Important Questions for CBSE Class 12 Biology Chapter 11 Biotechnology: Principle and Process 2024-25

Very Short Answer Questions.  (1 Mark)

1. A restriction enzyme digests DNA into fragments. Name the technique used to check the progression of this enzyme and separate DNA fragments.

Ans: Gel electrophoresis is the technique in which DNA fragments are separated after the digestion of DNA by a restriction enzyme that results in the formation of fragments.

2. Name two commonly used vectors in genetic engineering.

Ans: In genetic engineering, Plasmid and Bacteriophage are the two common vectors that are used.

3. Some enzymes are considered molecular scissors in genetic engineering. What is the name assigned to such enzymes?

Ans: In genetic engineering, restriction Enzymes are the enzymes that are responsible for the digestion of DNA strands resulting in the formation of fragments, thus they are called molecular scissors.

4. Write conventional nomenclature of EcoRI.

Ans: E. ​Escherichia is a bacterium where co stands for coli; R stands for ​the Name of Strain; I ​is the order in which the enzyme is isolated from the bacterial strain.

5. A linear DNA fragment and a plasmid have three restriction sites for EcoRI. How many fragments will be produced from linear DNA and plasmid respectively?

Ans: The linear DNA will produce 4 fragments while the plasmid produces 6 fragments after their digestion by a restriction enzyme.

6. An extra-chromosomal segment of circular DNA of a bacterium is used to carry the gene of interest into the host cell. What is the name given to it?

Ans: In bacterium, Plasmid is the extra-chromosomal segment of circular DNA that is useful in carrying the desired gene into the host cell.

7. Identify the recognition sites in the given sequences at which E. coli will be cut and make sticky ends.

5 ́-GAATTC-3 ́

3 ́-CTTAAG-5 ́

Ans: 

5 - G↓TAATTC3

3 - CTTAA↑G5 are the recognition sites that will make the sticky ends after they will be cut.       

8. Name the substance used as a medium in gel electrophoresis.

Ans: In the gel electrophoresis, Agarose will be a substance that will be used as a medium.

9. What is Bioconversion?

Ans: The process of conversion of raw materials into useful products with the help of various factors that include microbial, plant, or animal cells is called bioconversion.

10. Name the bacterium that yields thermostable DNA polymerase.

Ans: The thermostable DNA polymerase can be produced with the help of a bacterium which is named Thermusaquaticus.

11. Which enzymes are known as “molecular Scissors”?

Ans: The Restriction Endonuclease Enzymes are the enzymes that are responsible for the digestion of DNA strands resulting in the formation of fragments, thus they are called molecular scissors.

12. Name the commonly used vector for transformation in a plant cell?

Ans: The commonly used vector which is responsible for the transformation in plants cells is named Agrobacterium tumefacient.

13. Name the technique used for amplification of DNA?

Ans: The DNA amplification can be done by the technique named the Polymerase Chain Reaction.

14. Name the enzyme responsible for removal of 5 – phosphate group from nucleic acid?

Ans: To remove the 5 – phosphate group from nucleic acid, Alkaline Phosphates are the enzymes that are responsible.

15. Who isolated Restriction enzymes for the first time?

Ans: The Restriction enzymes were first isolated by Warner Arber & Hamilton-Smith.

16. Why do eukaryotic cells do not contain restriction enzymes?

Ans: In eukaryotic cells, the restriction enzymes are absent because the DNA is found to be methylated heavily.

17. Why does DNA moves towards the anode in the gel electrophoresis.

Ans: In the gel electrophoresis, the DNA is found to be moving towards the anode because the DNA is negatively charged due to the presence of a phosphate group that results in the movement of DNA towards the anode.

Short Answer Questions (2 Marks)

1. Name two main steps which are collectively referred to as the down streaming process. Why is this process significant?

Ans: Separation and Purification are the two main steps that are together referred to as the down streaming process.

This process is essential because the product needs to undergo clinical trial and quality control before it reaches the market.

2. How does plasmid differ from chromosomal DNA?

Ans: The differences between plasmid and chromosomal DNA are:

3. A bacterial cell is shown in the figure given below. Label the part ‘A’ and ‘B’. Also mention the use of part ‘A’ in rDNA technology.

Ans: Part A is labeled as Plasmid while part B is labeled as Nucleoid

The function of a plasmid is that, in rDNA technology, it acts as a vector that helps in transferring the desired gene into the host cell.

4. Mention two classes of restriction enzymes. Suggest their respective roles.

Ans: Exonucleases and endonucleases are two classes of restriction enzymes.

