Download SNAB Topic 5 On the wild side

SNAB T5 Teaching scheme • page 1
SNAB Topic 5 On the wild side
This teaching scheme is divided into three parts.
• Introduction.
• Road map: a suggested route through Topic 5.
• Guidance notes for teachers and lecturers. These include a commentary that runs parallel
with the student book with hints and tips on teaching and references to the associated
activities.
Note: There are more detailed notes about individual activities in the teacher/lecturer sheets that accompany
most of the activities.
Introduction
The Road map starting on page 2 is a suggested route through Topic 5.
The learning outcomes are numbered as in the specification.
If two teachers/lecturers are sharing a group for Topic 5, the first could start at Session 1 with
the second starting at Session 11. This means that the second teacher would have a larger
chunk of the content. The first teacher could either start the next topic once they have done
sessions 1 to 10, or pick up the final sessions 21–23. Care must be taken to link back to the
context of climate change and the Arctic if the splitting of the topic is not to end up producing
a series of traditional style sub topics.
It is assumed that each session is approximately an hour in length. There are more activities
than can be done in the time available in most centres, so select a balanced collection
according to your and your students’ interests, and the time and resources available. Some
activities are labelled ‘Core’. Core activities contain experimental techniques included in the
specification, and may appear in questions on the unit exam for this topic. These learning
outcomes are in bold in the specification, and in the Road map grid below. They are
underlined in the Guidance notes below. In the Road map grid, activities are in italics if there
is an additional activity covering the same material more directly. Choose which activities
students complete, and substitute your own activities as appropriate.
There are various activities – particularly the interactive tutorials associated with some of the
activities – which could be completed by students outside of class time. These activities are
shown in the lower half of each ‘Possible activities’ box.
There is an A2 summary chart at the end of the guidance notes. This shows where concepts
are introduced and revisited in later topics. .
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This sheet may have been altered from the original.
SNAB T5 Teaching scheme • page 2
SNAB Road map: a route through Topic 5 On the wild side
Session Areas to be covered
Possible activities
1
Introductory presentation
(Interactive tutorial)
2
Ecosystems – abiotic and biotic
factors
Activity 5.1 The brine shrimp
ecosystem (A5.01L) (Practical)
10 Explain that the numbers and
distribution of organisms in a habitat
are controlled by biotic and abiotic
factors.
Checkpoint question 5.1
12 Explain how the concept of niche
accounts for distribution and
abundance of organisms in a habitat.
Studying ecosystems
3/4
11 Describe how to carry out a
study on the ecology of a habitat to
produce valid and reliable data
(including the use of quadrats and
transects to assess abundance and
distribution of organisms and the
measurement of abiotic factors,
e.g. solar energy input, climate,
topography, oxygen availability and
edaphic factors).
Succession
5
13 Describe the concept of
succession to a climax community.
Photosynthesis
6/7/8
3 Describe the overall reaction of
photosynthesis as requiring energy
from light to split apart the strong
bonds in water molecules, storing the
hydrogen in a fuel (glucose) by
combining it with carbon dioxide and
releasing oxygen into the atmosphere.
Activity 5.2 Looking for patterns
(Core) (A5.02L) (Practical)
Activity 5.3 Succession (A5.03L)
(Interactive tutorial)
Checkpoint question 5.2
Activity 5.5 Investigating
photosynthesis (Optional) (A5.05L)
(Practical)
Checkpoint question 5.3
Activity 5.4 Photosynthesis (A5.04L)
(Interactive tutorial)
Activity 5.6 How Calvin won the Nobel
prize (Optional) (A5.06L)
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5 Describe how phosphorylation of
ADP requires energy and how
hydrolysis of ATP provides an
immediate supply of energy for
biological processes.
4 Describe the light-dependent
reactions of photosynthesis including
how light energy is trapped by exciting
electrons in chlorophyll and the role of
these electrons in generating ATP,
and reducing NADP in
photophosphorylation and producing
oxygen through photolysis of water.
