B1 you and your genes answers

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B1.1- 2

B1 You and your genes

Guidance AB1.1.1 Inheritance traffic lights

Requirements (per student) • Activity sheet AB1.1.1 (optional) • small pieces of card (x3) per student (either

red, yellow, green or ×, , ?)

Teaching notes This activity is designed to review KS3 inheritance concepts and provide information on students’ starting points for this module. Give each student their cards. • Red or × means FALSE. • Green or means TRUE. • Yellow or ? means I’M NOT SURE. The game follows this sequence: a Read the question. b Allow a short period of time for students to

consider their answer. c Count ‘1, 2, 3, show your cards!’ d Students all hold up one of their cards at the

same time. The questions are available on Activity sheet AB1.1.1 if you wish to use them in a different type of activity.

Answers to questions 1 Sexual reproduction needs a male and a

female. T 2 Only animals use sexual reproduction. F 3 Characteristics are passed on from parents to

offspring in sexual reproduction. T 4 In humans the male sex cells are called sperm

and the female sex cells are called ova (or egg cells). T

5 In some people there is an extra type of sex cell that produces identical twins. F

6 In humans the sperm cell has a tail so it can move towards the ovum (egg cell). T

7 Fertilisation happens when a male sex cell and a female sex cell join together. T

8 The instructions to make a new person are in a fertilised egg cell nucleus. T

9 These instructions are called genes. T 10 All of a person’s characteristics are controlled by

their genes. F 11 Your blood group depends on what country you

grow up in. F 12 If you dye your hair red for more than two years,

it will make you have red-haired children. F



B1.1-3


Guidance AB1.1.3 Variation

Requirements • OHT sheets of graph axes (for teacher) • Activity sheet AB1.1.3 (optional-students)

Teaching notes This activity reinforces students’ understanding of causes of variation.

Procedure Ask the students to identify whether their earlobes are dangly or attached. Record the data as a block graph on the blank OHT axes. Emphasise lack of ‘inbetweens’. Ask students to suggest other characteristics that follow this pattern (eg blood group). Many of the ones students tend to suggest are not single-gene characteristics (eg eye colour is determined by several genes). Most characteristics are determined by several genes, and are affected by the environment. Superimpose provided graph of height data. This graph shows height distribution for a population of UK students aged 14–16. Ask students to suggest why the distribution looks different, not simply ‘tall’ or ‘short’: • Height is determined by several genes – like most

of our characteristics. • Height is also affected by environment – like many

of our characteristics. You may wish some students to complete the activity sheet as a record of the key ideas. There are Textbook questions as an alternative.

Further information If you have access to an interactive whiteboard you may prefer to prepare graph axes on this, rather than use OHT sheets.

Answers to questions 1 Class data. 2 a Graph shape showing two possible earlobe

shapes. b Graph shape showing continuous data for

height. 3 a Person’s earlobe shape is affected by just one gene.

b So you have either attached or dangly earlobes.

c Your height is affected by many genes.

d Height is also affected by your environment. e So people are not just either short or tall. f People’s height varies much more than their

earlobe shape.



B1.1-4





B1.1-5





B1.2-3


Guidance AB1.2.1 Cloning plants

Requirements (per group) • Activity sheet AB1.2.1 (sheets 1 and 2) • 100 cm3 sterile distilled water • 100 cm3 20% Domestos solution • test tubes containing 2–3 cm3 plant tissue

growth medium (x3) • sterile Petri dish • metal forceps and scalpel (count out/back) • non-absorbent cotton wool • aluminium foil • labelling pen • ethanol (for forceps/swabbing) (HIGHLY

FLAMMABLE)

Technical notes To make 775 ml of plant growth medium: • 20 g granulated sugar • 10 g agar • 4.7 g Murashige and Skoog (M&S) medium • 25 cm3 kinetin stock solution The kinetin stock solution contains 0.1 g kinetin in 1 litre of distilled water. Kinetin does not readily dissolve in water; adding one or two pellets of sodium hydroxide helps the dissolution process. Stock solution should be stored at 4°C. Dissolve the sugar, M&S medium, and agar in 725 cm3 of distilled water. Mix in the stock kinetin solution, then dispense into test tubes (2–3 cm3 per tube). Plug the tubes with non-absorbent cotton wool and cover the tops with aluminium foil. Autoclave at 121°C for 15 minutes in a pressure cooker. When cool, the tubes may be refrigerated until they are needed. M&S medium and kinetin are available from school science suppliers, e.g. Philip Harris Limited.

