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CBSE Questions for Class 12 Medical Biology Biotechnology: Principles And Processes Quiz 6 - MCQExams.com
CBSE
Class 12 Medical Biology
Biotechnology: Principles And Processes
Quiz 6
Polymerase chain reaction is useful in _______.
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DNA synthesis
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DNA amplification
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Protein synthesis
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Amino acid synthesis
First step in Southern blot technique is
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Digestion of DNA by restriction enzyme
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Production of a group of genetically identical cells
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Denaturation of DNA on the gel for hybridisation with specific probe
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Denaturation of DNA from a nucleated cell as from the scene of crime
Explanation
The
first step
in a
Southern blot
technique is to prepare the DNA mixture by breaking it into smaller fragments using a restriction enzyme.
Bacteria protect themselves from viruses by fragmenting viral DNA with
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Endonuclease
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Exonuclease
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Gyrase
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Ligase
Which one of the following is used as a vector for cloning into higher organisms?
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Salmonella typhimurium
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Rhizopus nigricans
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Retrovirus
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Baculovirus
Explanation
Retroviral vectors are created by replacing retroviral gag, pol, and env genes with therapeutic gene and used in gene therapy which is the process of introduction of DNA into living human beings in order to treat disease. It is used to replace a missing gene product or to correct mutant alleles.
So the correct answer is option C.
DNA or RNA segment tagged with a radioactive molecule is called
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Probe
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Clone
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Plasmid
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Vector
Explanation
DNA or RNA segment tagged with a radioactive molecule is called a probe
. The probes having sequence complementary to the gene to be identified are supplied. They bind with the particular gene segment. Radiation imaging identifies the location of that particular segment which bind with the probe. Probes are used as an identification tool.
So the correct answer is option A.
Which is used in gene cloning?
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Lomasomes
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Mesosomes
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Plasmids
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Nucleotides
Explanation
The traditional technique for
gene cloning
involves the transfer of a
DNA
fragment of interest from one organism to a self-replicating
genetic
element, such as a bacterial plasmid.
So the correct answer is option C.
Which is correctly matched ________________.
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Central dogma - Codon
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RNA polymerase -RNA primer
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Okazaki fragments - Splicing
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Restriction enzyme - Genetic engineering
Explanation
Restriction enzyme is an enzyme that is used in genetic engineering. Restriction endonuclease is also known a molecular scissors which cuts the DNA at a respective sides creating a sticky ends.
So, option D is the correct option.
Restriction enzyme was discovered by
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Alexander Fleming
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Smith and Nathans
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Berg
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Waksman
Explanation
Restriction enzyme, also called restriction endonucleases, a protein produced by bacteria that cleaves DNA at specific sites along the molecule.
These are discovered by Hamilton O. smith and Daniel Nathans in the late $$1960$$s and early $$1970$$s.
Source of Taq polymerase used in PCR is a
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Thermophilic fungus
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Mesophilic fungus
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Thermophilic bacterium
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Halophilic bacterium
Explanation
Taq polymerase is a thermostable DNA polymerase I obtained from the thermophilic bacterium
Thermus aquaticus.
Which can be used as a vector for transfer of DNA segment?
a) Bacterium
b) Plasmid
c) Plasmodium
d) Bacteriophage
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a, b and d
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a only
0%
a and c
0%
b and d
Explanation
Vector
is a DNA molecule
used
in
genetic engineering
as a vehicle to carry foreign
genetic
material from one cell into another cell where it is replicated or expressed. Examples of
vectors
include
plasmid
, cosmid, Lambda phages (bacterio phage).
So the correct answer is option D.
Restriction enzymes are also called
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Molecular markers
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Vectors
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Carriers
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Molecular scissors
Explanation
Restriction enzymes are also called molecular scissors. These are the enzymes that cleave the DNA at specific sites called restriction sites. They make a single cut on both the DNA strands.
Thus the correct answer is option D.
Polymerase chain reaction employs
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Primers and DNA ligase
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DNA ligase only
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DNA polymerase only
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Primers and DNA polymerase
Explanation
The polymerase chain reaction is defined as DNA replication in vitro. It employs a DNA template, two nucleotide primers, and a DNA polymerase enzyme. DNA template to be amplified.
The primers which are oligonucleotides, that hybridize to the target DNA region, one to each strand of the double helix are required. These two primers are oriented with each other facing ends to allow the synthesis of DNA.
