9A
Genetics and evolution
This unit recaps ideas about the causes of
variation and then looks at inherited variation in
more detail. DNA is introduced before students
consider how inherited genes can affect an
organism’s survival. The unit ends with coverage
of natural selection.
Recommended teaching time for unit:
7.5–10 hours
Topic 9Ab contains additional work on scientific
skills (statistics and probability). Topic 9Ac provides
an opportunity to look at how material in this unit is
used by genetic counsellors in helping and advising
people on the effects of their genes, with a focus
on STEM skills (pattern analysis). You may wish to
spend additional time on these topics, should you
feel that your students would benefit from these skills
development opportunities.
From previous units, most students will be able to:
• identify variation within and between species (7D)
• identify environmental and inherited causes of
variation (7D, 8B)
• classify variation as being continuous or
discontinuous (7D)
• explain how plants and animals are adapted to
their habitats (7D, 8C)
• describe what an ecosystem is (7D)
• describe how organisms are classified (8B, 8D)
• recall what biodiversity and extinction are (8B).
Topic 9Aa reminds students of work carried out in
Year 7 on environmental variation and the differences
between continuous and discontinuous variation.
Topic 9Ab looks at inherited variation. This is followed
by a Working Scientifically opportunity on probability.
Topic 9Ac introduces DNA as being the carrier of
genetic information. Students will learn about genes
and chromosomes and their roles in heredity. There
is an opportunity to find out about STEM and the
skills associated with being a genetic counsellor (with
a focus on application of knowledge).
Topic 9Ad considers how plants and animals are
adapted to their habitats and the genetic basis for
this. It goes on to look at how genes can affect the
survival of an individual or an entire species.
Topic 9Ae introduces students to the idea of natural
selection.
Curriculum coverage
This unit covers the following:
© Pearson
• heredity as the process by which genetic
information is transmitted from one generation to
the next
• sexual reproduction (gametes, fertilisation)
• a simple model of chromosomes, genes and DNA
in heredity, including the part played by Watson,
Crick, Wilkins and Franklin in the development of
the DNA model
• the variation between individuals within a species
being continuous or discontinuous, to include
measurement and graphical representation of
variation
• the variation between species and between
individuals of the same species means some
organisms compete more successfully, which can
drive natural selection
• abiotic and biotic changes in the environment
may leave individuals within a species, and some
entire species, less well adapted to compete
successfully and reproduce, which in turn may
lead to extinction
• the importance of maintaining biodiversity and the
use of gene banks to preserve hereditary material.
This unit also has a focus on the following aspects of
Working Scientifically/Scientific Enquiry:
• describe and calculate experimental and
theoretical probabilities
• express and interconvert probabilities (on a scale
of 0–1, percentage, decimal, fraction).
STEM skills
This unit explores these STEM skills and how they
are used:
• application of knowledge (spotting differences to
known patterns)
• use of maths (risk as a form of probability).
Cross-disciplinary opportunities
9Ac – Chemistry 9Eb – DNA as a polymer
Cross-curricular opportunities
9Ac – Art – DNA models
Maths skills
• explain what probability is
• calculate probabilities and present them as
fractions, decimals and percentages
• calculate experimental probabilities
• calculate theoretical probabilities.
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Genetics and evolution
9
A

9A Background information
9Aa Monsters and myth/Environmental
variation
Environmental variation was first met in this
course in Topic 7Dc. It is an area of biology that
is plagued with different words that all seem to
have similar meanings, such as environment,
environmental factor, environmental variation and
ecosystem.
The immediate surroundings of any organism
are known as its environment. The factors in an
environment are described as environmental
factors; these include living (biotic) factors, such as
other organisms, and non-living (abiotic or physical)
factors, such as the amount of sunlight.
All the living factors (organisms) and physical
factors in a large area (e.g. a habitat) are referred to
as an ecosystem.
Both living and physical environmental factors can
cause variation in a particular organism. These
factors are the agents of change or variation, and
so are said to cause environmental variation.
Environmental factors also include fashion!
Therefore, as far as humans are concerned,
differences in clothes, jewellery and make-up
are caused by environmental factors. Other
environmental factors also come into play, such
as peer pressure, availability of finance and
accessibility of certain shops.
9Ab Inherited variation/Probability
Inherited variation was first met in this course in
Topic 7Db, and then looked at again in Unit 8B.
Most variation is the result of a combination of
inherited and environmental effects. Eye colour, skin
colour and hair curliness are traditionally thought
of as being inherited, but these can all be altered
by the environment (e.g. coloured contact lenses,
sunbathing, perming).
Probability is the likelihood of something
happening. This can be expressed as a percentage,
a decimal or a fraction. The probability of an
impossible event is 0%, 0 or 0/1. The probability of
an event that is certain to happen is 100%, 1 or 1/1.
An experimental probability is an estimate based
on data from experiment or observation (e.g. hair
colour, number of times a drawing pin lands point
up). A theoretical probability is calculated based
on the idea of likely outcomes. So we calculate the
theoretical probability of a 6 on a die as 1/6, or a
head on a coin as 1/2. But if we do an experiment
and throw a coin 1000 times, we might find the
experimental probability is 532/1000, not 1/2. The
larger the number of experiments, the closer the
experimental probability is to the theoretical. Both
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types of probability can be used to predict future
events and computer modelling uses both.
9Ac DNA/Genetic counselling
Each inherited characteristic is controlled by part
of a chromosome called a gene. Chromosomes
(and therefore genes) are passed from parent to
offspring during reproduction. This transfer is
brought about by gametes, which in the case of
humans are the male sperm cells and female egg
cells. Each gamete contains 23 chromosomes,
whereas a normal human body cell contains
46 chromosomes – two of each type. During
fertilisation, a sperm cell will penetrate the wall of
the egg cell. Its tail is left outside the egg cell. The
jelly coat around the egg cell then expands, so
preventing any further sperm cells from entering.
The nucleus from the head of the successful
sperm cell then fuses with the egg cell nucleus.
The resulting cell, a fertilised egg cell or zygote,
contains a full set of chromosomes.
DNA (deoxyribonucleic acid) is the substance
that our genes are made up of. It consists of a
molecule made of repeating units of a sugar, a
phosphate group and one of four chemical ‘bases’:
adenine (A), thymine (T), cytosine (C) or guanine (G).
The sequence of these bases in a gene usually
determines what kind of protein is made; many
genes each produce one protein. For example, one
gene is responsible for producing the haemoglobin
protein found in red blood cells. The proteins
produced are responsible for characteristics.
All humans (except those with genetic anomalies)
have 23 pairs of chromosomes and (apart from sex
chromosomes in men) the chromosomes in a pair
are the same size and contain the same genes.
Imagine, for example, that there is one gene for eye
colour (there isn’t – it is controlled by many genes):
that gene always contains the instructions for eye
colour and is always found in the same place on
the same chromosome. Because you inherit two
chromosomes of each type, you will have two eye
colour genes. However, the eye colour gene comes
in different types called alleles. One allele contains
the instructions for green eyes, another for blue,
another for brown, etc. So, you can end up with two
‘blue’ alleles or one ‘brown’ and one ‘blue’ or any
other combination. It is the alleles (and the slightly
different proteins they produce) that cause variation
in inherited characteristics.
Some alleles are dominant, which means that, if
that allele is present, another allele’s effects will not
be seen. The allele that doesn’t have an effect is
described as recessive. To continue the example
from above, the allele for brown eyes is dominant
over the allele for blue eyes. So, people with one
‘brown’ and one ‘blue’ allele will have brown eyes.
© Pearson
Genetics and evolution
Sickle-cell anaemia is a genetic disease caused
by a single gene, the haemoglobin gene. The
difference between the sickle-cell allele and the
normal allele is only one base but this means that
the haemoglobin protein that is produced is not the
same and can cause blood cells to stack up and
stick together.
The concepts of alleles and genetic diseases are
covered at GCSE/IG but students may ask about
them while studying this unit.
9Ad Genes and extinction
Different plants and animals are adapted to living
in certain habitats and some can only survive in
certain environments. It should also be obvious
that adaptations required to live in one habitat are
often totally unsuitable for living in another. For
example, animals living in hot habitats need ways
of transferring energy out of their bodies (to the
surroundings). This will mean these animals cannot
survive in cold climates.
The instructions for the adaptations of organisms are
encoded in their genes. Many plants and animals
are so firmly adapted to the precise conditions in a
habitat that if conditions change even slightly (e.g.
a 1 °C rise in temperature) they will fail to survive in
great numbers and/or to reproduce. This can lead
to extinction, particularly when resources are scarce
because species with better adaptations for getting
the necessary resources ‘out-compete’ those that
are less well adapted.
9Ae Natural selection/Recreating animals
The genes/alleles in organisms vary by chance.
Many characteristics are controlled by a large
number of different genes, which produce variation
in that characteristic in different organisms of
the same species. This means that within any
population the organisms will have a range of
variation for each characteristic (e.g. giraffes all
have very slightly different neck lengths, birds all
have very slightly different beak shapes). These
slight variations in characteristics, although often
imperceptible, may mean the difference between an
organism finding enough resources and not.
Those organisms that do not get enough resources
may not survive and so the next generation of
organisms contains proportionally more of the
organisms with the variations that aided survival.
This is natural selection.
At this stage, natural selection is presented in these
slightly simplified terms in order for students to
get the idea of how it works. It is important that
students realise that there is variation in most
characteristics but that we often can’t see these
differences.
© Pearson
It is also important that students realise that natural
selection always acts on a population but its effect is
greater when resources become scarce. Biologists
tend to talk in terms of ‘selective pressure’ and the
selective pressure is greater when resources are
scarcer. So if food becomes scarce, organisms
with slightly better adaptations to get food are even
more likely to be the survivors than when food was
plentiful. To give another example: during a warm
winter, more of the organisms will survive whether
or not they are slightly better at surviving colder
temperatures. However, if the winter is very cold,
then there will be a greater selective pressure that
more strongly favours the survival of the organisms
that are slightly better adapted. Selective pressure
is also changed by diseases and the numbers of
predators. However, it is advisable to steer clear
of the term ‘selective pressure’ with students,
because this can lead to the misconception that the
environment somehow exerts a force that causes a
certain variation in a characteristic.
The idea of ‘more likely’ is also important. If a stand
of trees that a group of giraffes are totally dependent
on suddenly grow taller, then the giraffes with the
longer necks will be able to get more food than those
with shorter necks. Some of those with shorter necks
may not survive but some will. Therefore, in the
next generation there will still be variation in giraffe
neck length, it’s just that there will be proportionally
more with longer necks. Because of the way genes
interact with one another and mutate, the giraffes
with longer necks may sometimes produce offspring
with shorter necks, and so this can preserve the bellshaped curve that is usually seen with inherited traits
that show continuous variation. If the trees continue
to grow taller and taller, then the bell curve shifts
further in favour of long necks, but there is still a
continuous spread of different neck lengths.
Evolution is the gradual change in characteristics
over a long period of time. Darwin’s theory is that
this is caused by natural selection.
A clone is any organism that has identical genetic
information to its parent. A clone may not always look
like its parent, because environmental factors cause
much variation, particularly in plants. A few students
may be familiar with the film Jurassic Park, in which
dinosaur DNA was used to recreate dinosaurs. This
is not true cloning in the sense that, according to the
story, some of the DNA had degraded over time and
so the missing bits were filled in with frog DNA. There
are now various efforts to recreate extinct creatures
using these sorts of techniques, most famously the
woolly mammoth. However, DNA degrades rapidly
over time and, therefore, it is unlikely that we will see
woolly mammoths wandering around in the near
future. The idea of dinosaurs being recreated is even
more far-fetched.
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9
A

9Aa
Environmental variation
Objectives
Developing:
1. Explain how environmental variation is caused,
and identify and give examples.
2. Tell the difference between and identify examples
of continuous and discontinuous variation.
3. Correctly use the term ‘species’.
Securing:
4. Explain why environmental variation can
confuse the idea of a species and make
classification and identification difficult.
