NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Biology
Inheritance
Advice and Guidance
for Practitioners
[NATIONAL 5]
This advice and guidance has been produced to support the profession with the delivery of
courses which are either new or which have aspects of significant change within the new
national qualifications (NQ) framework.
The advice and guidance provides suggestions on approaches to learning and teaching.
Practitioners are encouraged to draw on the materials for their own part of their continuing
professional development in introducing new national qualifications in ways that match the
needs of learners.
Practitioners should also refer to the course and unit specifications and support notes which
have been issued by the Scottish Qualifications Authority.
http://www.sqa.org.uk/sqa/34714.html
Acknowledgement
© Crown copyright 2012. You may re-use this information (excluding logos) free of
charge in any format or medium, under the terms of the Open Government Licence.
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Where we have identified any third party copyright information you will need to
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Any enquiries regarding this document/publication should be sent to us at
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This document is also available from our website at www.educationscotland.gov.uk.
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Contents
Planning for Learning and teaching: inheritance
Introduction: Setting the scene in a Scottish context
Curriculum for Excellence
6
8
Learning in demand
10
Inheritance
11
Exemplification of learning and teaching
The Human Genome Project
DNA separation
Details for DNA separation
DNA structure
Darwin’s natural selection
Natural selection in mice
Reproduction and inheritance
12
12
14
16
17
18
20
24
Further research
27
Skills for learning, skills for life and skills for work
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Planning for Learning and Teaching: Inheritance
This advice and guidance is intended for use by practitioners. It is non mandatory. It is anticipated that practitioners will be creative and innovative
in planning approaches to meeting the needs of lear ners. This advice and
guidance should be used in a reflective and selective manner.
Reflective questions for learners are provided to aid practitioners in planning
learning and teaching to meet the needs of learners. These questions are
intended for practitioners’ use in the identification of big issues,
consideration of which underpins the learning and teaching for this context.
In many cases, investigative work and inquiry-based practical learning will
supplement the learning and teaching described here .
This advice and guidance suggests a context for learning and ideas for
learning and teaching offering opportunities to prepare learners in the
mandatory course key areas for National 5 Biology. These key areas are as
follows.
Multicellular organisms: reproduction and inheritance
 Identify phenotype and homozygous/heterozygous genotype of individuals
from family trees.
Multicellular organisms: health and disease
 The effect of lifestyle choices, environment and heredity on health .
Cell biology: DNA, production of proteins and genetic engineering
 Structure of DNA: double-stranded helix held by complementary base
pairs.
 Transfer of genetic information and genetic engineering .
Life on Earth: adaptation, natural selection and the evolution of species
 Mutation, variation, selection and the evolution of species .
 The role of adaptation for increased survival .
 Natural selection and speciation through isolation and selection .
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There are also opportunities for linking to other curriculum areas , for
example:
Geography: It may be possible to consider the global geographic spread of
inherited diseases and relate this to the movement of the population.
Modern Studies: The debate regarding ‘saviour siblings’ in response to
inherited disease may be explored. The Glow Science Saviour Siblings pages
may be useful for this discussion.
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Introduction: Setting the scene in a Scottish context
Every six minutes, someone dies from a heart attack – that is 10 people every
hour. Every year 94,000 of them die. Every day 179 people lose one of their
parents to a fatal heart attack.
Cancer, heart disease and strokes have long been known as the three big
killers for their prevalence in Scottish fatalities over a number of years.
Furthermore, since 1996, the number of people with diabetes in the UK has
increased from 1.4 million to 2.6 million. By 2025, it is estimated that deaths
due to diabetes in the UK will increase to 4 million.
Realising the importance of genetics in Scotland’s health, the Scottish
Government commissioned a study entitled Our Inheritance, Our Future:
Realising the potential of genetics in the NHS . It advised that advances in
genetics will have a profound impact on healthcare and radically alter the
approach to disease prevention, diagnosis and treatment.
Nothing in biology makes sense except in the light of evolution .
Theodosius Dobzhansky (American Biology Teacher, Vol. 35, pp 125–129,
1973)
The story starts with Darwin, and his connections with Scotland must not be
overlooked: his early studies around the Firth of Forth whilst a student at the
University of Edinburgh, along with his first presentation in Edinburgh on his
observations of sea shore creatures, surely shaped his career path.