The function of Exonucleases is to remove the nucleotides from the ends of the DNA while the Endonucleases play a major role in cutting the DNA at specific sites between the ends of DNA.

5. In the given process of separation and isolation of DNA fragments, some of the steps are missing, Complete the missing steps –

A: Digestion of DNA fragments using restriction endonucleases

↓

B: ..............................................................

↓

C: Staining with ethidium bromide

↓

D: Visualisation in U.V. light

↓

E: .............................................................

↓

F: Purification of DNA fragments.

Ans: At step B the process of Gel Electrophoresis takes place while at step E the process of Elution occurs.

6. Write any two properties of restriction endonuclease enzymes?

Ans: The properties of restriction endonuclease enzymes are:

(i) The Restriction endonuclease enzymes bind at the recognition sequence of the DNA after inspecting the length of the DNA sequence.

(ii) Its function is to cut the sugar-phosphate backbone at specific sites.

7. What are ‘Selectable markers’? What is their use in genetic engineering?

Ans: The host cells that contain the vector can be selected with the help of a gene called a selectable marker that results in the elimination of the non–transformant. It is used in genetic engineering for e.g. – the gene that encodes resistance towards the antibiotics are found to be useful selectable markers as they insert into a cell and result in the selective growth of transformants only.

8. How can the desired product formed after genetic engineering be produced on a commercial scale?

Ans: To make a commercial scale-out of the desired product that is formed after the process of genetic engineering there are a series of processes that need to be followed which are collectively called downstream processing and then it will lead to the final processes. The final processes that are involved in the downstream processing are Separation and purification.

9. What is “Insertional Inactivation”?

Ans: The insertional inactivation is the process of insertion of the recombinant DNA into the coding Sequence of enzyme B– galactosidase leading to the inactivation of the enzyme. An example is when the insert is absent in the plasmid of bacteria then it will lead to the insertional inactivation leading to the production of colorless colonies instead of blue-colored colonies due to the presence of chromogenic substrate.

10. What are the two basic techniques involved in modern Biotechnology?

Ans: The two basic techniques involved in modern Biotechnology are:

a) Genetic Engineering - the technique which involves the introduction of the genome into another host organism or results in the alternation of the nature of genetic material that leads to change in its phenotype.

b) Techniques that are performed under sterile conditions are for the manufacturing of a large number of the desired microbes or cells by the process of multiplication and growth.

11. Represent diagrammatically the E. coli. Cloning vector PBR 322.

Ans: The diagram of E. coli. Cloning vector PBR 322 is represented as:

12. Differentiate between plasmid DNA and chromosomal DNA? 

Ans: The difference between plasmid DNA and chromosomal DNA are:

13. What is the role of enzyme “Ligase” in genetic Engineering?

Ans: In genetic engineering, the enzyme “Ligase” acts as a molecular Suture that helps in binding the two DNA pieces together. This process of joining the two DNA pieces requires energy in the form of ATP and results in the formation of a phosphodiester bond between the two cohesive ends of DNA.

14. Name the components a bioreactor must possess to achieve the desired product?

Ans: The bioreactors are the devices in the form of the vessel which contains various organisms or chemical substances that undergo the chemical processes and result in the formation of the biologically active substances.  A bioreactor must consist of the following components that result in the formation of the desired product. These components include temperature, substrate, pH, oxygen, vitamins, and salts. 

15. The following proteins of given molecular weight are Subjected to Get electrophoresis. Write the order of Sequence in which these proteins are isolated in a gel?

Ans: The sequence of proteins obtained from top to bottom in a gel:

Myosin > Insulin >Haemoglobin> Ribozyme > Keratin > Albumin.

16. How is gene Z used as a marker?

Ans: The Lac Z Gene Is responsible for the coding of Β-galactosidase enzyme this results in the inactivation of the enzyme due to the insertion of recombinant DNA in the coding sequence of an enzyme Β-galactosidase. The bacterial colony normally produces blue-colored colonies by they get the insert into their plasmid then it will result in the production of colonies that are colorless.

17. What is Bioreactor? What are the advantages of Stirred tank Bioreactor over Shake flask? Show diagrammatically a simple Stirred tank Bioreactor?

Ans: The bioreactors are the devices in the form of the vessel which contains various organisms or chemical substances that undergo the chemical processes and result in the formation of the biologically active substances. They consist of large vessels where the raw materials using microbial, plant, animal, or human cells are converted biologically into specific proteins. The advantages of Bioreactor over shake flask are:

a) To produce the optimum growth of the desired product, it provides the optimal conditions e.g., temp, pH, etc.

b) For testing the sample, a small volume of cultures can be withdrawn periodically from the bioreactor.

c) It has an agitation system, temp control system, from control system & pH control system.

