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AS Biology Exam Doctor
GENETIC ENGINEERING
Question Question Question
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2
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AS Biology Exam Doctor
GENETIC ENGINEERING
QUESTION 1
The diagram shows the results of a DNA fingerprint analysis, using a blood sample from the
scene of a crime and blood samples from four suspects.
(a) State, with a reason, which suspect has been incriminated by the DNA analysis.
[3]
(b) Describe the part played by each of the following in the production of the DNA profiles:
(i) polymerase chain reaction.
[1]
(ii) restriction endonucleases.
[2]
(iii) radioactive DNA probes.
[3]
The diagram shows the results of a DNA fingerprint analysis, using a blood sample from the
scene of a crime and blood samples from four suspects.
(a) State, with a reason, which suspect has been incriminated by the DNA analysis.
Suspect 3, because the bands of suspect 3 DNA match the stained
bands of the ‘scene of crime’ DNA.
[3]
(b) Describe the part played by each of the following in the production of the DNA profiles:
(i) polymerase chain reaction.
It multiplies the copies of the DNA.
[1]
(ii) restriction endonucleases.
It cuts the DNA into shorter pieces at particular base sequences.
[2]
(iii) radioactive DNA probes.
These are lengths of DNA with complementary base sequences to the cut test
DNA pieces, to which they bond by complementary base pairing.
[3]
The diagram shows the results of a DNA fingerprint analysis, using a blood sample from the
scene of a crime and blood samples from four suspects.
(a) State, with a reason, which suspect has been incriminated by the DNA analysis
(b) Describe the part played by each of the following in the production of the DNA profiles:
(i) polymerase chain reaction.
(ii) restriction endonucleases.
(iii) radioactive DNA probes.
MARK SCHEME
(a) (i) suspect 3;
because the bands match closely to the DNA at the scene of the crime;
the bands of other individuals don't match to the crime scene DNA;
(b) (i) increase quantity/number of copies of DNA (under investigation)/
amplification of DNA;
(ii) used to cut DNA into fragments;
if the same restriction endonuclease is used, samples from all suspects are
cut at the same/similar places and so are comparable;
(iii) probes are DNA strands with a complementary sequence to cut fragments;
labelled using radioactive phosphate/phosphorus/P32;
probes bind to the complementary sequence;
fragments/radiation detected by autoradiography/using X-ray film;
specific sequences show up as dark bands;
2
1
2
3
TOTAL 9
The diagram shows the results of a DNA fingerprint analysis, using a blood sample from the
scene of a crime and blood samples from four suspects.
You also need to refer to the
DNA bands of the other
suspects, which do not match
the ‘scene of crime’ DNA, thus
eliminating them as suspects.
(a) State, with a reason, which suspect has been incriminated by the DNA analysis
1
Suspect 3,MPBecause
the bands of suspect 3 DNA match the stained

bands of the ‘scene of crime’ DNA.MP 2
[3]
(b) Describe the part played by each of the following in the production of the DNA profiles:
(i) polymerase chain reaction.
It multiplies the copies of the 
DNA.
(ii) restriction endonucleases.
[1]
MP 1

It cuts the DNA into shorter pieces at particular base sequences.
Also need to refer to ‘samples of all suspects are cut at the same places for comparability’.
(iii) radioactive DNA probes.
[2]
MP 1

These are lengths of DNA with complementary base sequences to the cut test
MP 3
DNA pieces, to which they bond by complementary
base pairing.

Total 6 out of 9
Needs more detail about labeling and how the bands are visualized – ref.
[3]
to autoradiography or X-ray film.
AS Biology Exam Doctor
GENETIC ENGINEERING
QUESTION 2
Read through the following account of genetic engineering and then fill in the spaces with the most
appropriate word or words.
During the process of hormone manufacture by genetic engineering, human RNA is extracted and
converted to single stranded DNA by treatment with ....................................... . This is then treated with
................................................... to produce double stranded (double helix) DNA. Plasmid DNA is also
extracted from suitable bacteria for use as a ..................................... .The human and plasmid DNAs are
then treated separately with .............................................. which cuts them into fragments which have
the same complementary................................................ .The fragments of human and plasmid DNA are
then mixed with................................................... .
This joins the two types of DNA together as .................................... DNA.
This will hopefully contain the gene required for hormone synthesis. The plasmids are then mixed
with host bacterial cells, such as cells of ...................................... . The presence of the chemical
................................................. aids the plasmid uptake by the bacteria. The bacteria can then undergo
large scale culture and should produce suitable quantities of the required hormones. Hormones made
in this way include........................................................ and……........................................ .
[11]
Read through the following account of genetic engineering and then fill in the spaces with the most
appropriate word or words.
During the process of hormone manufacture by genetic engineering, human RNA is extracted and
converted to single stranded DNA by treatment with .......................................
RNA polymerase . This is then treated with
DNA polymerase
...................................................
to produce double stranded (double helix) DNA. Plasmid DNA is also
vector
extracted from suitable bacteria for use as a .....................................
.The human and plasmid DNAs are
endonuclease
then treated separately with ..............................................
which cuts them into fragments which have
sticky ends
the same complementary................................................
.The fragments of human and plasmid DNA are
DNA ligase
then mixed with...................................................
.
recombinant
This joins the two types of DNA together as ....................................
DNA.
This will hopefully contain the gene required for hormone synthesis. The plasmids are then mixed
E.coli
with host bacterial cells, such as cells of ......................................
. The presence of the chemical
calcium
.................................................
aids the plasmid uptake by the bacteria. The bacteria can then undergo
large scale culture and should produce suitable quantities of the required hormones. Hormones made
insulin
somatotrophin
in this way include........................................................
and……........................................
.
[11]
MARK SCHEME
Read through the following account of genetic engineering and then fill in the spaces with the most
appropriate word or words.
During the process of hormone manufacture by genetic engineering, human RNA is extracted and
reverse transcriptase; . This is then treated with
converted to single stranded DNA by treatment with .......................................
DNA polymerase; to produce double stranded (double helix) DNA. Plasmid DNA is also
...................................................
vector;
extracted from suitable bacteria for use as a .....................................
.The human and plasmid DNAs are
restriction endonuclease; which cuts them into fragments which have
then treated separately with ..............................................
sticky ends;
the same complementary................................................
.The fragments of human and plasmid DNA are
DNA ligase;
then mixed with...................................................
.
This joins the two types of DNA together as ....................................
DNA.
recombinant;
This will hopefully contain the gene required for hormone synthesis. The plasmids are then mixed
E. coli/any correct example; The presence of the chemical
with host bacterial cells, such as cells of ...................................…………...
calcium chloride/any
.................................................
aids the plasmid uptake by the bacteria. The bacteria can then undergo
appropriate salt;
large scale culture and should produce suitable quantities of the required hormones. Hormones made
insulin; somatotropin; growth hormone;
(max 2)
in this way include........................................................
……........................................
.
TOTAL 11
Read through the following account of genetic engineering and then fill in the spaces with the most
appropriate word or words.
During the process of hormone manufacture by genetic engineering, human RNA is extracted and