Furthermore, after completing his famous voyage on the Beagle, Darwin
embarked on a less well known Scottish expedition in 1838, travelling via
Glasgow, Edinburgh, Loch Leven and Glen Roy. On describing his Scottish
travels, he said that it had been ‘by far the most remarkable area I ever
examined’. Darwin was undoubtedly influenced by Scottish scientists at the
time, such as botanist Joseph Hooker, who was educated at the University of
Glasgow, and also Charles Lyell, who supported his theories on natural
selection.
Although there has been a tremendous revolution in the biological sciences in
the past 20 years, there is still a great deal that remains to be discovered. The
completion of the sequencing of the human genome has increased
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immeasurably the possibilities of genetic research. Although there is
currently no cure for diabetes, scientists working in the field of genetic
engineering and gene therapy have made considerable progress towards that
goal. Given the prevalence of diabetes in Scotland, the relevance of this area
of work to learners cannot be questioned.
It is vital that learners are well equipped to make informed decisions
regarding topical developments in genetic science. Over the past decade,
approximately 25,000 genes in human DNA have been identified, catal ogued
and stored along with the three billion base pairs that make up DNA. The
debate over who should acquire or even profit from this kind of information
is a long-standing one that requires knowledge of the many possible benefits
and concerns. Due regard has therefore been given to allow learners to
explore aspects of arguments such as those regarding drug development, the
human genome project, and inheritance and disease.
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Curriculum for Excellence
Curriculum for Excellence supports the developme nt of relevant careers skills
in many ways:
 The driving force behind
Curriculum for Excellence is that
it is a curriculum for learning,
life and work, and it should fully
equip learners with the skills,
knowledge and confidence to
thrive and succeed in the
increasingly globalised world of
the 21st century
 The development of skills within
learners is at the heart of
Curriculum for Excellence in
recognition of the fact that, in a
fast-changing world, skills will allow learners to adapt to changing
circumstances and are the key to success. These include the entire
spectrum of skills from leadership to interpersonal skills to career
management skills. Building the Curriculum 4 gives further information
about the importance of skills within Curriculum for Excellence and how
they have been embedded within the experiences and outcomes for all
learners, from which the skills within the learning for National 4 should
progress. The Skills for Learning, Skills for Life and Skills for Work
Framework will also aid your planning to meet the needs of learners.
 Interdisciplinary learning is a key aspect of Curriculum for Excellence a nd
is an exciting way for schools to develop rich learning experiences that
build upon the strengths and expertise within different disciplines. T opics
such as Inheritance and Health can be used as complex themes for
interdisciplinary learning or taught within the biology context to link with
wider learning. These also offer excellent vehicles for learners to develop
higher-order thinking skills and prepare learners for the life of work where
interdisciplinary approaches to complex tasks are often the norm.
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 Curriculum for Excellence encourages approaches to learning that are
motivational, fun, relevant, challenging and, importantly, develop the
skills of learners. Such approaches to learning include co-operative, active,
collaborative and outdoor learning.
There are many ways in which this learning journey can develop, and you
will know best how to plan learning and teaching that meets the needs of your
learners. By planning opportunities for skills development in context you may
find that the learners’ interests, strengths, prior learning and locality, as well
as local, national and global events, lend themselves to progressing learning
in different ways from the suggestions within this advice and guidance. Ideas
for learning and teaching can be adapted to allow development and
application of skills for learning, life and work, or to incorporate ICT and
take account of a range of learners’ needs.
GLOW provides an opportunity for learners to work together across
geographical areas.
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Learning in demand
Scotland is an internationally recognised research and bio -manufacturing
base and renowned service centre, facilitating numerous clinical trials and
bringing innovative drug products to market readiness. Over 625
organisations and 31,000 employees make up Scotland ’s powerful life
sciences industry.
Talent Scotland, Welcome to Life Sciences
The life science industry is one which is highlighted whenever Scotland’s
health and future are mentioned. Further research of the main common adult
diseases that are a major cause of ill-health in Scotland is suggested to be
vital. The greatest impact of new genetics knowledge on healthcare in the
shorter term is believed to come from developments in pharmacogenetics.
These may take the form of research, development of new interventions and
their implementation and evaluation. In 2011 the University of Dundee
opened a new £3.2 million cancer research centre, The Pat McPherson Centre
for Pharmacogenomics and Pharmacogenetics.