The DNA polymerase required which is stable at high temperature (
Taq
polymerase,
Vent
polymerase) for the synthesis of DNA.
So, the correct answer is option D.
DNA polymerase or taq enzyme used in PCR is isolated from
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Thermus aquaticus
0%
E. coli
0%
Salmonella typhimurium
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None of these
Explanation
Taq polymerase is a thermostable DNA polymerase I obtained from the thermophilic bacterium
Thermus aquaticus.
Melting of DNA at 70$$^o$$ C is due to breakdown of
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Phosphodiester bonds
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Hydrogen bonds
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Glycosidic bonds
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Disulphide bonds
Explanation
Dissociation of the double-stranded DNA helix into single coils is referred to as DNA melting. It can be accomplished by simply heating double-stranded DNA. The temperature at which the DNA strands dissociates into single coils depends on the number of hydrogen bonds holding the complementary strands. When DNA is heated at 70°C the hydrogen bonds are broke and caused DNA melting.
So the correct answer is option B.
Microparticles for coating with DNA to be bombarded with gene gun are made of
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Silver or platinum
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Platinum or zinc
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Silicon or platinum
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Gold or tungsten
Explanation
For gene transfer into the host cell without using vector microparticles made of tungsten and gold coated with foreign DNA are bombarded into target cells at a very high velocity. This method is called biolistics or gene gun which is suitable for plants.
So the correct answer is option D.
Gene amplification using primers can be done by
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Microinjection
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ELISA
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Polymerase chain reaction
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Gene gun
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Electrophoresis
Explanation
A
primer
is a short, single-stranded DNA sequence used in the polymerase chain reaction (PCR) technique. In the PCR method, a pair of
primers
is used to hybridize with the sample DNA and define the region of the DNA that will be
amplified
.
So the correct answer is option C.
Biolistic gun is suitable for
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Transformation of plant cells
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Disarming pathogen vectors
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DNA finger printing
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Constructing recombinant DNA
Explanation
A gene gun is used for delivery of exogenous DNA to cells. This method is known as 'biolistics'. Gene guns can be used effectively on most cells but are mainly used on plant cells.
So the correct answer is option A.
There is a restriction endonuclease called EcoRI. What does 'co' stand for?
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Coenzyme
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Coli
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Colon
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Coelom
Enzymes necessary for recombinant DNA technology are
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Endonucleases and polymerases
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Restriction endonucleases and ligases
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Peptidases and ligases
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Restriction endonucleases and topoisomerases
Explanation
Recombinant DNA technology is the method of joining two or more DNA molecules to create a hybrid. This technology is made possible by two types of enzymes, restriction endonucleases and ligase. A restriction endonuclease recognizes a specific sequence of DNA and cuts within, or close to, that sequence. DNA fragments generated by digestion with a restriction endonuclease can be joined together again by the enzyme ligase.
So the correct answer is option B.
Agarose extracted from sea weeds is used in
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PCR
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Gel electrophoresis
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Spectrophotometry
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Tissue culture
In the three steps (a, b, c) of polymerase chain reaction, select the correct step
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c - Extension in presence of heat stable DNA polymerase
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a - Annealing with two sets of primers
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b - Denaturation at high temperature
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a - Denaturation at 50$$^o$$ C
What is true about DNA polymerase used in PCR?
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It is used to ligate introduced DNA in recipient cells.
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It serves as selectable marker.
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It is isolated from a virus.
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It is active at high temperature.
Explanation
DNA polymerase enzyme is an essential component for PCR due to its key role in synthesizing new DNA strands. Taq DNA polymerase ( synthesized from the thermophilic bacteria Thermus aquaticus) is the most common enzyme used for PCR amplification. This enzyme is extremely heat resistant with a half-life of 40 minutes at 95°C.
So the correct answer is option D.
Amplification of gene of interest by using PCR may go upto
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0.1 million
0%
1.0 million
0%
1.0 billion
0%
1.0 trillion
Explanation
The Polymerase chain reaction (PCR) is a method widely used in molecular biology to make many copies of a specific DNA segment. Using PCR, a single copy (or more) of a DNA sequence is exponentially amplified to generate thousands to millions of more copies of that particular DNA segment.
The number of double-stranded DNA
pieces is doubled in each cycle
so that after
n cycles we
have 2^n (2 to the n: the power) copies of DNA
.
The cycle is usually repeated 30 times and 1 billion copies are made at the end of 30 PCR cycles.
So the correct answer is option C.
