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Biology Book 8
Public examination questions
Suggested Answers
36 Biotechnology and Its Modern Techniques
Structured questions
1.
(a)
(i)
2
(1 mark)
(ii)
5
(1 mark)
(b)
8000 bp + 2000 bp = 10000 bp
(1 mark)
(c)
Viral DNA has a larger molecular size,
(1 mark)
as the sum of basepair of all DNA fragments of viral DNA is larger than that of
(d)
plasmid DNA.
(1 mark)
(i)
fingerprint
(1 mark)
(ii)
Any two of the following: (1 mark each)
(2 marks)
- to detect the presence of this virus and plasmid
- to identify this virus and plasmid
- to study the relationship between viruses and the relationship between bacteria
(accept other correct answers)
(e)
Main concept: (1 mark each)
(Max. 3 marks)
- Human DNA is large in size.
- The restriction enzyme cuts the DNA into many different DNA fragments / many
restriction sites.
- Some fragments are close in size.
- cannot be separated effectively so merge as a smear
(Total: 11 marks)
2.
(a)
(i)
(ii)
The bands of P come from either R (mother) or Q.
(1 mark)
Thus, Q is her father.
(1 mark)
S has many bands common to P. The bands of S come from either R or Q.
(1 mark)
Thus, S is a son of Q and R, i.e. a brother of P.
(b)
(1 mark)
The closer evolutionary relationship of two groups of living organisms, the more
common bands they will have in their DNA fingerprinting patterns.
(1 mark)
(Total: 5 marks)
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3.
(a)
(i)
plasmid
(1 mark)
(ii)
Any one of the following:
(1 mark)
- The bacteria divide / grow, producing many copies of desired gene / plasmid.
- The bacteria divide / grow to cover the agar.
(iii) Only the plant tissue that has antibiotic resistance survives
(1 mark)
so the plant tissue which has desired gene / plasmid can be identified.
(1 mark)
(iv) To clone plants / produce genetically identical plants with desired gene (1 mark)
(b)
(i)
at a fast rate / on a massive scale.
(1 mark)
Any one of the following:
(1 mark)
- Plants are protected throughout their lives, i.e. more convenient / saves costs of
application of spray.
- no spray drift onto other fields / insects
(ii)
Any one of the following:
(1 mark)
- killing of harmless / useful insects that feed on wild plants
- damage to food chains starting with wild plants
(Total: 8 marks)
4.
(a)
to separate the two strands / break the hydrogen bonds between DNA strands (1 mark)
(b)
(i)
enables replication / sequencing to start
(1 mark)
(ii)
joins DNA nucleotides to form a long DNA strand
(1 mark)
(i)
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(1 mark)
(ii)
replication of DNA from crime scene / tissue sample / for DNA sequencing /
(c)
gene cloning
(d)
(1 mark)
Any two of the following: (1 mark each)
(2 marks)
- Transcription uses RNA polymerase; PCR uses DNA polymerase.
- Transcription uses RNA nucleotides / uracil; PCR does not uses RNA nucleotides.
- Transcription occurs in one template strand / PCR has both strands used.
- Transcription involves the use of start / stop codons.
(Total: 7 marks)
5.
(a)
genetically identical cells / individuals
(1 mark)
(b)
mitotic cell division
(1 mark)
(c)
There is no differentiation at this stage / Same genes are being expressed.
(1 mark)
(d)
Brown
(1/2 mark)
because the genes of nucleus are expressed.
(1/2 mark)
(e)
(f)
Embryo cells are diploid while the egg cells are haploid.
(1 mark)
They contain different alleles / forms of the colour gene.
(1 mark)
Nuclei and cells are easily damaged during transfer.
(1 mark)
(Total: 7 marks)
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37 Biotechnology in Medicine
Structured questions
1.
(a)
(i)
Concept for mark award:
- obtain the gene coding for the enzyme
(1 mark)
- introduce the genes into cultured cells through a vector
(1 mark)
- expression of the gene forming the enzyme
(1 mark)
- mass production of the enzyme
(1 mark)
- purification of the enzyme
(1 mark)
(Max. 4 marks)
e.g.
The DNA sequence coding for the functional enzyme is synthesised in bacteria /
Restriction enzyme is used to cut the non-defective gene from the host cell.
(1 mark)
The DNA / gene is introduced into cultured cells via a plasmid / vector. (1 mark)
The gene is expressed in the cultured cells to produce the enzyme.
(1 mark)
The cultured cells are mass cultured / fermented to mass produce the enzyme.
(1 mark)
The enzyme is finally purified for use.
(1 mark)
(Max. 4 marks)
(ii)
Concept for mark award:
- comparison in terms of:
 any introduction of the gene into patient’s body
(1 mark)
 source of enzyme
(1 mark)
e.g.
