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2010 HSC Notes from the Marking Centre — Senior Science

Contents

Introduction

This document has been produced for the teachers and candidates of the Stage 6 course in Senior Science. It contains comments on candidate responses to the 2010 Higher School Certificate examination, indicating the quality of the responses and highlighting their relative strengths and weaknesses.

This document should be read along with the relevant syllabus, the 2010 Higher School Certificate examination, the marking guidelines and other support documents which have been developed by the Board of Studies to assist in the teaching and learning of Senior Science.

General comments

Teachers and candidates should be aware that examiners may ask questions that address the syllabus outcomes in a manner that requires candidates to respond by integrating their knowledge, understanding and skills developed through studying the course, including the prescribed focus areas. It is important to understand that the Preliminary course is assumed knowledge for the HSC course.

Candidates need to be aware that the marks allocated to the question and the answer space (where this is provided on the examination paper), are guides to the length of the required response. A longer response will not in itself lead to higher marks. Writing in excess of the space allocated may reduce the time available for answering other questions.

Candidates need to be familiar with the Board’s Glossary of Key Words which contains some terms commonly used in examination questions. However, candidates should also be aware that not all questions will start with or contain one of the key words from the glossary. Questions such as ‘how?’, ‘why?’ or ‘to what extent?’ may be asked, or verbs may be used which are not included in the glossary, such as ‘design’, ‘translate’ or ‘list’.

Section I – Core

Part B

Question 21

  1. Better responses provided an appropriate difference between a colloid and a suspension.

    Poorer responses gave properties of either a colloid or a suspension.

  2. Better responses provided an advantage of mayonnaise being a colloid or emulsion.

Question 22

  1. Better responses identified pH as a measure of acidity.
  2. Better responses identified that either pH meters or appropriate chemical indicators could be used to measure pH.
  3. Better responses identified an internal and external organ of the body, their (optimal) operating pH, and gave an appropriate reason for these pH requirements.

    Poorer responses only provided one example of either an internal or external organ, its pH and an appropriate reason for this pH requirement.

    Weaker responses identified an organ and gave its pH or a reason for its pH requirement.

Question 23

  1. In better responses, candidates used correct scientific terms in their answers, such as ‘dissolved’ and ‘circulated’ as opposed to ‘breakdown’.

    In weaker responses, candidates confused sub-dermal implants with pacemakers and transcutaneous patches. Another misconception was that implants themselves travelled through the circulatory system to reach the affected organ and then released the drug/medication.

  2. In better responses, candidates provided at least three supported reasons for the preferable use of sub-dermal implants. Possible answers included the need for a continuous or steady concentration of the medication in the body, long-term usage making it more convenient for medication that was needed on a daily basis, and the fact that some medications were unable to be absorbed through the digestive route because of their labile nature.

    Weaker responses used comparative phrases such as ‘it acts faster’ without indicating what they were comparing it to.

Question 24

  1. In better responses, candidates drew and correctly labelled the positions of the muscle, tendon and the cartilage. This included the tendon attaching the muscle onto the bone and placing the cartilage over the ends of the bones. The best diagrams were clear, simple diagrams, anatomically correct and without heavy shading.

    In poorer responses, candidates incorrectly labelled the position of the ligament (which was not required) for the tendon. Many weaker responses included diagrams that were anatomically impossible.

  2. In better responses, candidates correctly identified and contrasted the functions of both the cartilage and the tendons.

    Weaker responses stated only the functions of the cartilage or the tendon. Some candidates confused the function of the ligaments with the function of the tendon, stating that a tendon joins bone to bone rather than muscle to bone.

Question 25

In the best responses, candidates provided justification, using knowledge from beyond that given in the table.

In poorer responses, candidates demonstrated a lack of understanding of the relationship of the ball to the shaft, but understood the articulation between the ball and the socket.

In weaker responses, candidates confused shock absorption with weight bearing.

Better responses demonstrated an understanding of the structure of the joint by including a labelled joint and correct matching of materials. These identified that P and Q could be used in both parts of a hip joint, outlining the use of the low friction material as a coating on the ball.