Exceeding:
Exceeding objectives are designed to broaden
students’ skills and knowledge beyond what is
required, often introducing a higher level of challenge.
5. Recall that some animal behaviour is learned
(environmental) and some is innate (inherited).
6. Describe how a learned behaviour is beneficial
to an organism.
Student materials
Topic notes
• The material in this topic has previously been
covered in 7Da (continuous and discontinuous
variation, species), in 7Db (inherited variation)
and in 7Dc (environmental variation).
• There are other activities in Topics 7Db and 7Dc
that will widen the choice of tasks for this topic.
• It is important that teachers review all materials
that they intend to use with students before use,
to ensure suitability.
• It is envisaged that in the course of studying the
biology component of this topic, students will use
one Starter idea, Explaining 1, one further Exploring
or Explaining idea, and one of the plenaries.
Additional activities can be added as time allows.
Be prepared
Starter 4 requires five or six pieces of fruit of the
same type but some of different varieties to show
both inherited variation (e.g. shape, colour) and
environmental variation (e.g. disease).
Exploring 2 requires bramble leaves collected
from dark and well-lit areas. Note that these
may be hard to find in winter.
Explaining 3 requires two trays of germinated
seeds (e.g. cress), one tray of which has been
germinated in the light and one tray of which
has been germinated in the dark.
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STARTERS
1: Quick Quiz
BA
Use the 9A Quick Quiz for baseline assessment.
Students can use the 9A Quick Quiz Answer
Sheet to record their answers. You could use all
of the Quick Quiz as a starter for the whole unit
and then summatively at the end of the unit to
show progress. Alternatively, just use the first four
questions, which relate to this topic.
Once students have carried out the quiz, they will
be aware of what they know and any questions
they have about the Unit 9A topics. Ask students
to decide whether they would like to cover all the
topics in detail or whether there are topics that they
think they can just revise quickly. Topics 9Aa and
9Ab revise material on environmental and inherited
variation, and if students are feeling confident about
these topics it is suggested that these are the ones
to revise rather than cover in full.
Course resources
ASP: 9A Quick Quiz; 9A Quick Quiz Answer Sheet.
2: Features
BA
Ask students to write down five of their body
features. Then ask them to say why they have
these features. Pose the questions: Do we get all
our features in the same way? In what ways are
our features caused? Remind students that some
features are inherited and some are caused by
factors in our surroundings (environmental factors).
Then ask students to name one feature about
themselves that has been caused by inheritance
(e.g. ear shape) and one feature caused by their
surroundings (e.g. haircut).
3: Differences caused by the environment
BA
Ask students to write down a list of words to do
with hair and hairstyles. These might include:
blonde, black, brown, straight, curly, short, long.
Ask students to submit words to the class and
write them up on the board. Then ask students to
suggest categories into which these words could
be grouped. Go through the words one at a time,
putting them into categories (e.g. hair colour,
hair type). If not already included in the category
© Pearson
Genetics and evolution
list, remind students of inherited variation and
environmental variation and ask them to put the
words into those categories (some will be able to
go into both).
4: Fruit differences
BA
Display a set of fruits (e.g. apples) for students
to see. Challenge students to write down the
differences between the apples and to suggest
how each difference was caused. It is suggested
that you get fruits of different varieties (e.g. red
and green apples), including some that have
been damaged in some way (e.g. by a disease,
by bruising, by eating a chunk out of one apple).
Ask students to share their thoughts in groups
and then select a random group to read out their
findings. Remind students, if necessary, that some
characteristics are inherited and others are caused
by the environment.
Do not damage fruit by eating them in the
lab. Students should not consume the
foods investigated.
Equipment
Five or six examples of the same type of fruit
showing different characteristics, e.g. apples
that differ in shape or colour (inherited variation)
and preferably some that show signs of disease
(environmental variation).
EXPLORING TASKS
1: Seeds and acid rain
WS
In this investigation students monitor the effect of
different concentrations of acid on the germination
of cress seeds. Full instructions are given on
Worksheet 9Aa-2. Students should discover that
the lower the pH, the fewer the number of cress
seeds that germinate. Some students will notice
that those that do germinate grow less tall. The type
of acid does not have much effect. The seeds must
be covered to prevent evaporation.
Developing: Students follow the instructions on
Worksheet 9Aa-2. It is suggested that students are
given a range of acids with different pH levels to
choose from (e.g. solutions at pH 2, 4 and 6 of nitric
and sulfuric acids). Students then pick the ones that
they will use and should choose one acid at three
different pH levels, therefore only using pH as the
independent variable. Some students may choose
to vary the type of acid as well.
© Pearson
Securing: Challenge students to safely make up
their own acid dilutions from a stock solution of
1 mol dm–3 sulfuric acid. Alternatively, students
could plan their own investigations using Worksheet
9Aa-3, which suggests that they could investigate
two independent variables: dilutions and type
of acid could be tested simultaneously, whilst
still performing a fair test. If this is beyond some
students, they can be instructed to choose one
independent variable to test.
Exceeding: Explain to students that they need
to plan (and carry out) an investigation into the
effects of acid rain on the germination of seeds.
Show students the apparatus that they could use
and ask them to work in a group to agree on a
plan. You could include hydrochloric acid as a
distractor; hydrochloric acid is not responsible for
acid rain.
1 mol dm–3 sulfuric acid is an irritant.
Hands must be thoroughly washed after
handling seeds. Seeds and seedlings
must not be eaten. Universal indicator
paper needs to be held using forceps.
Wear eye protection.
Course resources
AP: Worksheets 9Aa-2; 9Aa-3.
Equipment
A range of solutions of nitric, sulfuric and
possibly hydrochloric acids made up at different
pH levels (e.g. 2, 4 and 6), cress seeds, 4–6
Petri dishes with lids, cotton wool or kitchen
towel, forceps, universal indicator paper, marker
pen or pencil and labels, measuring cylinder,
eye protection.
Optional (if students are to make their own
dilutions): 4–6 beakers, distilled water,
1 mol dm–3 sulfuric acid.
2: Bramble leaves
WS
Give students bramble leaves from well-lit areas
and from dark areas. (Note that brambles lose their
leaves in winter.) Ask students to comment on the
differences between the leaves. They could work
out the surface areas of the leaves using squared
paper. Ask students to think of a hypothesis to
explain their results. Many plants grown in shaded
areas have bigger leaves than those grown in
brightly lit areas in order to maximise the amount of
photosynthesis for food production.
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Genetics and evolution
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Beware of bramble thorns. Wash hands
after handling leaves.
Equipment
Bramble leaves from shaded area, bramble
leaves from well-lit area.
Optional: squared paper.
3: In the garden
Worksheet 9Aa-4 provides a scenario for students
to spot examples of environmental variation in
characteristics and the environmental factors that
caused them.
Course resources
AP: Worksheet 9Aa-4.
4: Variation graphs
BA WS
Ask students to conduct a survey amongst the
class about one example of environmental variation
that is continuous (e.g. hair length) and one that
is discontinuous (e.g. number of teeth fillings).
Ask them to collect data and to plot them on
appropriate graphs and charts. This will involve
dividing the continuous variation into grouped
sets and plotting a bar chart without gaps. The
discontinuous data should be plotted on a bar chart
with gaps between the bars.
The AL spreadsheet Human environmental
variation data contains some data that students
may use for this activity.
Be aware that some students may not
wish to provide personal information.
make sure that the plants can be found both in
short grass and in long grass.
Developing: Show students the plant that you wish
them to observe and ask them to predict whether
the leaves of the plant will be the same size,
smaller or bigger depending on whether the plant is
growing in short or long grass. Challenge them to
give reasons why they think this. Then ask them to
conduct a short qualitative survey.
Securing: Students should conduct a more
quantitative survey, making use of quadrats to
select areas in which to sample and measure a
characteristic of the plant leaves. Skills Sheet UE 13
from the Year 8 Activity Pack may prove useful for
this. Challenge students to explain why differences
in what the plants look like in the different areas
may confuse the classification of a plant. This
works well if you are looking at buttercups. There
are two species normally found, creeping buttercup
(Ranunculus repens) and meadow buttercup
(Ranunculus acris). Students could be challenged
to spot the variation between the two species
and then to consider how environmental variation
(height of grass leading to shading) can make
creeping buttercup appear more like meadow
buttercup.
Dandelions contain a powerful diuretic.
Students should wash their hands after
handling plants and should not visit areas
contaminated with animal faeces.
Course resources
AP: Skills Sheet UE 13 (Year 8).
Equipment
Ruler, quadrat.
EXPLAINING TASKS
Course resources
AL: Spreadsheet Human environmental
variation data.
5: Growing differences
BA WS
The leaves of many plants will be different
depending on whether they are growing in long
or short grass. Differences include surface area,
length, width and height above the ground. A
variety of plants can be used for this activity (e.g.
dandelion, buttercup, clover) but you will need to
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1: 9Aa Monsters and myth (Student Book)
BA
The start of this unit reminds students of some of the
ideas that they have met previously and will meet
again in this unit, including variation and extinction.
The AL presentation Classifying dinosaurs reminds
students of how classification is usually done,
including the concept of, and naming of, species.
Course resources
AL: Presentation Classifying dinosaurs.
© Pearson
Genetics and evolution
2: 9Aa Environmental variation (Student Book)
FA
This spread reminds students of the idea of
environmental factors (such as other organisms
and physical environmental factors) and how they
can cause variation. Continuous and discontinuous
variation are recapped, along with classification
and the concept of species. Worksheet 9Aa-1 is the
Access Sheet.
Questions 3 and 4 are suitable for formative
assessment, with students working on the
questions in groups.
The AL spreadsheet Human environmental
variation data contains some data that students can
use to explore variation in humans caused by the
environment. See Exploring 4.
The AL presentation Continuous or discontinuous
explores how to chart continuous and
discontinuous data. See Explaining 4.
The AL presentation 9Aa Thinking skills can be
used for this activity. See Plenary 2.
Course resources
AP: Worksheet 9Aa-1.
AL: Presentations 9Aa Thinking skills;
Continuous or discontinuous. Spreadsheet
Human environmental variation data.
3: Etiolation
Show students some plants that have been grown
without light and compare them with some that
have been grown in light. This could be darkgrown versus light-grown cress seeds. Point out
the characteristics of the seedlings (e.g. leaves)
and the variation between the two (e.g. leaf colour)
and how this has been caused by environmental
factors (e.g. light). Reinforce the idea that
environmental factors cause environmental
variation. Point out that, if an animal came along
and ate the leaves off some of the plants, this
would create environmental variation as well, and
the animal is the environmental factor.
Equipment
Two trays of germinated seeds (e.g. cress), one
tray of which has been germinated in the light
and one tray of which has been germinated
in the dark (ensure the seeds are covered, to
prevent evaporation).
4: Continuous or discontinuous?
The AL presentation Continuous or discontinuous
provides a range of data examples of continuous
© Pearson
and discontinuous variation. Remind students of
the differences and point out the different ways in
which continuous and discontinuous datasets are
presented in charts and graphs. Ask students to
decide whether the examples are continuous or
discontinuous and challenge them to spot the data
that show environmental variation.
Course resources
AL: Presentation Continuous or discontinuous.
PLENARIES
Most plenaries can be used for formative
assessment. Suggested assessment, feedback and
action strands of formative assessment can all be
modified. See the ASP for further information and
ideas on formative assessment.
1: Quick Check
FA
Assessment: The 9Aa Quick Check sheet contains a
‘reverse word’ in which students have to write clues
for a crossword. This revises the keywords used in
this topic.
Feedback: Once students have completed the
sheet, ask them to cut the clues into strips and
hand them in. Select clues randomly and ask
students which word on the crossword grid they
think that the clue is asking for. Invite suggestions
for ways in which a clue is good and ways in which
a clue could be improved.
Action: As you go through the clues, it will
become apparent which of the words are less well
understood. Revise these terms with reference
to the glossary in the Student Book or the Word
Sheets for this unit.