Cloning cauliflower Procedure 1 The working area should be swabbed with 70%

ethanol prior to the experiment. 2 Once the cauliflower pieces have been sterilised

in bleach, quick, aseptic technique is needed to prevent contamination.

3 To flame metal instruments, dip them in alcohol, pass briefly through a flame to ignite the ethanol. As the ethanol burns off, it heats the surface of the instruments to 70°C, killing any contaminating organisms. Do not heat forceps and scalpels until red hot.

4 The cauliflower pieces can be left in the final beaker of sterile distilled water (covered with a Petri dish lid) until required.

5 Before placing the cauliflower into each test tube, remove the cotton wool plug, then briefly flame the tube neck. Use flamed, cooled forceps to drop a piece of cauliflower into the tube. Return the forceps to the ethanol beaker. Flame the neck of the tube before replacing the cotton wool plug.

6 The tubes should be kept in a warm, light place. Growth should be visible within 10 days.

7 If contamination has occurred it will also be visible by this time. Failure of any growth usually indicates that the bleach solution has not been rinsed sufficiently from the plant tissue.

Further information The procedure for cloning cauliflower is adapted from Practical Biotechnology, National Centre for Biotechnology Education (NCBE), 1995. Further information and protocols for a wide range of school biotechnology practical work can be found on the NCBE website; see WEBLINKS.



B1.2-4


Guidance AB1.2.1 Cloning plants

Health and safety notesEthanol should be kept away from exposed flames. You may wish to pre-prepare flamed forceps and scalpels for students in some classes. Alternatively, they can be pre-sterilised in an autoclave. Plastic gloves should be worn when handling kinetin – the solution used by the students present no problem. Students should wear eye protection. Students need to take especial care when using scalpels.

Answers to questions 11 To kill any microorganisms on the surface of the

cauliflower. Contamination of the growth medium could prevent the new plant from growing properly.

12 To reduce water loss from the test tube. 13 Every plant cell contains all the genetic

information needed to make a new plant. When the plant is growing, some of the plant cells stay unspecialised. They can develop into any type of plant cell.



B1.2-5


Guidance AB1.2.2 Twin studies

Requirements (per student) • Activity sheet AB1.2.2 • graph paper

Teaching notes As students work through this activity they practise converting data from a table to bar charts. The bar charts will then make it easier for them to draw conclusions from the information they are given. The data comes from an early (1937) but important US study on twins, which showed how different genetic characteristics appear to be affected to a greater or lesser degree by environmental influences. Subsequent studies have confirmed the concept although there is still considerable variation in results. If anything, the consensus of data is that genes have a stronger influence than was originally thought, and environment less. Students need to grasp the idea that, the smaller the differences between them, the more alike the pair are and so the stronger the genetic influence. This data suggests that height is surprisingly strongly genetic, mass much less so and IQ clearly influenced by both genes and environment.

Answers 1 Suitable bar charts 2 Characteristic mainly decided by genes –

environment has little effect, so little difference between identical twins reared apart or together. The bigger the influence of the environment, the bigger the difference between identical twins reared apart and identical twins reared together.

3 Height – different environment has relatively small impact on final height of identical twins.

4 They have identical genes but have been reared in different environments, so can see the effect of environment on different characteristics. This allows scientists to discover how much genes and the environment influence different characteristics.

5 They are affected by the environment more or less equally.

6 Any valid points, eg how many pairs of twins were studied, the age at which they were measured, if the data was all collected by the same people in the same place using the same instruments, etc.

To find out This provides extension for some students. Direct students to the weblinks provided for this lesson. Ask them to find out more about twin studies. Look for evidence that students have extracted scientific understanding from the twin stories, and that they recognise the type of data that would need to be collected to have validity, etc: see WEBLINKS



B1.3-3


Guidance AB1.3.1 Inheriting genes

Requirements (per student or group)

• Activity sheets AB1.3.1 • Animation IB1.3.6

Teaching notes The animation (IB1.3.6) is designed for students to work through themselves. If you have access to an interactive whiteboard, you may prefer to use a whole-class teaching approach. If you do not have access to the animation, students could complete the activity sheet using the Textbook.

Answers to questions Fertilisation 1 Humans have 23 pairs of chromosomes. 2 The bands on the chromosomes show different

genes. 3 Chromosomes are in pairs, so genes come in

pairs too. 4 The only cells that don’t have pairs of

chromosomes are the sex/gamete cells.

Why don’t brothers and sisters look the same? 5 Sperm cells get a copy of just one of the

chromosomes from each pair a man has. 6 It is very unlikely that two sex cells get the same

combination/mix of chromosomes. 7



B1.4-2


Guidance AB1.4.1 Male or female?