Question 26

In the best responses, candidates applied information about the nature of forms of energy, combined with historical development of communication and the invention of a device used in either communication or medicine or both (like the cochlear implant), then gave benefits to society in their explanations. These responses were often structured with sub-headings and paragraphs that contained ideas expressed clearly and simply.

Weaker responses included energy forms and lists of technologies/devices without links or benefits to society. Some responses gave examples such as ultrasound as a diagnostic tool but with ultraviolet light, or microwaves as the energy it uses.

Question 27

Better responses indicated an advantage of having a range of communication devices.

Most responses did indicate an application or advantage of a communication device or devices, without the advantage of having a range of communication devices.

Poorer responses indicated one device or one advantage of a device only.

Question 28

  1. In better responses, candidates correctly identified more than one feature that caused a satellite’s orbit to be geostationary.

    In poorer responses, candidates identified only one feature that caused a satellite’s orbit to be geostationary.

  2. In the best responses, candidates correctly used both text and a clear diagram to show the relative positions of a satellite, Australia and the equator, and explained why a satellite must face north.

    Poorer responses either gave correct reasons as to why a satellite dish must face north, without including a diagram, or had a diagram and did not explain fully.

Question 29

In better responses, candidates outlined four changes to the experimental method and correctly indicated if each change improved validity or reliability.

In poorer responses, candidates identified changes that would improve the method, but did not correctly indicate if each improved the validity or reliability.

Question 30

In the best responses, candidates identified specific technological advances and provided an assessment of their impacts on both individuals and society, giving relevant examples.

Poorer responses simply described technological advances, without including their impacts.

Section II – Options

Question 31 – Polymers

    1. In better responses, candidates gave a simple strategy that was related to the problem that they had identified in (b) (i) and then justified that strategy.
    1. Better responses clearly described the results of a relevant first-hand investigation.
    2. In better responses, candidates referred to the need to wear protective equipment of some sort and how it would reduce the risks. In poorer responses, candidates listed protective equipment but did not give a reason for wearing the equipment.
  1. In better responses, candidates linked scientific investigations in bank note technology to advances in other fields like medicine. Weaker responses tended to only consider the benefits of bank note technology.
  2. Most candidates demonstrated awareness of the environmental impacts of using plastics. Better responses referred to the properties of specific plastics when addressing their environmental impact, and gave reasons why the plastics could continue to be used by society.

Question 32 – Preservatives and additives

    1. Most candidates could name a food additive that was not a preservative but some candidates referred to preservatives, eg salt, sugar.
    2. Better responses identified and contrasted the roles of preservatives and additives, using examples.

      Poorer responses made only general statements about preservatives and other additives.

    1. Better responses identified a possible problem or cause for the microbes growing, ie not preserved, get sick, etc.
    2. Better responses identified a strategy for or means of eliminating the growth of microbes in a home situation, explaining why the strategy was appropriate.

      Weaker responses just gave a strategy or means without any justification.

    1. Better responses described the results of an investigation done to distinguish the solubilities in water of the chemicals named and ranked them according to results.
    2. Better responses related the need for solubility with the roles of these preservatives: nitrates and nitrites in the curing of meat (ie turning pink), eg ham, frankfurts; or sulphites used in fresh meats, sausages, ie anti-microbial.
  1. In better responses, candidates used the information provided to clearly describe and assess the contribution of scientific work on preservatives and additives to society.

    Weaker responses briefly described contributions with minimal reference to the information provided.

  2. In better responses, candidates provided a judgement about the use of additives and described their labelling. These provided relevant examples to support their judgement, ie problems of allergies, intolerance, diabetes etc. and using specific examples, eg MSG, salt, sulfur, colourings, etc.

    Weaker responses made general statements, without using examples.

Question 33 – Pharmaceuticals

    1. In better responses, candidates correctly contrasted the structures and blood-carrying capacities of two of their named blood vessels from part (a) (i).

      In poorer responses, candidates often contrasted structures but made no mention of blood-carrying capacities. Others simply referred to features of blood flow in the vessels such as ‘towards/away from the heart’ and ‘to all the cells’.