Course resources
ASP: 9Aa Quick Check; 9A Word Sheets.
Equipment
Scissors.
2: Thinking about environmental variation
FA
Assessment:
Plus, Minus, Interesting: Plant species should
show no variation. (Possible answers: Plus – It
would be easier to identify a species; Minus – The
whole species might be wiped out by a disease
or natural disaster; Interesting – How do growers
change the environment to affect plant growth? The
world record for pumpkin growing is 921.7 kg.)
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Genetics and evolution
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Consider All Possibilities: Carrots grown in
different areas of a farm may be different sizes.
(Possible answers: varying environmental
conditions such as different types of soil; different
amounts of water available.)
Consider All Possibilities: Michael only has one
leg. (Possible answers: he lost one in an accident;
he was born with only one leg; his leg had to be
amputated because it was infected or damaged
due to smoking.)
Odd One Out: having teeth with fillings, speaking
Italian, having naturally brown hair. (Possible
answers: having teeth with fillings is discontinuous
variation; speaking Italian is a behaviour and not a
physical characteristic; having naturally brown hair
is not caused by the environment.)
Odd One Out: golden retriever, dalmatian, lion.
(Possible answers: dalmatians are not yellow;
dalmatians show obvious variation between
individuals in spots; lions are a different species,
golden retrievers have long hair.)
What Was The Question: continuous variation.
(Possible questions: Is hair length an example of
continuous or discontinuous variation? What sort of
variation is shown by human height?)
Feedback: Students answer the thinking skills
questions in groups, thereby feeding back their
thoughts to one another.
Action: Ask students to choose a best answer from
their group and consider why they think it’s the best.
Ask a spokesperson from a number of groups to
read out their best answers. Create an agreed class
list of ‘what makes a good answer’. If understanding
is poor then revise environmental variation with
students at the start of the next lesson.
The AL presentation 9Aa Thinking skills can be
used for this activity.
Course resources
AL: Presentation 9Aa Thinking skills.
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3: The facts
FA
Ask students to write down one fact they have
learned about environmental variation. Then ask
them to compare their facts in groups and compile
a master list of facts for their group. Groups should
note the most and least common facts recorded.
Select a spokesperson for one group at random to
share their ideas with the class. Then ask whether
the other groups had the same most common facts
and if there are any facts that are missing. Produce
a list of the ‘most important facts’ on the board.
HOMEWORK TASKS
1: More environmental variation
Worksheet 9Aa-5 contains straightforward
questions about environmental variation.
Course resources
AP: Worksheet 9Aa-5.
2: Environmental variation in plants
Worksheet 9Aa-6 contains questions about
environmental variation, including data
interpretation.
Course resources
AP: Worksheet 9Aa-6.
3: Do starlings learn?
In Worksheet 9Aa-7 students learn about innate
behaviours and learnt behaviours as forms of
inherited and environmental variation, respectively.
Students are challenged to apply new information
and what they know about inherited and
environmental variation to the idea of behaviour
rather than physical features.
Course resources
AP: Worksheet 9Aa-7.
© Pearson
9Ab
Inherited variation
Objectives
Developing:
1. Explain how inherited variation is caused, and
identify and give examples.
2. Describe what genetic information does, and
how it is stored in the nucleus of a cell. (UK NC
and CEE only)
Securing:
3. Identify normal distribution. (UK NC only)
4. Interpret information on continuous genetic
variation using normal distribution curves.
(UK NC only)
Exceeding:
Exceeding objectives are designed to broaden
students’ skills and knowledge beyond what
is required, often introducing a higher level of
challenge.
5. Describe the work of Mendel in discovering the
basis of genetics.
Focused Working Scientifically/Scientific
Enquiry objectives
1. Describe and calculate experimental and
theoretical probabilities.
2. Express and interconvert probabilities (on a
scale of 0–1, percentage, decimal, fraction).
Student materials
Topic notes
• The material in this topic has previously been
covered in 7Db and there are other activities in
that topic that will widen the choice of tasks for
this topic.
• It is important that teachers review all materials
that they intend to use with students before use,
to ensure suitability.
• It is envisaged that in the course of studying the
biology component of this topic, students will
use one Starter idea, Explaining 1, one further
Exploring or Explaining idea, and one of the
plenaries. Additional activities can be added as
time allows.
Be prepared
Exploring 1 requires different varieties of apple.
Exploring 2 requires fresh and frozen peas.
© Pearson
STARTERS
1: Thinking about inherited and environmental
variation 1
BA FA
Use the following Consider All Possibilities activities
to start students thinking about the different causes
of variation. You could record students’ answers
and repeat the exercise as part of Plenary 3, to see
if students can add to their answers. Some students
may be sensitive about their physical characteristics,
so the statements suggested should be general.
Consider All Possibilities: A boy has brown skin.
(Possible answers: he has a suntan; one or both
parents have brown skin.)
Consider All Possibilities: A girl has curly hair.
(Possible answers: she has had her hair permed;
she has inherited curly hair from parent(s).)
Consider All Possibilities: A girl has blonde hair.
(Possible answers: she has dyed her hair; she has
inherited blonde hair from parent(s).)
Consider All Possibilities: Two apples look
different from each other. (Possible answers: one
came from a tree that has had more light/water/
fertiliser, etc.; they are from two different varieties/
species; one might be diseased.)
Consider All Possibilities: A boy is taller than his
friend. (Possible answers: his parents may be taller
than his friend’s parents; he may be older; he may
have had better nutrition when he was growing up.)
The AL presentation 9Ab Thinking skills can be
used for this activity.
Course resources
AL: Presentation 9Ab Thinking skills.
2: Breeds and varieties
BA FA
Ask students to write a definition for ‘inherited
variation’. Ask random students to share their
definitions and then ask other students to refine the
definition if necessary. Challenge students to explain
how inherited variation is different from environmental
variation.
Extend this by asking students to summarise what
a breed is and what a variety is and to suggest:
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• why two organisms of the same variety/breed
will produce offspring that also have similar
characteristics
• why two organisms of different varieties/breeds
will produce offspring that have characteristics
from both varieties/breeds.
3: How do we get our features?
BA FA
Ask students to write down five of their physical
characteristics. Then ask them to write down why
they have these characteristics. Ask students to
compare their ideas in groups before posing some
questions:
• Do we get all our characteristics in the same way?
• In what ways are our characteristics caused?
• How do we get characteristics from our parents?
Use the pose–pause–pounce–bounce method to
obtain feedback for each of the questions above.
Give students a few minutes to think of their
answers, and then pounce randomly on a student
for an answer. Next, bounce that answer to another
student, asking ‘What did you think of the answer?’.
EXPLORING TASKS
1: Apple variation
WS
Each group is given five apples of one variety and
five apples of another variety to compare. The
overall aim of this investigation is to show that
inherited characteristics vary more between two
varieties than within a variety.
Developing: Students follow the instructions
on Worksheet 9Ab-2 to compare the masses
of two varieties of apples both qualitatively and
quantitatively. To help the students it would be better
if the apple varieties differed considerably in mass.
Securing: Read out the introduction and aim from
Worksheet 9Ab-2 and then challenge students
to plan their own investigations. You can further
increase how demanding this is by asking students
to calculate apple density.
The AL spreadsheet Apple data contains a
dataset of apple masses from two different
varieties, which Developing students could use
as a dataset instead of measuring the masses
themselves. Other students could use this as a
source of secondary information or as a template
for recording their own measurements.
Students must not eat the apples.
22
Course resources
AP: Worksheet 9Ab-2.
AL: Spreadsheet Apple data.
Equipment
Five apples of variety 1, five apples of variety 2,
balance.
Optional: beaker, displacement cans, water.
2: Pea practical
WS
This practical can be used to carry out a Working
Scientifically Investigation. A set of descriptions
to assign progression bands (developing,
securing or exceeding) to the work is provided
in the ASP. Note that use of the worksheets will
prevent the assessment of some strands (notably
planning). Even if this is not formally assessed,
the descriptions could be used by students to
mark each other’s work and to provide formative
feedback to each other.
Students design an experiment to compare frozen
peas that have been thawed with fresh peas. They
should try to formulate questions to investigate,
such as: ‘Do frozen peas have as much mass as
fresh peas?’; ‘Do they have the same diameter?’;
‘Are they the same colour?’. Students should
choose one of these characteristics and design
an experiment to test the question they have
chosen. They should decide on an appropriate
sample size, apparatus and method to investigate
their chosen variable. Students could use a
spreadsheet to organise and present their data.
Once the experiment has been carried out, students
should state what conclusions they have come to,
comparing variation within the variety and between
the varieties.
Developing: Students use Worksheet 9Ab-3 as a
guide.
Securing: Tell students that there is an idea that
the peas used for frozen peas are a different
variety from those that are sold as fresh. Challenge
students to find out whether this is true by planning
an investigation. Allow students access to Skills
Sheets RC 6 and RC 7 from the Year 7 Activity
Pack.
Exceeding: Students are given the same information
as Securing students but are challenged to
investigate at least two variables and should work
without help.
Do not allow students to eat the peas.
© Pearson
Genetics and evolution
Course resources
AP: Skills Sheets RC 6 (Year 7); RC 7 (Year 7).
Worksheet 9Ab-3.
ASP: 9A WS Investigations.
Equipment
Balance, ruler, fresh and thawed frozen peas
(100 of each so students can choose an
appropriate sample size).
Optional: beaker, displacement cans, water.
3: Eye colour probabilities
WS
Worksheet 9Ab-4 provides the setting for a survey
in the class or year group in which hair and eye
colours are divided up into categories, to produce
sets of discontinuous data, which are then
analysed. Students will need to consider how they
are going to categorise the data, whom they will
ask, how they will record their results and how they
will account for environmental factors (such as hair
dye and coloured contact lenses). Students will
find that there has been a proportional shift in hair
colours to darker shades due to immigration in the
last 100 years. Skills Sheet MS 8 from the Year 8
Activity Pack may be useful.
Securing: It is recommended that students carry out
a survey into either eye colour or hair colour. They
should work in groups to consider how they are
going to categorise the data (step B on the sheet).
Ensure that students are confident at working out
the angles for pie charts (Question 3; Skills Sheet
PD 7 from the Year 7 Activity Pack may be useful
for this).
Exceeding: Students should survey both eye
and hair colours. Challenge students to suggest
how they would adapt the survey in order to find
out how the proportions of different hair and eye
colours have changed across England, Scotland
and Wales in the last 100 years. Students should
be able to say that they would survey samples of
people from each of the countries and categorise
their hair and eye colours in the same way as the
study on the sheet. Better answers will allude to the
need to ensure that the sample contains the same
numbers of people from different age groups and
that the samples are proportionally representative of
the ethnic mix in the country.
Course resources
AP: Skills Sheets MS 8 (Year 8); PD 7 (Year 7).
Worksheet 9Ab-4.
© Pearson
4: Statement keys
Remind students of their work on statement keys
(e.g. in 8Dc), which allow scientists to identify
organisms based on inherited variation. Students
could then construct their own keys, either using a
set of organisms that they choose for themselves or
using the invertebrates or the vertebrates shown on
Skills Sheet DS 1.
Encourage students to swap their completed keys
with one another to try to them out, and then to
make improvements based on feedback.
Course resources
AP7: Skills Sheet DS 1.
5: Normal distribution
WS
The AL document Normal distribution in leaves
is a set of axes on which students rearrange the
bars to form a normal distribution curve for leaf
length. In the AL interactive Normal distribution
students complete sentences about variation in
characteristics and the distribution they show when
plotted on a bar chart.
Extend this by asking students to measure
something about themselves that they would
expect to show a normal distribution. Ideas include
height, arm span, finger length, hand span and arm
length. Ask students to work in groups to produce
grouped datasets in order to construct bar charts,
before combining the class results together and
drawing a bar chart. If results are to be combined
in this way, ensure that all groups use the same
group categories for their data (e.g. height groups
125–129 cm, 130–134 cm, 135–139 cm, etc.).