Requirements (per student) • Activity sheet AB1.4.1

Requirements (per group) • small bag with 20 circles of card, each

marked with an X (‘ova’ bag) • small bag with 20 sperm-cell shaped cards,

half marked X and half Y (‘sperm’ bag)

Technical notes It is helpful for clearing away if the ova and sperm cards are different colours.

Teaching notes The activity illustrates the random nature of fertilisation. Check that students know the sex chromosomes of a human male and female before starting the game. Students select randomly an ‘ovum’ and ‘sperm’ card from each bag. The cards should be replaced in the bags and mixed well after each ‘fertilisation’.

Answers to questions 1 X or Y 2 All X 3 Sperm cell 4 Students usually consider that Henry VIII was

incorrect in blaming his wives for his lack of male heirs.

Further information Students may be aware of anecdotal stories of families which appear to produce a greater proportion of male or female children. The small sample sizes within a family do not make this data significant. The 2001 UK census lists 28 581 233 males and 30 207 961 females. There have been individual research reports that suggest sperm carrying a Y chromosome are more susceptible to toxins, such as those in cigarette smoke, than X-carrying sperm.



B1.4-3


Guidance AB1.4.2 Inheriting sex

Requirements • Activity sheet AB1.4.2 (per student) • Animation IB1.4.4 Sex

Teaching notes The animation is designed for students to work through themselves. If you have access to a data projector or an interactive whiteboard, you may prefer to use a whole-class teaching approach. If you do not have access to the animation students could complete the activity sheet using the Textbook.

Answers to questions 1 A human body cell has 23 pairs of

chromosomes. 2 Pair 23 control a person’s sex. 3 A woman’s sex chromosomes are XX.

4 A man’s sex chromosomes are XY. 5 A human sex cell has 23 single chromosomes. 6 Row 1: XX XX Row 2: XY XY Chance of child being male: 50%; ½



B1.4-4


Guidance AB1.4.3 Caster Semenya’s story

Requirements (per student) • Activity sheet AB1.4.3 • Internet • use WEBLINK to get students started

Teaching notes This activity provides students with an opportunity to explore a contemporary story of an athlete where sex testing and gender issues meet. Caster Semenya is a young South African who has been brought up and schooled and has competed as a girl. However, once she appeared on both the national and international stage, questions were raised as to her biological sex as a result of both her appearance and her performances. In July 2010, a year after winning the gold medal, the International Association of Athletic Federations (IAAF) announced that its panel of medical experts concluded she could compete again. Students are asked to investigate the story and produce a presentation or article summarising the main facts and the problems that have arisen. It provides another opportunity to discuss the sex/ gender issues and also to consider how and why it might have proved so difficult to determine whether Caster is male or female. Use the WEBLINK available.



B1.4-5


Guidance AB1.4.4 Looking at sets of chromosomes


• Activity sheets AB1.4.4

Teaching notes This is an extension activity.

Answers to questions 1 Pair 23 in a male body cell is XY; in a female

body cell it is XX. 2 The Klinefelter’s karyotype has three sex

chromosomes instead of a pair – XXY. 3 A person with Klinefelter’s is male because they

have a Y chromosome with the gene for male sex hormone. So the embryo develops into a male.

4 The instructions for how an organism develops are found in the form of genes found on chromosomes. Genes describe how to make proteins which might be structural or functional. If there are sections of genes missing or duplicated the proteins may not form or form incorrectly, affecting their function and causing the serious symptoms.



B1.5-3


Guidance AB1.5.1 Alleles


• Activity sheets AB1.5.1 • Animation IB1.5.4

Teaching notes The animation (IB1.5.4) is designed for students to work through themselves. If you have access to an interactive whiteboard, you may prefer to use a whole-class teaching approach. If you do not have access to the animation, students could complete the activity sheet using the Textbook.

Answers to questions 1 People have two copies of every gene because

they inherit one copy from each parent. 2 Different versions of a gene are called alleles. 3 4 John has one allele for attached and one for

unattached earlobes. The unattached allele is dominant. (You only need to have one dominant allele for a feature for it to show up.)

5 Carl has two alleles for attached earlobes. (There is no dominant unattached allele, so he has the recessive feature.)



B1.5-4


Guidance AB1.5.2 Modelling fertilisation

Requirements (per group)

• Activity sheets AB1.5.2 (sheet 1 Foundation/sheet 2 Higher)

• beads (e.g. plastic poppet beads) in two contrasting colours (200 of each colour)

• beakers for the beads (× 3) • marker pen or chalk • OHT of following guidance (for teacher)

Health and safety notes It is probably worth mentioning not to put beads in mouth, ears, etc!