Short Answer Question (3 Marks)

1. Since DNA is a hydrophilic molecule, it cannot pass through cell membranes. Name and explain the technique with which the DNA is forced into 

(i) a bacterial cell 

Ans: In the bacterial cell, the DNA can enter by the technique of Chemical treatment and may be exposed to cold and high temp (42°C) alternatively.

(ii) a plant cell 

Ans: The DNA in the plant cell can enter through the technique called Biolistic or gene gun.

(iii) an animal cell.

Ans: The DNA in the animal cell can enter through the technique called Micro-injection. 

2. How will you obtain purified DNA from a cell?

Ans: Various enzymes are used to treat cells that will result in the release of DNA. Various enzymes are cellulose (plant cells), Lysozyme (bacteria), and chitinase (fungus) while ribonuclease and protease enzymes are used for the treatment of and removal of RNA and proteins respectively.

3. In recombinant DNA technology, vectors are used to transfer a gene of interest in the host cells. Mention any three features of vectors that are most suitable for this purpose.

Ans: The vectors in the recombinant DNA technology are utilized in transferring the gene of interest in the host cells due to the following features of vectors:

(i) Vectors constitute of origin of replication (Ori) where the gene of interest attaches.

(ii) They constitute various selectable markers for the various genes of interest.

(iii) They are also composed of at least one recognition site.

4. Why is Agrobacterium-mediated genetic engineering transformation​ in plants considered natural genetic engineering?

Ans: Agrobacterium tumefaciens is a pathogen in many dicot plants due to its ability to deliver a piece of DNA (T​DNA) that results in the transformation of normal plant cells into a tumor cell leading to the production of chemicals by these tumor cells that are required by the pathogen.

5. Observe the given sequence of nitrogenous bases on a DNA fragment and answer the following question​

5 ́ - CAGAATTCTTA - 3 ́

3 ́ - GTCTTAAGAAT - 5 ́

(a) Name a restriction enzyme that can recognize this DNA sequence.

Ans: EcoRI is the name of a restriction enzyme that helps in the recognition of various sequences of DNA.

(b) Write the sequence after digestion.

(c) Why are the ends generated after digestion called sticky ends?

Ans: The ends that are obtained after the digestion of the DNA sequences are called the sticky ends because they result in the formation of hydrogen bonds with their complementary cut parts.

6. A selectable marker is used in the section of recombinants on the basis of their ability to produce color in presence of chromogenic substrate.

(a) Mention the name of the mechanism involved.

Ans: The insertional inactivation is the process of insertion of the recombinant DNA into the coding Sequence of enzyme B– galactosidase leading to the inactivation of the enzyme.

(b) Which enzyme is involved in the production of color?

Ans: The b-galactosidase is the enzyme that helps in the production of color in presence of chromogenic substrate.

(c) How is it advantageous to overuse antibiotic-resistant genes as a selectable marker?

Ans: The use of antibiotic-resistant genes as a selectable marker is more beneficial because due to the inactivation of antibiotics the selection of recombinants requires simultaneous plating on two plates that are having different antibiotics.

7. Mention the important properties which a good vector must possess?

Ans: The important properties which a good vector must possess are -

i) Size - The size of the vector must be small so that it helps them in purification and isolation easily.

ii) Origin of Replication – A site where replication starts and is made up of the sequence of base pairs. When the DNA is attached to this sequence then it will result in the replication within its host cell & thus, controls the number of copies of linked DNA.

iii) Selectable Marker - The host cells that contain the vector can be selected with the help of a gene called a selectable marker that results in the elimination of the non–transformant. It is used in genetic engineering.

iv) Cloning Sites - The site in the vector where the foreign/alien DNA attaches is also called the unique recognition site. A particular restriction enzyme will cut the vector-only at a particular recognition site.

8. Describe any three vectors less method of introducing the rDNA into a competent host cell?

Ans: The three vectors less method of introducing the rDNA into a competent host cell are:

i) Transformation: The bacterial cell is first treated with the specific concentration of divalent cation e.g., Ca2+ so that they can be competent enough to take up the DNA in the plasmid. The calcium ions increase the efficiency of DNA to enter into a bacterium through pores in its cell wall. By the process of incubating the cells with recombinant DNA on ice, then placing them at 420 C, and then again putting them back into ice the recombinant DNA can then be forced into cells. This helps the bacteria in taking up the recombinant DNA.

ii) Microinjection: With the help of a microneedle of the tip with a diameter (~ 4mm), the recombinant DNA can be injected directly into the nucleus of an animal cell.

iii) Biolistic / Gene gun: The cells of the DNA that are coated with particles of gold or tungsten are bombarded with high-velocity micro-gun.

