Synoptic Biology by hcj


									                         ST MARY’S GUIDE TO
                          SYNOPTIC BIOLOGY
Synoptic biology is the ability to select and apply general principles to unfamiliar

Modules 5 and 8 will have questions that test your understanding of modules
1,2,3 and 4. This is called the synoptic assessment.

The synoptic element of modules 5 and 8 is worth more marks that the actual
module content. This means you have to get to grips with the synoptic element
in order to do well. This booklet is designed to help you to do so.

How much of module 5 and 8 is synoptic?
50% of the marks on the module 5 paper are synoptic and 70 % of the module 8
paper is synoptic.

In what form are the questions?
Module 5: general questions just like you are used to but they require
information from other modules to answer
Module 8: some general questions…but also data handling & experimental
techniques questions and an essay. Watch out for these!

So there are 3 main types of synoptic questions in the exams:

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Which Synoptic subject knowledge topics are going to be
You have to be able to show the ability to select or apply general principles to
unfamiliar data/situations. These are the main topics you need to revise:

       Tertiary structure of proteins                      Genetic engineering
       Membrane receptors                                  Transport principles
       Movement across membranes                           Use of tracers
       Enzymes                                             Photosynthesis/respiration
       SA/Vol ratio                                        Stimulus/response
       DNA/genetic code                                    Negative feedback
       Translation/transcription                           Variation
       Basic genetics                                      Natural selection

Sometime between Easter and Half Term you should prepare your own
individual 1side of A4 summaries for each one of these topics to help you with
your revision.

Deciding exactly what level to learn these topics in is pretty tricky. Looking at
past paper questions will help. You won’t be asked for the same level of recall
that you needed for each module, but you will be expected to know all the main
principles involved in each topic.

The questions you will get on synoptic knowledge are in module 5 and section A
of module 8


Data Handling
You have to be able to:
   Use mathematical skills in a range of concepts
   Analyse unfamiliar data
   Use general biological ‘nous’ to suggest explanations, biological
     advantages etc

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Mathematical skills that they can ask you to use in questions:
   Use an appropriate number of significant figures;
   Find arithmetic means
   Construct and interpret frequency tables and diagrams, bar charts and
   Have sufficient understanding of probability to understand how genetic
     ratios arise
   Use ratios, fractions and percentages
   Understand the principles of sampling as applied to biological data
   Understand the importance of chance when interpreting data
   Understand the terms mean, median and mode
   Use a scatter diagram to identify a correlation between two variables
   Use a simple statistical test (you will only get examination questions on
     the 2 test)

NB You should be familiar with the use of the Chi-squared test, understand
when it might be validly applied and be able to interpret results obtained. You
will not be expected to recall the formula in written papers.

Synoptic skills and understanding relating to practical work
Practical work has the following key areas:
          o Overview
          o Defining the question
          o Planning
          o Implementation
          o Data analysis

You can be asked questions which test your understanding of these areas. The
back of this booklet contains example past paper questions


One of the aims of the specification is that you should develop an understanding
of scientific method. You should know the following:
     Hypothesis – a suggested explanation of an observation that can be
       tested by experiment
     Theory – a well established hypothesis that is supported by a substantial
       body of evidence.
     ‘Proof’ and experiment can either support or disprove a hypothesis, but it
       cannot prove that it is certainly true
     Variable are things which can be changed e.g. light intensity, pH, etc

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The independent variable is the thing that you change in experiments (it always
goes on the x axis on graphs). In an experiment you change one independent
variable and keep all the others constant. The effect is shown on the dependant
variable e.g. exercise intensity can be an independent variable heart rate would
be a dependent variable. In this practical external temperature would be one of
the other independent variables you would keep constant. The dependent
variable is always plotted on the y axis on graphs

You should be able to:
 Formulate a hypothesis/suggested explanation
 Examine data/results/observations, then suggest one plausible biological
  hypothesis consistent with the information given.
 Analyse whether a suggested explanation is consistent with the data.

Planning Investigations

You should be able to:
   Describe how one independent variable would be varied
   Describe experimental controls- keeping all conditions constant except
     independent variable
   describe how dependant variable would be measured
   Explain how reliable data could be obtained/dealing with variability in living


You should be familiar with the following methods of measurement:

       Methods of measurement                              Colorimetry
       Biochemical tests                                   Dilutions
       Chromatography and Rf                               Safety measures
       Isotonic solutions                                  Replication
       Indicators                                          Centrifugation
       Controlling temperature

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Data Analysis

Chi-squared is the only statistical test you need to know so it will probably be
examined in module 5.

This is a very typical chi squared type exam question

Table 1. Data from a survey
                                                            Population of meadow
                 Management Scheme                            brown butterflies      2
                                                              1976         1983
          Area X: Grazed by sheep in
                                                              435           415     0.47
          Area Y: Grazed by sheep in
                                                              522           595     4.77
          Area Z: Not grazed by sheep                         287           239     4.38

Table 2 shows part of chi-squared table
         Degrees of freedom
                                       0.50    0.25          0.10 0.05       0.02   0.01
                      1                0.45    1.32          2.71 3.84       5.41   6.64
                      2                1.39    2.77          4.61 5.99       7.82   9.21

Are there any significant differences between the population sizes in areas X,Y
and Z between 1976 and 1983? Explain your answer.