When group data are pooled, it should be clear
that the more data that are collected, the closer the
chart looks to a normal distribution, because the
effects of individual values upsetting the pattern are
reduced. It may be possible to use a spreadsheet
and show the effect of adding more and more data
from the class results to create the bell-shaped
pattern. Saving results from previous years and
adding these in will help to reinforce this. You may
have enough data to produce bar charts of males
and females, or different year groups, to see how
the peak of the bell-shaped pattern shifts.
Extend this activity by asking students to point
out the modal class of their grouped data (the one
with the most values in it) and then to use their
ungrouped data to calculate the mean, mode and
median of their results. A spreadsheet is useful for
doing this.
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Genetics and evolution
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Extend this activity further by challenging students
to measure two parts of their bodies, plot bar charts
for both, then combine their results and plot scatter
graphs using both datasets to see if there is a
correlation.
Course resources
AL: Document Normal distribution in leaves.
Interactive Normal distribution.
6: Characteristics
Worksheet 9Ab-6 provides a grid for students
to consider whether certain characteristics are
inherited, environmental or both. Students should
try to complete the sheets on their own before
gathering in groups to discuss their work and make
amendments and corrections as necessary.
Course resources
AP: Worksheet 9Ab-6.
7: Probabilities
WS
Worksheet 9Ab-5 asks students to complete a
probability scale and contains questions on working
out various probabilities to display on the scale.
There is also a question on normal distribution.
As an alternative or an extension, the AL
spreadsheet Probabilities contains some worked
examples to show how probabilities can be
calculated from a dataset. There are then questions
for students to complete, including converting
probabilities between percentages, decimals and
fractions.
Course resources
AP: Worksheet 9Ab-5.
AL: Spreadsheet Probabilities.
Equipment
Scissors, glue.
EXPLAINING TASKS
1: 9Ab Inherited variation (Student Book)
FA
This spread in the Student Book reminds students
of the idea of inherited variation of characteristics.
Continuous and discontinuous variation are again
recapped, along with a reminder of what a normal
distribution is. Worksheet 9Ab-1 is the Access
Sheet.
24
Questions 4 and 10 are suitable for formative
assessment, with students working on the
questions in groups.
The AL spreadsheet Apple data contains
experimental data on variation in apples. See
Exploring 1.
The AL interactive Normal distribution explores
variation in characteristics and the distribution
they show when plotted on a bar chart. See
Exploring 5.
The AL document Normal distribution in leaves
looks at the shape of a normal distribution plotted
on a bar chart. See Exploring 5.
The AL presentation Continuous or discontinuous
explores how to chart continuous and
discontinuous data. See Explaining 3.
The AL presentation 9Ab Thinking skills can be
used in this activity. See Starter 1 and Plenary 3.
Course resources
AP: Worksheet 9Ab-1.
AL: Document Normal distribution in leaves.
Interactive Normal distribution. Presentations
9Ab Thinking skills; Continuous or
discontinuous. Spreadsheet Apple data.
2: 9Ab Probability (Student Book)
FA WS
This spread looks at probabilities, including the
different types and how they are presented as
fractions, decimals and percentages.
Question 5 is suitable for formative assessment,
with students working on the questions in groups.
The AL spreadsheet Probabilities contains some
worked examples to show how probabilities can be
calculated from a dataset. See Exploring 7.
Course resources
AL: Spreadsheet Probabilities.
3: Continuous and discontinuous
WS
The AL presentation Continuous or discontinuous
provides a range of data examples of continuous
and discontinuous variation. Remind students of
the differences and point out the different ways
in which continuous and discontinuous datasets
are presented in charts and graphs. Ask students
to decide if the examples are continuous or
discontinuous. Challenge students to spot data
that show environmental variation, data that show
© Pearson
Genetics and evolution
inherited variation and data that show a normal
distribution.
Course resources
AL: Presentation Continuous or discontinuous.
PLENARIES
Most plenaries can be used for formative
assessment. Suggested assessment, feedback and
action strands of formative assessment can all be
modified. See the ASP for further information and
ideas on formative assessment.
1: Quick Check
FA
Assessment: The first question on the 9Ab Quick
Check sheet challenges students to design a
missing words/cloze exercise based on the first four
objectives for this topic. Students then swap their
exercises with peers and receive feedback. The
feedback can be recorded on the Quick Check sheet
before students complete the rest of the questions.
Feedback: Ask students to look back at the
four statements at the top of the page and their
feedback ticks. Tell students that you are going to
read out each statement and they have one vote to
cast for the most difficult statement to remember or
understand. Find out the statement that students
are least confident about.
Action: Refer to the Student Book topic pages and/
or glossary to remind students about their work on
the most difficult statement. Challenge students to
write another ‘missing words’ sentence to cover this
statement. Ask students to swap their sentences
with their peers and again ask for feedback.
Course resources
ASP: 9Ab Quick Check.
2: Quick Check WS
FA WS
Assessment: Students complete the 9Ab Quick
Check WS sheet.
Feedback: Ask students to hold up a coloured card
(green, amber, red) to indicate how confident they
are about their answers to Question 2 (green card –
very confident, amber card – so-so, red card – not
confident).
Action: Ask random students who had held up a
card to go through their working for the different
parts of Question 2. Encourage students who were
less confident of their answers to ask questions,
and then to correct their work.
© Pearson
9
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Course resources
ASP: 9Ab Quick Check WS.
Equipment
Calculator (optional).
3: Thinking about inherited and environmental
variation 2
FA
Assessment:
Use the Consider All Possibilities activities in Starter
1 and the activities below.
Odd One Out: blood group, height, hair length.
(Possible answers: blood group is discontinuous;
blood group never changes with age; blood group
is not affected by environmental factors; hair length
can quickly be changed.)
Plus, Minus, Interesting: Offspring should inherit
identical characteristics from one parent. (Possible
answers: Plus – it would be easier to identify
families; Minus – it would be very difficult to tell
people apart; Interesting – it may be possible to do
this in the future using cloning. What is cloning?)
What Was The Question: genetic information.
(Possible questions: What sort of information
causes variation in inherited characteristics? What
sort of information is contained in the nuclei of
cells? What factor causes inherited variation?)
Feedback: Students answer the thinking skills
questions in groups, thereby feeding back their
thoughts to one another.
Action: Ask students to choose a best answer
from their group and to consider why they think
it’s the best. Ask a spokesperson from a number
of groups to read out their best answers. Identify
any ideas that are missing and share them with
the class. If understanding is poor then revise the
causes of, and differences between, inherited and
environmental variation at the start of the next
lesson.
The AL presentation 9Ab Thinking skills can be
used for this activity.
Course resources
AL: Presentation 9Ab Thinking skills.
4: Using keywords
FA
Assessment: Ask students to write one sentence
using all the following words: Developing: inherited
variation, fertilisation, genetic information; Securing:
inherited variation, normal distribution, genetic
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information. The words don’t need to be explained,
they just need to be used in an appropriate fashion.
Feedback: Working in pairs, students read each
other’s sentences. For each sentence they say what
is good about it and suggest something that could
be improved.
Action: If there is disagreement on words or their
use, these should be looked up and their definitions
checked in the Student Book glossary or on the 9A
Word Sheets. The best examples could be displayed
on a noticeboard for all students to refer to.
Course resources
ASP: 9A Word Sheets.
HOMEWORK TASKS
1: Inheritance
Worksheet 9Ab-7 contains straightforward
questions about inherited variation.
26
Course resources
AP: Worksheet 9Ab-7.
2: Wild tomatoes
Worksheet 9Ab-8 contains questions about
inherited variation, including normal distribution.
Course resources
AP: Worksheet 9Ab-8.
3: Mendel
Worksheet 9Ab-9 contains information about
Mendel’s work followed by some questions to test
understanding. No prior knowledge of Mendel,
genes or chromosomes is required.
Course resources
AP: Worksheet 9Ab-9.
© Pearson
9Ac
DNA
Objectives
Developing:
1. State the number of pairs of chromosomes in
most human cells and what they are made of.
(UK NC only)
2. Describe how genes control characteristics (in
terms of containing instructions). (UK NC only)
3. Describe the roles played by Watson, Crick,
Franklin and Wilkins in the discovery of the
structure of DNA. (UK NC only)
Securing:
4. Describe the relationship between DNA,
chromosomes, genetic information, genes and
the cell nucleus. (UK NC only)
Exceeding:
Exceeding objectives are designed to broaden
students’ skills and knowledge beyond what
is required, often introducing a higher level of
challenge.
5. Describe the structure of a DNA molecule.
Student materials
Topic notes
• It is important that teachers review all materials
that they intend to use with students before use,
to ensure suitability.
• It is envisaged that in the course of studying the
biology component of this topic, students will
use one Starter idea, Explaining 1, one further
Exploring or Explaining idea, and one of the
plenaries. Additional activities can be added as
time allows.
Be prepared
Exploring 1 requires frozen peas and a
protease.
2: The secret of life
BA
Tell the students that they are acting out a scene
in which they are in a quiet café having lunch.
Once the scene is established, ask one student
to go outside (as though doing an errand) and to
come back in, announcing in a loud voice ‘I have
discovered the secret of life!’ (It might be possible,
and more effective, for you to take on this role.
The students may think that you’ve gone mad but
that’s the reaction that Watson and Crick got when
they did a similar thing.) Tell students that this is
what a man called Francis Crick announced at
lunchtime on 28 February 1953, just after walking
into The Eagle in Cambridge, where people were
having lunch. Challenge students to suggest what
he meant by this. After students have had some
guesses, ask them to read the first part of Topic
9Ac in the Student Book.
3: Putting things in order
FA
BA
Ask students to write the following words on scraps
of paper: cell, chromosome, DNA, gene, nucleus.
Securing: Challenge students to put the items in
order of size. Then ask randomly selected students/
groups what their ordering was and why they
put the things into that order. Explain that a cell
contains a nucleus, which contains chromosomes,
which have sections in them called genes, which
are made out of DNA. Point out that there is one
DNA molecule in a chromosome, which has many
genes along its length.
Exceeding: Add the term ‘genetic information’ to the
list and challenge students to come up with a single
sentence that links all of the terms together. An
example might be: A cell contains a nucleus, which
contains chromosomes, each of which is a single
DNA molecule and has sections along its length
called genes, which contain genetic information.
STARTERS
1: DNA evidence
BA
Challenge students to list some of the evidence that
scenes of crime officers collect at crime scenes.
Elicit the idea that cells are collected in order to
provide ‘DNA evidence’, because most cells (apart
from red blood cells) contain DNA. You could
support this by showing students a video of scenes
of crime officers from an Internet video storage site.
© Pearson
EXPLORING TASKS
1: Extracting DNA
WS
Use this practical to help students remember that
DNA is stored inside cells. Full instructions are
given on Worksheet 9Ac-2. The sheet suggests the
use of two drops of an enzyme solution. This should
be a protease, to break down some of the proteins
that are in the solution, allowing the final DNA to be
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purer. The recommended protease is Novozymes
Neutrase®; however, cheaper alternatives include
using a spatula of powdered meat tenderiser (often
found in Oriental/Asian food stores), 1–2 cm3 of
fresh (unpasteurised) papaya or pineapple juice,
or 1 cm3 of contact lens cleaning solution. Note
that the practical still works without the addition
of a protease but the resulting DNA will be quite
contaminated with protein.
Extend the practical by asking students to read
the instructions and then to come up with a list
of hazards before they start. Then ask them to
say how they will reduce the risks from each of
the hazards (e.g. no naked flames near ethanol,
handle glassware with care, report any breakages
or spillages immediately, don’t touch broken
glassware, wash hands, wear eye protection).
Exceeding: consider making the practical into an
investigation by asking whether washing powder
works better than washing-up liquid. You could try
out a variety of detergents. Alternatively, students
could test the different types of protease suggested.
Wear eye protection. Wash your hands
after doing the experiment.
Course resources
AP: Worksheet 9Ac-2.