In PCR, Taq polymerase is used between
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Extraction and denaturation
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Denaturation and annealing
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Annealing and extension
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Extension and amplification
In genetic engineering, restriction enzymes are used for cutting
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Bacterial DNA only
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Eukaryotic DNA
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Viral DNA
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Any DNA fragment
Explanation
A restriction enzyme (or restriction endonuclease) is an enzyme that cuts any DNA at or near specific recognition nucleotide sequences (known as restriction sites).
So the correct answer is option D.
The colonies of recombinant bacteria appear white in contrast to blue colonies of nonrecombinant bacteria because of
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Inactivation of glycosidase enzyme in recombinant bacteria
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Nonrecombinant bacteria contain beta galactosidase
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Insertional inactivation of $$\alpha$$-galactosidase in nonrecombinant bacteria
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Insertional inactivation of $$\alpha$$-galactosidase in recombinant bacteria
Explanation
Correct Option: D
Explanation:
In vector-based cloning research,
blue-white screening
enables for the fast detection of recombinant bacteria.
The plasmid contains an internal multiple
cloning
site inside the lacZ gene.
This MCS can be cut by restriction enzymes, allowing foreign DNA to be introduced and interrupting the gene, resulting in the synthesis of -peptide.
Furthermore, no functional -
galactosidase
may be produced in cells carrying the plasmid with an insert.
This produces a distinctive blue colour in cells having functioning -galactosidase.
Blue colonies indicate the presence of a vector, whereas white colonies indicate the presence of an insert in
lacZ
that prevents the production of an active -galactosidase.
Hence, the colonies of recombinant bacteria appear to be white in contrast to the other blue colonies of nonrecombinant bacteria because of insertional inactivation of $${\alpha}$$-galactosidase in recombinant bacteria.
DNA fragments generated by restriction endonucleases in a chemical reaction can be separated by
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Restriction mapping
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Centrifugation
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Polymerase chain reaction
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Agarose gel electrophoresis
Explanation
Correct Option: D
Explanation:
Electrophoresis can be used to separate
DNA
fragments produced by restriction endonucleases in a chemical process.
Electrophoresis is a method for separating DNA, RNA, or protein molecules depending on size and electrical charge.
An electric current is utilized to drive molecules across a gel for separation (
agarose gel
).
Smaller molecules have the ability to travel quicker than bigger ones because the pores in the gel act like a
sieve
.
Electrophoresis can be used to separate molecules of a certain size range.
Hence, DNA fragments generated by restriction endonucleases in a chemical reaction can be separated by process called an Agarose gel electrophoresis..
Which technique is used in separating fragments of DNA ______________.
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Eastern blotting
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Western blotting
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Northern blotting
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Southern blotting
Explanation
Southern blotting is a laboratory technique used to detect a specific DNA sequence in a blood or tissue sample. A restriction enzyme is used to cut a sample of DNA into fragments that are separated using gel electrophoresis. The DNA fragments are transferred out of the gel to the surface of a membrane.
So the correct answer is option D.
Which cleaves DNA at specific sites producing sticky ends?
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Clearing enzyme
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Proteases
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Lyases
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Restriction endonuclease
Explanation
A restriction enzyme, restriction endonuclease, or restrictase is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class of the broader endonuclease group of enzymes.
So, option D is the correct option.
During the process of isolation of DNA, chilled ethanol is added to
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Break open the cell to release DNA
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Facilitate action of restriction enzymes
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Remove proteins such as histones
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Precipitate DNA
Explanation
It is well known that Ethanol has a lower dielectric constant than water, making it promote ionic bond formations the $$Na^+$$ (from the salt) and the $$PO^{3-}$$ (from the DNA backbone), further, causing the DNA to precipitate.
So the correct answer is option D.
At which temperature a DNA molecule is denatured by heat in PCR
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70$$^o$$ - 80$$^o$$C
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90$$^o$$ - 95$$^o$$C
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42$$^o$$C
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50$$^o$$ - 65$$^o$$C
Explanation
Denaturation: The reaction temperature is increased to 95 degree centigrade, which melts (disrupts the hydrogen bond between complementary bases) all dsDNA into single-stranded DNA (ssDNA).
So, option B is the correct option.
EcoRI cleaves DNA strands to produce
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Blunt ends
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Sticky ends
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Satellite ends
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ori replication end
Explanation
Sticky ends are formed when the restriction enzymes cut the DNA molecule at such a position that it leaves an overhanging stretch of the nitrogenous base which can pair with the complementary base pairs.