6 Describe the light-independent
reactions as reduction of carbon
dioxide using the products of the lightdependent reactions (carbon fixation
in the Calvin cycle, the role of GP,
GALP, RuBP and RUBISCO) and
describe the products as simple
sugars that are used by plants,
animals and other organisms in
respiration and the synthesis of new
biological molecules (including
polysaccharides, amino acids, lipids
and nucleic acids).
2 Describe the structure of
chloroplasts in relation to their role in
photosynthesis.
Energy flow in the ecosystem
9/10
11
7 Carry out calculations of net primary
productivity and explain the
relationship between gross primary
productivity, net primary productivity
and plant respiration.
Activity 5.7 Constructing food webs
(A5.07L)
Activity 5.8 Energy flow in an
ecosystem (A5.08L)
8 Calculate the efficiency of energy
transfers between trophic levels.
Checkpoint question 5.4
Evidence for climate change –
temperature records
Activity 5.9 Long datasets: the
importance of being trendy (A5.09L)
18 Analyse and interpret different
types of evidence for global warming
and its causes (including records of
carbon dioxide levels, temperature
records, pollen in peat bogs and
dendrochronology) recognising
correlations and causal relationships.
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Evidence for climate change – pollen
in peat bogs
12
18 Analyse and interpret different
types of evidence for global warming
and its causes (including records of
carbon dioxide levels, temperature
records, pollen in peat bogs and
dendrochronology) recognising
correlations and causal relationships
Activity 5.10 Pollen analysis (A5.10L)
(Interactive)
Evidence for climate change –
dendrochronology
13
18 Analyse and interpret different
types of evidence for global warming
and its causes (including records of
carbon dioxide levels, temperature
records, pollen in peat bogs and
dendrochronology) recognising
correlations and causal relationships
The link between carbon dioxide and
warming
14
15
16
17
14 Outline the causes of global
warming — including the role of
greenhouse gases (carbon dioxide
and methane, CH4) in the greenhouse
effect.
Activity 5.11 Tree ring studies
(A5.11L) (Interactive tutorial)
Activity 5.12 Do higher carbon dioxide
levels lead to warmer conditions?
(A5.12L) (Practical)
Activity 5.13 Carbon dioxide levels
and global temperatures (A5.13L)
Controversy surrounding the issue of
climate change
Activity 5.15 Who is right? (A5.15L)
Optional
20 Discuss the way in which scientific
conclusions about controversial
issues, such as what actions should
be taken to reduce global warming or
the degree to which humans are
affecting global warming, can
sometimes depend on who is
reaching the conclusions.
Activity 5.14 Global warming – fact or
fiction? (A5.14L)
Climate modelling
Activity 5.16 Global warming model
(A5.16L) (Interactive tutorial)
19 Describe that data can be
extrapolated to make predictions, that
these are used in models of future
global warming, and that these
models have limitations. (Activity 5.16)
Effect of climate change on flora and
fauna – distribution
Student research on changing
distribution of species using book and
Internet.
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18
15 Describe the effects of global
warming (rising temperature,
changing rainfall patterns and
changes in seasonal cycles) on plants
and animals (distribution of species,
development and life cycles).
Activity 5.17 Coral bleaching (A5.17L)
Optional
Temperature and enzyme activity
Activity 5.18 Investigating the effect of
temperature on enzyme activity
(A5.18L) (Practical)
16 Explain the effect of increasing
temperature on the rate of enzyme
activity in plants, animals and microorganisms.
Effect of climate change on flora and
fauna – development
19
17 Describe how to investigate the
effects of temperature on the
development of organisms (e.g. seedling
growth rate, brine shrimp hatch rates).
Effect of climate change on flora and
fauna – life cycles
20
21 Describe how evolution (a change
in the allele frequency) can come
about through gene mutation and
natural selection.
23
Activity 5.20 The effect of
temperature on the hatching
success of brine shrimps (Core)
(A5.20L) (Practical)
Activity 5.19 Effect of climate
manipulations on a grassland
community (Core) (A5.19L)
(Practical)
Activity 5.21 Are insects emerging
earlier? (A5.21L) (Interactive tutorial)
15 Describe the effects of global
warming (rising temperature,
changing rainfall patterns and
changes in seasonal cycles) on plants
and animals (distribution of species,
development and life cycles).
