NCERT Exemplar Class 12 Biology Chapter 11 Biotechnology Principles And Processes
NCERT Exemplar for Class 12 Biology Chapter 11
NCERT Exemplar for Class 12 Biology will aid in deepening the knowledge of students related to the topic of Biotechnology Principles and Processes. This provided exemplar by SimplyAcad allows learners to cover up all the sections presented in the chapter 11 of the biology textbook. There are MCQs based, very short, and long answer type answer questions to ensure students understand the concepts better. It will be beneficial for students, they can prepare their own study and revision notes from them. Students can easily access this NCERT exemplar for class 12 biology in this article below to perform incredibly well in their upcoming 12th board examinations. Apart from these there are several NCERT exemplar for class 12 science of all the chapters provided in a detailed manner.
Access the NCERT exemplar class 12 biology Chapter 11 Biotechnology Principles and Processes
MCQ Type Questions: NCERT exemplar class 12 biology Chapter 11 Biotechnology Principles and Processes
Question 1
Rising of dough is due to:
a. Multiplication of yeast
b. Production of CO₂
c. Emulsification
d. Hydrolysis of wheat flour starch into sugars.
Answer: Rising of dough is due to the presence of CO₂. Yeast present in the dough consumes the sugar and releases carbon dioxide and ethanol. The released CO₂ gets trapped inside the dough due to the presence of gluten, causing it to rise.
Correct Answer: (b)
Question 2
Which of the following enzymes catalyze the removal of nucleotides from the ends of DNA?
a. Endonuclease
b. Exonuclease
c. DNA ligase
d. Hind – II
Answer: Exonuclease is the enzyme that removes nucleotides from the ends of the DNA.
Correct Answer: (b)
Question 3
The transfer of genetic material from one bacterium to another through the mediation of a viral vector is termed as:
a. Transduction
b. Conjugation
c. Transformation
d. Translation
Answer: The transfer of genetic material from one bacterium to another through the mediation of a viral vector is termed Transduction.
Correct Answer: (a)
Question 4
Which of the given statements is correct in the context of visualizing DNA molecules separated by agarose gel electrophoresis?
a. DNA can be seen in visible light
b. DNA can be seen without staining in visible light
c. Ethidium bromide stained DNA can be seen in visible light
d. Ethidium bromide stained DNA can be seen under exposure to UV light
Answer: DNA stained with Ethidium bromide can be seen under UV light after gel electrophoresis. DNA cannot be seen in visible light either with staining or without staining.
Correct Answer: (d)
Question 5
‘Restriction’ in Restriction enzyme refers to:
a. Cleaving of the phosphodiester bond in DNA by the enzyme
b. Cutting of DNA at a specific position only
c. Prevention of the multiplication of bacteriophage by the host bacteria
d. All of the above
Answer: Restriction enzymes can recognize specific base sequences in DNA and restrict (cut) the DNA at the specific site. Bacteria use restriction enzymes to protect themselves from viral infections by cutting the viral DNA.
Correct Answer: (d)
Question 6
Which of the following is not required in the preparation of a recombinant DNA molecule?
a. Restriction endonuclease
b. DNA ligase
c. DNA fragments
d. E.coli
Answer: E. coli is a bacteria used in various experiments, but it is not required in the preparation of a recombinant DNA molecule.
Correct Answer: (d)
Question 7
In agarose gel electrophoresis, DNA molecules are separated based on:
a. Charge only
b. Size only
c. Charge to size ratio
d. All of the above
Answer: Gel electrophoresis separates DNA, RNA, or proteins according to their molecular size.
Correct Answer: (c)
Question 8
The most important feature in a plasmid to serve as a vector in a gene cloning experiment is:
a. Origin of replication (ori)
b. Presence of a selectable marker
c. Presence of sites for restriction endonuclease
d. Its size
Answer: The origin of replication (ori) is the most important feature in a plasmid to serve as a vector, as it initiates replication and controls the copy number of the linked DNA.
Correct Answer: (a)
Question 9
While isolating DNA from bacteria, which of the following enzymes is not required?
a. Lysozyme
b. Ribonuclease
c. Deoxyribonuclease
d. Protease
Answer: Deoxyribonuclease is not required while isolating DNA from bacteria.
Correct Answer: (c)
Question 10
Which of the following contributed in popularizing the PCR (polymerase chain reactions) technique?
a. Easy availability of DNA template
b. Availability of synthetic primers
c. Availability of cheap deoxyribonucleotides
d. Availability of ‘Thermostable’ DNA polymerase
Answer: Thermostable DNA polymerase obtained from Thermus aquaticus bacteria remains active at high temperatures, making it essential for PCR.