Equipment
100 cm3 measuring cylinder, two 250 cm3
beakers, 100 cm3 beaker, granular sodium
chloride, frozen peas (thawed), balance,
washing-up liquid, pestle and mortar, water bath
at 60 °C, filter funnel, filter paper, clamp and
stand, boiling tube and rack, pipette, protease
solution (e.g. Novozymes Neutrase®, powdered
meat tenderiser (often found in Oriental/Asian
food stores), fresh, unpasteurised papaya or
pineapple juice, contact lens cleaning solution),
ice-cold ethanol, stirring rod.
2: Chromosome sorting
WS
Worksheet 9Ac-3 provides a set of chromosomes
for students to sort and use to determine the sex
of the person that they came from (female). The
chromosomes have bands on them: this is the
result of staining them, a technique that is used
so the chromosomes can be identified more easily
under a microscope. Each chromosome has a
distinct pattern of banding (depending on the stain
used). The bands are not genes.
28
Developing: Ask students to sort the chromosomes
into pairs in order to identify the sex. Remind
students that girls have two, larger, X sex
chromosomes and that boys have one X and one
much smaller Y.
Securing: As above, but then ask students to use
the chromosomes to draw a labelled diagram
showing the relationship between a cell, DNA,
chromosomes, genetic information and genes.
Course resources
AP: Worksheet 9Ac-3.
Equipment
Scissors, glue.
Optional: large sheet of paper.
3: Models for genetics
WS
Worksheet 9Ac-6 provides images of a cell and a
wallet. Challenge students to annotate the sheet to
show how the idea of a wallet can be used to help
explain the relationship between a cell, its nucleus,
DNA, chromosomes, genetic information and
genes.
Course resources
AP: Worksheet 9Ac-6.
4: DNA model
WS
Worksheet 9Ac-4 contains instructions for making a
DNA model.
Course resources
AP: Worksheet 9Ac-4.
Equipment
Scissors, glue, coloured pencils, mini-bulldog
clips, paperclips or clothes pegs, stapler, string.
5: Genetic diseases
Explain to students that people can have genetic
tests that allow them to find out whether they carry
certain genes that can cause problems, such as
cystic fibrosis. Tell students that a couple have
been tested to find out if either of them have a gene
for cystic fibrosis. They have been told that they
both do, which gives them a 25% chance that any
child they have will have this disease (which causes
the lungs and digestive system to clog with mucus,
and requires life-long care and treatment). Ask
© Pearson
Genetics and evolution
students to discuss in groups how this would affect
the choice of the couple about whether to have
children or not. Point out that this is a question
that science cannot answer but can contribute to.
Then tell students that sperm cells and egg cells
from the couple could be fertilised in a dish (IVF)
and each embryo tested to see whether it would
grow into a baby with cystic fibrosis. Only those
embryos that are free of the condition are implanted
into the mother. Ask students how this new piece of
information alters what they think the couple would
do.
Exceeding: Follow this up by asking students to
describe the characteristics of an ‘ideal child’. Ask
them to describe how a knowledge of genetics
could be used by scientists to create a child with
desirable characteristics (it’s the same process as
described above, but selecting desirable genes
such as the gene for being musical, if such a thing
exists). Then ask whether they think this would be a
good idea.
Care should be taken when discussing
genetic diseases such as cystic fibrosis,
because some students may have these
conditions or have friends/relatives
who do.
6: STEM – Down’s syndrome
At the end of the STEM spread, 9Ac Genetic
counselling, there is an activity in which students do
some research into Down’s syndrome.
Students are then asked to look at a set of
chromosomes and provide advice to a person
with this set of chromosomes, if they wish to
start a family. Students should work in groups to
discuss this. Ask for ideas from different groups
and then guide the discussion to cover the
following points:
• the person is a man (because photo D shows an
X and Y chromosome)
• so he will not cause an increase in the risk of
having a Down’s syndrome baby (as explained in
the introduction to Question 2)
• his partner/wife could also be tested, to make
sure that her chromosomes are normal
• he may pass on his chromosomes to his child,
and if that child is female she would be at greater
risk of having a Down’s syndrome baby.
Equipment
Internet/library access.
© Pearson
EXPLAINING TASKS
1: 9Ac DNA (Student Book)
FA
This spread reminds students of the idea of
inherited variation of characteristics. Continuous
and discontinuous variation are again recapped,
along with a reminder of what a normal distribution
is. Worksheet 9Ac-1 is the Access Sheet.
Questions 2 and 5 are suitable for formative
assessment, with students working on the
questions in groups.
The AL video Watson and Crick provides an
overview of how Watson and Crick came up with
their model of DNA.
The AL animation Inside a cell explains where
genetic information is stored. See Explaining 3.
The AL spreadsheet Numbers of chromosomes
contains data showing the number of chromosomes
in various different species. Students could
construct a further column to show the number of
chromosomes in a gamete of each species and/or
use the data to plot charts to show chromosome
numbers in different types of animal.
The AL presentation 9Ac Thinking skills can be
used for this activity. See Plenary 2.
Course resources
AP: Worksheet 9Ac-1.
AL: Animation Inside a cell. Presentation
9Ac Thinking skills. Spreadsheet Numbers of
chromosomes. Video Watson and Crick.
2: 9Ac Genetic counselling (Student Book)
This spread looks at the job of a genetic counsellor
and the skills and training that genetic counsellors
need. There is a particular focus on application of
knowledge, and how this can be done by looking
for differences in known patterns.
Before starting the spread ask students if they know
of any genetic disorders/diseases. They may have
heard of sickle-cell anaemia/sickle-cell disease,
cystic fibrosis and beta thalassaemia. Some
students may also be aware that certain versions of
genes can increase the likelihood (probability) of a
person getting some sorts of cancer or dementia.
3: Inside a cell
The AL animation Inside a cell shows the different
parts of a cell, starting with the whole cell and
working down to the idea of a gene. The animation
then explains why a zygote ends up with the same
number of chromosomes as a body cell in the
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parent. There are questions for students to think
about as you work through the scenes.
Course resources
AL: Animation Inside a cell.
4: Chromosomes and fertilisation
WS
Use two copies of the chromosomes on Worksheet
9Ac-3 to model how gamete-making cells produce
gametes with half the number of chromosomes
of normal body cells and how, when the gametes
fuse, the zygote ends up with a full set of
paired chromosomes. This can be done either
electronically on an interactive whiteboard or using
pieces of paper under a video camera. Don’t try to
use all 46 chromosomes on the sheets! Selecting
three or four types of chromosomes will illustrate
the idea. You might tell students that the example
you are showing them is of fruit flies, which have
four pairs of chromosomes.
Exceeding: Take this further and use X and Y
chromosomes to illustrate sex determination. Cut
one of the X sex chromosomes down to about a
quarter of its size to create the Y. If you then also
use three other chromosome pairs, you can again
tell students that this models what happens in
fruit flies, with XX being female and XY being male
(although the precise determination of sex using X
and Y chromosomes is rather different in fruit flies
than in humans). Elicit the idea that the theoretical
probability of offspring being male is ½ or 50%.
Course resources
AP: Worksheet 9Ac-3.
PLENARIES
Most plenaries can be used for formative
assessment. Suggested assessment, feedback and
action strands of formative assessment can all be
modified. See the ASP for further information and
ideas on formative assessment.
1: Quick Check
FA
Assessment: Students are challenged to use the
words on the 9Ac Quick Check sheet to create a
concept map, starting at the animal cell drawn in
the centre of the sheet.
Feedback: Ask students to look back at the Student
Book and to amend their concept maps as they feel
fit. Ask them to write down two things that they are
pleased about with their original concept map and
one thing that they could have done better.
30
Action: Pick random students and for each one, flip
a coin – ‘heads’ for ‘heading in the right direction’
(in which students have to read out one way in
which their original concept map was good) and
‘tails’ for ‘tail me about it’ (in which students need
to say how they have improved their concept map
after looking back at the Student Book pages).
Make a note of any aspects that seem to be a
recurring problem and go over them again.
Course resources
ASP: 9Ac Quick Check.
Equipment
Coin.
2: Thinking about DNA
FA
Assessment:
Odd One Out: red blood cell, muscle cell, sperm
cell. (Possible answers: red blood cells cannot
move on their own; red blood cells do not contain a
nucleus/chromosomes; a muscle cell has a full set
of chromosomes.)
Plus, Minus, Interesting: We should try to discover
all the genes in humans. (Possible answers: Plus –
we could use the information to help people;
Minus – it is expensive; Interesting – what was the
human genome project? We think that there are
about 24 000 genes in humans.)
Plus, Minus, Interesting: We should create new
genes. (Possible answers: Plus – we could make
people do things that they currently can’t do,
such as make their own vitamin C; Minus – we
might create genes that make people behave in a
dangerous way; Interesting – the first artificially
created gene was created in 1972. Are there any
laws on whether you can create new genes?)
Put In Order: cell, nucleus, chromosomes, DNA.
(Possible answers: alphabetical order; order of size;
order of discovery.)
What Was The Question: DNA. (Possible
questions: What long molecule do chromosomes
contain? Watson and Crick worked out the
structure of which substance? What do forensic
scientists look for in cells?)
What Was The Question: Francis Crick. (Possible
questions: Who was the other scientist, besides
James Watson, who worked out the structure of
DNA? Who shouted out ‘We have discovered the
secret of life’ in The Eagle, where people were
eating lunch? To whom did Maurice Wilkins show
the picture of DNA taken by Rosalind Franklin?)
© Pearson
Genetics and evolution
Feedback: Students answer the thinking skills
questions in groups, thereby feeding back their
thoughts to one another.
Action: Ask students to choose a best answer from
their group and to consider why they think it’s the
best. Ask a spokesperson from a number of groups
to read out their best answers. Identify any ideas
that are missing and share them with the class. If
understanding is poor then revise the concept of
DNA and the relationship between it and genes,
chromosomes, genetic information and cells at the
start of the next lesson.
The AL presentation 9Ac Thinking skills can be
used for this activity.
Course resources
AL: Presentation 9Ac Thinking skills.
3: Know, Want to know, Learned on DNA
FA
Ask students to look back at their work from Starter
1 and add to it. Challenge students to look up
anything that they still want to know about DNA and
to add it to their sheets.
Equipment
Work from Starter 1.
4: What is it?
FA
Ideally this activity should be done using a drawing
app on a tablet, so an individual’s images can then
be displayed to the rest of the class. Give students
a word and ask them to draw a picture to represent
it (or ask them to choose their own words to
represent as a picture). Randomly choose drawings
© Pearson
to display and invite the rest of the class to guess
what the drawing represents. Ideas for words
include: chromosome, DNA, cell, nucleus, gamete,
sex chromosome, gene, genetic information,
Rosalind Franklin, fertilisation.
Equipment
Best done on networked tablets.
HOMEWORK TASKS
1: Chromosomes, genes and DNA
Worksheet 9Ac-5 contains straightforward
questions about chromosomes, genes and DNA.
Course resources
AP: Worksheet 9Ac-5.
2: Chromosomes
Worksheet 9Ac-7 contains questions about
chromosomes, genes and DNA.
Course resources
AP: Worksheet 9Ac-7.
3: DNA structure
WS
Worksheet 9Ac-8 explains the overall structure of
DNA and then challenges students to work out the
base pairing rules using the results from Chargaff’s
experiments. Students will need to be able to
calculate ratios in order to complete this sheet –
Skills Sheet MS 1 from Year 7 may be helpful.
Course resources
AP: Skills Sheet MS 1 (Year 7); Worksheet 9Ac-8.
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Objectives
Developing:
1. Explain how changes in abiotic (physical
environmental) and biotic factors in an
ecosystem affect populations and communities,
and can lead to endangerment and extinction.
2. Explain how particular adaptations increase the
chances of survival.
3. Explain why preserving biodiversity is important.
(UK NC only)
Securing:
4. Explain how particular adaptations limit an
organism’s distribution and abundance.
5. Make predictions about how changes in abiotic
and biotic factors will interact with adaptations
and affect survival.