Given the current concerns regarding sustainability and climate change,
genetic studies of organisms and their patterns of inheritance will prove vital
to monitoring and identifying the effects which human developments are
having on them. Environmental research provides another avenue of
employment through the areas of conservation, species survival and
protection. This may be through government organisations such as
Department for Environment, Food and Rural Affairs DEFRA and businesses
or charities such as the Foundation For Endangered Species (FES) and the
World Wildlife Fund (WWF).
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Inheritance
Put simply, inheritance is the passage of genes from parents to their
offspring.
Genetics is the branch of science that deals with the study of genes, patterns
of heredity and the variation amongst organisms. Although all built around
the key principles first discovered by Darwin and Mendel and then developed
further by Watson and Crick, there are many avenues which the study of
inheritance now takes.
These include:




molecular genetics: studies the structure and function of DNA at a
molecular level
population genetics: studies the distribution and frequency of genes in a
population
genomics: studies the large-scale genetic patterns amongst a species
ecological genetics: studies the genes of natural populations of organisms
with reference to their environment.
Bionewsonline sets out the key definitions of inheritance along with a time
line of notable scientific discoveries on the topic.
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Exemplification of learning and teaching
The Human Genome Project
The Human Genome Project, completed in 2003, allows scientists to read the
complete blueprint for a human being. This provides a rich context for
exploring ideas of inheritance and heredity, incorporating topical science and
the opportunity to increase learners’ scientific literacy: assessing evidence to
express an informed opinion. The National Human Genome Research Institute
provides a range of resources that might be useful for adaptation for your
learning and teaching. The Wellcome Trust page on the Human Genome
provides in-depth files linking to developments and articles for a range of
issues, e.g. asthma, cancer, chromosome disorders, key legislation and drug
discovery.
The idea for learning and teaching included here could be used as a starter or
a plenary for learners’ work around this topic, with the aim of developing
learners’ appreciation of the implications of increased knowl edge of our
DNA.
The start point for this idea is a video called The Chosen Child: Screening
Genetic Content (click on Genetics/Heredity). This provides an introduction
to the Human Genome Project and what it has achieved.
The activity described here is a washing line activity, which is a useful
technique for stimulating discussion and deepening understanding.
Approximately 0.5–1.0 m of wool or string can be used to create a washing
line above the bench. One end of the wool should be labelled ‘+’ (positive),
the middle ‘0’ (neutral) and the other end ‘–’ negative.
Each learner in the group should take a sticky label, wri te his/her own name
on it and affix it to the line using a clothes peg, with the following meaning:
‘+’: absolutely clear that I should all know all the details of my genetics and
this should be available to others
‘0’: neutral – neither for nor against
‘–’: against anyone knowing about my genetics, including me.
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A number of statements (some are suggested here) to stimulate discussion
should be prepared within a bag or a box so the learners choose at random.
Each learner should take a turn to select a st atement, read it out to the others
in the group and discuss. The learner who chose the statement should then
decide on the importance of the statement to his/her own personal opinion
and decide whether he/she should move his/her own named clothes peg as a
result.
This activity could be used in a different way, where each individual
examines a number of statements, moves his/her named clothes peg and then
each person discusses the statements they considered and justify why this
resulted in a move of clothes peg or not.
It should become clear from this that in some aspects learners feel differently
about the use of genetics compared with other aspects, and that there is no
clear-cut answer. This could lead on to exploration of how scientific
advancement is legislated, and the potential benefits and risks of either overly
lax or overly stringent regulation.
Suggested statements:
 Health insurance will exclude/not pay for certain treatments if you are
genetically predisposed to them.
 The NHS will scan you for certain diseases earlier if you are found to be
genetically likely to get that condition.
 Employers may want to see your genome before offering you a job, to
make sure you don’t carry or are likely to suffer from any possible
inherited diseases.
 The police may choose to segregate and lock up certain people who have
the genetic potential for violent characteristics .
 You may not be allowed to have children if you carry genes for certain
dangerous characteristics.
 You may be denied a mortgage due to a genetic medical condition and thus
never be able to own your own home.
 If you are more aware of certain hereditary diseases earlier, you may be
able to spot them sooner.
 If you know you carry a gene for a hereditary disease, you can take steps
to prevent it developing earlier.
 Doctors can better determine appropriate drug therapies for individuals
based on genetic information (pharmacogenetics) .
 Parents can find out if their unborn child has any genetic diseases .
 Knowing a person’s genetics can help them to make a more informed
decision about how to live their life.
 Knowing more about the changing genetics of the human population can
help us to predict changes that might occur in the future .
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 Certain religions and cultures are against genetic screening as they be lieve
the future in is God’s hands.