Evolution by natural selection –
molecular evidence
21/22
Checkpoint question 5.5
Checkpoint question 5.6
Activity 5.23 Evolution revealed
(A5.23L)
Activity 5.22 Debunking the myth of
the polar bear hair (A5.22L)
23 Describe the role of the scientific
community in validating new evidence
(including molecular biology, e.g.
DNA, proteomics) supporting the
accepted scientific theory of evolution
(scientific journals, the peer review
process, scientific conferences).
Speciation
Activity 5.24 Speciation (A5.24L)
22 Explain how reproductive isolation
can lead to speciation.
(Interactive tutorial)
The carbon cycle
Activity 5.25 The carbon cycle
(A5.25L)
9 Discuss how understanding the
carbon cycle can lead to methods to
Checkpoint question 5.7
reduce atmospheric levels of carbon
dioxide (including the use of biofuels
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reforestation).
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24
SNAB T5 Teaching scheme • page 6
dioxide (including the use of biofuels
and reforestation).
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SNAB T5 Teaching scheme • page 7
Guidance notes for teachers and lecturers
There are no GCSE style reviews and tests at the start of the A2 topics.
Introduction
The context for this topic is climate change; this builds on ideas covered in Topic 4 about
threats to biodiversity. The topic focuses on the evidence for climate change and the possible
consequences for both plants and animals. The introductory spread considers the classic
example of the polar bear and associated species in the threatened Arctic ecosystem.
The interactive introductory presentation provides an overview of the topic. This presentation
is best used as an out-of-class activity if time is likely to be limited. It raises many of the
issues that are considered in the topic.
There is no introductory activity but an excellent introduction to this issue would be to show
the first episode in the BBC series Nature’s Great Events. This David Attenborough narrated
programme is about the effects of the annual melt on a range of different species including
the Polar bear; it goes on to consider the potential impact of climate change.
5.1 What is an ecosystem?
Before considering the potential impact of climate change it is necessary to understand what
an ecosystem is, and how it functions. In the text book ecosystems and the various
ecological terms used to describe their components are discussed, followed by a more
detailed consideration of abiotic and biotic factors. Students could be asked to make a table
of definitions for the terms. It should quickly become clear that producing a simple definition
for ‘ecosystem’ is not straightforward. It could be defined as ‘a relatively self-contained,
interacting community of organisms and the environment in which they live and with which
they interact’. In the textbook this is initially illustrated using the brine shrimp ecosystem. The
term ecosystem itself does not appear in the specification but habitats and the role of abiotic
and biotic factors are included.
Activity 5.1 The brine shrimp ecosystem (A5.01L)
The brine shrimp ecosystem could be used as a demonstration of an ecosystem at the start
of this section. This activity lets students identify the key components of an ecosystem and
investigate the effects of altering conditions. Enthusiasts could complete the investigation
aspects of this activity outside of lessons, rather than using limited class time.
Students need to be able to describe how to carry out a study on the ecology of a named
habitat and also to explain that the numbers and distribution of organisms in a habitat are
controlled by biotic and abiotic factors. There is a link back to niche in Topic 4, students need
to explain how the concept of niche accounts for distribution and abundance of organisms in
a habitat; this is linked to Checkpoint question 5.1. It is highly desirable for students to obtain
first-hand experience of practical fieldwork. This can be a full-scale field course or a smallscale trip onto a school/college field or to the local park. The latter may not provide the
opportunity to relate many biotic and abiotic factors to organism distribution but it should
provide students with experience of ecological studies.
Activity 5.2 Looking for patterns (A5.02L) Core practical
This core activity encourages students to plan a field investigation and outlines some
techniques for investigating plant and animal distribution.
The idea of adaptations allowing organisms to cope with the conditions that prevail in a
particular habitat introduced in Topic 4 is revisited here. In the textbook this is illustrated
using the rocky shore with some examples of the organisms that are found on different parts
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SNAB T5 Teaching scheme • page 8
of the shore. There is a virtual rocky shore tour on the British Ecological Society website; the
website can be found in the weblinks that accompany activity 5.2.
