Unit 6 examiners mark scheme

Explaining and illustrating the criteria The following should be read in conjunction with the section on practical biology and investigative skills in the specification.

Research and rationale Assessment criteria

Research and rationale

Level of response a)

focuses on the rationale and biological background of the investigation.

b)

focuses on the selection of additional, relevant information which is used effectively in the report.

a)

There is some attempt to provide a rationale for the choice of investigation in terms of its scope and its relation to biological principles.

b)

Few sources have been consulted and their scope is limited in providing a context for the investigation to assist with the planning or execution of laboratory or field work, and in informing the interpretation of results.

Mark range

0–2 marks

At this level the rationale is very simple and sources used are quoted in a vague manner. Very few relevant sources beyond, perhaps, a core text are used. There is only very limited evidence of progression from AS. Attempts to interpret the data are not linked to the researched information. Researched information is simply listed again with little comment. a)

There is a partial rationale for the choice of investigation. The biological background to the investigation is developed to some extent.

b)

Information gathered from some relevant sources has some bearing on the context for the investigation, and assists in a limited way with the planning or execution of the laboratory or field work, or to inform the interpretation of results.

3–6 marks

There is some relevant biological background but it is not carefully selected and contains irrelevant material. The logical progression, linking biological knowledge to the suggested hypothesis, is rather vague. Interpretations of the collected data make only limited use of relevant biological background or the quoted sources.

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Tutor support materials — Edexcel GCE in Biology — Support booklet for Unit 6 (6BI06) — Issue 1 — November 2008 © Edexcel Limited 2008

a)

The rationale for the investigation is clear in terms of its scope and relationship to biological principles.

b)

Several relevant sources are consulted and are used to provide a context for the project, to assist with the planning or execution of laboratory or field work, and to inform the interpretation of results.

7–9 marks

There is a good selection of relevant sources. The sources quoted are clearly referenced within the text to illustrate where they have been used. There is very little irrelevant information and it is clear to the reader how the hypothesis and methods used have been developed. Interpretation of results is clearly linked to A2 level biological knowledge and understanding. Information from the rationale is not merely reiterated but is used to try to explain the actual trends and patterns in the data rather than make theoretical assertions. NOTE this is concerned with the use of sources not the overall quality of conclusions, which are assessed in Interpreting. a)

The rationale for the investigation is clearly justified in terms of its scope and appropriate biological principles are discussed.

b)

Additional sources beyond those that were most readily to hand or were initially suggested by the teacher, are selected. The material chosen is selected for its relevance to the investigation and it is used effectively to provide a context for the project, to assist with planning or execution of laboratory or field work, and to inform the interpretation of results.

10–11 marks

There is no irrelevant information and there is a concise account of the background to the chosen investigation, which uses a range of sources, which demonstrates very good personal research. It is clear how all sources have been used both in the rationale and in interpreting the collected data. Interpretation of data uses these sources effectively and in an integrated way to show a clear understanding of the trends and patterns identified. NOTE this is concerned with the use of sources not the overall quality of conclusions, which are assessed in Interpreting.


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Planning Assessment

Level of response

criteria

a)

focuses on effective planning to control variables and produce meaningful data.

b)

focuses on assessing risks and suggesting ways to minimise them.

c)

focuses on the use of a trial investigation to modify an initial plan, where necessary.

a)

There is some attempt to plan and select the method or apparatus chosen. Some relevant variables are identified.

b)

Some potential safety hazards and the steps to avoid or minimise them are identified.

c)

A trial experiment may be carried out.

Planning

Mark Range

0–2 marks

This is the basic level where a student has written a simple plan or where considerable help has been given to ensure that some useful data is collected. NOTE: Where there is no clear evidence of a trial investigation 2 marks is the maximum, which can be awarded for planning. a)

There is a plan for investigation, with some explanation of the selection of apparatus and methods. There are some details of how variables are to be controlled, manipulated or taken into account and how relevant observations are to be made.

b)

Most potential safety hazards and the steps to avoid or minimise them are identified.

c)

A trial experiment is performed that has some bearing on the planning of the project.