EcoRI cut through the DNA strands at nucleotides that overhangs at the end. This overhanging nucleotide strand is called a sticky end because it can easily bond with complementary DNA fragments.
So, the correct option is sticky ends.
Products of restriction enzyme digestion are separated by
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Agarose gel electrophoresis
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Centrifugation
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Polyacrylamide gel electrophoresis
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PCR
Which vector can clone only a small fragment of DNA?
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Yeast artificial chromosome
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Plasmid
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Cosmid
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Bacterial artificial chromosome
Explanation
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. Due to their independent self-replicating property, they are used as a cloning vector in recombinant DNA technology.
They are the stand
ard cloning vectors and the ones most commonly used.
Most general plasmids may be used to clone a DNA insert of up to 15 kb in size.
So the correct answer is option B.
Taq polymerase is isolated from which bacteria?
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E. coli
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Bacillus thuringiensis
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Thermus aquaticus
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Agrobacterium
Explanation
A heat-stable DNA polymerase called Taq, an enzyme isolated from the thermophilic bacterium Thermus aquaticus, which inhabits hot springs.
So the correct answer is option C.
Taq polymerase is isolated from a
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Virus
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Bacterium
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Fungus
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Protozoan
Explanation
A. Correct option -B
B. Explanation for correct option -B
Taq polymerase is a thermally stable DNA polymerase
It is used in a polymerase chain reaction.
It is obtained from the bacterium
Thermus aquaticus
that lives in the high-temperature regions.
Select the matched one :
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Biolistics - Bioreactor
0%
Thermus aquaticus
- T-DNA
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Plasmid DNA - vector
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EcoRI - Restriction exonuclease
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Agrobacterium tumefaciens
- Bt toxin gene
Explanation
Biolistic is a special high- performance method for direct delivery of foreign DNA, RNA, or protein into plant cells, whereas bioreactor is an
apparatus for growing organisms (yeast, bacteria, or animal cells) under controlled conditions.
The transfer DNA (abbreviated T-DNA) is then transferred DNA of the tumour-inducing (Ti) plasmid of some species of bacteria such as Agrobacterium tumefaciens.
A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. In molecular biology, plasmids are used as vectors, ferrying genetic material from one cell to another, for replication or expression.
EcoRI is a restriction endonuclease enzyme isolated from species E. coli.
Bacillus thuringiensis (Bt), a soil-dwelling bacterium that naturally produces a toxin that is fatal to certain herbivorous insects. This toxin is known as Bt toxin.
So the correct answer is option C.
Which of the following restriction endonuclease was discovered first?
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Hind II
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EcoRI
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Bam HI
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EcoR II
Explanation
In 1970, Hamilton O. Smith, Thomas Kelly and Kent Wilcox isolated and characterized the first type II restriction enzyme, HindII, from the bacterium Haemophilus influenzae.
So the correct answer is option A.
One of the methods of which DNA cannot be transferred to the host cell is by
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Microinjection
0%
Gene gun
0%
Disarmed pathogen vectors
0%
Polymerase chain reaction
Explanation
Polymerase chain reaction (PCR) is a method used to rapidly make millions to billions of copies of a specific DNA sample, not the method to transfer DNA to the host cell.
So the correct answer is option D.
Identify the cloning vector.
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Amp and Tet' loci
0%
Ori minus pBR 322
0%
DNA of Salmonella typhimurium
0%
Ti plasmid
Explanation
A cloning vector is a small piece of DNA that can be stably maintained in an organism, and into which a foreign DNA fragment can be inserted for cloning purposes. The cloning vector may be DNA was taken from a virus, the cell of a higher organism, or it may be the plasmid of a bacterium.
So the correct answer is option D.
EcoRI is _________
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A restriction enzyme
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A plasmid
0%
Used to join two DNA fragments
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The abbreviation for bacterium
Escherichia coli
Explanation
EcoRI is a restriction endonuclease isolated from the species
E. coli
.
Restriction sites for Pvu I and Pvu II respectively are in which genes of pBR 322
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$$rop$$, $$amp^R$$
0%
$$amp^R$$, $$rop$$
0%
$$rop$$, $$ori$$
0%
$$ori$$, $$rop$$
Explanation
Restriction sites for Pvu I and Pvu II for pBR322 are present on the amp$$^R$$ and rop gene sites of the plasmid. The amp$$^R$$ is the ampicillin resistance site which is used as a selectable marker. The rop gene codes for rop protein in the vector.