Students need to be aware that ecosystems are not static but continually changing. The
textbook goes on to consider succession.
Activity 5.3 Succession (A5.03L)
This activity suggests a variety of possible approaches to look at succession. The interactive
tutorial takes students through the process and they complete the accompanying student
sheet to provide a summary of succession. At the end of the interactive tutorial, students
analyse sand dune data provided within Fieldworks software. Please note that this software
can only be used for the data provided; new data cannot be entered. The student sheet also
suggests some fieldwork options to enable students to apply the ideas seen in the interactive
tutorial and realise that at a given time only a snapshot of an on-going process is available. A
fieldwork study undertaken by A level students is also described; this case study includes
questions and could be used as a homework exercise.
Checkpoint question 5.2 requires students to compare primary and secondary succession
and explain what is meant by deflected succession.
5.2 Ecosystems rely on energy transfer
The section begins by linking back to the Arctic ecosystem, before going on to look at how an
ecosystem works in terms of energy, including photosynthesis and the transfer of energy.
The overview of photosynthesis first considers the process in terms of making and breaking
bonds and the energy levels of the reactants and products. It then focuses on the underlying
principles that hydrogen is removed from water by photolysis and is ‘stored’ within an organic
fuel until the energy it contains is required, and is then released by reacting the hydrogen
and oxygen in respiration.
The textbook goes on to describe the reactions of photosynthesis; there may appear to be
less detail than might sometimes be taught at A level. The aim is for students to concentrate
on the key features and not get bogged down with detail that can lead to confusion. For
example, neither the textbook nor the interactive tutorial presents the light-independent
reactions as a Z-scheme; instead the fundamental idea of transfer of electrons leading to
formation of ATP and reduced NADP is stressed. For the more ambitious, the Z-scheme is
included in an extension sheet. Respiration appears in Topic 7 and at that point we build on
the material presented here in Topic 5, extending understanding of electron transfer by
adding the chemiosmotic theory.
There are three activities and two extensions associated with the photosynthesis section.
The first, Activity 5.4, is an interactive tutorial with associated worksheets to guide the
student through photosynthesis. If time permits, Activity 5.5 provides a practical opportunity
to reinforce the ideas. Activity 5.6 can be used to confirm understanding of photosynthesis.
The specification does not require students to have looked at the structure of the leaf, which
is covered in on of the extensions, but they do need to be able to describe the structure of
chloroplasts in relation to their role in photosynthesis.
Activity 5.4 Photosynthesis (A5.04L)
This interactive tutorial takes students through both the light-dependent and lightindependent reactions. There are extensive worksheets that aim to focus students on the
relevant concepts as they complete the activity and, on completion, provide summary
diagrams and notes.
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Extension 5.2 Leaf structure and function (X5.02L)
This extension relates photosynthesis to the structure of leaves. This is not required
knowledge for the Topic 5 specification but should help students recall aspects of Topic 4
such as plant cell structure, lignification for strengthening, and the role of the xylem vessels.
Extension 5.3 Light-dependent reactions for the more ambitious (X5.03L)
This extension provides a more detailed account of the cyclic and non-cyclic
phosphorylation; these terms are not included in the specification.
Activity 5.5 Investigating photosynthesis (A5.05L) Optional
This practical uses extracted chloroplasts to show the reduction that occurs in the lightindependent stage of photosynthesis. Interpretation of the results should confirm students’
understanding of the reactions in photosynthesis.
Activity 5.6 How Calvin won the Nobel prize (A5.06L) Optional
The experimental techniques used by Calvin to elucidate the reactions of photosynthesis are
described. Students apply their knowledge of photosynthesis when interpreting simplified
results.