For gene therapy, foreign gene is introduced into the patient’s body but this does
not occur in enzyme replacement.
(1 mark)
Also, for gene therapy, enzyme is produced by the patient but in enzyme
replacement enzyme is obtained from an external source.
(b)
Any three of the following: (1 mark each)
(1 mark)
(3 marks)
- There may be adverse side effects if the target gene is misplaced OR
mutation, errors occur when target gene is introduced,
- defective or harmful gene products are produced and
- normal gene product is absent.
- Microorganisms / chemicals used to carry the gene into patient’s cells may bring
about adverse / unknown effect on human health. OR
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The vector may trigger undesirable response in the patient / allergy / inflammation.
- Accept other correct answers
(Total: 9 marks)
2.
(a)
introduction of healthy gene / replacement of defective gene
(b)
Any two of the following: (1 mark each)
(1 mark)
(2 marks)
- can enter cells / infect cells / inject DNA into cells
- can target specific cells
- can replicate in cells
(c)
Reproductive cells / Gametes do not contain ADA allele / gene.
(1 mark)
(d)
(i)
to prevent rejection / immune response
(1 mark)
(ii)
T lymphocytes have a limited life span / do not reproduce
(1 mark)
but bone marrow provides continual supply of T lymphocytes.
(1 mark)
(Total: 7 marks)
3
(a)
Main stages in producing genetically
Order of
modified bacterium
stages
a plasmid is taken from a bacterium
1
bacterium is cloned
6
human gene is placed into bacterial plasmid
4
modified plasmid is put into bacterium
5
relevant gene is cut from human DNA
3
the plasmid is cut open
2
(1 mark each)
(b)
(c)
(i)
(5 marks)
Fertilised egg / Zygote,
(1 mark)
because the genes can be passed on to all sheep’s cells.
(1 mark)
(ii)
half / 50%
(1 mark)
(i)
Any one of the following:
(1 mark)
- can produce large quantities of antibodies
- can pass the genes on to offspring
(ii)
Products are safer / more reliable.
(1 mark)
(Total: 10 marks)
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38 Biotechnology in Agriculture
Structured questions
1.
(a)
Mitotic cell division
(1 mark)
so that all the GM crop plants produced carry the inserted genes / are genetically
identical.
(b)
(1 mark)
Any one set of the following: (2 marks each)
(2 marks)
It may kill some other species / lead to a drop in the insect population,
thus leading to the extinction of the species / reduction of biodiversity.
OR
It may kill some beneficial insects,
which may help the pollination of other plants.
OR
If the corn is dispersed into the natural environment,
the plants formed will outcompete / displace some other species because of its
resistance to insects.
(Accept other correct answers)
(c)
Any one set of the following: (2 marks each)
(2 marks)
Increase the ability of producing vitamins, e.g. vitamin A
so that the food produced has a higher nutritive value.
OR
Increase the ability of fixing nitrogen / nitrogen fixation
so that the food produced has a higher protein content.
(Accept other correct answers)
(Total: 6 marks)
2.
(a)
Any four of the following: (1 mark each)
(4 marks)
- identify / locate the Bt gene in the bacterial genome
- cut the Bt gene from the bacterial genome
- insert the gene into a plasmid / vector
- select the vector carrying the Bt gene
- infect the cultured cells of cotton plants with the vector
(b)
Any two of the following: (1 mark each)
(2 marks)
- Bt toxin kills insect pests specifically / is not toxic to vertebrates (including humans)
while insecticides may have toxic effect on vertebrates / humans
- Bt toxin has no residual effect whereas insecticides have residual effects
- Bt toxin does not accumulate along the food chain while insecticides may accumulate
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to a high enough level, thus being toxic and killing the top consumers
- there is no need to re-introduce the Bt gene into the Bt plants so they are protected
throughout their life but insecticides have to be regularly applied to protect the plants
- it costs less to grow Bt plants due to reduced insecticides application
(c)
Cloning takes much shorter time to produce offspring with the desired trait
(1 mark)
while it takes many generations for traditional breeding to achieve the result. (1 mark)
Also, in cloning, all the offspring will obtain the desirable characters of their parents
(1 mark)
because there is no genetic variation.
(1 mark)
And it is possible to introduce selected genes from other organisms to animal’s genome
(1 mark)
to confer superior traits.
(1 mark)
(Max. 3 marks)
(Total: 9 marks)
3.
(a)
The gene is cut out from the amaranth plant cell using a restriction enzyme.
(1 mark)
Since the restriction enzyme only cuts site with specific base sequence,
(1 mark)
the same restriction enzyme is used to cut plasmid / virus
(1 mark)
to produce complementary base sequence.