3–6 marks

Plans here would contain all the main elements of selection of apparatus, a detailed method and sound control of variables but lack depth and detail. Repetition of basic well-documented experiments or core practicals is unlikely to go beyond the lower range of this level. There will be evidence of risk assessment rather than simple statements. Trial experiments will be relevant and there will be some evidence of their application such as simple data or recorded observations.

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a)

There is a clear plan of action, both for the initial trial phase and for the main period of data collection. Apparatus selected and methods chosen are appropriate to the investigation. There is a discussion about how variables are controlled, manipulated or taken into account and about the collection of relevant observations or data.

b)

All potential safety hazards are identified and suitable steps taken to avoid or minimise them.

c)

A well-thought out trial is conducted in advance of the main data collection phase, and is used to inform the planning of the investigation.

7–9 marks

The initial plan outlines the whole process clearly. Apparatus and methods are described concisely and it is clear why they have been chosen. Evidence obtained from the trial phase is discussed and there is a logical progression to the final methodology.

a, b, c) There is evidence of thought and ingenuity in the design of experiments or the recording of data, with good attention to detail including the way that variables are controlled, manipulated or taken into account and how relevant observations are made or data collected. Apparatus is devised or modified to suit the project as necessary.

10-11 marks

All of the criteria for 7-9 marks are met to a high standard. This level of marks is designed to reward students who have gone beyond standard techniques and shown some ability to adapt and modify their chosen techniques in the light of the findings from the trial phase. Whilst this need not involve sophisticated apparatus there must be evidence of some original ideas.


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Observing and recording Assessment Level of response criteria a) focuses on accurate recording and tabulation of data.

Observing and recording

b)

focuses on the selection of a suitable range of readings and an appropriate response to anomalous readings during data collection.

a)

Some appropriate measurements and observations are recorded, which are adequate for the method used and reasonably accurate.

b)

There is some repeating or checking of values obtained.

Mark range

0–2 marks

At this level there is just sufficient data to make basic conclusions linked to the hypothesis. The level of accuracy is just acceptable for an A2 investigation. a)

Measurements and observations are recorded methodically and accurately in appropriate units, and some thought is given to precision and repeatability.

b)

A reasonable number and range of observations and measurements are carried out. Any anomalous results are noted. There is some appropriate modification of procedures for data collection if necessary.

3–6 marks

Results will be recorded in suitable tables with clear headings. Units should be clearly indicated in the headings only and should follow the Institute of Biology guidelines. It is not necessary to find anomalies where they clearly do not exist but some comment on this will be expected. Judgements on the extent of data and reasonable number of repeats should be viewed in the context of the investigation. In particular, is there a reasonable amount of data to make a meaningful judgement on the hypothesis bearing in mind what could be expected from an A Level student in the circumstances. Students use common sense in checking their data as it is collected, to identify and possibly repeat experiments if unusual figures or readings are obtained. a)

Observations and measurements are carried out over a suitable range of values and conditions. Sufficient observations are made to allow a conclusion. Numerical results are recorded to an appropriate degree of precision.

b)

Measurements and observations are repeated as appropriate. Any anomalous results are noted and investigated. If problems arise in the making of measurements or observations, procedures are adapted to ensure data is reliable.

7–8 marks

The range of values or conditions is well-matched to the investigation. This may be justified by checking a running mean or by reference to the requirements of a chosen statistical test. Tables of collected or manipulated data quote figures to a level of accuracy that can be justified by the methods employed. The tabulated data reflects good practice in accurately identifying possible anomalies and shows sound scientific practice in dealing with variations. There is objective analysis rather than a determination to conform to a preconceived model. Tutor support materials — Edexcel GCE in Biology — Support booklet for Unit 6 (6BI06) — Issue 1 — November 2008 © Edexcel Limited 2008

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Interpreting and evaluation Assessment criteria

Interpreting and evaluation


focuses on statistical analysis of the recorded data and its interpretation.

b)

focuses on the use of biological knowledge and understanding to interpret the data.

c)

focuses on the ability to draw summary conclusions and evaluate their validity by a discussion of the limitations of the experimental techniques employed.

a)

There is some data processing. Statistical analysis is only completed with detailed guidance. Application of calculated statistical values is present, though limited or confused.

b)

There is an attempt to apply biological principles.

c)

Some conclusions are stated. There is some awareness of the limitations of experimental results and conclusions.