Teaching notes These activities are designed to clarify the distinction between gene and allele, and to illustrate that fertilisation and the transfer of alleles from a pair into sex cells are both random processes. Before starting, clarify with students what is meant by a ‘scientific model’, i.e. to a scientist a model is a simplified way of explaining how something is arranged or how it functions. In this activity students model the way information is passed on from parents to their offspring using beads. Using these models they test the ideas used to explain in theory how different characteristics are inherited – and see if those ideas work.

To show that fertilisation happens by chance (sheet 1) a In this investigation the beads represent sex

cells – the egg and sperm cells. Use red beads to be sperm, and yellow beads to be egg cells. Put all the 200 sperm beads in a ‘male’ container, and all the egg cell beads in a ‘female’ container. Mark 20 of the sperm beads and 20 of the egg cell beads with a black spot. Put them back in their containers and mix them in with the unmarked beads.

b Pull out one sperm and one egg bead without looking. These two beads represent the fertilised egg cell. Record if either bead carries a black spot on the tally chart.

c Students will make 50 fertilised eggs. Ask them to predict how many pairs of beads will have: • a black spot on just one bead • black spots on both beads • no black spots at all

Answers to questions 1 This depends on the predictions made. 2 In the experiment it was chance which bead you

picked up each time. Fertilisation is like that too. You cannot predict which sperm will fertilise an egg cell.

Using beads to show how different alleles can be inherited (sheet 2) a Students will make 100 new plants. Ask them to

predict the number of tall and short plants expected.

b Put 100 red and 100 yellow bead ‘alleles’ in the ‘male’ container and mix them up well. Do the same for the ‘female’ container to show the alleles in the female sex cell.

c Take one bead from each container to determine the alleles in the new plant. Students use a tally chart to record the pair – 2 red, 1 red and 1 yellow, or 2 yellow.

d Replace the beads in the container they came from each time.

Answers to questions 1 & 2 These will depend on the predictions made. 3 How well they were mixed. Whether students

looked in the beaker when they picked. These simulation exercises work well, but it is important to make sure that students are clear about what the beads and beakers are representing in each case. It is particularly important that the concepts of genes and alleles are explained carefully, as students often get these confused. Students need to make a fairly large number of fertilised ova for the statistics to work. This does not add much to the time required for the activity. Alternatively, collect group results into whole-class data.



B1.5-5


Guidance AB1.5.2 Modelling fertilisation

Using beads to show how different alleles can be inherited Pea plants are either tall or short. Their height is controlled by just one gene with two different possible alleles. The tall allele is dominant. The short allele is recessive. (This is different from humans. Human height is affected by many genes.) In this investigation you are going to model the breeding between two tall plants. Both these tall plants had one tall and one short parent. You will use beads to represent the alleles for tall and short, e.g. red for tall, yellow for short.



B1.5-6


Guidance AB1.5.3 Genetic crosses

Requirements (per student)

• Activity sheet AB1.5.3 • Animation IB1.5.5

Teaching notes The animation is designed for students to work through themselves. If you have access to an interactive whiteboard, you may prefer to use a whole-class teaching approach. If you do not have access to the animation, students could complete the activity sheet using the Textbook.

Answers to questions Genetic crosses



B1.5-7


Guidance AB1.5.4 Pairing up

Requirements (per class)

• Activity sheets AB1.5.4 (one or more sheets per student)

• OHT of animal outlines copies (x5) • packs of OHT pens of various colours (x5)

Technical notes A set of chromosome cards could be cut out and laminated before the lesson.

Teaching notes This is a very quick, simple, activity to consolidate or recap students’ knowledge of symbol representation for dominant and recessive alleles. Depending on class size, give each student one or more chromosome cards until all are distributed. The task is to find their matching chromosome pair, and mark the OHT animal with the feature the alleles determine. There are five animal outlines. Give one OHT sheet to each of five students around the room. They are the base for that animal. When students find their matching pair, they annotate the feature on the OHT sheet. Use the completed OHT sheets as a basis for quick check questions, eg what would this feature have been if the animal had different allele pairs?



B1.5-8


Guidance AB1.5.4 Pairing up



B1.5-9


Guidance AB1.5.5 Predicting inheritance



Teaching notes The activity sheets present questions to practise genetic crosses. The later questions have less student support. You will want to select questions most appropriate to your students. The final sheet has blank Punnett square diagrams to support students if required on the more difficult questions.

