CBSE Class 12 Biology HOTs Biotechnology Principles and Processes

Question. Why foreign DNA cannot pass through cell membrane?
(a) DNA is hydrophobic
(b) DNA is hydrophilic
(c) DNA is rich in proteins
(d) DNA is heavy
Answer : B

Question. 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.
Answer : D

Question. 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. 
Answer : C

Question. 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 : A

Question. Consider the following statements and select the correct option.
(a) A soil inhabiting plant bacterium, Agrobacterium tumefaciens, a pathogen of several dicot plants is able to transfer a piece of DNA known as T-DNA
(b) The T-DNA causes tumours
(c) Tumour formation is induced by Ti plasmid
(d) All of the above
Answer : D

Question. Which of the following statement is incorrect?
(a) Each restriction endonuclease recognises a specific palindromic nucleotide sequence
(b) Specific base sequence is known as recognition sequence
(c) Restriction enzymes cannot cut DNA
(d) Restriction enzymes belong to enzymes called nucleases
Answer : C

Question. Which of the following statement is incorrect?
(a) EcoRI cuts the DNA between bases G and A
(b) Making multiple identical copies of any template DNA is called cloning
(c) pBR322 is a natural plasmid
(d) Agrobacterium tumefaciens is a natural genetic engineer
Answer : C

Question. Which of the following statements does not hold true for restriction enzyme?
(A) It recognises a palindromic nucleotide seq-uence.
(B) It is an endonuclease.
(C) It is isolated from viruses.
(D) It produces the same kind of sticky ends in different DNA Molecules. 
Answer : C

Question. Which of the following should be choosen 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 outlets.
(C) A continuous culture system.
(D) Any of the above.
Answer : C

Question. Choose the incorrect statement.
(a) Ori also controls the copy numbers of the linked DNA
(b) If a foreign DNA ligates at the Bam HI site of tetracycline resistance gene in the vector pBR322, the recombinant plasmid loses the tetracycline resistance due to insertion of foreign DNA
(c) Copy number refers to the number of copies of plasmid present in a cell
(d) Copy number of plasmid varies from 50-100 per cell
Answer : D

Question. Which of the statements given is incorrect?
(a) In microinjection method, foreign DNA is directly injected into the nucleus of animal cell by using microneedles
(b) Microinjection method is used in oocytes, eggs and embryo
(c) Electroporation is the formation of temporary pores in the plasma membrane of host cell by using lysozyme or calcium chloride
(d) In chemical mediated gene transfer method, certain chemicals such as Ca phosphate help foreign DNA to enter the host cell
Answer : C

Question. Consider the following statements.
I. RecombinantDNAtechnology popularly known as genetic engineering is a stream of biotechnology which deals with the manipulation of genetic material by manin vitro.
II. pBR322 is the first artificial cloning vector developed in 1977 by Boliver and Rodriquez from E. coli plasmid.
III. Restriction enzymes belong to a class of enzymes called nucleases.
Which of the statements given above are correct?
(a) I and II
(b) I and III
(c) II and III
(d) I, II and III
Answer : D

Question. 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. 
Answer : D

Question. 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
Answer : C

Question. Given below are four statements pertaining to separation of DNA fragments using gel electrophoresis. Identify the incorrect statements.
I. DNAis negatively charged molecule and so it is loaded on gel towards the anode terminal.
II. DNAfragments travel along the surface of the gel whose concentration does not affect movement of DNA.
III. Smaller the size ofDNAfragment larger is the distance it travels through it.
IV. PureDNAcan be visualised directly by exposing UV-radiation.
Select the correct option from the following.
(a) I, III and IV
(b) I, II and III
(c) II, III and IV
(d) I, II and IV
Answer : D

Question. The treatment of host cell with divalent cation leads to the
(a) change in permeability of DNA
(b) increased efficiency with which DNA enters the bacterium
(c) decreased efficiency with which DNA enters the bacterium
(d) change in permeability of host
Answer : B

Question. Which vector can clone only a small fragment of DNA?
(a) Bacterial artificial chromosome
(b) Yeast artificial chromosome
(c) Plasmid
(d) Cosmid
Answer : C

Question. The DNA used as a carrier for transferring a fragment of foreign DNA into a suitable host is called 
(a) cloning vector
(b) vehicle DNA
(c) gene carrier
(d) All of these
Answer : D

Question. Which of the following is a plasmid vector?
(a) pBR322
(b) Bam II
(c) SaI I
(d) Eco RI
Answer : A

Question. The method which is used to introduce recombinant DNA into animal cell?
(a) Gene gun method
(b) Changing permeability of host
(c) Biolistic method
(d) Microinjection
Answer : D