 The people who hold genetic information may be subject to bribery and
corruption.
 People who have greater likelihood for genetic diseases may be charged
more in tax.
 Funding for the project may mean that less money is sp ent on the NHS
looking after sick people.
 Knowing things about your health can lower anxiety/stress levels for some
people.
 Testing may become commercialised and interpretation of the results is not
always clear cut.
There are a number of routes to build further on this activity. Washing lines
could remain in place and as learners’ knowledge and understanding develops
through the topic they could continue to move the pegs. Each lesson or each
week, one learner who has moved a peg could be asked to summarise why
he/she chose to do so; another who has not could be asked to justify this
choice.
Learners could also use the statements as a basis for further work. To what
extent are the statements true at this time, based on current science ? To what
extent is the suggestion a likely reality for the future? The US Department of
Energy Office of Science Human Genome Project Information provides
information on gene testing, including regulation. Once the learners have
completed further work, all the statements could be revisited and grouped
into arguments for genetic information being shared and arguments against.
Learners could use a Glow blog or a Wiki to construct a website that gathers
scientific evidence around one or more issues, including how legislation
controls the misuse of scientific advancement, in a Scottish context.
Alternatively, a global look at the viewpoints of different countries on
genetic testing and the genome project might provoke further discussion and
deepen understanding of the potential issues.
The University of Utah’s Learn Genetics site includes a variety of ideas for
developing learning and teaching, eg Gene Therapy: Molecular Bandage.
DNA separation
Aspects of the protocol described in the resource have been adapted from
materials provided by the biology team at the Scottish Schools Education
Research Centre (SSERC). In most cases such materials are available via one
of SSERC’s websites (www.science3-18.org) or on request via e-mail
sts@sserc.org.uk.
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SSERC has developed similar suggestions for this experimen t using different
themes. The following links contain their suggested activities, experimental
protocol and diagrams of equipment set -ups that may prove helpful to those
unfamiliar with this experiment:
Wonderful Wizardry Finding a Gene
Wonderful Gene Wizardry
Food Dyes and Electrophoresis
This idea, which incorporates investigative work, is intended to offer
opportunities to develop learners’ understanding of the terminology of
chromosomes, DNA and genes and their relative sizes.
A CSI style scenario can be used to set the scene for learners. An outline of a
body may be chalked onto the floor or marked out with tape. Ideally, a name
tag or a teacher’s identification tag may be left on the outline for effect. ‘Do
not Enter’ tape may be placed across the doorway to add to the setting.
Learners can be instructed that the kidnapping of a teacher has taken place.
The last time he/she was seen was in this room. The kidnapper left the outline
as a taunt and it is up to the learners to solve the mystery. This will involve
them learning about the structure of cells in greater detail.
This work should offer progression from the broad general education.
I have extracted DNA and understand its function. I can express an informed
view of the risks and benefits of DNA profiling. SCN 3-14b
I can use my understanding of how characteristics are inherited to solve
simple genetic problems and relate this to my understanding of DNA, genes
and chromosomes. SCN 4-14c
The MayoClinic has a short slide show that can be used to visualise the
concept of chromosomes, genes and DNA, recapping on prior learning.
Electrophoresis is the process of using electric current to separate DNA
molecules. The Molecular Biology Notebook Online: DNA Electrophoresis
provides further information. The electrophoresis tank can introduced as a
method of splitting up a person’s DNA into genes. As the genes are unique to
the individual, a unique pattern can be created. ABPI Resources for Schools
illustrates DNA splicing and electrophoresis. A pre-run tank can be used to
illustrate the effect for learners. All Scottish schools have been given
electrophoresis tanks by SSERC in the past two years (2009–2011). If these
are not currently available or cannot be borrowed from local establishments,
tanks may be loaned from SSERC for the duration of this section of work.
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The scenario is continued by indicating that a sample of the kidnapper’s DNA
has been left on the door handle and removed for evidence. Learners can then
be provided with 3 ‘samples’ of suspects’ DNA which they will use to match
up to the kidnapper’s DNA to identify the culprit. The DNA is in fact simply
dyes made up using the recipe provided.
Whilst waiting for the experiment to run, there are a number of options for
learners. Some may record a diagram of the tank and the four wells,
subsequently recording the pattern for each run and the conclusion on the
match with the crime scene sample. Alternatively , learners could explore how
well this laboratory experiment models processes used in real life, e.g. where
electrophoresis might be used.