6. Explain how biodiversity can be preserved
using gene banks, seed banks, tissue banks,
cryopreservation and pollen banks. (UK NC only)
Exceeding:
Exceeding objectives are designed to broaden
students’ skills and knowledge beyond what is
required, often introducing a higher level of challenge.
7. Evaluate the evidence for suggested physical
and behavioural adaptations of extinct species.
Student materials
Topic notes
• Adaptations should be familiar to students from
Topics 7Db and 7Dc. The idea of biodiversity
and reasons for its preservation have been met
before in Topic 8Ba.
• It is important that teachers review all materials
that they intend to use with students before use,
to ensure suitability.
• It is envisaged that in the course of studying the
biology component of this topic, students will use
one Starter idea, Explaining 1, one further Exploring
or Explaining idea, and one of the plenaries.
Additional activities can be added as time allows.
Be prepared
Exploring 1 involves fieldwork and the booking
and risk assessment of a suitable site may need
to be undertaken.
Exploring 2 requires woodlice.
Exploring 3 involves fieldwork and the booking
and risk assessment of a suitable site may need
to be undertaken. This practical also needs large
quantities of strong (English) mustard powder.
32
STARTERS
1: What’s the connection?
BA
Write the following list of words up on the board:
nature reserve, zoo, breeding programme. Ask
students to suggest what the link is between the
words (they are all methods of trying to conserve
species). Challenge students to list other methods
of conservation, and write a list of suggestions on
the board (e.g. gene bank, ban on hunting, ban
on trade of animals, restoring habitats, educating
people who live nearby). Ask students what might
happen if we didn’t conserve some types of plants
and animals and elicit the idea that they may
become endangered or extinct.
2: Adaptations for different habitats
BA
The AL presentation Different habitats: revision
(first seen in Year 7) shows different habitats.
Ask students to match up the descriptions of the
physical environmental factors with the correct
habitat and with some of the organisms that
live there. Challenge students to suggest what
adaptations the organisms have that mean that they
are well suited to living in that area.
Extend this activity by asking students to describe
and explain what would happen if there were a
sudden permanent change in one of the physical
environmental factors in a habitat.
Course resources
AL: Presentation Different habitats: revision.
3: Unsuitable adaptations
BA FA
Ask students to consider the following adaptations
and come up with a plus point, a minus point and
an interesting fact or question for each.
Plus, Minus, Interesting: Amphibians should
have a waterproof skin. (Possible answers: Plus –
they would not lose so much water through
evaporation; Minus – less oxygen would get into
their bodies; Interesting – how much oxygen do
amphibians get through their skins? The Bornean
flat-headed frog has no lungs and gets all its
oxygen through its skin.)
Plus, Minus, Interesting: Cactus plants should
have lots of leaves. (Possible answers: Plus – they
would be able to grow faster; Minus – they would
need much more water; Interesting – do any cacti
© Pearson
Genetics and evolution
have leaves? Some cacti do have leaves, such as
many Opuntia species, but generally the leaves do
not last for very long.)
Plus, Minus, Interesting: Bluebells should flower
in the autumn. (Possible answers: Plus – it would
make woodlands more colourful in autumn;
Minus – they might get covered in dead leaves;
Interesting – bluebells flower in the spring before
leaves on the trees have come out fully. Why do
some plants have flowers in autumn and others in
spring?)
Plus, Minus, Interesting: Polar bears should
be black. (Possible answers: Plus – they would
absorb more heat from the Sun when it is shining;
Minus – prey would be able to see them and it
would be much more difficult for them to catch
their food; Interesting – polar bears have black
skin. Are there any Arctic animals that are black in
colour?)
Plus, Minus, Interesting: Elephants should not
have such big ears. (Possible answers: Plus –
their ears would be less likely to get damaged;
Minus – elephants would not be able to keep cool;
Interesting – why do different species of elephants
have different-sized ears? Elephants pick up the
sounds made by other elephants using both their
ears and the soles of their feet.)
Plus, Minus, Interesting: Dolphins should have
gills. (Possible answers: Plus – they wouldn’t have
to come up for air; Minus – they wouldn’t be able
to spend much time with their heads out of the
water; Interesting – how long can a dolphin stay
under water for? Dolphins can stay under water for
about 15 minutes on a single breath.)
The presentation 9Ad Thinking skills can be used
for this activity and in Plenary 2.
Course resources
AL: Presentation 9Ad Thinking skills.
EXPLORING TASKS
1: Comparing environmental factors
WS
In this practical students record how two
environmental factors vary in two different habitats
and then look for a relationship between them.
They also look for and collect small organisms
from each habitat, identify them and count
their numbers. They could also take pictures of
organisms that they find. Physical environmental
factors could be measured using dataloggers and
sensors.
© Pearson
Point out to students that organisms must
be returned to the places in which they were
found. This is so that populations of organisms
in an area remain as they were and diseases
that some animals might have are not spread to
new areas.
Developing: Students use Worksheet 9Ad-3, which
provides guidance for the investigation and poses
some questions for students to answer.
Securing: Ask students to compile their findings
as a report. They should include lists of organisms
found, any photographs they have taken and
graphs of environmental data. They should draw
conclusions about whether there are relationships
between the two physical environmental factors
that they have measured and between one of those
factors and the abundance of certain organisms.
Allow students access to appropriate Skills Sheets
(such as RC 6 and RC 7 from the Year 7 Activity
Pack).
Exceeding: Challenge students to focus on
evaluation in their reports. Students should be
encouraged to think about how they can collect
data of this type in a more systematic fashion
and how this would help them to collect more
reliable data.
Students should wash their hands after
this investigation – plants and soil may
both be contaminated with animal urine
and/or faeces. The area where this
task is carried out should be assessed
for risks beforehand and any obvious
physical hazards removed. Pooter tubes
should be sterilised in sterilising fluid for
30 minutes before and after use. Any
animals removed from a habitat should
be replaced where they were found.
Course resources
AP: Skills Sheets RC 6 (Year 7); RC 7 (Year 7).
Worksheet 9Ad-3.
Equipment
Pooters, quadrats, hand lenses, white plastic
specimen trays, specimen bottle, paintbrushes
(for handling small invertebrates), camera, light
meters, anemometers, moisture meters, pH
meters, any relevant measuring and sampling
equipment (e.g. dataloggers), field guides, keys.
Optional: datalogger and sensors.
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2: Woodlice choice chambers
WS
Instructions for this investigation are found on
Worksheet 9Ad-2. At a simple level woodlice could
be placed in a choice chamber, and half of it could
be covered to block out the light. Alternatively,
the stimulus of dampness can be looked at by
putting a layer of water in one half of the bottom
of the choice chamber and a drying agent (such
as anhydrous calcium chloride or silica gel) in
the other half. Worksheet 9Ad-2 combines the
investigation of these two factors to set up four
different conditions. Skills Sheets RC 6 and RC 7
from the Year 7 Activity Pack could be useful for
this investigation.
Note that woodlice show a response away from
light (towards darkness) and away from dry
conditions (towards damper conditions). This allows
them to locate their food source (rotting plant
material).
Developing: Students use Worksheet 9Ad-2.
Securing: Students use the first page of Worksheet
9Ad-2 but then complete the results tables, draw
conclusions and evaluate the investigation on their
own.
Exceeding: Challenge students to extend their
investigation by considering other stimuli, such
as temperature (by putting water at different
temperatures in the different lower compartments of
the choice chamber) or various odours (by putting
volatile substances in the compartments).
Anhydrous calcium chloride is an irritant
and should not be handled with bare
hands. Eye protection must be worn
when handling it. Students should wash
their hands after handling woodlice.
Course resources
AP: Skills Sheets RC 6 (Year 7); RC 7 (Year 7).
Worksheet 9Ad-2.
Equipment
Woodlice, piece of thick card, water, four-part
choice chamber, wide-bore funnel, drying agent
(e.g. anhydrous calcium chloride or silica gel),
eye protection.
3: Earthworms and moisture
WS
Earthworms may be coaxed to the surface of the
soil using mustard and water (15 g strong (English)
34
mustard powder per litre and use 10 litres per 1 g).
The use of a quadrat (see also Topic 8Ba) will allow
students to test the hypothesis that the number
of earthworms in a patch of soil depends on the
moisture of the soil.
There are different ways in which a quadrat can
be used to randomly sample an area. Quadrats
can be thrown like a flying disc to try to ensure
that they land in random areas. This method will
give a less random sample of an area (because the
experimenter is choosing where to throw) and may
not be suitable with some classes. Alternatively,
draw a map of a lawn and divide it into a grid. You
can number the grid squares and use a random
number generator on the Internet or a calculator
to choose the squares. Students then place their
quadrats down roughly where they think a grid
square lies. Another option is to generate a random
number between 0 and 360 (to give a compass
bearing), followed by another random number
to give you the number of paces to walk in that
direction. A further method involves putting random
numbers in a bag, and laying out two long tape
measures or pieces of marked string at right angles
to one another (as though forming the axes for a
graph on the ground). Students work in pairs and
one student picks a number from the bag and
walks to that number on the horizontal axis while
another student does the same but walks up the
vertical axis. The two students then walk in a line
perpendicular to their axes to the grid point defined
by those two numbers. One student carries a
quadrat and places it where the two students meet.
For each quadrat, a sample of soil is taken from the
middle of the quadrat (50–100 g). The area is then
treated with 10 litres of the mustard solution. After
five minutes, the number of earthworms that have
appeared on the surface of the soil is counted. The
soil sample is placed in an evaporating basin and
has its mass measured before being dried, in order
to determine its moisture content. The formulae
required for working this out are:
wet mass of soil = (wet mass of soil + basin) –
(mass of basin)
dry mass of soil = (dry mass of soil + basin) –
(mass of basin)
moisture content (%) by mass =
wet mass – dry mass × 100
dry mass
(
)
To dry the soil, place the basin in an oven set at
95–100 °C overnight. If the temperature used to
heat the soil is too great, it will burn the organic
matter in the sample, which will result in a reading
for moisture that is too high.
© Pearson
Genetics and evolution
An easier alternative is to use a soil moisture
sensor connected to a datalogger. Some students
could be challenged to compare the results
obtained using dried soil samples with the data
from the sensor.
The AL spreadsheet Earthworms and moisture
contains sample data for this activity. Students use
the data to calculate the amount of moisture in a
sample and then plot a scatter graph to see if there
is a correlation between the soil moisture and the
number of earthworms found.
Developing: Explain to students how a quadrat
is used to randomly sample an area and explain
the importance of random sampling. Give the
instructions to students orally and/or on the board,
and ask students to divide themselves up in their
groups to do different parts of the method (e.g.
prepare the mustard solution, design the grid for
random sampling, place the quadrat, pour the
mustard solution, count the earthworms).
Securing: Challenge students to explain why
there are more earthworms in damper soil, which
may involve some research. A basic answer is
that earthworm skin allows too much moisture to
escape from the animal if it is in dry soil, meaning
that the animal becomes dehydrated. However,
some students should be able to find out that
earthworms need to keep their skins moist because
the skin acts as a surface for gas exchange. Ask
students to plan a way of finding out how accurate
the method of using mustard to raise worms to the
surface is (this will probably involve them digging
up the earth and sifting through it). Studies have
shown that only about 40% of worms in the soil
emerge when treated with mustard. There are other
chemicals that are more effective but these can be
harmful to the worms or plants, whereas mustard is
not.
Exceeding: Challenge students to plan this
investigation for themselves, telling them only that
mustard powder mixed with water can encourage
worms to come out of the ground. They should
plan to do a pre-test in order to test the strengths
of different possible mustard mixtures and should
recall work from Unit 8B on using a quadrat.
Students should wash their hands after
this investigation – plants and soil may
both be contaminated with animal urine
and/or faeces. The area where this task is
carried out should be assessed for risks
beforehand and obvious physical hazards
removed hygienically. Students must not
eat the mustard.
© Pearson
Course resources
AL: Spreadsheet Earthworms and moisture.