Answers to questions 1 a

b Short plant must have alleles tt.

The percentage of tall plants is 50%. 2 3

4



B1.6-3


Guidance AB1.6.1 Cystic fibrosis


• Activity sheet AB1.6.1 • Animation IB1.6.7 (optional)

Teaching notes This activity is an alternative to note-making which may be appropriate for some students. Students identify symptoms and treatments for cystic fibrosis. The second sheet has instructions which you may prefer to photocopy, or alternatively display on OHT/whiteboard for students to follow. The first part of Animation IB1.6.7 Reading the gene shows the location of the lungs and pancreas, and illustrates mucus build-up along lining tissue. It may be useful to show this briefly to the class.



B1.6-4


Guidance AB1.6.2 Two inherited conditions



Teaching notes Students should conclude for themselves that cystic fibrosis is determined by a recessive allele.

Answers to questions 1

Name of disorder

Huntington’s disease

Cystic fibrosis

Key H = Huntington’s allele h = normal allele

F = normal allele f = cystic fibrosis allele

Does one of the parents of the affected people also have the disease?

yes no

What are the allele pairs of people with the disorder?

HH or Hh ff

What are the allele pairs of people without the disorder?

hh Ff or FF

2 A recessive allele will only cause an effect when there are two of them.

3 a Huntington’s disease: there are no carriers. Cystic fibrosis: Rob, Jane, Paula and Keith must be carriers for the cystic fibrosis allele. Some students may understand that Leon and Clare, and Owen, could be carriers. We cannot be certain they are not from the information in the family tree.

b The allele for cystic fibrosis is recessive. A person with one copy of the allele will not have the disorder. They are a carrier. The allele for Huntington’s disease is dominant. A person with one copy of the allele will have the disease. So there are no carriers of Huntington’s disease.



B1.7-2


Guidance AB1.7.1 Shall we have the test?


• Activity sheets AB1.7.1 • OHT of possible viewpoint (or student copies) • Internet access or printed web pages with

background information on reliability of genetic testing (optional – also provided in Textbook sections E & G)

Teaching notes Students are given four different scenarios and asked to plan the advice they would give to the couples who are all concerned about having fetal genetic testing for different reasons. Students can work in small groups or individually. Help students to understand that the advice given will vary from couple to couple depending on their circumstances and the importance of the information they are seeking. They also need to suggest that couples consider whether they would proceed to a termination if they found there was a problem with the fetus. In one instance in particular, where the parents are simply desperate to know the sex of the unborn baby, the risks of the test outweigh the benefits of the knowledge and they will probably be able to find out a little later in the pregnancy with an ultrasound scan and virtually no risk.

Useful websites The websites provided are for the Royal College of Obstetrics and Gynaecology; and genetics in general. They are very clear and informative about chorionic villus sampling and amniocentesis: see WEBLINKS



B1.7-3


Guidance AB1.7.3 Decision making


• Activity sheet AB1.7.2 • Activity sheet AB1.7.3 • OHT of possible viewpoint (or student copies) • Internet access or printed web pages with

background information on reliability of genetic testing (optional – also provided in Textbook sections F & G)

Teaching notes In this sequence of activities students develop a role-play to explore the ethical issues surrounding pre-natal testing for a genetic disease. There are three roles within each group: a couple and their genetic counsellor. When grouping students, keep in mind that the role of genetic counsellor will need a reasonable grasp of the science ideas. The first activity is a small-group discussion of the options available to the couple. A summary (in the form of a flowchart) of the available options for the couple is provided at the end of these notes to copy onto OHT or give to students. As this is the first occasion during the module that students focus in depth on the Ideas about Science explored in this module, they are likely to need help in structuring their discussion. This is provided by the table on sheet 2 of the activity. Alternatively, if you wish to give students less structured support, you could use AB1.7.2 Ethics. The table on sheet 2 can be completed by one member of the group as a record of their research and discussion. It focuses students on the key information they need to consider before developing their role-play. At the end of their discussion each group should have ranked the options available to the couple. Differences in opinion are likely, but a group should try to reach agreement if they can. If this is not possible, students should reflect this controversy in their role-play. When students hold strongly opposed viewpoints it can be useful to step in and bypass the rank ordering. Sensitivity to this possibility is important where, for example, any questioning of a firmly held family position may be considered as an insult to students’ family beliefs. Controversy involves values, so it is reasonable to set the discussion in the context of respect for each other, acting in the interests of the group by listening to opposing views, and prohibiting remarks which may be offensive to other members of the class. It is worth reminding students that they are going to be expressing views in the context of a role-play, and that therefore these views are not necessarily their own. Perhaps suggest to different groups that the two people within each couple are in broad agreement, or that they disagree. In this way students are directed to consider and present

viewpoints that they may not be in agreement with. Possible viewpoint statements which you could use with students are listed at the end. Students should then be given a set time period to prepare and present their role-play.