Mark Range

0–3 marks

Data is only manipulated in the simplest way eg the calculation of totals. A maximum mark of 2 will be applied where there is no evidence of statistical testing. Biological knowledge and understanding is applied to explain trends and patterns in the data in a very simple way or information is merely quoted with no evidence of its application to the tabulated results. There is a short statement of conclusions, which are directly related to the hypothesis. Limitations are discussed superficially and are concerned mainly with basic errors.


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a)

Data is processed with some thought as to the choice of method. The chosen statistical test may be inappropriate or provide limited analysis of the stated hypothesis. Calculations are clearly set out but the interpretation of the calculated values lacks detailed explanation. Some trends and patterns are identified.

b)

Some attempt is made to interpret results using biological principles and draw conclusions based on experimental results.

c)

Conclusions are supported by results. The limitations of results and conclusions based upon them, are recognised.

4–6 marks

It is expected that these will be discriminating criteria. To move to this mark range students must show they have used a suitable statistical test and that they have a basic understanding of its meaning (see additional notes on statistical testing). Identification of trends and patterns is simple but does go beyond just a word description of the data. Application of biological knowledge is sound but lacks a detailed discussion linking it closely to the trends and patterns described. Discussion of limitations identifies some important shortcomings of the apparatus and the methods employed but lacks a detailed objective review. There is clear evidence of biological knowledge and understanding gained from initial research being applied in an attempt to explain the findings and support any conclusions. a)

Data are processed using appropriate methods that reveal trends and patterns. The chosen statistical tests are appropriate to the data to be analysed and the hypothesis to be tested. Calculations of statistical tests are clearly set out and interpreted, using a null hypothesis and a 5% confidence level where appropriate. Trends and patterns are identified.

b)

Results are interpreted using biological principles and concepts of Advanced GCE standard. Relevant biological principles are applied correctly throughout.

c)

Conclusions are supported by results. The limitations of results and the conclusions based upon them, are recognised and evaluated. Any limitations of the procedure are commented upon, and sensible modifications are suggested.

7–9 marks

To reach this level the whole analysis should be accurate and objective. Students must have selected their information carefully and applied it accurately. They should avoid sweeping generalisations and demonstrate an awareness that the conclusions they make are likely to lead to other questions or are part of a wider pattern of interactions. A consideration of limitations must also include an analysis of the underlying principles and assumptions of the chosen methodology. Suggestions for modifications must be linked to such an analysis. Collecting more data or repeating again are not suggestions that can be given credit at this level.

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Communicating Assessment criteria

Communicating


focuses on the organisation of the report as a scientific record of the investigation.

b)

focuses on the ability of the student to select the most appropriate form of graphical presentation that is wellmatched to their hypothesis and is presented accurately.

c)

focuses on the accuracy of the written report and the correct listing of sources in a bibliography.

d)

focuses on the range of sources used and an evaluation of their scientific credibility.

a)

The layout of the paper largely conforms to that expected of a scientific paper. The organisation of the report shows evidence of some thought and the aim of the investigation is stated. Images, when used, are relevant to the points made.

b)

Data is presented in graphs, tables or diagrams, which are mostly appropriate and follow scientific conventions for presentation.

c)

Spelling, punctuation and grammar are generally correct, some technical terms are used appropriately and most sources used are acknowledged in a bibliography.

d)

Sources include at least one professional scientific journal.