Equipment
Quadrat, measuring tape, measuring cylinder,
bucket, strong (English) mustard (supermarket
own brand is cheaper), trowel or spade,
evaporating basins for soil samples, oven on a
low heat.
Optional: moisture sensor and datalogger. If you
are pre-mixing the mustard and water, you need
15 g of mustard powder per litre of water and
10 litres of that per 1 m2 of ground. The mixture
is inclined to get rather lumpy and so it is often
best to mix the mustard in 200 cm3 of water
and then dilute it to strength.
4: Tiger and deer adaptations
Worksheet 9Ad-4 is a simple sheet that asks
students to match adaptations of tigers and deer.
You could extend the activity by asking students to
download an animal image from the Internet and to
label it with as many adaptations as they can. Note,
however, that some images from the Internet are
subject to copyright.
The AL presentation Animals and their
adaptations (first seen in Year 7) looks at animals
and how they are adapted to their habitats. As
an addition or alternative to the extension above,
show students the images of animals without the
labelling and challenge them to list some of the
adaptations before going through the exercise in
which adaptations are added.
Course resources
AP: Worksheet 9Ad-4.
AL: Presentation Animals and their adaptations.
Equipment
Scissors, glue.
Optional: Internet access.
5: Endangered animals research
Worksheet 9Ad-5 challenges students to choose
one (or more) of four animals and then to do some
research to answer the questions. Students should
present their findings as a report.
Course resources
AP: Worksheet 9Ad-5.
Equipment
Internet/library access.
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6: Rising sea levels
Remind students that global warming is a theory
used to explain why the temperature of the
atmosphere has been increasing in recent times.
Remind students of the possible causes of this (e.g.
burning fossil fuels). Explain that computer models
predict that temperatures will rise further, which will
result in more and more ice melting at the poles.
Ask students to write about the consequences of
this in two of the following ways:
• a paragraph from a novel describing an animal
that is having difficulty surviving
• a paragraph from a newspaper report on the
problems caused by melting ice
• a paragraph from a leaflet handed out by
environmental campaigners on a street
• a paragraph of voiceover text for an advert
encouraging people to donate money to an
environmental charity
• a paragraph from a shipping magazine describing
the advantages of less sea ice.
Equipment
Optional: Internet/library access.
7: Dinosaur hypotheses
The AL interactive Dinosaur adaptations contains
a piece of text which asks students to identify
pieces of evidence for and against the theory that
dinosaurs were warm-blooded.
Course resources
AL: Interactive Dinosaur adaptations.
EXPLAINING TASKS
1: 9Ad Genes and extinction (Student Book)
FA
The central idea in this topic is that genes allow
organisms to be adapted to the habitats in which
they live, but if the conditions in that habitat
change, then the organism may no longer have
the adaptations it needs to continue to survive in
the area. This idea is then taken further in the next
topic, which considers natural selection. Worksheet
9Ad-1 is the Access Sheet.
Questions 3 and 8 are suitable for formative
assessment, with students working on the
questions in groups.
In the AL interactive Adaptations to habitats
students match adaptations to habitats, giving the
reasons why them improve an organism’s chances
of survival.
36
The AL presentation Different habitats looks at
different environments. See Starter 2.
The AL spreadsheet Earthworms and moisture
contains sample data for students to study how soil
moisture affects the number of earthworms. See
Exploring 3.
The AL presentation Animals and their
adaptations looks at animals and how they are
adapted to their habitats. See Exploring 4.
The AL interactive Dinosaur adaptations asks
students to identify pieces of evidence for and
against the theory that dinosaurs were warmblooded. See Exploring 7.
The AL video Conservation outlines some
methods of conservation used around the world.
See Explaining 2.
The AL presentation 9Ad Thinking skills can be
used for this activity. See Starter 3 and Plenary 2.
Course resources
AP: Worksheet 9Ad-1.
AL: Interactives Adaptations to habitats;
Dinosaur adaptations. Presentations 9Ad
Thinking skills; Animals and their adaptations;
Different habitats. Spreadsheet Earthworms and
moisture. Video Conservation.
2: Conservation
The AL video Conservation outlines some
methods of conservation used around the world.
Ask students to watch the video and then to do
some research to find out about the conservation
of some organisms. Ask them to produce a table
to show the names of some organisms and the
conservation method or methods that are being
used to conserve their numbers.
Course resources
AL: Video Conservation
3: Yellowstone’s wolves
When wolves were reintroduced to Yellowstone
National Park after a 70-year absence, the
populations of other organisms and even the
landscape changed. The wolves hunted deer, so
the deer stopped grazing in open spaces like the
valleys around streams. Overgrazed shrubs and
trees such as cottonwood, willow and aspen were
re-established. This brought birds and beavers
back to the area. Beavers dammed the streams,
creating habitat for otters, fish and other wildlife.
Bear numbers increased as bears scavenged wolf
kills and ate berries from the regrown shrubs.
Other carrion-eaters like ravens and bald eagles
© Pearson
Genetics and evolution
multiplied too. The wolves also killed coyotes,
so rabbit and rodent populations could increase,
feeding more foxes, weasels and hawks. Finally, the
new vegetation slowed soil erosion and prevented
stream banks from collapsing, so rivers developed
narrower, less meandering courses.
This case study can be found online (search for
‘How wolves change rivers’). Either describe the
changes, or show the video, and ask students
to take notes. In groups, students should draw
a diagram of the relationships of the different
organisms. This could take the form of a concept
map, with organism names connected by lines
showing how they affect one another.
Course resources
AP: Skills Sheet RC 3 (Year 7).
Equipment
Internet access.
PLENARIES
Most plenaries can be used for formative
assessment. Suggested assessment, feedback and
action strands of formative assessment can all be
modified. See the ASP for further information and
ideas on formative assessment.
1: Quick Check
FA
Assessment: Students answer the questions on the
9Ad Quick Check sheet.
Feedback: Go through the questions one at a time
and ask for a show of how confident students are
about their answers. You could use coloured cards
(red, amber, green) or an electronic student voting
system. Rank the questions in order of confidence
and start by giving out answers (from the 9A Mark
Scheme) to the questions students were least
confident about. Ask students to amend their
answers as you go through them.
Action: Pick random students and ask what
their least confident question was, and how
they have changed their answers. Repeat the
confidence voting again and discuss any remaining
points of uncertainty with reference to the Student
Book.
Course resources
ASP: 9Ad Quick Check; 9A Mark Scheme.
© Pearson
2: Thinking about genes and extinction
FA
Assessment:
Odd One Out: dodo, pterodactyl, Tyrannosaurus rex.
(Possible answers: Tyrannosaurus rex is a scientific
name; dodo was not a reptile; pterodactyl could fly.)
Plus, Minus, Interesting: We should ban all hunting
of animals. (Possible answers: Plus – it would help
to protect endangered species; Minus – we would
not be able to hunt species that were causing a
problem, such as wild, introduced goats that are
destroying a habitat; Interesting – what animals is it
illegal to hunt? There has been about a 10% rise in
the numbers of blue whales since a ban on hunting
them was introduced.)
Put In Order: least concern, critical endangerment,
extinction, endangerment. (Possible answers:
alphabetical order; decreasing numbers of
organisms.)
What Was The Question: It has a very long neck.
(Possible questions: What adaptation does a giraffe
have for reaching the top leaves on a tree? What
adaptation does a giraffe have for seeing predators
far in the distance? Why does a giraffe need to have
such high blood pressure?)
What Was The Question: gene bank. (Possible
questions: Suggest one way of preserving
biodiversity. Where might you find a store of sperm
cells, egg cells and pollen grains?)
Feedback: Students answer the thinking skills
questions in groups, thereby feeding back their
thoughts to one another.
Action: Ask students to choose a best answer from
their group and to consider why they think it’s the
best. Ask a spokesperson from a number of groups
to read out their best answers. Identify any ideas
that are missing and share them with the class.
If understanding is poor then revise ideas about
adaptation and survival at the start of the next lesson.
The AL presentation 9Ad Thinking skills can be
used for this activity. See Starter 2.
Course resources
AL: Presentation 9Ad Thinking skills.
3: Word meanings
FA
Using the Word Sheet for this topic (and any of the
previous topics), blank out some definitions and
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some of the words. Ask students to fill in the words
and definitions. They should then compare their
work with a full copy of the 9A Word Sheet and
make amendments and additions as appropriate.
End the activity with a vote for the easiest word
and the most difficult word. Ascertain what the
problems with the most difficult word are and make
a point of using it more often and in context during
the last topic of this unit.
Course resources
ASP: 9A Word Sheets.
HOMEWORK TASKS
1: A well-adapted animal
Worksheet 9Ad-6 asks students to design an
imaginary animal that would be adapted to a
certain set of environmental conditions. It then asks
students to describe what would happen if various
things about the ecosystem changed.
38
Course resources
AP: Worksheet 9Ad-6.
2: Adaptation problems
Worksheet 9Ad-7 contains questions about
adaptations, the effects of changes on an
ecosystem and preserving biodiversity.
Course resources
AP: Worksheet 9Ad-7.
3: Dodo evidence
Worksheet 9Ad-8 takes students step by step
through the construction and evaluation of a model
of what dodos looked like.
Course resources
AP: Worksheet 9Ad-8.
© Pearson
9Ae
Natural selection
Objectives
Developing:
1. State that the individuals in a population are
likely to vary from one another genetically.
(UK NC only)
2. Explain how natural selection determines the
survival of certain variations of adaptations
within a population. (UK NC only)
Securing:
3. Explain how natural selection can lead to
evolution. (UK NC only)
Be prepared
Exploring 1 requires coloured pasta shapes
(including green pasta) and access to a large
area of grass.
Exploring 2 requires a variety of seeds. Check
for students suffering seed allergies before
purchasing seed varieties.
Exploring 3 requires pasta and access (for a
few days) to terrain which matches one pasta
colour. The pasta may need to be dyed to get
an appropriate colour match.
Exceeding:
Exceeding objectives are designed to broaden
students’ skills and knowledge beyond what
is required, often introducing a higher level of
challenge.
4. Explain how evidence from fossils supports
Darwin’s theory.
Student materials
Topic notes
• Misconception: Students often develop the idea
that a change in the environment somehow
causes a variation in characteristics. It is vitally
important that students are careful about the
terminology they use and understand that it is
natural genetic variation that is allowing some
individuals to survive better than others.
• Misconception: Students often think that when
conditions change all of the less well-adapted
organisms will die. This is not true. It is just
that the survival rates are shifted in favour of
the better-adapted organisms. This shift often
becomes more marked when a resource is in
short supply.
• It is important that teachers review all materials
that they intend to use with students before use,
to ensure suitability.
• It is envisaged that in the course of studying the
biology component of this topic, students will
use one Starter idea, Explaining 1, one further
Exploring or Explaining idea, and one of the
plenaries. Additional activities can be added as
time allows.
© Pearson
STARTERS
1: How do you vary, why do you vary?
FA
BA
Ask students to work together to prepare a
paragraph to answer the question: ‘How do you
vary, why do you vary?’. They should make use of
what they have learned so far in this unit, including
the causes of environmental and inherited variation.
After a few minutes ask random groups to read out
their work and say ‘pause’ whenever they say a key
term (i.e. those on the 9A Word Sheets). Write this
word up on the board and then say ‘play’. Carry
on in this manner until there is a suitable list of key
terms on the board. Challenge students to say what
each key term means and to identify others that
have not been read out.
Course resources
ASP: 9A Word Sheets.
2: Adaptations for habitats
BA
Ask students to draw a life-size picture of a bird
that eats insect larvae (such as maggots) that are
usually found in the crevices of trees. Then get
students to measure the lengths of the beaks that
they have drawn, and if possible display them on
the board. Point out that there is a range of beak
lengths, and this is what happens in populations of
organisms – their adaptations/characteristics vary
(although probably not quite as much as the beak
lengths in this exercise!).