The textbook goes on to consider the transfer of energy through the ecosystem. It starts with
feeding relationships and although these are not stated as a learning outcome in the
specification, they underpin the ideas of transfer of energy in an ecosystem. Food chains and
webs seem to be covered at every key stage and so this is really recall from KS3 and KS4. A
very brief reminder might be all that is needed in class to confirm students’ understanding of
trophic levels and introduce any new terminology; they may not be familiar with autotrophs
and heterotrophs. Checkpoint question 5.4 could be used in a subsequent session to check
learning.
Activity 5.7 Constructing food webs (A5.07L)
The textbook describes the terminology associated with feeding relationships and this activity
is a simple paper-based exercise in which students draw out a food web based on a series of
feeding relationship statements. There are suggestions in the teacher/lecturer notes for video
and CD-ROM resources that could be used here. This activity can be completed out of class.
Activity 5.8 Energy flow in an ecosystem (A5.08L)
The textbook defines gross and net primary productivity before discussing the efficiency of
energy transfer. This activity complements the textbook, looking at the energy budget of a
bullock and at energy flow through an ecosystem.
5.3 Is the climate changing?
The topic now moves on to climate change. It first looks at the scientific evidence for climate
change both in the past and present. Each type of evidence described in the textbook is
accompanied by an activity.
Activity 5.9 Long datasets: the importance of being trendy (A5.09L)
The activity looks at long-term temperature records; it also aims to give students practice in
interpretation of data presented in graphical form. Q5.23 in the textbook also appears in the
activity.
Activity 5.10 Pollen analysis (A5.10L)
The textbook describes the process of pollen analysis and how it provides evidence for
changes in climate. In this activity students examine a virtual sediment sample. The student
sheet can be completed using either the interactive version or the downloaded pollen and
tree information sheets.
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SNAB T5 Teaching scheme • page 10
Activity 5.11 Tree ring studies (A5.11L)
This activity has an interactive tutorial showing how tree ring studies can be used to help
date old wood and deduce past climates.
Putting the data together
The final part of this section in the textbook brings together the different sources of evidence
to provide a picture of conditions over more than 100 000 years, with the changes in
atmospheric temperature over the last hundred years provided in more detail. The Climate
Research Unit at the University of East Anglia regularly updates the temperature data on
their website. A weblink to the site can be found in the weblinks that accompany Activity 5.9.
Students need to look at the graphs and realise that we are in a period of rapid global
warming although this is not the only period of warming in the past.
5.4 Why are global temperatures changing?
The role of the atmosphere in maintaining warm, stable temperatures on Earth is described
at the start of this section. Students should be familiar with this from KS4 so a spot test/quiz
should be sufficient to refresh memories. A diagram with missing information could be used.
Activity 5.12 could be introduced before it is completed in the next session. Activity 5.13
could be started prior to the practical and completed as a homework assignment.
Carbon dioxide is often held up as the culprit in current global warming. The experiment in
Activity 5.12 helps investigate whether raised levels of carbon dioxide can lead to
atmospheric warming. The textbook compares carbon dioxide with other gases, showing that
it is not only carbon dioxide that is involved in global warming.
Activity 5.12 Do higher carbon dioxide levels lead to warmer conditions? (A5.12L)
‘Milk’ bottles are used in this experiment to investigate if there is a link between carbon
dioxide and warming. The experiment on the student sheet describes how datalogging can
be used but the experiment can also be undertaken using conventional thermometers.
Activity 5.13 Carbon dioxide levels and global temperatures (A5.13L)
Students gain more experience comparing and interpreting a range of graphs and discuss
possible relationships between atmospheric carbon dioxide levels and global warming.
A controversial issue
The reasons why climate change is controversial are described in the textbook, which
highlights the idea that scientific conclusions about controversial issues can sometime
depend on who is reaching the conclusion. The activities provide the opportunity to evaluate
writing published about the issue of global warming.
Activity 5.14 Global warming – fact or fiction? (A5.14L)
The first part of this activity provides a framework for evaluating the views expressed in
published articles. The articles in Activity 5.15 could be used for this part of the activity
although some shorter recent articles would be better. Students do not have to learn the
statements in the grid; rather, they need to realise that information presented may be
influenced by the position held by the individual or organisation expressing the view. The
information from the CO2 Climate Resource Centre on the archived Greening Earth Society
website which illustrates this point could be downloaded and used as handouts if Internet
access is difficult. The second half of the activity involving Internet research can be quite time
consuming.