Mark range

0–2 marks

At this level there will be some basic organisation of the report into clear sections. Data will be presented in a suitable format which aids analysis but this may be limited or of unsuitable format. There is limited technical language and some spelling errors or poor grammatical expression which can confuse the underlying meaning. Sources are very limited and listed in a format which does not identify them accurately. The term ‘professional scientific journal’ will be judged in the light of what could reasonably be accessible to an A Level student but there are many sources which are freely available to all students. (See additional notes.)

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a)

The layout of the report mostly conforms to that expected of a scientific paper with subheadings used effectively. The aim(s) and conclusion(s) of the investigation are stated. Images, when used, illustrate points clearly.

b)

Data is presented in well chosen graphs, tables or diagrams, which usually follow scientific conventions and mostly use SI units, where appropriate, correctly.

c)

Spelling punctuation and grammar are correct, appropriate technical terms are used throughout. Sources are selected and used appropriately and are correctly referenced within a properly constructed bibliography.

d)

There is some discussion of the credibility of sources used.

3-4 marks

To reach this level it is essential that the report is well-structured and it is likely that the aim(s) and a summary of conclusions will be included in a concise abstract. Any images should be clearly labelled and if they are not referred to in the report it will be difficult to judge which points they illustrate At this level some form of graphical presentation would normally be expected. The graphical format would be appropriate to the data and useful in analysing the data with respect to the hypothesis. Any manipulated data used to construct such graphs will be clearly tabulated. There will be very few typographical errors although an inability to spell scientific terms or correct names of organisms under investigation is weak for this level. The report will be easy to read and understand. All references quoted should be accurately identified so that it is easy for the reader to gain access to the actual article, paper or web page. It should be clear where in the report the sources quoted have been used. It is hoped students will use skills gained at AS level to discuss the credibility of some of their sources.


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a)

The layout of the report conforms to that expected of a scientific paper with appropriate and helpful subheadings. The organisation of the report shows evidence of thoughtful planning and aim(s) and conclusion(s) of the project are clearly stated and discussed. Images illustrate the points effectively and enhance the clarity of the report.

b)

Data is presented effectively in graphs, tables or diagrams that follow scientific conventions and are clearly and accurately labelled using SI units where appropriate.

c)

Spelling, punctuation and grammar are correct, and appropriate technical terms are used throughout.

d)

Sources used are evaluated with reference to their credibility within the wider scientific community.

5–6 marks

The report at this level would be expected to be concise and very well-organised. There would be a short abstract summarising the main features including the conclusion(s). Graphical presentation must be selective with a small number of graphs to illustrate important trends and patterns on the correct format. They will be accurately labelled and carefully plotted. There will be very few minor spelling errors and all scientific or technical terms will be correct. All quoted sources will have some comment as to their credibility as acceptable scientific knowledge.

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Appendix 2: Unit 6 Individual Investigation — Checklist

Criterion Research and rationale

A2 level Biological knowledge used to explain the nature of the investigation. All the information included is relevant to the hypothesis. There is a good range of sources researched. It is clear where in the report sources have been used.

Planning

Report has a clear plan of action and describes how all the main variables are to be controlled. Which statistical test is to be applied is included in the plan. Risk assessment is included. A trial experiment has been carried out and simple results recorded. Method has been amended in the light of trial experiment if necessary.

Observing and recording

There is sufficient data to make some conclusions. Tables have correct units in headings only and consistent use of sensible significant figures. Readings are repeated if possible. Any significant anomalies are dealt with during data collection.

Interpreting and evaluation

The table needed for the statistical test is included. I have explained, in my own words, what the statistical test shows me about my hypothesis. The main trends and patterns are described. Researched information is used to try to explain the data that has been collected. There is a discussion of the main limitations of the methods used. Sensible modifications to the procedure have been suggested.


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Criterion Communicating

The report has been checked for spelling errors. There are subheadings for each different section of the report. The report has a word count on each page and is not longer than 3300 words. The graphs are carefully selected to be useful in interpreting the data and making conclusions concerning the hypothesis. Sources of information are accurately listed and include at least one professional scientific journal. There is a comment on each source describing its credibility.

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