Class 12 Important Questions for Biology

Class 12 Important Questions for Biology – Biotechnology: Principles and Processes

NCERT Exemplar Class 12 Biology is very important resource for students preparing for XII Board Examination. Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 12.

Question from very important topics are covered by NCERT Exemplar Class 12. You also get idea about the type of questions and method to answer in your class 12th examination.
Here you can get Class 12 Important Questions Biology based on NCERT Text book for Class XII. Biology Class 12 Important Questions are very helpful to score high marks in board exams. Here we have covered Important Questions on Biotechnology: Principles and Processes for Class 12 Biology subject.

Biology Important Questions Class 12 are given below.

Multiple Choice Questions

Rising of dough is due to:
- a. Multiplication of yeast
- b. Production of CO₂
- c. Emulsification
- d. Hydrolysis of wheat flour starch into sugars.
An enzyme catalysing the removal of nucleotides from the ends of DNA is:
- a. endonuclease
- b. exonuclease
- c. DNA ligase
- d. Hind – II
The transfer of genetic material from one bacterium to another through the mediation of a vector like virus is termed as:
- a. Transduction
- b. Conjugation
- c. Transformation
- d. Translation
Which of the given statement is correct in the context of observing DNA 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
Restriction’ in Restriction enzyme refers to:
- a. Cleaving of phosphodiester bond in DNA by the enzyme
- b. Cutting of DNA at specific position only
- c. Prevention of the multiplication of bacteriophage in bacteria
- d. All of the above
A recombinant DNA molecule can be produced in the absence of the following:
- a. Restriction endonuclease
- b. DNA ligase
- c. DNA fragments
- d. E.coli
In agarose gel electrophoresis, DNA molecules are separated on the basis of their:
- a. Charge only
- b. Size only
- c. Charge to size ratio
- d. All of the above
The most important feature in a plasmid to be used as a vector is:
- a. Origin of replication (ori)
- b. Presence of a selectable marker
- c. Presence of sites for restriction endonuclease
- d. Its size
While isolating DNA from bacteria, which of the following enzymes is not used?
- a. Lysozyme
- b. Ribonuclease
- c. Deoxyribonuclease
- d. Protease
Which of the following has popularised the PCR (polymerase chain reactions)?
- a. Easy availability of DNA template
- b. Availability of synthetic primers
- c. Availability of cheap deoxyribonucleotides
- d. Availability of ‘Thermostable’ DNA polymerase
An antibiotic resistance gene in a vector usually helps in the selection of:
- a. Competent cells
- b. Transformed cells
- c. Recombinant cells
- d. None of the above
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
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 purime and pyrimidine bases
- d. None of the above
Which of the following bacteria is not a source of restriction endonuclease?
- a. Haemophilus influenzae
- b. Escherichia coli
- c. Agrobacterium tumefaciens
- d. Bacillius amyloli
Which of the following steps are catalysed by Taq 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
A bacterial cell was transformed with a recombinant DNA 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 intron 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
Which of the following should be chosen for 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 in-lets and out-lets
- c. A continuous culture system
- d. Any of the above
Who among the following was awarded the Nobel Prize for the development of PCR technique?
- a. Herbert Boyer
- b. Hargovind Khurana
- c. Kary Mullis
- d. Arthur Kornberg
Which of the following statements does not hold true for restriction enzyme?
- a. It recognises a palindromic nucleotide sequence
- b. It is an endonuclease
- c. It is isolated from viruses
- d. It produces the same kind of sticky ends in different DNA molecules

Very Short Answer Type Questions

How is copy number of the plasmid vector related to yield of recombinant protein?
Would you choose an exonuclease while producing a recombinant DNA molecule?
What does H in’ ‘d’ and ‘III’ refer to in the enzyme Hind III?
Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.
What does ‘competent’ refer to in competent cells used in transformation experiments?
What is the significance of adding proteases at the time of isolation of genetic material (DNA).
While doing a PCR, ‘denaturation’ step is missed. What will be its effect on the process?
Name a recombinant vaccine that is currently being used in vaccination program.
Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions?
What modification is done on the T i plasmid of Agrobacterium tumefaciens to convert it into a cloning vector?

Short Answer Type Questions

What is meant by gene cloning?
Both a wine maker and a molecular biologist who had developed a recombinant vaccine claim to be biotechnologists. Who in your opinion is correct?
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?
Restriction enzymes that are used in the construction of recombinant DNA are endonucleases which cut the DNA at ‘specific-recognition sequence’. What would be the disadvantage if they do not cut the DNA at specific-recognition sequence?
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.
How does one visualise DNA on an agarose gel?
A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment?
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?
Describe the role of CaCl₂in the preparation of competent cells?
What would happen when one grows a recombinant bacterium in a bioreactor but forget to add antibiotic to the medium in which the recombinant is growing?
Identify and explain steps ‘A’, ‘B’ and ‘C’ in the PCR diagram given below.
Name the regions marked A, B and C.

Long Answer Type Questions

For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chormogenic substrate. Give reasons.
Describe the role of Agrobacterium tumefaciens in transforming a plant cell.
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.

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Class 12 Important Questions for Biology – Biotechnology: Principles and Processes (NCERT Exemplar)