Correct Answer: (d)
Question 11
An antibiotic resistance gene in a vector usually helps in the selection of:
a. Competent bacterial cells
b. Transformed bacterial cells
c. Recombinant bacterial cells
d. None of the above
Answer: Antibiotic resistance genes in a vector help in selecting transformed cells by acting as a selectable marker.
Correct Answer: (b)
Question 12
Significance of ‘heat shock’ method in bacterial transformation is to facilitate:
a. Binding of DNA to the cell wall
b. Uptake of DNA through membrane transport proteins
c. Uptake of DNA through transient pores in the bacterial cell wall
d. Expression of antibiotic resistance gene
Answer: The heat shock method facilitates the uptake of DNA through transient pores in the bacterial cell wall.
Correct Answer: (c)
Question 13
The role of DNA ligase in the construction of a recombinant DNA molecule is:
a. Formation of phosphodiester bond between two DNA fragments
b. Formation of hydrogen bonds between sticky ends of DNA fragments
c. Ligation of all purine and pyrimidine bases
d. None of the above
Answer: DNA ligase facilitates the joining of sticky ends of two DNA strands by forming phosphodiester bonds.
Correct Answer: (a)
Question 14
Which of the following bacteria is not a source of restriction endonuclease?
a. Haemophilus influenzae
b. Escherichia coli
c. Entamoeba coli
d. Bacillus amyloliquefaciens
Answer: Entamoeba coli is a protozoa, not a source of restriction endonuclease.
Correct Answer: (c)
Question 15
Which of the following steps are catalyzed by Taq DNA polymerase in a PCR reaction?
a. Denaturation of template DNA
b. Annealing of primers to template DNA
c. Extension of primer end on the template DNA
d. All of the above
Answer: Taq DNA polymerase catalyzes the extension of the primer end on the template DNA in a PCR reaction.
Correct Answer: (c)
Question 16
A bacterial cell was transformed with a recombinant DNA molecule that was generated using a human gene. However, the transformed cells did not produce the desired protein. Reasons could be:
a. Human gene may have introns which bacteria cannot process
b. Amino acid codons for humans and bacteria are different
c. Human protein is formed but degraded by bacteria
d. All of the above
Answer: The human gene may have introns that bacteria cannot process, leading to the failure in producing the desired protein.
Correct Answer: (a)
Question 17
Which of the following should be chosen for the best yield if one were to produce a recombinant protein in large amounts?
a. Laboratory flask of largest capacity
b. A stirred-tank bioreactor without inlets and outlets
c. A continuous culture system
d. Any of the above
Answer: A continuous culture system should be chosen to produce a recombinant protein in large amounts.
Correct Answer: (c)
Question 18
Who among the following was awarded the Nobel Prize for the development of the PCR technique?
a. Herbert Boyer
b. Hargovind Khurana
c. Kary Mullis
d. Arthur Kornberg
Answer: Kary Mullis was awarded the Nobel Prize for inventing the Polymerase Chain Reaction (PCR) technique.
Correct Answer: (c)
Question 19
Which of the following statements does not hold true for a restriction enzyme?
a. It recognizes a palindromic nucleotide sequence
b. It is an endonuclease
c. It is isolated from viruses
d. It can produce the same kind of sticky ends in different DNA molecules
Answer: Restriction enzymes are isolated from bacteria, not from viruses.
Correct Answer: (c)
Very Short Answer Type Questions: NCERT exemplar class 12 biology Chapter 11 Biotechnology Principles and Processes
Question 1
How is the copy number of the plasmid vector related to the yield of the recombinant protein?
Answer: Higher number of plasmid vectors results in the yield of a higher number of recombinant proteins.
Question 2
Would you choose an exonuclease while producing a recombinant DNA molecule?
Answer: No, I would not choose exonuclease while producing a recombinant DNA molecule because it removes nucleotides from the ends of the DNA, and thus it cannot help in producing circular DNA.
Question 3
What does “H” in “Hind III” refer to in the enzyme HindIII?
Answer: The “H” in “Hind III” refers to the genus Haemophilus, from which the enzyme is derived.
Question 4
Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.
Answer: Restriction enzymes should not have more than one site of action in the cloning site because multiple recognition sites will create many DNA fragments, complicating the process.
Question 5
What does “competent” refer to in competent cells used in transformation experiments?
Answer: “Competent” refers to cells that have been treated to create transient pores in their cell wall, allowing the uptake of foreign DNA.
Question 6
What is the significance of adding proteases at the time of isolation of genetic material (DNA)?
Answer: Proteases help in removing proteins during the process of obtaining pure DNA.
Question 7
While doing a PCR, the “denaturation” step is missed. What will be its effect on the process?
Answer: If the denaturation step is missed, primers will not join the template, halting the process and preventing DNA amplification.
