Part 2
((For the 8 main keywords refer to part 1))
Mind you I will be use papers from subjects that you may or may not study, but that does not matter. The same things apply to other subjects.
*NOTICE how it obtains the criteria from the specific HSC keywords*. These will be bolded in the examples given
1
Analyse: identify components and the relationships between them; draw out and relate implications
2004 HSC, BIO, Q34e
Question
Using this information, analyse how scientists use technologies and the result they generate, to deduce ideas on hominin history which could modify existing theories.
Answer
The fossil bone is intact, so radiocarbon dating is appropriate. Scientists would look at the ratio of carbon 14 to carbon 12 and compare it to the same ratio in living species. Using published half-life of carbon 12 they can calculate how many half-lives have elapsed. Approximately six half-lives would have elapsed for the radioisotopes in the Russian fossils for a 41, 000 age estimate.
Marking Guidelines
Demonstrates a sound understanding of relevant technologies
Describes the results generated by the relevant technologies
Relates the use of technologies and results to the deductions on hominin history
Identifies significant new ideas on hominin history
Describes fully how existing theories on hominin evolution could be modified as a consequence
2
Assess: make a judgement of value, quality, outcomes, results or size
2004 HSC, BIO, Q33c
Question
Assess the use of blood groups and highly variable genes for paternity testing.
ANSWER
Highly variable genes are the repeat sequence of junk DNA found at defined locii in the human genome. Individuals vary in the number of repeat sequences for each allele at any one locus. Ten variable genes are isolated from the offspring and potential parent and are compared (using electrophoresis).
If the suspected father and the child share the same variable genes at the same locii and the mother does not, then the suspected father is almost certainly the childs father.
Using blood groups can give negative answers with clarity, eg a type O man could not be the father of a type AB child if the mother was type A. However if the man was type B he might be the father of the child, but not certainly. Another individual who is type B could also be the father, as type B is common.
The fact that blood groups are not as varied as the highly variable genes makes the blood group technologies less useful in paternity testing
MARking guidelines
Describes use of highly variable genes in paternity testing
Describes use of blood groups in paternity testing
Makes an appropriate judgement about the validity for each technology for paternity testing with supporting arguments
3
Compare: show how things are similar or different
2015 HSC, CHEM, Q30d
Question
Compare the membrane cell method with ONE other method used in the industrial production of sodium hydroxide in terms of technical and environmental issues
Answer (shortened as it is too long to quote)
Sodium hydroxide can be produced by the membrane cell method and a similar technique known as the diaphragm cell. The chemistry involved in each of these techniques is very similar, but there are significant technical and environmental differences between them.
In the diaphragm cell,... brine is placed in a half-cell with a titanium anode where Cl ions are oxidised to Cl.. Problems associated with this method include the use of the asbestos diaphragm.
As an alternative, the membrane cell uses identical chemistry to the diaphragm cell, but the anode and cathode compartments are separated by a semipermeable membrane produced from polytetrafluoroethylene (PTFE or Teflon).
This prevents contamination of the depleted brine with hypochlorite and the contamination of NaOH with NaCl. In addition, the PTFE is harmless. Hence, the membrane cell is superior as it allows uncontaminated NaOH to be produced compared to the diaphragm method. It also prevents release of ClO into the depleted brine, and prevents risk of exposure of workers to asbestos.
Marking Guidelines
Includes correct structure and chemistry of each method
Elaborates on technical and environmental issues associated with each method to show how the methods are similar and/or different
Provides a coherent and concise response with no extraneous information
4
Describe: provide characteristics and features
2004 HSC, BIO, Q32dii
Question
These two species of bacteria were mixed. Describe how a biotechnologist in the 1940s would have isolated them from each other using an experimental procedure based on these data and standard techniques.
ANswer
Make two batches of agar plates: one batch with a pH of 2.5, one batch with a pH of 7.0.
Flame an inoculating loop in a Bunsen flame. Cool by touching on sterile agar. Touch the loop onto the mixture of bacterial strains.
Streak the pH 2.5 with the loop, while holding the lid of the plate just ajar to prevent airborne bacteria entering.
Re-flame and cool the loop and repeat to streak a plate at pH 7.0.
...etc etc
Marking Guidelines
Describes the process for isolating the two species, including:
sterile agar prepared at pH 2.5 and pH 7.0
mixture of strains streaked on both types of agar plates
details of appropriate sterile technique
5
Discuss: identify issues and provide points for and/or against
2004 HSC, BIO, Q32dii
Question
Discuss ONE strength and ONE limitation of using the data shown to determine the evolutionary relationships between these species.
