Microsoft word - trial 07 marking criteria.doc

Q.20
Criteria
Correctly describes the work of Watson, Crick, Franklin and Wilkins, explains the effect of communication and collaboration, and evaluates the statement Correctly describes the work of Watson, Crick, Franklin and Wilkins, and explains the effect of communication and collaboration, OR explains and evaluates the effect of communication and collaboration Correctly describes some aspects of the work of Watson, Crick, Franklin and Wilkins, and 3-4 identifies the quality of communication and collaboration Outlines some aspects of the work of Watson, Crick, Franklin and Wilkins
Sample answer:
The work of Watson, Crick, Franklin and Wilkins indeed proved that scientists working together in
a collaborative approach, that is, sharing information, insights and discoveries and correcting and
re-evaluating proposed ideas, are necessary aspects of achieving breakthroughs.
Watson and Crick were able to discover the structure of DNA because they were able to confer with
each other and discuss theories. However, it was Franklin’s data from her research and the vital
photo 51 that enabled them to hit upon the correct model of DNA structure. It was her findings that
gave them the exact dimensions and parameters of the DNA molecule, and it was the signature X
shape of the photo that told them that the DNA molecule bore the form of a helix. Without Wilkins
supplying Watson and Crick with Franklin’s data, we do not know if the model of DNA structure
would have been discovered when it was.
This demonstrates the importance of scientists collaborating and communicating their findings in an
open manner. Working alone is not a bad thing, but working together is better. It is an important
aspect of reaching speedy and correct conclusions and discoveries; however, it is not necessary that
this communication should take place using modern technology. It is only necessary that scientists
exchange information, collaborate, confer and communicate their individual thoughts and ideas in
an open manner for the benefit of arriving at speedy conclusions.
Q. 21
Criteria
Correctly identifies the type of inheritance, predicts the probability of thalassemia major and minor, and justifies this answer. Does some of the above. Sample answer:
(b) Probability of thalassemia major = 0; probability of thalassemia minor = 0.5. this is shown by the Punnett square, in which normal is NN, thalassemia minor is NT and thalassemia major would be TT.
Q. 22
Criteria
Correctly identifies the cause of a named non-infectious disease, the symptoms and outlines a strategy for the effective treatment of a patient. Does some of the above. Sample answer:
(a) Down syndrome is caused by an inheritance of an extra chromosome 21 when the chromosomes do not separate properly during meiosis. (b) Two symptoms are protruding tongue and mental retardation. (c) There is no specific treatment for Down syndrome, but physical and occupational therapy can help with development of motor and cognitive skills respectively.
Q. 23
Criteria
Full and accurate description of operation of immune system on virus; good explanation of memory cells, specificity and effect of mutation. Good description of operation of immune system on virus but with some confusion of terms or events; good explanation of memory cells, specificity and effect of mutation.
Partial description of operation of immune system, memory cells, specificity and effect of 1-2
mutation.
Phagocytes encountering the viruses will ingest them and display viral proteins on their surface. T
helper cells encountering these proteins send messages to stimulate the appropriate B cells multiply
to become plasma cells and produce antibodies, which latch onto the viruses and attract phagocytes
to destroy them. The T helper cells also stimulate production of the appropriate T killer cells, which
destroy cells infected with the virus.
When the virus is destroyed, some of the B and T cells remain in the blood and lymph as memory
cells, which attack the virus if it ever infects again; however, these memory cells are very specific
in their action, and if the virus mutates and thus changes its protein coat, the memory cells may not
recognise it, and so the process will have to begin again for the “new” virus.
Q.24 (a)

Criteria
Sample answer: Information gathered from the Internet, biology textbooks and handouts was
compared for reliability. I then highlighted the major points and synthesised them into the
categories of cause, transmission, prevention, control and scientists who helped our understanding
of malaria, and placed them on a timeline. I omitted all irrelevant and unreliable information.
(b)
Criteria
Gives at least 3 significant events in the history of treatment of malaria Gives 1-2 significant events in the history of treatment of malaria During the 1600’s, quinine was extracted from the bark of the cinchona tree and used to treat malaria patients, but there was no method of prevention other than moving away from swampy areas. After Laveran discovered that malaria is caused by the protozoan Plasmodium and Ross showed that the protozoan is transmitted by Anopheles mosquitoes, prevention was carried out by draining swamps and using insecticides to kill mosquitoes. Meanwhile, other anti-malarial drugs such as chloroquine were developed for both treatment and prevention.

Source: http://web1.strathfieg-h.schools.nsw.edu.au/staffnet/Faculties/Science/HSC/BIO/Trial%2007%20marking%20criteria.pdf