9. Why is Agrobacterium-mediated genetic transformation described as Natural Genetic engineering in plants?

Ans: The Agrobacterium tumefaciens-interceded plant genetic transformation measure requires the presence of two genetic segments situated on the bacterial Ti-plasmid. Basically, the main basic part is the T-DNA, which is characterized by conserved 25-base pair imperfect repeats at the closures of the T-region known as a border sequence. The tumor-inducing (Ti) plasmid is used as a cloning vector to transfer the desired gene into plants as they insert a part of their DNA in plants during the infection. The second is the virulence (vir) region, which is made out of in any event seven significant loci (virA, virB, virC, virD, virE, virF, and virG) encoding parts of the bacterial protein machinery which is mediating the T-DNA processing and transfer. The gene of interest is attached to the T-DNA so that it automatically gets transformed into plant cells thus, Agrobacterium tumefacien is known as the “Natural Genetic Engineer” of plants.

10. Mention the important tools required for genetic engineering technology?

Ans: The process of genetic engineering is accomplished only when we have the following key tools:

a) Restriction Enzymes: In genetic engineering, restriction Enzymes are the enzymes that are responsible for the digestion of DNA strands resulting in the formation of fragments, thus they are called molecular scissors. They are of types: Endonucleases and Exonucleases.

b) Cloning Vector: The cloning Vector is the part of the DNA molecule that is attached to the DNA Segment of an organism that is desired and then transfers into the cell or DNA of another organism.

c) Desired Foreign DNA: The desired foreign DNA segment is the part of DNA that consists of genes having desired characters that are being transferred into the genome of another cell with the help of the cloning vector.

Long Answer Questions (5 Marks)

1. The development of bioreactors is required to produce large quantities of products.

(a) Give optimum growth conditions used in bioreactors.

Ans: The bioreactors are the devices in the form of the vessel which contains various organisms or chemical substances that undergo the chemical processes and result in the formation of the biologically active substances. To produce the optimum growth of the desired product the optimum temperature, pH, substrates, salts, vitamins, and oxygen are required.

(b) Draw a well-labeled diagram of a simply stirred ​ tank bioreactor.

Ans: A simply stirred​ tank bioreactor is shown below:

(c) How does a simply stirred tank​ bioreactor to differ from sparged stirred – tank’ bioreactor?

Ans: In the simply​ stirred tank bioreactor the stirrer facilitates the even mixing and the oxygen availability throughout the process, whereas for proper mixing throughout the reactor in the case of sparged stirred-tank bioreactor the air is found to be bubbled.

2. In the given figure, one cycle of polymerase chain reaction (PCR) is shown-

(a) Name the steps A, B, and C.

Ans: A: Denaturation, B: Annealing, and C: Extension.

(b) Give the purpose of each of these steps.

Ans: The purpose of each step is:

(i) Denaturation: ​ Due to high temperature, the heat will break or denature the two complementary strands of DNA and results in their separation.

(ii) Annealing: The hybridization of the denatured DNA strands takes place with the help of the primers.

(iii) Extension: The target DNA sequence will synthesize its copies by the process of the extension of the primers.

(c) State the contribution of the bacterium Thermus Aquaticus in this process.

Ans: The Taq polymerase enzyme is found to be isolated from the bacterium Thermus Aquaticus which functions at a very high temperature and results in the denaturation of double-stranded DNA.

3. Study the figure of vector pBR322 given below in which foreign DNA is ligated at the Bam H1 site of the tetracycline resistance gene.

Answer the following questions:

(a) Mention the function of rop.

Ans: The ​rop is responsible for the​ coding of the proteins that are involved in the replication of plasmids.

(b) What will be the selectable marker for this recombinant plasmid and why?

Ans: The selectable marker for this recombinant plasmid will be the ampicillin resistance gene. They after placing them on an ampicillin-containing medium will undergo the process of plating that will help in the differentiation between the trAns.formants from non-trAns.formants.

(c) Explain transformation.

Ans: Transformation is the process of transferring DNA from one cell and then placing them into the other cell which will result in the formation of the recombinant cell consisting of the properties of both the cells. 