Details for DNA separation
Resources:
Carbon fibre electrodes, set of positive/negative electrical
wires, battery pack, micropipettor, micropipette tips, crocodile
clips, discharge beaker, electrophoresis tank and comb, agar
gel, black card (min. 5 cm × 3 cm per tank), three DNA (dye)
‘samples’, computer with internet access
Experimental set-up and process
Beforehand, the electrophoresis tanks with agar should be prepared by
technicians using 0.6 g of agar and 20 cm³ of water per tank. This should be
heated on a hot plate and cooled, then poured (with comb in place) and left to
set. Once set, a thin layer of water should be poured over the gel to cover it
and the combs removed.
The dyes must also be prepared. Problems with supermarket dyes have been
reported, therefore the latest recommended source is FastColours.
(www.fastcolours.co.uk/food-dyes—lakes-9-c.asp) Stock solutions should be
prepared in distilled water as follows:
Green S: 0.2%
Brilliant blue: 0.2%
Allura red: 0.2%
Quinoline yellow: 0.4%
Carmiosine: 0.5%
The learners should carry out the following protocol:
1.
Label wells 1, 2, 3 and 4.
2.
Use micropipettes and tips to load each well with 20 µl of a different
sample. One dye should be used for well 1. Learners should be told this
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is the ‘sample’ taken from the crime scene. The three suspects ’ DNA
should be located in the other three wells; one of these should match the
dye in well 1. Place the black card underneath the wells in the tank to
help learners to see the wells clearly.
3.
Insert carbon fibre electrodes at each end of the tank, touching the
water.
4.
Attach crocodile clips and leads to the electrodes and to the end of the
tank.
5.
Wire up the tank to the battery (the negative end goes nearest the
wells), switch on at 27 V and leave for approximately 25 minutes.
6.
Turn the battery off and remove the water carefully.
7.
Compare the patterns on the agar from well 1 to the others to indicate
the culprit.
Reflective questions for learners
Review your learning in this section to identify the skills you have used.
Which of these skills are transferable?
Identify job roles in which your learning today could be applied.
Should every individual’s DNA profile be held on a database for matching in
the event of a crime? Is this any different from taking fingerprints from a
suspect or does it raise other issues? Consider your learning about the
potential use of genetic information when responding to this and justify your
response.
DNA structure
Learners understanding how our genetics can be used in medicine , eg
pharmacogenetics should be underpinned by the science associated with DNA
and genetics, e.g. base sequence structure. This idea aims to familiarise
learners with the base sequence structure of DNA.
The Learn Genetics Tour of the Basics from the University of Utah can be
used to familiarise learners with the basic structure of DNA, including the
sugar phosphate backbone and the four bases in the double helix arrangement.
Prior to showing the clip, learners could complete a graffiti or a placemat
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task to explore prior learning. The ABPI Schools’ Genes and DNA website
also includes useful information.
Reflective question for learners
What are the potential applications of knowledge of the individuals’ base
sequence?
What job roles might make use of or apply this knowledge?
The Learn Genetics Pus Poppin’ Frogs activity from the University of Utah
can be used to enhance learners’ understanding of the use of base sequencing
in pharmacogenetics.
The Univeristy of Utah’s Learn Genetics site is under development to include
a range of new ideas for learning and teaching, e.g. Finding a Gene on a
Chromosomal Map.
A revision summary quiz busters activity can be found on the Teachers Direct
website.
Darwin’s Natural Selection
The purpose of this section is to develop understanding of the terms
‘adaptation’ and ‘natural selection’ by using Darwin’s theory to explain the
adaptation of the Galapagos Island finches to their environment.
The theory of evolution provides a good opportunity to enhance learners’
understanding of the nature of science and the scientific p rocess. This, and
other issues such as evidence and belief, is explored in more depth in the
Wellcome Trust’s Big Picture on Evolution site.
The learning in this section should provide progression from the broad
general education, as described within Concept Development in the Sciences:
Evolution is introduced at the second level (SCN 2-01a), where learners
relate the physical and behavioural characteristics of living things to their
survival and extinction. They develop their understanding of the diversity of
plants and animals by exploring a range of resources, including the local
environment. They can explore simple adaptations which have taken place in
plants and animals, such as features that allow flight and swimming, feeding
mechanisms, and plant adaptations for drought or living on water. The
concept of evolution can be introduced by studying the evidence of fossil
records to develop an appreciation of organisms which have become extinct.