So, the correct answer is option B.
A dicotyledonous plant forms crown gall when
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Agrobacterium tumefaciens comes in contact with the plant
0%
Agrobacterium rhizogenes comes in contact with the plant
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A specific part of DNA from the Ti plasmid gets integrated with the plant chromosome
0%
A specific part of DNA from the Ri plasmid gets integrated with the plant chromosome
Explanation
Crown gall
is a disease
caused
by the bacterial
plant
pathogen, Agrobacterium tumefaciens.
Crown gall
bacteria enter
plant
roots through wounds. Wounds may have been created by planting, grafting, soil insect feeding, root damage from excavation or other forms of physical damage.
Pathogenic agrobacteria are attracted to chemicals leaking from plant wound sites, then colonise and firmly attach to injured plant cells. The presence of these plant compounds can activate the transfer of part of their tumour-inducing plasmid (T-DNA) directly into the chromosomal DNA of the host plant cells. The T-DNA, once functional inside the plant cells, code for the production of plant hormones (e.g. indoleacetic acid and cytokinins) and carbon-nitrogen compounds called opines. Opines become food for the resident agrobacteria that colonise around the gall tissue.
So the correct answer is option C.
The first Nif genes were isolated from __________________.
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Klebsiella aerogenes
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Klebsiella oxytoa
0%
Klebsiella pneumonia
0%
Klebsiella granulonatis
Explanation
C. Klebsiella pneumonia
Solution : The first nif gene for nitrogen fixation was isolated from Klebsiella pneumonia
So the correct answer is " Klebsiella pneumonia"
Which one is correct answer for plasmid ?
i) It can be readily isolated from cells
ii) It possesses a single recognition site for one restriction enzyme
iii) It should have high molecular weight
iv) Plasmids and bacteriophages have the ability to replicate within bacteria
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i, ii, iv
0%
i, ii, iii, iv
0%
ii, iii, iv
0%
i, ii, iii
Explanation
A. i.ii, iv
Solution : Plasmids can be isolated from the the cells by plasmid isolation techniques.Plasmids possess single recognition sites for one restriction enzyme and they have the ability to replicate within bacteria because of the presence of an ARS.
So the correct answer is " i,ii,iv"
Which of the following has revolutionized the discipline of biotechnology ___________________.
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Restriction endonucleases
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Discovery of DNA structure
0%
Recombinant DNA
0%
All of the above
Explanation
D. All of the above
Solution : Restriction endonucleases have been helpful to cut DNA at specific size and join our DNA of interest to get a recombinant DNA. Also the structure of DNA revolutionized the whole knoeldge about biotechnology.
So the correct answer is " all of the above"
Polymerase chain reaction
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Is a method of synthesising human protein from human DNA
0%
Uses restriction enzymes
0%
Can produce billions of copies of a DNA fragment
0%
Takes place naturally in bacteria
Explanation
C. Can produce billions of copies of a DNA fragment
Solution : PCR or polymerase chain reaction is technique used in RDT to amplify or create a many copies of a gene in a very short time.
So the correct answer is "
Can produce billions of copies of a DNA fragment"
Isolation of DNA from a fungal cell involves the use of enzyme
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Chitinase
0%
Lysozyme
0%
Eco RI
0%
Hind II
Explanation
Chitinase is an enzyme that degrades chitin, which is a chief
constituent
of fungal cell walls.
Restriction endonucleases are enzymes that
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Restrict the action of other enzymes
0%
Break phosphodiester bond between specific nucleotides of DNA
0%
Break nucleus into pieces
0%
Break H-bond between two strands of DNA
Explanation
Correct Option: B
Explanation:
Break the
phosphodiester
link between two DNA nucleotides.
Optional: Restriction
endonuclease
enzymes were developed from bacteria and function by cleaving the sugar
phosphate
link of the DNA at particular locations.
Hence, restriction endonuclease are enzymes that break phosphodiester bond between specific nucleotides of DNA.
Genes can be inserted into human cells by
Report Question
0%
PCR
0%
Xenotransplantation
0%
Modified viruses
0%
Modified microarrays
Explanation
C. Modified viruses
Solution : Modified viruses and their cos sites play a great role as vectors for inserting genes into cells. PCR is used for amplifying a small DNA fragment and microarrays are used for gene expression studies and xenotransplantation is grafting of new tissues into animals.
So the correct answer is " Modified viruses"
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