Question 8
Name a recombinant vaccine that is currently being used in a vaccination program.
Answer: The Hepatitis B vaccine.
Question 9
Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions?
Answer: No, biomolecules do not exhibit biological activity in anhydrous conditions as they may get damaged and proteins can denature.
Question 10
What modification is done on the Ti plasmid of Agrobacterium tumefaciens to convert it into a cloning vector?
Answer: The Ti plasmid is disarmed, meaning the genes causing crown gall disease are removed, making it a cloning vector for delivering genes of interest into plants and animals.
Short Answer Type Questions: NCERT exemplar class 12 biology Chapter 11 Biotechnology Principles and Processes
Question 1
What is meant by gene cloning?
Answer: Gene cloning is the process of producing multiple copies of a specific gene. This is done by:
- Selecting a specific gene.
- Ligating the selected gene to a vector.
- Producing recombinant DNA (rDNA).
- Transforming this rDNA into a bacterial cell.
- As the bacteria reproduce, their progeny will contain the rDNA, increasing the number of copies of the gene.
Question 2
Both a winemaker and a molecular biologist who developed a recombinant vaccine claim to be biotechnologists. Who is correct?
Answer: Both are correct. Biotechnology involves using living organisms to produce products for humankind. Thus, both winemaking and developing recombinant vaccines are applications of biotechnology.
Question 3
A recombinant DNA molecule was created by ligating a gene to a plasmid vector. By mistake, an exonuclease was added to the tube containing the recombinant DNA. How does this affect the next step in the experiment i.e., bacterial transformation?
Answer: Exonuclease removes nucleotides from free DNA ends. Since recombinant DNA is circular, exonuclease will not affect the process as it cannot act on the circular DNA, allowing the bacterial transformation to proceed unaffected.
Question 4
Restriction enzymes used in the construction of recombinant DNA are endonucleases that cut the DNA at a “specific-recognition sequence”. What would be the disadvantage if they do not cut the DNA at specific-recognition sequence?
Answer: If restriction enzymes do not cut at specific-recognition sequences, they would not produce the necessary sticky ends required for recombination, leading to the failure of gene cloning.
Question 5
A plasmid DNA and a linear DNA (both are of the same size) have one site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis, plasmid shows one DNA band while linear DNA shows two fragments. Explain.
Answer: Plasmid DNA is circular, and when cut, it forms a single linear piece, showing one band. Linear DNA, when cut at one site, results in two fragments, hence two bands on the gel.
Question 6
How does one visualize DNA on an agarose gel?
Answer: DNA is visualized on agarose gel by staining it with Ethidium Bromide and exposing it to UV light, where it fluoresces as orange bands.
Question 7
A plasmid without a selectable marker was chosen as a vector for cloning a gene. How does this affect the experiment?
Answer: Without a selectable marker, it is not possible to identify and separate transformants (cells with the desired gene) from non-transformants, complicating the experiment.
Question 8
A mixture of fragmented DNA was electrophoresed in an agarose gel. After staining the gel with ethidium bromide, no DNA bands were observed. What could be the reason?
Answer: Possible reasons include:
- DNA might have been contaminated or degraded by nuclease enzymes.
- The electrodes may have been placed incorrectly, causing DNA to move in the wrong direction.
- The ethidium bromide concentration may have been insufficient for proper staining.
Question 9
Describe the role of CaCl₂ in the preparation of competent cells.
Answer: CaCl₂ provides Ca²⁺ ions that create transient pores in the bacterial cell wall, facilitating the uptake of foreign DNA, thus making the cells “competent.”
Question 10
What would happen when one grows a recombinant bacterium in a bioreactor but forgets to add an antibiotic to the medium in which the recombinant is growing?
Answer: Without the antibiotic, there is no selective pressure for the bacteria to maintain the antibiotic resistance gene (and thus the recombinant DNA), leading to potential loss of the desired gene and failure to produce the recombinant protein.
Question 11
Identify and explain steps “A”, “B”, and “C” in the PCR diagram given below.
Answer:
- A: Denaturation – DNA strands are separated into single strands by breaking hydrogen bonds between base pairs.
- B: Annealing – Primers attach to the template DNA during this heat treatment process.
- C: Extension – DNA polymerase extends the primers, copying the DNA strand.
Question 12
Name the regions marked A, B, and C.
Answer:
- A: Tetracycline resistance site
- B: Restriction site Pst I
- C: Ampicillin resistance site
Long Answer Type Questions: NCERT exemplar class 12 biology Chapter 11 Biotechnology Principles and Processes
Question 1
For visualizing specific recognition and selection of recombinants, insertional inactivation of an antibiotic marker has been superseded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.