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Learners could study features which did not allow these organisms to survive
in the changing environment, e.g. flightless birds such as the dodo; and
dinosaurs. Examples of living things under threat due to environmental
changes can also be discussed. The concepts of species diversity, distribution
and adaptation for survival are further developed at third and fourth levels
(SCN 3-01a and 4-01a).
Biology Online considers the adaptation of finches and presents an argument
for natural selection related to sickle cell , a genetic defect common in Africa.
Learners could be presented with a map of the Galapagos Islands and their
geography to set the scene for the understanding. This clip from the Open
University describes Darwin’s arrival on the Galapagos Islands.
Darwin’s work illustrates the importance of scientists making careful
observations ‘live’ in order to provide evidence for drawing conclusions. It
also illustrates the importance of recording what is observed, rather than what
fits with the scientists’ hypothesis. Darwin’s publication On the Origin of the
Species celebrated its 150th anniversary in 2009. ‘The Making of the Fittest:
Natural Selection and the DNA Record of Evolution ’ is a lecture from the
anniversary year that is relevant to this topic.
Darwin examined, drew and made notes on hundreds of species living on the
Galapagos Islands. He found that one species in particular varied a great deal
in appearance – the finches. Learners could be presented with images of
finches and identify differences in their appearance.
http://www.youtube.com/watch?v=l25MBq8T77w&feature=relmfu
discusses Darwin’s Galapagos finches.
Reflective questions for learners
On return from the Galapagos Islands, it was confirmed that Darwin had
identified 13 species of finch. What other information had Darwin recorded
that was even more important in formulating his theory of evolution and why
was it important?
Consider finches taken from different areas of the largest of the islands ,
Isabela Island and the food sources available on the northern and southern
tips of this island. Looking at images of the finches, which would be best
adapted to living in each part of the island? Justify your answer.
Considering your learning on adaptation in the context of Darwi n’s theory of
evolution, what selection pressures might affect the survival of a species?
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Survival of the fittest or survival of the fit enough?
The Berkeley resource Welcome to Understanding Evolution for Teachers ,
particularly the potential pitfalls section, offers a wealth of ideas for planning
learning and teaching to develop learners’ skills and overcome
misconceptions. Using this as a basis for formulating reflective questions for
learners offers rich opportunities for demonstrating understanding, through
essay answers, podcasting or another approach appropriate to the learner.
The context of adaptation and species survival lend s itself to exploring how
changing environments, as a result of climate change, may impact on species
survival.
Natural selection in mice
In this section, an activity is used to illustrate examples of variati on that exist
between organisms and the process of evolution through natural selection.
Learners should be introduced to Darwin’s work, including the terms ‘natural
selection’, ‘evolution’ and ‘survival of the fittest’. This could be done using
the ideas for learning and teaching given in the previous section.
Alternatively, the Howard Hughes Medical Institute clip Natural Selection
and the related animation could be used.
Learn Genetics from the University of Utah has a useful animation called
Rock Pocket Mice.
Provide each learner with a mouse outline, either selecting from the
template(s) below or using your own. Each learner should also be given a list
of features.
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Based on a mouse living in Scotland and considering the environmental
conditions present, learners should select and underline the one form of each
feature they think will prove most beneficial to the mouse ’s survival.
Learners should illustrate this on their paper outline of the mouse.
List of features:
coat colour: black, brown, grey, albino
coat depth: fine, medium, thick
coat shape: curly, wavy, straight
eye location: more central in skull, lateral, more lateral
whisker length: short, medium, long
claw length: short, medium, long
whiskers: 10, 15, 20 each side of face
number of pairs of premolars/molars: 2, 3, 4
coat length: short, medium, long
tail length: short, medium, long
size: small, medium, large
number of claws on hind feet: 4, 5
Once this is completed, all learners should stand with the mouse held up. The
storyline with the various situations should be read out. At each stage, any
learner whose mouse has not survived should sit down. The last learner(s)
standing is the winner, with the best adapted mouse.
The storyline
For five years snow falls for a much longer period over the winter, co vering
the ground for up to 3 months of the year. Black mice are much more visible
to predators and therefore are preyed on over the lighter coloured mice, who
are more camouflaged. Black mice die out.
As the winter gets much colder, some mice face difficulties keeping warm in
the freezing temperatures and die due to hypothermia. Only mice with
medium or thick coats survive.