    1. In better responses, candidates stated a problem evident in the scenario, such as ‘the bacteria had become resistant to the antibiotic’. In weaker responses, candidates incorrectly stated that the patients had ‘become immune to the antibiotic’.
    2. In better responses, candidates proposed a strategy that could be used to solve the identified problem and provided support for their justification.
    1. Better responses provided features of cultures – often with detailed descriptions of the bacterial colonies and their numbers under different incubation temperatures or environmental conditions.

      In weaker responses, candidates often described the procedure in detail but did not mention the results. Others gave conclusions without reference to the results.

    2. In better responses, candidates identified at least two risks to health and clearly showed how they could be managed.

      Weaker responses often provided safe management practices without identifying the risks.

  1. In the best responses, candidates demonstrated with a coherent and logical argument how scientific investigations such as Eccles’ led to further research and development of pharmaceuticals, which could be used to treat pain or neurological diseases such as Parkinson’s disease or schizophrenia. They also described many social and economic benefits afforded by appropriate treatment of such conditions with pharmaceuticals.
  2. In better responses, candidates demonstrated thorough knowledge of the nervous system by describing nervous pathways from detection of the stimulus through to response by effectors such as muscles. These referred to a reflex action as being a critical response to a painful stimulus, while also mentioning the brain’s delayed interpretation of the pain. Such responses included specific scientific terms such as ‘receptors’, ‘sensory neurones’, ‘interneurones’, ‘motor neurones’, ‘PNS’ and ‘CNS’.

Question 34 – Disasters

    1. In better responses, candidates identified community organisations such as Salvation Army, Red Cross, Care Australia, Caritas.
    2. Better responses were specific about the roles of the SES and RFS, indicating similarities and differences.

      In some responses, candidates described the structure of each or both organisations, rather than outlining their roles. In other responses, candidates described the role of only one of the services.

      In poor responses, candidates used general terms such as ‘help’, ‘attend to’, or ‘deal with disasters’ without specifically saying what the services did.

    1. In better responses, candidates proposed a relevant strategy to solve the problem identified in part (i), showing a link to the scenario. A statement to justify this strategy was provided.

      Often in weaker responses, candidates provided a relevant strategy and link, without justification.

    1. In better responses, candidates linked the increased flammability of dry leaves to the strategies such as back burning and clearing gutters, where dry leaves were removed as a fuel source. Some of these candidates also mentioned the fuel, heat and oxygen triangle.

      Poorer responses identified strategies to remove dry leaves, with little explanation.

  1. In better responses, candidates clearly referred to the stimulus material and included relevant examples of scientific work and disasters. These candidates also related the scientific work on disasters to its contribution.

    Poorer responses often did not include an assessment. Poorer responses did not provide a clear link to the passage, or rewrote the passage and used it as the basis for their answer.

  2. Better responses gave two or more well-explained examples of disasters caused by atmospheric pressure changes such as cyclones and tornadoes. These included suitable measuring techniques used in more than one location.

    Poorer responses gave only one disaster example and did not fully describe measuring techniques. Other poorer responses gave examples of disasters caused by changes in atmospheric pressure with little explanation of how they formed.

Question 35 – Space Science

    1. Most candidates could name two correct ‘spin-offs’.
    2. In better responses, candidates described the original and current use of a spin-off.

      Often in weaker responses, candidates described either the original or current use of a spin-off.

    1. Most candidates were able to state a problem associated with weightlessness.
    2. In better responses, candidates described a solution to the problem and explained why the solution would be effective in a space environment.

      In weaker responses, candidates gave a generalised answer, eg exercise, without describing the solution or explaining why the solution would work in space.

    1. In better responses, candidates described a suitable system in detail or used the correct descriptive terminology as well as naming the system/s in use before the space shuttle.

      Weaker responses gave brief descriptions.

    2. In better responses, candidates clearly stated advantages and disadvantages of the shuttle in a comparison with the system described (c) in part (i).
  1. The best responses used information in the stimulus material, differentiated between the scientific work and the contribution to society that the stimulus had suggested.

    Poorer responses gave only a very general description of scientific space research.

  2. Most candidates were able to list strategies and materials. In better responses, candidates were able to differentiate between strategies and materials for safety and health, and explained each clearly with examples. The best responses provided a judgement.

    Weaker responses gave few strategies and/or materials used by space scientists for safety and/or health.

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