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Now explain that the birds need the most food in
spring and summer but in this particular year the
spring and summer are very cold. This has meant
that the larvae are very deep inside the trees and
difficult to reach. Ask students which of the birds
will be able to catch the larvae, and establish
that it is only those with the longest beaks. Ask
students what might happen to the other birds
and elicit the idea that they may not survive. This
will mean that in the next generation of birds
there will be more with longer beaks because
more of the longer-beaked birds have survived to
reproduce.
Equipment
Blank paper, ruler.
3: Spreading diseases
BA
Ask students whether, if one person in the class
gets a cold, everyone will get it. Elicit the idea that
not everyone gets ill (although with some colds
more people get them than with others). Challenge
students to explain why not everyone gets the cold
and introduce the idea that this is partly due to
our inherited variation – some people are naturally
immune to some colds/diseases.
Extend this by asking what would happen if a ‘killer
cold’ came along. Tell students about Spanish
flu in 1918, which killed 50–100 million people
worldwide. Some people did not catch it because,
by chance, they were naturally immune to it. What
would happen to the number of people in the next
generation who had immunity to the disease?
(There would be more of them.) Why would there
still be some people in the next generation who
could still get this type of flu? (Because there were
parts of the world that the flu did not reach, some
people were never in the vicinity of an infected
person and some people, by chance, would be
naturally susceptible to it even if both parents were
immune.)
EXPLORING TASKS
1: Camouflage
WS
This investigation needs to be done in a reasonably
large area of grass. Divide the class into groups
and explain that they will conduct this investigation
in groups. Each group will get some pasta shapes,
which are models for insects. They must organise
themselves so that the numbers of each different
colour of pasta shape are recorded. The shapes
40
are then spread out in an area. One student is
‘the bird’ and is given a pair of tongs/forceps.
The student has two minutes to pick up as many
pasta shapes as possible, returning to the ‘start
line’ upon picking up each shape to put it into the
collecting pot. After two minutes, students count
the numbers of each colour returned and calculate
percentages. This can then be repeated with a
different student being the bird and mean values
calculated. Ask students to state their findings as
experimental probabilities.
Developing: After the experiment, explain to
students how this is a model for natural selection.
Explain that if we imagine the pasta shapes
to be insects, then the surviving insects (the
greener ones) have more chance of surviving and
reproducing and so the next generation of insects
will have proportionally more green insects. They
could also draw pie charts of the data.
Securing: Challenge students to explain how this
experiment is a model for natural selection and
what the next generation of insects would be like.
Ask students to choose a way of best presenting
their data.
Exceeding: Show students the apparatus (including
the tape measure, which can be used to ensure that
the same sized area is used in each test) and ask
them to design their own games to show natural
selection. Encourage them to devise their own
criteria that they will use to judge how well their
models explain natural selection.
Ensure that any outside area in which
this practical is to be done is free from
obvious dangers, such as animal faeces,
pieces of metal and broken glass.
Students should wash their hands if
the pasta has been handled directly,
as the pasta shapes may have been
contaminated by being scattered on
the grass. It would be sensible to wash
and dry any pasta that will be reused for
further classes. Students must not eat
the pasta.
Equipment
Packets of different coloured pasta, which must
contain green pasta pieces as well as other
colours (500 g per 4–5 students), forceps or
tongs, stop clock, pot to collect pasta shapes,
area of grass.
Optional: measuring tape.
© Pearson
Genetics and evolution
2: Beak shape
WS
Students investigate how the shape of a bird’s beak
is important for a certain seed size. Tell students
that a range of forceps and tongs are going to be
used to model the slightly different beak shapes
of a group of birds of one species, who have been
blown off course and landed on an island where
there is only one type of seed to eat.
Students should use a range of fine and bluntended forceps/tweezers and/or tongs to transfer
seeds from one container to another, one at a time,
in a set length of time (e.g. one minute).
Students should describe how this model could
be used to show natural selection and what would
happen to the proportions of birds with the different
beak shapes in the next generation. Challenge
students to use this as a model to show how
Darwin’s theory of evolution works.
Do not use nuts. Do not use seeds
that students may be more tempted to
eat. Some seeds may be treated with
antifungal agents. Students should wash
their hands thoroughly afterwards. Seeds
should be bought from a health food/
organic shop, which will have untreated
seeds. Check for students suffering
seed allergies before purchasing seed
varieties.
cooking time. It is better to buy pasta that is
pre-coloured, but it can be dyed by adding food
colouring during cooking. The dye does, however,
tend to fade outside. Students should record the
numbers of ‘caterpillars’ remaining each day. Birds
will remove the pasta and a clear pattern of results
is normally obtainable in 2–3 days. Areas that could
be tried include a sports field, a tennis court or a
tarpaulin.
Students must not eat the pasta.
Equipment
100 pieces of pasta (2–3 cm long) cooked for
half the recommended time – use 50 pieces
each of two different colours, metre ruler.
Optional: food dye, tarpaulin.
4: Resistance to poison
Worksheet 9Ae-3 shows a model of natural
selection using imaginary insects and an
insecticide. Students are taken through two
sprayings of the insecticide and two generations of
the insects, demonstrating how natural selection
will eventually cause the species to evolve so that
all the individuals are resistant to the insecticide.
Step 2 on the sheet could be repeated over and
over again, using blank copies of the second
diagram.
Securing: Help students to work through the steps.
Equipment
Access to seeds (e.g. carrot, poppy, dried pea,
horse chestnut ‘conker’), plastic cups, selection
of blunt-ended forceps/tweezers, fine forceps/
tweezers and tongs, stop clock.
3: Birds and pasta caterpillars
WS
Short lengths (2–3 cm) of pasta (e.g. spaghetti or
tagliatelle) are placed at regular intervals across
an area outside. The pasta ‘caterpillars’ are to be
collected by birds, so it is important to choose
an area that will remain undisturbed by other
‘predators’. The caterpillars must be placed at
regular intervals so that gathering results is easy.
The pasta should be of two different colours, one
of which matches the terrain, each type being laid
out randomly. The pasta needs to be cooked until it
is just soft – normally about half the recommended
© Pearson
Exceeding: Students should be able to complete
the sheet on their own, including the extra
challenge question.
Course resources
AP: Worksheet 9Ae-3.
Equipment
Dice.
5: Debate
There is an opportunity for a debate presented on
Student Book page 9Ae Recreating animals. Refer
to Skills Sheet RC 5 from the Year 7 Activity Pack
for ideas on how to run a debate.
Course resources
AP: Skills Sheet RC 5 (Year 7).
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EXPLAINING TASKS
1: 9Ae Natural selection (Student Book)
FA
This spread explains natural selection and takes
a brief look at Darwin’s theory of how natural
selection leads to evolution. Worksheet 9Ae-1 is the
Access Sheet.
Questions 3 and 4 are suitable for formative
assessment, with students working on the
questions in groups.
The AL video Whales, evolution and Darwin looks
at some of the evidence that supports the idea of
evolution and then examines Darwin’s theory of
evolution by natural selection. DNA ‘fingerprinting’
has shown that whales have a common ancestor
with hippos. This fact provides more evidence for
the way in which nature selects organisms that
have by chance inherited certain variations in their
characteristics (due to the genetic information in
their DNA), and so supports Darwin’s theory that
evolution occurs by natural selection.
The AL presentation 9Ae Thinking skills can be
used for this activity. See Plenary 2.
Course resources
AP: Worksheet 9Ae-1.
AL: Presentation 9Ae Thinking skills. Video
Whales, evolution and Darwin.
2: 9Ae Recreating animals (Student Book)
FA
This picks up on some of the themes running
through this unit and introduces the idea of
cloning, which will be covered in more detail
during GCSE/IG.
PLENARIES
Most plenaries can be used for formative
assessment. Suggested assessment, feedback and
action strands of formative assessment can all be
modified. See the ASP for further information and
ideas on formative assessment.
1: Quick Check
FA
Assessment: The 9Ae Quick Check sheet is a freewriting (and drawing) exercise in which students
need to explain how natural selection has led to a
change in a characteristic.
Feedback: Ask students to check each other’s
work, and to provide feedback in the form of two
42
points that were good and one point that may
need some further work (‘two stars and a wish’).
Students should then work together to improve
their work. Choose students at random to explain
how they have improved their work, taking note of
any persistent misconceptions.
Action: Look back at the Student Book to
explain again any points that students are still
unsure of.
Course resources
ASP: 9Ae Quick Check.
2: Thinking about natural selection
FA
Assessment:
Odd One Out: having teeth with fillings, blood
group, height. (Possible answers: having teeth
with fillings is only an environmental variation/is
not controlled by genes; height is an example of
continuous variation.)
Plus, Minus, Interesting: Evolution using Lamarck’s
idea should be possible. (Possible answers: Plus – if
you developed big muscles, your children would
also have big muscles; Minus – you’d have to be
very careful what you did in your life; Interesting
– are there any situations in which Lamarck’s idea
works? There is now evidence that indicates that the
diet eaten by parents and grandparents does affect
inherited variation in their offspring but scientists are
still not sure how this works.)
What Was The Question: natural selection.
(Possible questions: What process does Darwin’s
theory of evolution rely upon? What process
causes changes in characteristics over time due to
changes in the conditions in an ecosystem?
What Was The Question: Darwin. (Possible
questions: Name one person who came up with
a theory of evolution. Who are the finches on the
Galapagos Islands named after?)
Feedback: Students answer the thinking skills
questions in groups, thereby feeding back their
thoughts to one another.
Action: Ask students to choose a best answer
from their group and to consider why they think
it’s the best. Ask a spokesperson from a number
of groups to read out their best answers. Identify
any ideas that are missing and share them with
the class. If understanding is poor then revise
natural selection using the Student Book and invite
students to indicate which are the hardest parts to
understand.
© Pearson
Genetics and evolution
The AL presentation 9Ae Thinking skills can be
used for this activity.
Course resources
AL: Presentation 9Ae Thinking skills.
3: Quick Quiz revisited
FA
Revisit the 9A Quick Quiz to test students’
knowledge of the content of this unit. Students
could fill in their answers on the 9A Quick Quiz
Answer Sheet. Encourage students to identify areas
for themselves that are still weak and decide how
they are going to remedy this.
Course resources
ASP: 9A Quick Quiz; 9A Quick Quiz Answer
Sheet.
4: End of Unit Test
Use either or both of the End of Unit Tests. A
mark scheme is given in the ASP. Encourage
students to identify areas that are still weak and
to formulate plans to strengthen those areas.
Summary Sheets are provided to help students
with revision.
Course resources
ASP: 9A End of Unit Test Standard (S); 9A End
of Unit Test Higher (H); 9A Mark Scheme; 9A
Summary Sheets.
5: Progression Check
Students should circle the stars next to each
statement on the Progression Check to record
what they feel they know, and how certain they
are of it. Encourage students to plan how to do
further work on the things about which they remain
unsure.
Course resources
ASP: 9A Progression Check.
© Pearson
6: Triceratops: Open-ended Assessment Task
FA
The top of the Assess Yourself! sheet describes
Triceratops. Students are challenged to describe its
variations and adaptations and their causes, and
to suggest how its horn evolved from a possible
ancestor called Titanoceratops.
You can assess this activity by using the Openended Assessment Task sheet or students can
rate their own performance by using the Assess
Yourself! sheet (see the ASP). Get students to
reflect on what they did well in this activity and
what they need to improve on. After feedback, give
students an opportunity to improve their work and
have it reassessed.
Course resources
ASP: 9A Assess Yourself!; 9A Open-ended
Assessment Task.
HOMEWORK TASKS
1: Genetic variation and selection
Worksheet 9Ae-4 contains straightforward
questions about genetic variation and natural
selection.
Course resources
AP: Worksheet 9Ae-4.
2: Natural selection in birds
Worksheet 9Ae-5 contains questions about natural
selection in birds.
Course resources
AP: Worksheet 9Ae-5.
3: Fossils and evolution
Worksheet 9Ae-7 challenges students to interpret
fossil evidence in the evolution of horses.
Course resources
AP: Worksheet 9Ae-7.
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