Over the summer, a serious outbreak of mites occurs. Mice suffering from
these mites itch and scratch themselves until they develop open wounds,
which become badly contaminated with bacteria. The mice lose weight and
eventually die due to serious bacterial infection. The mice that are much more
prone to picking up and harbouring the mites are those with curly coats , and
they eventually die off.
As winter kicks in again, predators are on the hunt for food, which is scarce.
Those mice with eyes located laterally are able to spot and hide from
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predators such as owls on the hunt. Those with eyes located more centrally in
the skull are unable to do this, therefore, they quickly die off due to high
levels of predation.
In the warm summer, mice reproduce and very quickly become a pest to
humans in the area. The council decides to deal with this on an industrial
scale and hundreds of traps are laid out around key areas of known mice
habitats throughout the entire summer period. Only th ose mice with medium
and long whiskers of at least 15 in number on each side are able to detect the
mouse traps and avoid the trap. Mice with short, few whiskers die off.
The damp, fairly warm autumn season provides ideal conditions for growth of
a fungus called Trichophyton mentagrophytes. Untreated, this develops into a
painful fungal infection in the feet of the mice, leaving them unable to retreat
from predators as quickly as previously. Those with long claws harbour this
fungus much more readily and therefore die off due to increased predation.
A long, cold winter sees the main food source for the mice – seeds – freeze
for long periods of time. Only mice with sufficient molars are able to
mechanically break down the seeds enough to release the nutrients inside
through digestion. Those mice with only two pairs of molars suffer death due
to starvation.
Learners could consider natural selection in humans, in the context of sickle
cell and malaria in Africa, watching the Howard Hughes Medical Institute
film ‘The Making of the Fittest: Natural Selection in Humans ’.
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Using the cartoon below, generate discussion among learners. From this,
learners could make an explanatory note of their understanding using the
words ‘natural selection’, ‘evolution’ and ‘adaptation’, and the example of
the rock pocket mouse. Learners may alternatively use a mind map or
ongoing learning log.
A revision quiz is av ailable o n the Te achers Direct website.
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Reproduction and inheritance
This section offers opportunities to illustrate the genetic inheritance of genes
and alleles through a hands-on activity.
Resources:
50 large seeds, whiteboard marker pens, 20 test-tubes, 10 testtube racks, plasticine, plastic straws, scissors
Part 1
Place three test-tubes in a test-tube rack: one at each end and one in the
middle. The test-tubes at either end should be labelled ‘P’ for parents, and the
one in the centre labelled ‘F1’ for the offspring.
Eight seeds are required: on four of the seeds write ‘A’ and on the other four
‘a’.
Start by placing two ‘A’ seeds in each of the ‘P’ test-tubes. The model and
what it represents should be discussed with learners, including any
shortcomings of this as a model for the actual processes.
Shake each test-tube to allow one seed (representing an allele) from each
parent ‘P’ to fall out into the ‘F1’ tube. Learners should identify that this
represents meiosis.
Repeat this using four ‘a’ seeds and discuss the alternative form of the gene.
Repeat starting with an ‘A’ and an ‘a’ seed in each ‘P’ test-tube. At this
point, learners should begin recording results in an appropriate form (a
suggested layout for recording results is provided).
The terms ‘homozygous’ and ‘heterozygous’ should now be explained,
linking to other words that are similar, to help learners understand the
meanings, eg homogenous (composed of elements that are all the same),
homogenised (to make similar, e.g. milk where fat is distributed evenly
throughout).
Prior learning about ‘dominant’ and ‘recessive’ can be explored at this point.
Learners may have encountered these terms in earlier learning, with a
straightforward understanding that can be built on through this activity.
Learners’ understanding of these four terms can be checked by highlighting
on the record sheet in one colour all heterozygous genes, in another colour
homozygous genes. Learners could also summarise or circle a definition of
‘recessive’ and ‘dominant’.
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Two short clips on the Genesareus Genes Count website describe a dominant
and recessive inherited disease.
Part 2
Four seeds are required: on two of the seeds write ‘dom’ and on the other two
‘rec’.
Start by placing two seeds (one ‘dom’ and one ‘rec’) in each of the ‘P’ testtubes.
Shake each test-tube to allow one seed from each parent ‘P’ to fall out into
the ‘F1’ tube. Learners should note the variation in the results among the
learners, highlighting the random nature of the combination of all eles of each
gene. Discuss what each of the combinations represent s.
The terms ‘genotype’ and ‘phenotype’ can now be introduced and discussed.
