copy numbers.

13. How can the cloning vector pBR322 be used in separating the transformants and recombinants. Explain [3 Marks]

Answer:
1. pBR322 has two antibiotic resistance genes acting as selectable markers - ampicillin resistance (amp^R) and tetracycline resistance (tet^R).
2. When a foreign DNA is inserted into one of these marker genes (e.g., tet^R using BamHI), it undergoes insertional inactivation, causing loss of resistance to that antibiotic.
3. Recombinants lose resistance to tetracycline (the tetracycline site is cut to insert the desired DNA) but retain ampicillin resistance, whereas transformants with non-recombinant plasmids are resistant to both tetracycline and ampicillin.

Teacher's Note:
a) Insertional inactivation is a crucial screening technique in gene cloning.
b) Replica plating methods are often used to test growth on different antibiotic plates.

14. Do you agree with the construction of rDNA to give new traits in animals. How do you think it can be done. State any issue of concern in this? [4 Marks]

Answer:
1. Yes, construction of rDNA to give new traits in animals has immense potential in medicine (e.g., production of pharmaceuticals) and agriculture.
2. It is done by isolating the gene of interest, inserting it into a suitable vector, and introducing the recombinant vector into animal cells, embryos, or microinjecting it directly.
3. Major issues of concern include biosafety questions regarding unintended ecological impacts, ethical issues regarding animal welfare and manipulation of natural species.
4. There are also risks of allergenicity and transfer of antibiotic resistance markers to human or animal pathogens.

Teacher's Note:
a) Recombinant DNA in animals is strictly regulated by institutional bodies like GEAC in India.
b) Balancing scientific advancement with ethical considerations is paramount.

15. How is Agrobacterium tumefaciens used in rDNA technology. Explain ii) What and how are other pathogens used for the purpose? State two other methods by which host organism can be transformed? [5 Marks]

Answer:
1. Agrobacterium tumefaciens, a pathogen of several dicot plants, delivers a piece of DNA known as T-DNA to transform normal plant cells into a tumor and direct the tumor cells to produce chemicals required by the pathogen. Its tumor-inducing (Ti) plasmid is modified into a cloning vector to deliver genes of interest into plants safely.
2. Retroviruses are other pathogens used in animals; they are disarmed and used to deliver desirable genes into animal host cells.
3. Microinjection is a direct method where foreign DNA is directly injected into the nucleus of an animal cell.
4. Biolistics or gene gun method uses high-velocity micro-particles of gold or tungsten coated with DNA to bombard plant cells.

Teacher's Note:
a) Pathogens are disarmed (made non-pathogenic) before using them as vectors.
b) Direct gene transfer methods bypass the need for vectors entirely.

16. Sequentially state the process you would adopt for getting a recombinant protein? [5 Marks]

Answer:
1. Isolation of the gene of interest using restriction endonucleases and gel electrophoresis.
2. Ligation of the isolated gene of interest into a suitable cloning vector using DNA ligase to form recombinant DNA.
3. Insertion of the recombinant DNA into a suitable host organism (bacteria, yeast, plant, or animal cell) through transformation or other methods.
4. Culturing the host cells on a large scale in bioreactors under optimal conditions (temperature, pH, nutrients) to maximize the yield of the recombinant protein.
5. Downstream processing of the expressed protein involving separation and purification steps before marketing as a finished product.

Teacher's Note:
a) Bioreactors are essential for large-scale production (stirred-tank bioreactors are most common).
b) Downstream processing and quality control testing are vital to ensure the safety and efficacy of the protein product.

1. Mention two core techniques that enabled the birth of modern biotechnology. [1 Mark]

Answer:
1. Genetic engineering.
2. Maintenance of sterile ambience.

Teacher's Note:
a) Genetic engineering alters the chemistry of genetic material.
b) Sterile ambience enables growth of only the desired microbe.

2. How does genetic engineering help in overcoming the limitations of traditional hybridization procedures used in plants & animals? [1 Mark]

Answer:
It allows the isolation and introduction of only the desirable genes without introducing undesirable genes.

Teacher's Note:
a) Sexual reproduction preserves genetic variations.
b) It permits selective combination of traits.

3. How does DNA ligase act in recombinant DNA technology? [1 Mark]

Answer:
1. It makes the joining of DNA molecules easy.
2. It acts on complementary sticky ends.

Teacher's Note:
a) DNA ligase forms phosphodiester bonds between adjacent nucleotides.
b) It seals the nick in the sugar-phosphate backbone.

4. Why is replication possible only if a foreign DNA is linked to the origin of replication (ori)? [1 Mark]

Answer:
The foreign DNA must be linked to the ori site of the host genome so that it can initiate replication independently inside the host cell.

Teacher's Note:
a) The origin of replication controls the copy number of linked DNA.
b) Without ori, foreign DNA cannot replicate within the host.

5. Name the enzymes used to cut DNA at specific sites. [1 Mark]

Answer:
Restriction enzymes (Restriction endonucleases).