Answer:
Insertional inactivation of an antibiotic marker, though effective, requires complex procedures such as simultaneous plating on different antibiotics, making the selection process cumbersome. This method has been largely replaced by insertional inactivation of a marker gene coding for a chromogenic substrate because:
- Ease of Identification: Recombinants and non-recombinants can be easily distinguished based on their ability to produce color in the presence of a chromogenic substrate. For example, the use of the lacZ gene, which encodes for the enzyme beta-galactosidase, allows for a simple color-based screening. Recombinant colonies (where the lacZ gene is inactivated) will not produce color in the presence of a chromogenic substrate (like X-gal), appearing white, whereas non-recombinant colonies will appear blue.
- Elimination of Multiple Plating: The chromogenic substrate method eliminates the need for multiple plates with different antibiotics, simplifying the process.
- Higher Accuracy: This method reduces the chances of false positives, as color differentiation is more straightforward than growth on selective media.
Question 2
Describe the role of Agrobacterium tumefaciens in transforming a plant cell.
Answer:
Agrobacterium tumefaciens is a soil bacterium that is known for its natural ability to transfer DNA to plants. This bacterium contains a large plasmid called the Ti (Tumor-inducing) plasmid, which has a region known as T-DNA. The role of Agrobacterium tumefaciens in plant transformation involves:
- Infection and T-DNA Transfer: When A. tumefaciens infects a plant, it transfers a segment of its T-DNA from the Ti plasmid into the plant’s genome. The T-DNA integrates into the plant’s chromosomal DNA and causes the plant cells to proliferate uncontrollably, forming a tumor-like growth (crown gall disease).
- Disarming the Ti Plasmid: For genetic engineering purposes, the tumor-inducing genes within the T-DNA are removed, and the Ti plasmid is “disarmed.” The T-DNA region is then used as a vector to carry foreign genes of interest into the plant genome.
- Gene Delivery: The modified T-DNA region (carrying the gene of interest) is transferred into the plant cells in the same natural manner as the original T-DNA, but instead of causing disease, it facilitates the stable integration of the desired gene into the plant’s genome.
- Transformation and Regeneration: The transformed plant cells are then cultured and regenerated into whole plants that carry the new gene, leading to the expression of the desired trait (such as disease resistance, improved yield, or herbicide tolerance).
Thus, Agrobacterium tumefaciens serves as a natural and highly efficient tool for plant genetic engineering.
Question 3
Illustrate the design of a bioreactor. Highlight the difference between a flask in your laboratory and a bioreactor which allows cells to grow in a continuous culture system.
Answer:
Design of a Bioreactor:
A bioreactor is a large, controlled vessel designed to facilitate the growth of microorganisms or cells for the production of biologically derived products. A typical bioreactor has the following components:
- Cylindrical Body: A large vessel, typically made of stainless steel, with a curved base for better mixing of the contents.
- Agitator System: This system stirs the contents, ensuring uniform distribution of nutrients and gases, and maintaining the cells in suspension.
- Oxygen Delivery System: To supply oxygen to the growing culture, usually through spargers that distribute gas bubbles throughout the medium.
- Temperature Control System: Ensures that the bioreactor operates at the optimal temperature for cell growth, usually maintained by a heating or cooling jacket.
- pH Control System: Monitors and adjusts the pH of the culture medium.
- Foam Control System: Prevents excessive foam formation by using antifoam agents or mechanical foam breakers.
- Sampling Port: Allows for periodic collection of samples to monitor the progress of the culture.
Difference Between a Flask and a Bioreactor:
- Scale: A laboratory flask is typically used for small-scale experiments, holding a few hundred milliliters of culture, whereas a bioreactor is designed for large-scale production, holding up to thousands of liters of culture.
- Control: A flask provides limited control over environmental conditions such as temperature, pH, and oxygen levels. A bioreactor, on the other hand, offers precise control over all these parameters, ensuring optimal conditions for cell growth and product formation.
- Continuous Culture: In a flask, the culture grows in a batch mode, where nutrients are depleted over time, and waste products accumulate. A bioreactor can operate in a continuous culture mode, where fresh medium is continuously supplied, and waste products are removed, allowing cells to grow exponentially over an extended period.
- Productivity: Due to the controlled environment and the ability to operate continuously, a bioreactor is capable of producing a much higher yield of the desired product compared to a laboratory flask.
A bioreactor is therefore essential for industrial-scale production of recombinant proteins, enzymes, and other biotechnological products.
NCERT Exemplar For Class 12 Science
Students must practise these additional questions for their own benefits, the ncert exemplar are curated by the best subject-matter experts to boost your knowledge on the presented topic. Students can easily access the ncert exemplar for class 12 science by visiting our website SimplyAcad and solve all the questions listed to secure maximum marks.
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