Large numbers of student asked this did not understand degrees of freedom.
Because there were three areas X,Y and Z, they opted for (3-1)=2. The trouble
is the table shows 3 individual chi squared tests each with 1 degree of freedom.
So the correct answer was one.

Many student gained one mark for ‘There are significant differences in areas Y
and Z,’ but did not explain why, nor note that there is a significant increase in Y
and a significant decrease in Z.

General Points
You need to understand the concept of null hypothesis and understand X2 value
in relation to table values at probability of 0.05

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Standard Deviation
This is another reasonably advanced mathematical concept – it is the average
distance individual results are from the mean. So spread out data have a high
standard deviation and closely grouped data have a small standard deviation.

The table below shows the typical type of question you could get

                Distance from pollution Zinc concentration /mg dm-3
                source /km              ( mean & standard deviation)
                           3                       3.0  2.5
                           4                       1.6  0.9
                          10                       1.3  0.6
                          13                        0.8  0.2
                          22                       0.4  0.04

What is the range of the concentration of zinc
1     within 1 standard deviation at 4km
2     within 2 standard deviations at 22 km

1   at 4km; 0.7-2.5 mg dm-3
2   at 22 km; 0.032-0.48 mg dm-3

The Essay

The essay question will be part of the module 8 exam. You will have to choose
one of two titles. It is vital to choose the one, which is easier to answer bringing
in information from lots of the course

Important points about writing the essay:
   In the answer to this question you should bring together relevant principles
     and concepts for as many different areas of biology as possible.
   Your essay will be marked not only for its scientific accuracy, but also for
     the selection of relevant material.
   The essay should be written in continuous prose not bullet points.
   Unless diagrams are clearly annotated they are a waste of time.

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Essays the titles from summer 2002

     The different ways in which organisms use ATP
     How the structure of cells is related to their function

The ways in which organisms use ATP
the role of ATP could have been described in:
    Muscle contraction
    Active transport
    Maintaining resting potential
    Re-synthesis of acetylcholine and rhodopsin
    Glycolysis of respiration
    Light independent reactions of photosynthesis
    Synthesis (anabolism)
    Kidney function
    Translocation
    Nitrogen fixation

At least 50% of candidates went into great detail about ATP production and
consequently lost 1 relevance mark.

Some candidates stated that what they were about to write was not a use, but
continued nevertheless.

The bombproof approach to writing your essay is to write 8 paragraphs, each
on a relevant scientific concept. If you wrote 4 paragraphs per page your
essay would be approximately two sides long. This is a good length. Aim to stay
under three sides if you go any longer you could be wasting time that you should
be spending on the other exam questions

How the structure of cells is related to their function

Many candidates were not clear what a cell is, confusing cells with:
   Organelles such as mitochondria and chloroplasts
   Tissues
   Organs
   Villi

Some students did not relate structure to function eg ‘red blood cells carry

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Common mistakes included the following
   Nerve cells – but did not relate length to function
   Blood cells – did not relate shape to function also must say red blood cells
    if you mean that
   Sperm – has a tail so it can swim is far too simplistic
   Ova – but no structural detail (should have said large reserve of nutrients
    for developing embryo)
   Epithelial cells –‘ have villi to increase the surface area for digestion’ – it
    should have been microvilli
   ‘Leaf cells’ – have a large SA for light absorption – should be palisade
    mesophyll cells shape for light absorption.
   Xylem – confusion between tissue and cell
   Phloem – same structure as xylem’
   Stomata – confused with guard cells

Students should have known 2 cells well from AS:

Intestinal epithelial
 Microvilli – increase S?A and uptake of products of digestion
 Site of enzymic breakdown of disaccharides
 Many mitochondria to release energy for active transport in the form of ATP
 Large extensive golgi bodies for mucus/enzyme secretion

Palisade mesophyll
 Cell wall – support/resistance to turgor
 Shape – uptake of light, CO2
 Chloroplasts – arrangement of grana
 Vacuole – turgor, economical deployment of cytoplasm

Marking Essays

Essays are marked on the following sections:
   Scientific Content /16
   Breadth /3
   Relevance /3
   QWC /3

Which makes the total marks available 25.

Based on the cells essay for 3 breadth marks candidates should refer to at least
6 different cell types including at least one plant

Tips for scoring breadth mark:
    Aim to use information from at least 2-3 different modules.
    Make sure you include plant information if appropriate.

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Students who write a paragraph about an irrelevant topic (such as detailed
biochemistry of respiration for the ATP question) will lose one relevance mark.


The essay should be structured in a reasonable logical way appropriate and
relevant to the title. Ideas and concepts should be explained sufficiently clearly
to be readily understood. Continuous prose should be used and sentences
should generally be complete and constructed grammatically. However, minor
errors of punctuation or style should not get penalized.

Appropriate A level terminology should be used. You should not use such
phrases as ‘fighting disease’ ‘messages passing along nerves’ enzymes being
killed etc but a single lapse would not necessarily disqualify.

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