Guide to Synoptic Biology



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St Mary’s Guide to

Synoptic Biology


Synoptic biology is the ability to select and apply general principles to unfamiliar situations/data.
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:

  • synoptic knowledge

  • data and investigations

  • essay

1. Synoptic knowledge


Which Synoptic subject knowledge topics are going to be assessed?
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

  • Membrane receptors

  • Movement across membranes

  • Enzymes

  • SA/Vol ratio

  • DNA/genetic code

  • Translation/transcription

  • Basic genetics

  • Genetic engineering

  • Transport principles

  • Use of tracers

  • Photosynthesis/respiration

  • Stimulus/response

  • Negative feedback

  • Variation

  • 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

2. Data and Investigations




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


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 histograms

  • 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:



  • Overview

  • Defining the question

  • Planning

  • Implementation

  • Data analysis

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



Overview

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

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 organisms.



Implementation

You should be familiar with the following methods of measurement:




  • Methods of measurement

  • Biochemical tests

  • Chromatography and Rf

  • Isotonic solutions

  • Indicators

  • Controlling temperature

  • Colorimetry

  • Dilutions

  • Safety measures

  • Replication

  • Centrifugation


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

Management Scheme

Population of meadow brown butterflies

2

1976

1983

Area X: Grazed by sheep in summer

435

415

0.47

Area Y: Grazed by sheep in winter

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

Probability

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



Question

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

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 source /km

Zinc concentration /mg dm-3

( mean & standard deviation)



3



4



10



13



22





Question

What is the range of the concentration of zinc

1 within 1 standard deviation at 4km

2 within 2 standard deviations at 22 km

Answers

1 at 4km; 0.7-2.5 mg dm-3

2 at 22 km; 0.032-0.48 mg dm-3

3. Essay

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.


Essays the titles from summer 2002





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 oxygen’


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.

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


QWC

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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