ANSWER
Since the average rate of mutation is known, the number of mutations between organisms can be used as a measure of time since divergence from a common ancestor. The data on % genetic similarity in the eye control gene shows that Species 2 (85% genetic similarity) would be more closely related to the mouse than Species 4 (71.66% genetic similarity), because it must have diverged more recently.
Limitation of Data Use for Deducing Evolutionary Relationships The data presented relates to one gene only, not the entire genome of the five species being compared. With the entire genome of the each organism taken into account, % genetic similarity figures might be different from that of the eye control gene. Hence the predictions
of evolutionary relationships might be different.
MARKING Guidelines
Demonstrates a thorough understanding of genetic evidence for common ancestry in terms of similar genes and identical gene product
Demonstrates a thorough understanding of the genetic evidence required to determine evolutionary proximity in terms of number of mutations/percentage genetic difference as a measure of divergence
Explains a limitation and a strength of using the data shown for the matter under investigation
>>> LIMITATION AND STRENGTH = pros and cons >>>>
6
Explain: relate cause and effect; make the relationship between things evident; provide why and/or how
Question
Explain how TWO specific personal hygiene practices reduce the risk of infection.
ANSWER
Washing hands after going to toilet removes pathogens from skin so they cannot get into the body.
Placing hand over mouth when coughing stops spread of water droplets which can carry pathogens.
MARKING Guidelines
Identifies TWO appropriate personal hygiene practices
Clearly relates each practice to reduction of transmission of pathogens
>>> looking for cause and effect >>>
7
Evaluate: make a judgement based on criteria; determine the value of
2004 HSC, BIO, Q32e
Question
Evaluate the ethics of the use of ONE specific biotechnology in relation to this framework.
ANSWER
GMOs are genetically modified organisms, ie they contain genes from another species of animal or plant. The genes that have been inserted into them provide for useful traits in the context of agriculture or animal husbandry.
The useful trait might mean that the GMO can be used for the good of society. An example of this is the insertion of a fish gene for antifreeze that has been inserted into strawberries to prevent the fruit from being affected by frost. This would increase farm productivity, make more food available and reduce the price of strawberries. However, does the inserted gene affect the other genes in the strawberry genome to change the food value of the strawberries in ways adverse to society?
Roundup-ready soybeans have a gene for tolerance to toxic weed killer inserted into their genomes. When used in agriculture, the farmer aerial sprays Roundup over the crops. This increases the toxic chemicals in the environment and the soybeans sold to the public might contain toxic residues of Roundup. These toxins can drift into natural ecosystems and biologically magnify in food chains. Does this harm outweigh the increases in farm productivity?
In the above cases the potential adverse effects should be studied and compared to the positive effects of increased farm productivity in order to decide the balance of good over harm. (Utilitarian ethics)
The proposers of the use of GMOs (chemical companies which profit from this) must be obligated to prove that the harm is not significant. For example, they must be able to prove that the genetic drift of GMO genes to non-GMO farms by insect cross-pollination does not occur. They should prove that residues of Roundup in crops are low or safe for human consumption. (The Precautionary Principle)
Since there is little evidence put forward to justify the safety of their use, I think that a valid case for the ethical use of GMOs has not been developed.
MARKING Guidelines
Describes thoroughly specific biotechnology
Describes the known good outcomes of identified applications of their chosen biotechnology for society and/or the environment
Describes the known harm of identified applications of their chosen biotechnology for society and/or the environment
Makes a judgement of known good vs known harm for their biotechnology
Describes some doubts about risks that need further proof of lack of significance provided by the proposer(s)
Relates the discussion to the given ethical framework
>>>> ethical framework =criteria >>>>
8
Justify: support an argument or conclusion
HSC 2015, PHYSICS, Q32bii
Question
After a patient had been treated for lung cancer, no tumours were detected in an X-ray image of the lungs. The doctor has now recommended that the patient have a whole-body PET scan.
Justify the doctors recommendation to use the whole-body PET scan.
ANSWER
The failure of the X-ray image to show the presence of any tumours is not sufficient to clear the patient of lung cancer. Conventional X-rays do not image soft tissue well and during treatment, the size of the tumours may have decreased to below the limit of resolution.
The PET scan, however, is very effective at detecting regions of high metabolic activity, which is characteristic of tumours, regardless of size. This is because the radioisotope/radiopharmaceutical used is metabolised at different rates by the body tissues and organs, resulting in an easily identifiable hot spot if the activity is unusually high. A whole body scan will also detect if the cancer has spread to other parts of the body.
MARKING Guidelines
Provides a justification that:
- includes relevant limitation(s) of conventional X-ray
- advantage(s) of PET scans
>> Notice that it is asking for pros and cons >>>
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