Techniques in Modern Biotechnology
Multiple Choice Questions
1
A.
2
B.
Ligating DNA fragments is a step of recombinant DNA technology.
3
C.
Amplifying the specific regions of DNA is one of the applications of polymerase chain
DNA ligase is responsible for joining the plasmid and the target gene together.
reaction.
4
D.
All the genes essential for growth and reproduction of the bacteria are located in the
bacterial chromosome.
5
B.
cloning does not involve restriction enzymes.
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(a)
B.
It is because the DNA fragments, which are negatively charged, will migrate
from the negative pole (cathode) to the positive pole (anode).
(b)
C.
DNA fragments with a larger molecular size will migrate slower than that with a
smaller molecular size in the process of gel electrophoresis.
7
D.
The baby must inherit its DNA fingerprint from its biological mother and father ((2)
and (4)).
8
A.
Both gene gun and microinjection are commonly used physical gene delivery methods.
They do not involve a vector (e.g. plasmid).
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Structured Questions
9
(a)
(b)
(c)
(d)
(e)
10
Plasmid is a small, circular DNA in bacteria. It can replicate independently of the bacterial
chromosome. (1)
The DNA containing the target gene is isolated from the cell. (1)
A restriction enzyme is used to cut out the target gene and cut open the plasmid. (1)
The culture medium containing ampicillin can be used to confirm the recombinant plasmid has entered
the bacterial cell successfully. (1)
If recombinant plasmid does not enter the bacterial cell successfully, the bacterium will not have the
gene for ampicillin resistance and so will not be able to grow on a medium containing ampicillin. (1)
In other words, any bacteria that grow and produce colony on the culture medium must have taken up
the recombinant plasmid. (1)
Bacteriophage. (1)
The target gene is first inserted into the DNA of the bacteriophage. (1)
When the bacteriophage infects the bacterial cell, the target gene will be injected into the cell together
with the bacteriophage DNA. (1)
Bacteria are very easy and economical to grow. (1)
They can express the target gene and produce the gene product in large quantities within a short period
of time. (1)
(Or other acceptable answers)
(a) Plant tissue culture. (1)
(b) Auxin is a kind of plant growth hormone. (1)
It can stimulate the growth of tissue samples. (1)
(c) Shorter time is needed for plant tissue culture. (1)
The desirable characteristics of plants can be maintained. (1)
Large amount of genetically identical plants can be produced at the same time. (1)
(d) The cost of production is higher that conventional planting methods. (1)
Not all plants can be successfully propagated by plant cloning methods. (1)
Contamination of the plants during cloning process may result in great losses in a short period of time. (1)
(Any two of the above or other acceptable answers)
(e) Arguments for applying plant cloning in our daily lives:
> It may help solving the problem of food shortage. (1)
> The traits of plants can be controlled easily. (1)
> It can improve the nutritional value of crops. (1)
(Or other acceptable answers)
Arguments against applying plant cloning in our daily lives:
> It may lead to a loss in biodiversity. (1)
> It may disturb the balance of the ecosystem. (1)
> Plants may lose the ability to adapt to the wild environment. (1)
(Or other acceptable answers)
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11
(a)
(b)
(c)
(d)
(e)
12
(a)
(b)
(c)
(d)
(e)
(f)
There are repeated sequences in the human genome called tandem repeats. The number
of repeats is variable among different individuals. (1)
This difference can be used to distinguish between different individuals. (1)
Restriction enzymes are added to cut the DNA samples into different restriction
fragments. (1)
Gel electrophoresis is carried out to separate the different restriction fragments. (1)
DNA fragments after electrophoresis are then transferred onto a nylon membrane and
then mixed with specific and radioactively-labelled DNA probes. (1)
The excess probes are washed off and the distribution of the bands can be detected with
an X-ray film. (1)
The bands in the DNA fingerprint from a person must be inherited from his or her
parents. (1)
There are some bands in Andrew that are not present in either Peter or Mary. So those
bands could not be inherited from Peter and Mary. Hence, Peter and Mary are not the
biological parents of Andrew. (1)
However, all the bands of Andrew can be found in either Mr. Wong or Mrs. Wong. (1)
The bands of Andrew either come from Mr. Wong or Mrs. Wong. Therefore, Mr. and
Mrs. Wong are the biological parents of Andrew. (1)
Short tandem repeats (STR) profiling. (1)
Identify the evolutionary relationship among different groups of living organisms /
forensic science (1)
This is to ensure that the cutting points of the plasmid and the target gene are the same
(1)
so that the target gene can be inserted into the plasmid. (1)
DNA ligase is responsible for joining the plasmid and the target gene together. (1)
The cells of transgenic tobacco plants can produce the coat proteins of TMV, making
the tobacco plants more resistant to the TMV. (1)
(i)
Using the gene gun. (1)
(ii) DNA containing the target gene is coated onto the surface of tungsten beads. (1)
The beads are physically forced into the target plant cells. (1)
Increase the resistance of crops to pests, tolerance to cold, drought or high salinity. (1)
Improve the nutritional value of crops. (1)
Increase the yield of crops, hence help tackling the food shortage problem. (1)
(Or other acceptable answers)
May lead a loss in biodiversity (1)
Disturb the balance of ecosystem. (1)
Transgenic crops may have negative impacts on our health. (1)
(Or other acceptable answers)
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