Useful websites The Guardian website has a special report on genetics and ethics covering a wide range of issues: see WEBLINKS.



B1.8-2


Guidance AB1.8.1 Finding the right medicine

Requirements (per student) • Activity sheet AB1.8.1 • Internet

Teaching notes Students are given a piece of extra reading about pharmacogenomics and then asked to answer a series of questions. Questions are provided at F and H levels.

Answers F 1 All of the human genes 2 The science of developing new medicines using

knowledge about drugs/pharmaceutical expertise and information on the human genome/individual genetic makeup.

3 Certain painkillers/ kappa opioids work better for females than males. OR Many over-the-counter painkillers work best in pale-skinned, red-haired women.

4 Only giving drugs to which you will not have a bad reaction. Calculating the lowest effective dose.

5 Costs lots of money to develop personalised medicines – to sequence the genome and find the right medicines. Drug companies might not do this for developing world countries which might not be able to afford the individual testing to use the specific drugs. Is it ethical if it is possible to develop drugs but they don’t do it? Any valid points which show student has thought about potential difficulties.

Answers H 1 All of the human genes 2 The science of developing new medicines using

knowledge about drugs/pharmaceutical expertise and information on the human genome/individual genetic makeup.

3 Certain painkillers/kappa opioids work better for females than males. OR Many over-the-counter painkillers work best in pale-skinned, red-haired women.

4 If they know the genome sequence of normal cells and cancer cells they can develop drugs which target only the cells with the changed genetic material of the cancer cells.

5 Any two sensible ideas, for example: • It allows doctors to use the minimum effective

dose of drug for each patient, which minimises risk of side effects and saves NHS money by reducing drug bill.

• It means doctors only prescribe drugs which are effective for a particular patient – benefits patient as always given effective drug and saves NHS money by avoiding trying drugs which don’t work for patient.

• It avoids adverse drug reactions. This benefits patients – they don’t risk death or hospital admission – and saves NHS money treating the result of adverse drug reactions.

6 It costs lots of money to develop personalised medicines – to sequence the genome and find the right medicines. Drug companies might not do this for developing-world countries which might not be able to afford the individual testing to use the specific drugs. Is it ethical if it is possible to develop drugs but they don’t do it? Any valid points which show student has thought about potential difficulties.

7 Any thoughtful point, eg in some cases one drug will work for the majority of people. If only a small group need an alternative, it won’t be financially viable for drug companies to develop an alternative drug. Should they be forced to do so? Or should people with the minority genetic sequence be left without effective treatment?



B1.8-3


Guidance IB1.8.4 Genetic testing of adults

Requirements (per student) • Presentation IB1.8.4 • Whiteboard and projector

Teaching notes Use Presentation IB1.8.4 Genetic testing of adults 1 to introduce genetic testing of adults and the ethical issues this raises. In this case testing adults before they start a family has prevented any babies with Tay Sachs disease being born in the US, Israel or the UK.

Slide 1: Introduction Slide 2: Image of crowd. Text reminds students that everyone has faulty genes with dangerous alleles but most of the time they don’t cause problems. Ask students when these alleles do cause problems. Answers should include: when the problem is a dominant allele or when two people carrying the same recessive faulty allele have a child. Slide 3: Introduction to Tay Sachs disease to support book content. As always with genetic diseases, this needs sensitive handling. However, as a result of the genetic screening described, it is highly unlikely that any pupils will have had any experience of this genetic condition in their families in recent years. Point out that it is the lack of a single enzyme that causes all the problems. Slide 4: Rabbi Joseph Ekstein devised the screening programme in response to losing four of his own children to Tay Sachs. There is a screening test which shows up carriers and this made the programme possible. Slide 5: Punnett square showing how two carriers can pass on the lethal combination. Slide 6: Since the 1980s, Jewish couples of European descent have taken genetic tests and, as far as possible, two carriers have not been matched. You could explain to students that in more traditional Jewish communities a matchmaker would arrange couples and so this made it easier to avoid matching two carriers. Carriers who marry use pre-natal fetal testing and termination to prevent the birth of affected children. Slide 7: Highly successful – virtually no babies with Tay Sachs have been born in the US, Israel or the UK in recent years.