RNA polymerase . This is then treated
converted to single stranded DNA by treatment with .........................................
Reverse transcriptase needed
DNA polymerase to produce double stranded (double helix) DNA. Plasmid DNA is also
With ........................................
vector 
extracted from suitable bacteria for use as a .....................................
.The human and plasmid DNAs are

endonuclease
then treated separately with ..............................................
which cuts them into fragments which have
Need ‘restriction endonuclease’
sticky ends 
the same complementary................................................
.The fragments of human and plasmid DNA are
DNA ligase 
then mixed with...................................................
.
recombinant  DNA.
This joins the two types of DNA together as ....................................
This will hopefully contain the gene required for hormone synthesis. The plasmids are then mixed
E.coli 
with host bacterial cells, such as cells of ......................................
. The presence of the chemical
salt – the element calcium mixed with water is explosive!
calcium Any calciumaids
.................................................
the plasmid uptake by the bacteria. The bacteria can then undergo

large scale culture and should produce suitable quantities of the required hormones. Hormones made in

somatotrophin
insulin
this way are........................................................
and……........................................
.
Spelling wrong – ‘somatotropin’.
From Greek: ‘tropos’ = ‘growth’, ‘trophos’ = ‘feeding’.
[11]
Total 8 out of 11
AS Biology Exam Doctor
GENETIC ENGINEERING
QUESTION 3
(a) The table refers to the uses of enzymes in genetic engineering. Write in the names of an
appropriate enzyme in each empty box
Use of enzyme
Name of enzyme
Enables transcription of DNA from
mRNA
Enables transcription of mRNA from
DNA
Cuts DNA at specific base sequences
Binds DNA fragments of different origin
together
[4]
(b) Outline the role of plasmids in genetic engineering?
[4]
(a) The table refers to the uses of enzymes in genetic engineering. Write in the names of an
appropriate enzyme in each empty box
Use of enzyme
Name of enzyme
Enables transcription of DNA from
mRNA
Reverse transcriptase
Enables transcription of mRNA from
DNA
Transcriptase
Cuts DNA at specific base sequences
Restriction endonuclease
Binds DNA fragments of different origin
together
DNA ligase
[4]
(b) Outline the role of plasmids in genetic engineering?
Bits of bacterial DNA.
They are inserted into bacteria and are used to make lots of useful products
e.g. insulin
[4]
MARK SCHEME
.(a) The table refers to the uses of enzymes in genetic engineering. Write in the names of an
appropriate enzyme in each empty box
Use of enzyme
Name of enzyme
Enables transcription of DNA from
mRNA
Reverse transcriptase;
Enables transcription of mRNA from
DNA
RNA polymerase;
Cuts DNA at specific base sequences
Restriction endonuclease;
Binds DNA fragments of different origin
together
DNA ligase;
4
(b) What are plasmids and what are they used for in genetic engineering?
circular molecules of bacterial DNA;
can replicate independently;
plasmid is cut;
ref. to sticky ends;
useful gene is cut with same enzyme;
gene is inserted into plasmid;
bacterial cell takes up plasmid;
4
TOTAL 8
(a) The table refers to the uses of enzymes in genetic engineering. Write in the names of an
appropriate enzyme in each empty box
Use of enzyme
Name of enzyme
Enables transcription of DNA from
mRNA

Reverse transcriptase
Enables transcription of mRNA from
DNA
Transcriptase
Cuts DNA at specific base sequences
Restriction endonuclease
Binds DNA fragments of different origin
together
DNA ligase 

‘Transcriptase’ is
a class of
enzymes,not a
specific enzyme.
RNA polymerase
was the specific
name wanted.

[4]
(b) Outline the role of plasmids in genetic engineering?
Bits of bacterial DNA.‘Circular molecules’ needed rather than the vague term ‘bits’.
7 are used to make lots of useful products
They are inserted into bacteriaMP
and
e.g. insulin

No attempt to make four clear marking points. This is an extremely
common question and you need to learn the mark scheme!
Total 4 out of 8
[4]