Again, learners could summarise their understanding or circle the definition
on their sheet.
Part 3
This scenario allows an opportunity for learners to apply their learning. The
scenario involves the discovery of the skeleton of an unknown Scottish
creature, for which until now there has been no visual image. A scientist has
extracted the DNA from a sample of the bone marrow from the freshly dug up
creature. By comparing the genes to those of similar organisms, a Scottish
scientist has identified the number of genes. The learners can use this
information to suggest a possible image of the creature.
It may be of interest to learners to explore this theme further in terms of
careers. The Conversations with Pathologists website at
http://www.pathsoc.org/conversations// includes an interview with Professor
Sue Black, Professor of Anatomy and Forensic Anthropology at the
University of Dundee, talking about information from bones and the
importance of this work in disaster and conflict zones worldwide.
The practical element of this follows the set up for part 2. For every gene, the
test-tubes should be shaken so that one seed falls out of each tube. The terms
‘genotype’ and ‘phenotype’ will be used extensively in this section. Learners
should record the genotype of each feature (using the information given
below). Once completed, learners should represent the phenotype using
plasticine, scissors and straws.
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Gene
Allele
letter
Genotype possibilities
Phenotype possibilities
Coat shape
S
SS, ss, Ss
SS, Ss = straight
ss = curly
Ear shape
I
II, ii, Ii
II, Ii = curved inwards
ii = curved outwards
Coat length
V
VV, vv, Vv
VV, Vv = short coat
vv = long coat
Legs
L
LL, ll, Ll
LL, Ll = four legs
ll = two legs
Horns
H
HH, hh, Hh
HH, Hh = horns absent
hh = horns present
Tail
T
TT, tt, Tt
TT, Tt = tail present
tt = tail absent
Teeth
C
CC, cc, Cc
CC, Cc = long pointed
canines
cc = canines absent
Eyes
E
EE, ee, Ee
EE, Ee = laterally set
ee = centrally set
Claws
K
KK, Kk, kk
KK, kk = three claws per
leg
kk = two claws per leg
Face shape
F
FF, Ff, ff
FF, Ff = long, narrow face
ff = short, rounded face
Reflective questions for learners
Why do recessive alleles not disappear altogether?
Is this the complete picture? What is meant by the term ‘polygenic
inheritance’?
How did our understanding of dominant and recessive genes develop?
The University of Utah’s Learn Genetics video ‘Things You May Not Know
about Evolution’ tackles common misconceptions.
A revision quiz is av ailable o n the Te achers Direct website.
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Further research
The Genesareus website is designed specifically for education use and
contains a number of excellent resources relating to genes, inheritance and
disease. The site contains real-life illustrative examples of people with
hereditary conditions, the issues they face and outcomes.
The charity Diabetes UK has published a report entitled Diabetes in the UK
2010: Key Statistics on Diabetes. It covers a wide range of issues around the
topic, including facts and figures, genetics, diagnoses and treatment. Given
the prevalence of diabetes in Scotland, this document proves current, relevant
and detailed.
GLOW Science contains short videos on inheritance, genetic modification
and DNA structure/function:
https://www.glowscience.org.uk/mindmap/#!/biology/cells_and_dna/genetics
https://www.glowscience.org.uk/mindmap/#!/biology/cells_and_dna/dna
https://www.glowscience.org.uk/mindmap/#!/biology/cells_and_dna/using_ge
netics
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Skills for learning, skills for life and skills for work
Literacy
Learners are required to follow precise protocols for experimentation .
Learners are required to read articles and scientific information in order to
identify, understand and reflect on key points.
Numeracy
Learners are required to use scales to measure and take measurements in an
accurate fashion.
Learners may be asked to calculate numbers from percentages to appreciate
actual values for the prevalence of inheritance-linked diseases.
Through Punnet squares, learners should develop the skills of calculating the
percentage likelihood of offspring carrying certain alleles.
Health and wellbeing
Learners are required to appreciate the genetically inherited aspect of certain
diseases.
Along with genetic inheritance, learners should appreciate the environmental
aspects of disease prevalence and link this to aspects of lifestyle.
Employability, enterprise and citizenship
Learners are given information to debate in a balanced way in order to
encourage them to think and to consider both sides of an argument.
Learners are encouraged to listen to peer viewpoints and identify key issues
in order to gain an informed perspective on the topic.
Thinking skills
Learners should be able to develop reasoned arguments to support their views
in response to ethical issues.
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