B1.9-2


Guidance AB1.9.2 Stereotype of the karyotype


Teaching notes This is an extension activity.

Answers to questions 1 Male sex cells usually have XY chromosomes. 2 Human body cells normally contain 46

chromosomes. 3 An XYY person has 47 chromosomes in each

body cell. 4 Three unusual phenotypes of XYY men are:

• minor out-turning of the elbows • pectus chest deformity • crooked left eye

5 The insurance company may think that he is more likely to show violent behaviour, and thus become injured. They may think that his chest deformity or crooked eye may make him more likely to need health treatment.

6 John’s bad behaviour could be due to his diet rather than just being because he is XYY. The fact that he is XYY does not mean that this is the cause of his bad behaviour.

7 No, because: • XYY men are tall so they are more noticeable

and may therefore be targeted more for fights, or be more memorable to people – making them more likely to be arrested.

• Most XYY men are not in prison, so all XYY men are not criminals.

8 A stereotype is a ‘label’. The XYY stereotype labels all XYY men as ‘likely to be violent criminals’. XYY men are mostly decent, good people, so the stereotype is unfair and unjust. When we label people as ‘abnormal’ in some way we may make assumptions about them which are not true.



B1.10-3


Guidance AB1.10.2 Embryo selection – what should be allowed?


• Activity sheets AB1.10.2 • Activity sheet AB1.7.2 • access to Internet (optional – depending on

time allocated to the activity)

Teaching notes In this activity students take on the role of a government regulatory body (currently, September 2010, the Human Fertilisation and Embryology Authority: see WEBLINKS Teachers should visit the above website, to make sure that they know the current rulings as these change. In summary, PGD is allowed for serious single-gene disorders such as cystic fibrosis; to select for an embryo which is a tissue match for a seriously ill child; in sex-selection for medical reasons but not for family balancing. Ensure that students are clear about the role of the regulatory body before beginning the activity. If time permits, more able students could be asked to research this information themselves. The relevant websites may not be accessible for all students. Alternatively, a summary card is provided in the activity sheets. Students should work in groups of four. It does not matter if there are extra students. Allocate each student in the group a ‘Case’ card 1–4. Rearrange the class so that all Case 1 students are together and so on. Using AB1.7.2 Ethics as guidance, students consider whether embryo selection should be allowed in their case. The activity sheets include a table for them to record their views. Students should have a set time limit to discuss their case so that they can present it to their group. At the end of this time they should be able to: • explain what the case is • say what the expert group decision was • explain the reasons for the decision, with

reference to the ethical framework on AB1.7.2. In their group of four, they are the ‘expert’ on their case. Running the activity in this way is therefore less threatening for students than presenting their views to a larger audience. This would be an alternative approach where students are more confident. Some students will not agree with embryo selection in any case. They should be encouraged to argue their case within the bounds of this role-play, i.e. embryo selection is allowed subject to regulation. As a member of the regulatory panel, they must develop arguments to win over their colleagues in particular cases, thus restricting the use of embryo selection as much as they are able to.

Notes Pre-implantation genetic diagnosis (PGD): this is a recent alternative treatment. It was first introduced in 1990 for gender selection of embryos in cases of sex-linked inherited diseases. In 1992 PGD was first successfully used in a case of cystic fibrosis. All applications to use PGD must currently be approved by the regulatory body. Friedreich’s ataxia: particularly recommended is ‘The Gift’, a video drama based around the issue of embryo selection, from the Wellcome Trust Education page. Set both in the present and 30 years in the future, it explores the options available to three generations of a family affected by the rare genetic disorder, Friedreich's ataxia. Human Fertilisation and Embryology Authority (HEFA): the HFEA is one of the few statutory bodies worldwide which regulates, licenses and collects data on fertility treatments such as IVF and donor insemination, as well as on human embryo research. It was set up in 1991 to monitor and inspect all clinics in the UK offering fertility treatments or storing eggs, sperm, or embryos. The HFEA consists of 21 members appointed by UK Health Ministers. Members should not be selected as representatives of a particular organisation, but in respect of their personal expertise. At least half of the HFEA members come from disciplines other than medicine or human embryo research. They should be appointed in line with the Nolan principles, seven guidelines for individuals holding public office: www.ost.gov.uk/policy/advice/copsac/annex.htm. The HFEA has carried out public consultations to gather views on pre-implantation genetic diagnosis, and its use in gender selection. The consultation documents are available on its website at time of press, and they are very useful sources of information about this technology.



B1.11-3


Guidance AB1.11.1 Asexual reproduction

Answers 1 Unicellular. 2 Asexual. 3 Clones. 4 The environment is also a source of variation.