Teacher's Note:
a) They inspect the DNA sequence for specific recognition sites.
b) They belong to a larger class of enzymes called nucleases.

6. List the key steps in constructing the first recombinant DNA by Stanley Cohen and Herbert Boyer. [2 Marks]

Answer:
1. Creation of recombinant DNA.
2. Gene cloning.
3. Gene transfer.
4. Work pioneered by Stanley Cohen and Herbert Boyer.

Teacher's Note:
a) Antibiotic resistance gene was linked to a plasmid vector.
b) This laid the foundation of genetic engineering.

7. What are the basic steps in genetically modifying an organism? [2 Marks]

Answer:
1. Identification of desirable DNA.
2. Introduction of the identified DNA into the host.
3. Maintenance of introduced DNA in the host.
4. Transfer of the DNA to its progeny.

Teacher's Note:
a) Complete genetic modification requires all four sequential steps.
b) Maintenance ensures the gene is stably inherited.

8. Enumerate the tools of recombinant DNA technology. [2 Marks]

Answer:
1. Restriction enzymes.
2. Polymerases.
3. Ligases.
4. Vectors and host organisms.

Teacher's Note:
a) These tools are essential for manipulating genetic material in vitro.
b) Each tool performs a specific catalytic or structural role.

9. What are nucleases. What are the two types? [2 Marks]

Answer:
1. Enzymes that act on nucleic acids are broadly classified into exonucleases and endonucleases.
2. Exonucleases remove nucleotides from the ends of the DNA strands, whereas endonucleases cut DNA at specific points within the DNA strand.

Teacher's Note:
a) Endonucleases are sequence-specific in recombinant DNA technology.
b) Exonucleases act progressively from the terminal ends.

10. Describe the steps involved in recombinant DNA technology with reference to standard biotechnology diagrams. [3 Marks]

Answer:
1. Isolation of genetic material (DNA).
2. Fragmentation of DNA by restriction endonucleases.
3. Ligation of DNA fragment into a vector to form recombinant DNA.

Teacher's Note:
a) Follows standard vector-host interactions.
b) Corresponds to process flowcharts in standard textbooks.

11. Explain the principle and process of gel electrophoresis. [3 Marks]

Answer:
1. Agarose gel electrophoresis separates DNA fragments based on their size under an electric field.
2. Negatively charged DNA fragments move towards the anode.
3. Smaller fragments move faster and farther through the agarose matrix pore size.

Teacher's Note:
a) Ethidium bromide and UV light are used to visualize DNA.
b) Separation depends entirely on molecular weight sieving effect.

12. What are the features required to facilitate cloning into a vector? [3 Marks]

Answer:
1. Origin of replication (ori).
2. Cloning sites.
3. Selectable markers.

Teacher's Note:
a) Ori is required to initiate replication.
b) Selectable markers help in identifying transformants from non-transformants.

13. Explain insertional inactivation with respect to selectable markers. [3 Marks]

Answer:
1. Tetracycline resistance site can be cut to insert the desired foreign DNA.
2. Recombinants will lose resistance to tetracycline due to insertional inactivation.
3. Transformants can still be screened based on ampicillin resistance.

Teacher's Note:
a) Simplifies screening of recombinant colonies.
b) Uses antibiotic resistance genes as markers.

14. Discuss the ethical and safety implications of using transgenic animals. [4 Marks]

Answer:
1. Transgenic animals serve several purposes like chemical testing, drug safety, and studying human diseases.
2. Production of biological products for treatment and studying complex physiological processes.
3. It is considered unethical when used purely for selfish human greed without animal welfare considerations.
4. It is unsafe if carried out without adequate caution and biosafety protocols.

Teacher's Note:
a) Balancing scientific utility with bioethics is essential.
b) Regulatory bodies like GEAC oversee these safety trials.

15. How do Agrobacterium tumefaciens and disarmed retroviruses act as vectors for plants and animals respectively? [5 Marks]

Answer:
1. Agrobacterium tumefaciens is used as a vector by modifying its tumor-inducing Ti plasmid.
2. The modified plasmid is non-pathogenic and successfully transforms host plant cells.
3. Retroviruses are similarly disarmed to deliver desirable genes into animal cells safely.

Teacher's Note:
a) Natural pathogens are disarmed to prevent disease.
b) They transfer foreign genes efficiently into eukaryotic hosts.

16. Outline the main steps of gene cloning and recombinant DNA technology processes. [5 Marks]

Answer:
1. Isolation of DNA using appropriate cell-lysing enzymes.
2. Cutting of DNA at specific locations using restriction enzymes.
3. Separation of DNA fragments using gel electrophoresis.
4. Amplification of gene of interest using Polymerase Chain Reaction (PCR).
5. Introduction of recombinant DNA into host cell, obtaining gene product in a bioreactor, and downstream processing.

Teacher's Note:
a) Covers the entire operational pipeline of biotechnology.
b) Downstream processing ensures product purity before marketing.