(1 mark)
The gene is inserted into the plasmid / virus by DNA ligase.
(1 mark)
The plasmid is injected into the potato plant cell / The virus is used to inject DNA into
the potato plant cell.
(b)
(1 mark)
Any three of the following: (1 mark each)
(3 marks)
- The introduced gene / characteristic can always be passed to offspring.
- It is a rapid process.
- A larger number of plants are produced.
- Asexual reproduction produces genetically identical offspring / sexual reproduction
causes variation.
(c)
Different genes are expressed,
(1 mark)
thus producing different enzymes / proteins.
(1 mark)
(Total: 11 marks)
4.
(a)
They are genetically identical.
(b)
Advantage: all of them have good characteristics.
(1 mark)
Disadvantage: they are more susceptible to disease.
(1 mark)
(i)
New genes / DNA are added.
(1 mark)
The genes / DNA may come from the same or other species.
(1 mark)
(c)
(ii)
Any two sets of the following: (2 marks each)
(2 marks)
(4 marks)
Pigs are given human insulin gene
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to produce human insulin.
OR
Transgenic sheep / cows produce milk
with proteins to treat cystic fibrosis / other named diseases.
OR
Transgenic pigs are used to grow human organs
for use in transplantation.
(Accept other correct answers)
(Total: 10 marks)
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39 Bioethics
Structured questions
1.
(a)
Advantages: (1 mark each)
- preserve desirable / good traits by maintaining the same genetic composition
- rapid means of producing offspring / it shortens the development process
- solve reproductive problems / difficulties in certain plants such as orchids
Applications: (1 mark each)
- can be used to save endangered plants / plants with low reproductive potential
- can be used to maintain specially-bred plants like orchids
- mass produce economically important plants for human use (like oil palm, pineapple
and banana)
- produce disease-free plants by tissue culture (such as bamboo in Taiwan) / save plant
population which is infected by diseases by culturing uninfected tissues
(At least one advantage and one application is required to award 5 marks)
(Max.5 marks)
Disadvantage:
Since there is no genetic variation, the plants may be less adapted to the changes to the
environment.
(b)
(1 mark)
Any three of the following: (1 mark each)
(3 marks)
- There is ethics of eugenics / selection of individuals for cloning.
- It causes confusion in family relationship / can change drastically the current family
structure.
- Human dignity is lost / humans are made to become specimens for a deemed purpose.
- The cloned human individuals are misused in experiments / for organ reserves /
military purposes (like cloning armies for wars) / as commodity for trading
- Many lives are sacrificed during the cloning process e.g. many embryos are wasted /
aborted.
- It may lead to trading of human egg cells and commercialisation of pregnancy.
- Any reasonable alternatives
(Total: 9 marks)
2.
(a)
Any four of the following: (1 mark each)
(4 marks)
- reservoir of genetic diversity / prevents inbreeding
- may carry alleles for future needs
- may contain genes for medicinal products
- Hybrid vigour may combine genes for beneficial characteristics.
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- more suited to local conditions
- accept correct alternatives
(b)
Arguments for: (1 mark each)
(Max. 4 marks)
- reduced cost of food production / reduced amount of land used for food production
- DNA and proteins are digested in body so it is unlikely to cause problems
- longer shelf life
- increased yield / faster growth
- less chemicals used because of resistance to pests so it causes less pollution
- healthier food produced because use of pesticides can be decreased
- increased food quality / nutritional value e.g. Golden rice
Arguments against: (1 mark each)
(Max. 4 marks)
- uncertain long-term health effects from eating transgenic crops
- Vegetarians may have eaten vegetables with animal genes.
- New proteins in food crops could cause allergies.
- Genes could escape from transgenic plants to wild plants / create superweeds.
- outcompete wild plants and may make them extinct / disrupt the balance of
ecosystem
- Monopoly created by large companies adversely affects small farmers
(6 marks)
(Total: 10 marks)
3.
(a)
(i)
(ii)
(b)
(i)
A clone has identical DNA / genes
(1 mark)
to another organism.
(1 mark)
A fertilised egg cell
(1 mark)
splits into two embryos / individuals.
(1 mark)
The egg cell is enucleated / has the nucleus removed.
(1 mark)
A diploid nucleus is inserted from a donor.
(1 mark)
The cell is then stimulated by an electric shock to divide / undergo mitotic cell
division.
(ii)
Any three of the following: (1 mark each)
(1 mark)
(3 marks)
- issues of eugenics
- reduction in biodiversity
- could be put in wrong uses e.g. in war
- conflict with religious belief
- risk of disease that kills all of a clone
- health problems of the clone e.g. premature aging
- the identity of the clone
(Total: 10 marks)
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