Activity 5.15 Who is right? (A5.15L) Optional
This discussion-based activity can be an alternative to the previous activity.
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5.5 Predicting future climates
This section of the textbook discusses the ideas behind extrapolation and prediction. It allows
students to use a computer model of climate change and consider the limitations of such
models.
Activity 5.16 Global warming model (A5.16L)
This interactive model gives students the chance to appreciate the complexity of climate
modelling.
Scientists undertaking research into climate change use several models. Predictions from
these models can be seen at the University of East Anglia Climate Research Unit and the
Meteorological Office Hadley Centre websites. Weblinks accompany Activity 5.16. Some
computer models give very different predictions of climate change; this is referred to in the
textbook in the section titled ‘Climate model predicts a colder UK’. This highlights the fact that
there are no definitive answers as yet, only predictions based on models derived using
available evidence.
5.6 Coping with climate change
This section considers the effects of climate change on flora and fauna (plants and animals).
It is divided into two parts; the changing distribution of species and the effects on
development and life cycles.
Activity 5.17 Coral bleaching (A5.17L) Optional
This activity provides a detailed example of one group of animals that appear to be affected
by climate change. The activity uses the US Department of Commerce sea surface records
to investigate the occurrence of coral bleaching and the potential link to global warming. The
US National Oceanic and Atmospheric Administration NOAA/NESOIS website is constantly
updated and if the link does not immediately go to the appropriate page, look for coral
bleaching which has a link to the 1998 data.
Extension 5.5 (X5.05S) looks at how the extinction of the dinosaurs may have been caused
by climate change. The first page of the activity can also be used when introducing the idea
that scientific theories must be supported by evidence. There is an excellent article in New
Scientist covering the major theories for the extinction of the dinosaurs: Ravilious K. (2002)
Killer blow. New Scientist, 2341, 28–31.
Changing distribution of species
There is evidence that the distribution of species will change as a result of global warming
with (in the northern hemisphere) a northwards shift. The textbook gives some examples of
changing species distribution and raises some of the problems that may result. Students
could be asked to research species for themselves using the Internet and share their findings
with the group.
The effects of rising temperature on plant growth and photosynthesis are discussed in
relation to the effect of temperature on enzymes involved in photosynthesis. A Key biological
principle box describes the effect of temperature on enzyme activity and there is an
associated activity.
Activity 5.18 Investigating the effect of temperature on enzyme activity (A5.18L)
The student activity sheet is a planning sheet for an investigation on the effect of temperature
on catalase activity. A suggested experimental set-up is included in the teacher/lecturer
notes.
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SNAB T5 Teaching scheme • page 12
Activity 5.19 Effect of climate manipulations on a grassland community (A5.19L) Core
practical
The activity describes the experimental design of a field investigation into the effects of
different temperature and rainfall conditions on the growth of grassland plants. The research
data are from the Unit of Comparative Plant Ecology at the University of Sheffield, kindly
supplied to us by Professor Philip Grimes. The activity highlights the difficulty of predicting
ecological consequences because of interacting factors. This is also discussed in the
textbook. Students can see the experimental plots at Buxton, near Sheffield, via their
webcam. This activity can be used to for the core practical requirement of specification point
17 Describe how to investigate the effects of temperature on the development of organisms (e.g.
seedling growth rate, brine shrimp hatch rates).
Activity 5.20 The effect of temperature on the hatching success of brine shrimps
(A5.20L) Core practical
The experiment in this activity is likely to show a fairly straightforward relationship between
temperature and hatching success. This activity can be used as the core practical for the
learning outcome 17 Describe how to investigate the effects of temperature on the development of
organisms (e.g. seedling growth rate, brine shrimp hatch rates).
Activity 5.21 Are insects emerging earlier? (A5.21L)
The effects of global warming on seasonal events are investigated using an online datasets
for the first appearance of insect species and mean flight times, and the UK phenology
website interactive garden. The need for long-term data to provide evidence of changes in
seasonal events is emphasised in the textbook.