Question. Which of the following methods(s) is used to introduce foreign DNA into plant host cells?
(a) Gene gun method
(b) Gel electrophoresis
(c) Elution
(d) Extension
Answer : A

Question. For transformation, microparticles coated with DNA to be bombarded with gene gun are made up of
(a) silver or platinum
(b) platinum or zinc
(c) silicon or platinum
(d) gold or tungsten
Answer : D

Question. DNA transfer with high velocity micro particles is present in
(a) biolistics
(b) hybridisation
(c) tissue culture
(d) vegetative propagation
Answer : A

Question. The different steps involved in the process of recombinant DNA technology are given below randomly? Arrange these in correct order.
I. Extraction of the desired gene product.
II. Amplification of the gene of interest.
III. Isolation of a desiredDNAfragment.
IV. Ligation of theDNAfragment into a vector.
V. Insertion of recombinantDNAinto the host.
Correct order is
(a) I, II, III, IV and V
(b) III, II, IV, V and I
(c) II, IV, V, III and I
(d) I, IV, V, III and II
Answer : B

Question. In bacterial cells, the membrane is digested with the help of enzyme
(a) cellulase
(b) lysozyme
(c) chitinase
(d) lipase
Answer : B

Question. Primers are
(a) small chemically synthesised oligonucleotides of about 10-18 nucleotides that are complementary to the region of template DNA
(b) chemically synthesised oligonucleotides of about 10-18 nucleotides that are not complementary to the region of template DNA
(c) the double-stranded DNA that need to be amplified
(d) specific sequences present on recombinant DNA
Answer : A

Question. The Taq polymerase enzyme is obtained from
(a) Thiobacillus ferroxidans
(b) Bacillus subtilis
(c) Pseudomonas subtilis
(d) Thermus aquaticus
Answer : D

Question. A single PCR amplification cycle involves
(a) denaturation
(b) extension
(c) annealing
(d) All of these
Answer : D

Question. In gel electrophoresis, restriction enzyme digested DNA is loaded in wells near
(a) anode
(b) cathode
(c) centre of gel
(d) any where in the gel
Answer : B

Question. Stirred-tank bioreactors are advantageous over shake flasks because they
(a) provide high temperature and pH
(b) provide better aeration and mixing properties
(c) do not allow the entry of CO2
(d) are easy to operate
Answer : B

Question. The components of a bioreactor are
I. an agitator system.
II. an oxygen delivery system.
III. foam control system.
IV. temperature control system.
V. pH control system.
VI. sampling ports towithdrawcultures periodically.
Choose the correct option.
(a) I, II, III, IV and V
(b) II, IV, V and VI
(c) I, II, III, IV and VI
(d) All of these
Answer : D

Question. The process of separation and purification of expressed protein before marketing is called
(a) upstream processing 
(b) downstream processing
(c) bioprocessing
(d) post-production processing
Answer : B

Question. Which of the following is not a component of downstream processing?
(a) Separation
(b) Purification
(c) Preservation
(d) Expression
Answer : D

I. Assertion and Reason
In each of the following questions, a statement of Assertion (A) is given followed by corresponding statement of Reason (R). Of the statements, mark the correct answer as
(a) If both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

Question. Assertion (A) Biotechnology deals with techniques that use living organism to produce products useful for humans.
Reason (R) It uses only a unicellular organism.
Answer : C

Question. Assertion (A) Maintenance of sterile environment is essential for manufacture of biotechnological products.
Reason (R) This is to enable growth of desired prokaryotic or eukaryotic cells.
Answer : A

Question. Assertion (A) Origin of replication is an essential part of a vector.
Reason (R) Ori is responsible for initiating replication.
Answer : A

Question. Assertion (A) Foreign DNA and vector DNA cut with the help of ligase.
Reason (R) Ligase acts by forming phosphodiester bonds.
Answer : D

Question. Assertion (A) In gel electrophoresis, DNA fragments are separated.
Reason (R) DNA is negatively charged, so it moves towards anode under electric field.
Answer : A

Question. Assertion (A) Restriction endonucleases are also called ‘molecular scissors’.
Reason (R) When fragments generated by restriction endonucleases are mixed, they join together due to their sticky ends.
Answer : B

Question. Assertion (A) All endonucleases cut DNA at specific sites.
Reason (R) Endonucleases were discovered from viruses.
Answer : C

Question. Assertion (A) The tumour inducing plasmid (Ti plasmid) of Agrobacterium tumefaciens acts as a cloning vector in recombinant DNA technology.
Reason (R) The Ti plasmid which is used in the mechanisms of delivering genes to a cell remains pathogenic.
Answer : C