4. Describe the various steps involved in Recombinant DNA technology with the help of a well labeled. Diagram?

Ans: The steps involved in the recombinant DNA are:

i) Identification of DNA with Desirable Genes: The addition of chilled ethanol will result in obtaining the purified DNA while by using various other appropriate techniques the other molecules in the target cell can also be removed.

ii) Cutting the DNA at a Specific Location: The source and vector DNAS after being cut will be introduced together having a gene of interest and specific restriction site and will be joined together with the help of an enzyme called ligase. 

iii) Insertion of Recombinant DNA into Host Cell: The bacterial cell is first treated with the specific concentration of divalent cation e.g., Ca2+ so that they can be competent enough to take up the DNA in the plasmid. The calcium ions increase the efficiency of DNA to enter into a bacterium through pores in its cell wall. It is a vector-less method.

iv) Selection & Screening: The selectable marker for this recombinant plasmid will be the ampicillin resistance gene. They after placing them on an ampicillin-containing medium will undergo the process of plating that will help in the differentiation between the trAns.formants from non-trAns.formants.

v) Obtaining the Foreign Gene product: The gene of interest after its cloning along with the presence of optimum growth conditions will result in the expression of target proteins which then needs to be produced on a large scale.

5. Expand PCR? Describe the different steps involved in this technique?

Ans: The Polymerase Chain Reaction is the method of making millions of DNA copies from a DNA sample. It has two main reagents: primers (short single-stranded DNA fragments that are a complementary sequence to the target DNA), and DNA polymerase. The DNA polymerase is heat stable, that is Taq polymerase which is extracted from the bacteria Thermus aquaticus. Each cycle has three steps:

a) DENATURATION: In the first step, the two strands of the DNA helix are physically separated at a heat during a process called macromolecule denaturation.

b) RENATURATION / ANNEALING: In the second step, the temperature is lowered so that the primers can bind to the complementary sequences of DNA.

c) EXTENSION: The third step is the target DNA sequence will synthesize its copies by the process of the extension of the primers.  The temperature is raised to 750c. At this temperature, Taq – polymerase initiates DNA Synthesis at the 3-OH end of the primer.

6. What are Restriction enzymes? Why do bacteria have these restriction enzymes? Show diagrammatically a restriction enzyme its recognition & the product it produces?

Ans: Restriction Enzymes are the endonuclease enzymes that are responsible for the digestion of DNA strands resulting in the formation of fragments, thus they are called molecular scissors. They are found in bacteria cells as they help in cutting the foreign DNA and results in the modification of the restriction system and thus results in the improving of the immunity in the bacterial cell. 

Name of Restriction enzyme- EcoRI Substrate DNA on which it acts

Download Important Question for Class 12 Biology Chapter 11 PDF

Some of the important topics covered in Class 12 Biology Chapter 11 important questions are - Biotechnology Principle and Processes, Tools of Recombinant DNA Technology, Processes of Recombinant DNA Technology.

Chapter 11 Biotechnology Principles and Its Processes Summary

Biotechnology is the broader field of research and development, which uses the technology and the application of living organisms to develop and produce products useful for human welfare. The term ‘Biotechnology’ was first coined by Karoly Ereky, so he is known as the father of biotechnology.

Principles of Biotechnology - According to modern biotechnology, some of the main principles are genetic engineering and bioprocess engineering. Genetic engineering is used to modify the DNA of the target organisms by changing the phenotype of the organism. Bioprocess engineering maintains the sterile condition to support the growth of large quantities of desired microbes and other eukaryotic cells. Which is used for the production of new or modified biotechnology products like antibiotics, enzymes, and vaccines.

Genetic engineering primarily includes the isolation of DNA fragments from the donor organism. Then it is inserted into the vector DNA, later it is transferred into an appropriate host. Then cloning of recombinant DNA in the host organism.

Recombinant DNA Technology - It is also known as genetic engineering, it is the process of joining two DNA molecules from two different organisms. Some of the important steps involved in the processes of recombinant DNA technology are - Isolation of DNA, DNA fragmentation using restriction endonucleases. Then ligation of the desired DNA fragment into the vector and transfer of the recombinant DNA into the host. Later culture of the transformed cells in a nutrient medium and extraction of the desired product.

DNA Cloning - It is the process of making multiple, identical copies of a piece of DNA, this process requires cloning vectors. With some of the properties like - It should be smaller in size but should be able to carry a large DNA insert. The cloning vector should have the origin of replication so that it can autonomously replicate in the host organism. It should have a restriction site with a selectable marker to screen recombinant organisms. And It should also possess multiple cloning sites.

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