Checkpoint 5.5 requires students to summarise the effects of climate change on plants and
animals.
5.7 Adapt or die
Linking back to polar bears and whether they will cope with the changing conditions,
adaptation and evolution by natural selection are revisited. The textbook outlines Darwin’s
observations and conclusions to summarise his theory. The text links back to the ideas
presented in Topic 4 about evolution as a change in allele frequency over time. It may be
sufficient to recall the ideas using Checkpoint 5.6, this requires student to explain how
natural selection can lead to evolution. The text book goes on to discuss the role of the
scientific community in validating new evidence, this is linked to the work of Darwin but the
principles remain the same for molecular evidence for evolution. This evidence is described
in the textbook.
Activity 5.22 Debunking the myth of the polar bear hair (A5.22L)
This activity is a discussion style activity based around a series of statement cards. The
statements are linked to adaptations of polar bears, it includes the much published idea that
Polar bear hairs act as fibre optics transferring energy through their hollow shaft to the skin
surface. This suggestion was not based on experimental evidence and the aim of the activity
is to get students to appreciate the process of validating evidence. The associated
specification point is not about polar bear hair, but concerned with molecular evidence for
evolution. This type of How Science Works outcome can appear in any context within the unit
papers so presenting it in one context and then referring to it again in Activity 5.23 will help
prepare students for questions on HSW that are not presented in the obvious context
presented in the specification statement.
Activity 5.23 Evolution revealed (A5.23L)
The amino acid sequence of cytochrome C is used to illustrate molecular evidence for
evolution. Students are also referred to the DNAtoDarwin which uses case studies to explore
DNA sequences evidence for evolution. The idea of validating new evidence should be linked
to in this activity.
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SNAB T5 Teaching scheme • page 13
The text book questions whether climate change will result in the formation of new species
and discusses speciation.
Activity 5.24 Speciation (A5.24L)
The interactive tutorial accompanying this activity presents an example of reproductive
isolation leading to speciation. Students work through the tutorial and then write a summary.
5.8 Getting the balance right
There is no traditional detailed description of the processes in the carbon cycle within the
textbook. As most students are likely to have come across the carbon cycle in previous
courses and in the GCSE review it was felt that a lengthy account was not required. There is
a Key biological principle box that contains a carbon cycle diagram and the accompanying
question provides definitions of the processes involved in the cycle. The aim is to encourage
a more thoughtful approach; the student must look at the carbon cycle diagram and think
about the cycle.
Activity 5.25 The carbon cycle (A5.25L)
In this activity students are made aware of the size of the different carbon fractions by
calculating their percentage of the total carbon in the global ecosystem. The students then
construct a carbon cycle diagram. There are questions about the movement of carbon
through the different carbon reservoirs. The activity seeks to encourage students to think
about the carbon cycle in a way that moves on from anything done at GCSE.
The School Science review article ‘Making the invisible visible: monitoring levels of gaseous
carbon dioxide in the field and classroom. By Roger Delpech’ uses CO2 sensors and dataloggers to monitor CO2 levels in a range of situations.
Factors that upset the carbon balance are described in the textbook and reforestation and
the use of biofuels as methods to maintain the balance are discussed. Students do not need
to know the detailed production or chemistry of biofuels. Checkpoint 5.7 requires student to
think through the pros and cons of the methods discussed.
Activity 5.26 Check your notes
Students can use the checklist of learning outcomes in this activity in their revision.
End-of-topic tests
There is an online interactive end-of-topic test. This test is not accessible to students unless
set by their teacher/lecturer. There is also a paper-based test for Topic 5 with examinationstyle questions. A mark scheme is also available. The questions are similar in layout and
style to those that are found on exam papers. However, the restriction of questions to only
one topic in each test has meant that it has not been possible to include some types of
questions that draw on material from different topics.
Salters-Nuffield Advanced Biology, Pearson Education Ltd 2009. © University of York Science Education Group.
This sheet may have been altered from the original.