Question. Assertion (A) Use of chitinase enzyme is necessary for isolation of DNA from fungal cells.
Reason (R) Fungal cell wall is made up of chitin and chitinase is able to digest it.
Answer : A

Statement Based Questions

Question. Which one is a true statement regarding DNA polymerase used in PCR?
(a) It is used to ligate introduced DNA in recipient cells
(b) It serves as a selectable marker
(c) It is isolated from a virus
(d) It remains active at high temperature
Answer : D

Question. Following statements describe the characteristics of the enzyme restriction endonulease. Identify the incorrect statement. NEET 2019
(a) The enzyme binds DNA at specific sites and cuts only one of the two strands
(b) The enzyme cuts the sugar-phosphate backbone at specific sites on each strand
(c) The enzyme recognises a specific palindromic nucleotide sequence in the DNA
(d) The enzyme cuts DNA molecules at identified position within the DNA
Answer : A

Question. Which of the following statement is incorrect?
(a) Nucleic acid is fragmented by nucleases
(b) Construction of recombinant DNA involves cleaning DNA segments with endonuclease and rejoining with ligase
(c) Genetic engineering is making artificial limbs and diagnostic instruments
(d) Ti plasmid transforms cells of plants
Answer : C

Question. Which of the following statement is incorrect?
(a) DNA being a hydrophilic molecule cannot pass through cell membranes
(b) Agrobacterium tumefaciens delivers a piece of DNA known as ‘Z-DNA’ which transforms normal plant cells into tumour cells and directs these tumour cells to produce chemicals against pathogens
(c) Retrovirus, adenovirus, papillomavirus are also now used as cloning vectors in animal because of their ability to transform normal cells into cancerous cell
(d) In genetic engineering, DNA from different sources are cut with the same restriction enzymes so that both DNA fragments have same kind of sticky ends
Answer : B

Ans.i)Taq polymrrase

     ii)Thermus aquaticus

     iii) Thermostable

 

Q3. Match the following

                  A                                                                         B

          i) Bacteria                                                             i) Celluase

ii) Chitinase                                           ii)Microparticles of gold or tungsten coated with DNA

iii) Plant cell                                                                  iii) Microinjection

iv) Recombinant DNA injected

to nucleus of an animal cell                                             iv) Lysozyme

v) Biolistic /Gene gun                                                       v) Fungus

 

Ans  Match the following

                  A                                                                         B

Bacteria --- ----------------------                                         Lysozyme

Chitinase ---------------------                                                Fungus

Biolistic /Gene gun -----------                        Microparticles of gold or tungsten coated with DNA

Plant cell ---------------------                            Celluase Recombinant DNA injected to

nucleus of an animal cell ------ ------                                  Microinjection

 

Q4. Write the pallinodromic sequence of the following     5'-------GAATTC--------3'

 

Ans.4 3'------CTTAAG-------5'

 

Q5

i)What dose the fig shows?

ii)What is the matrix used for the above process?

Iii)Name the chemical compound used for staining?

iv)Name the process for the separation of DNA from the agarose gel.

Q.1. Agrobacterium tumefaciens is called natural genetic engineer. It infects only dicot plants. Unfortunately, many important crop plants, including corn, rice, and wheat, are monocots and thus could not be easily transfected using this bacterium. Scientists discovered that by using certain processes, naked DNA molecules can be introduced into plant cell types that are not susceptible to A. tumefaciens transfection. Explain any two.

Q.12. After completion of the biosynthetic stage the products has to be subjected through a series of processes before it is ready for marketing.

a) List these processes?

b) What are they collectively known as?

c) List any other measures to be taken care of?

 

Ans12.a. Separation, purification

    b. Downstream processing

    c. Quality control testing

 

Q.13. Traditional hybridization procedures used in plant and animal breeding very often leads to inclusion and multiplication of undesirable genes along with the desirable ones. What are the steps involved in genetic engineering to over come this limitation?

 

Ans13 (i) Gene cloning

(ii) Gene transfer

 

Q.14. Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure. Why? Explain the alternative method to overcome this difficulty?

 

Ans14(i) It requires simultaneous planting on two plants having different antibiotics.

(ii) Development & use of selectable marker which differentiate recombinats from nonrecombinats on the basis of there ability to produce colour in the process of a chromogenic substance.

 

15. Following figures show a biotechnological Procedure which requires template DNA strand, primers, DNA polymerase, and nucleotides.

a..Name the procedure.

b.List and explain the steps shown in figures 2 - 5