B1.11-4


Guidance AB1.11.2 Stem cells

Requirements (per student or pair)

• Activity sheet AB1.11.2 • Scissors and glue • Computer and printer access (optional – as

alternative to cut and stick)

Teaching notes This activity introduces students to different viewpoints on embryo cloning, and recaps the decision-making ethical framework introduced through the Ideas about Science in this module. The first sheet of the activity presents a number of viewpoints for/against cloning embryos to produce stem cells for potential medical treatments. Students should separate the arguments into for and against piles then distinguish them by type: • decision made by weighing up consequences for

all involved • decision made because process is considered

fundamentally right or wrong. The second page of the activity sheet introduces students to some of the language they will meet throughout GCSE Science when discussing or developing arguments: opinion, speculation, evidence, explanation, fact. The first question introduces the terminology to the class. If you have copies of a recent news story, extend this introduction by asking students to identify key statements in the report. The terminology is then put in the context of stem cells and diabetes.

Answers 1 Opinion - Someone's viewpoint. May not be

based on evidence. Speculation - Suggesting possibilities that might happen. Goes beyond facts. Evidence - Information that is linked to the issue. Explanation - An idea to explain some evidence. Fact - Something that people accept as being proved true

3 a Description: transplants of stem cells from their own bone marrow

b Evidence: Out of 23 patients, 20 no longer required insulin injections. One patient remained insulin-free for up to 4 years. Speculation: This treatment could relieve diabetics from injecting synthetic insulin

4 a Explanation:This is because the cells that make insulin are all destroyed after that time.

b Opinion: This treatment could relieve diabetics from injecting synthetic insulin. However, this treatment is unlikely to be a cure.

5 No, this account seems impartial. 6 Ethical arguments in relation to using embryos



B1.12-2


Guidance AB1.12.1 Adult stem cells


Teaching notes Students are given a sheet of comments giving them information and opinions about adult stem cells. They use these sheets along with the Textbook, if needed to fill in the table provided. This could also be done as a class exercise, filling in the table together and using the process as a basis for discussion about the ethical issues raised by both processes. There are many different valid and sensible points which could be raised – a few possibilities are given here.

Possible answers

Embryonic stem cells Adult stem cells

Large numbers can be produced

Only found in tiny numbers

Relatively easily grown Relatively difficult to grow

Cells very flexible – can be used to produce very wide range of tissues

Cells can be used to produce a more limited range of tissues

Cells relatively undamaged Cells may have DNA damage – mutations – depending partly on the age of the adult

Tissues formed may be rejected – recipient needs immunosuppressant drugs

Tissues formed have same antigens as original cells so no rejection problems

Ethical issues for some people with using embryonic cells

No ethical issues as cells taken from patient



B1.12-3


Guidance AB1.12.2 The cloning debate

Requirements (per student) • Activity sheet AB1.12.2 • Internet access

Teaching notes There are four scenarios for students to work with. Depending on the size and ability of the class, students can work individually or in groups. They may manage only one of the activities during the lesson or they may work through all four! Some of the activities can be completed more successfully with access to ICT; if it is not available students will be more limited in the scope of their answers. In most of these answers students are required to express opinions as well as report biological facts.

Answers A Cloning farm animals and animals for medicines Students should show awareness of the benefits of cloning of top-quality animals and embryo cloning in farm animals, and the importance of adult cell cloning in producing as many animals which give medicines in their milk as possible. Disadvantages include the small numbers of animals which result, the risks and problems of adult cell cloning, etc. Students should show clear understanding of different ethical positions.

B Cloning pets 1 a Different environment – different mother,

different uterus, different time so different foods, etc will be available. Environment affects the phenotype as well as the genotype so the animal is likely to have a different character – and behave differently – it will have different experiences, etc. Cats’ coats, even with identical genes, can have a very different pattern and colour, so the clone may not look the same as the original. Any other sensible points.

b Look for biological and ethical comments in student’s answers to this question.

2 a The foal will be genetically identical to the original champion horse but will be a stallion and therefore able to act as a stud when it is adult, so high-quality genes can be passed on. It can make a lot of money for the owners. Any other sensible points.

b Any sensible and thoughtful points.

C Cloning endangered or extinct animals 1 No living tissue to get DNA from; high-quality

fossils rare; difficulties of getting DNA from extinct animals; no animals of the same species to provide eggs or act as surrogate mothers; different habitat, food resources, etc. Any sensible points.

2 Look for evidence that students understand both the science and the concept of ethical arguments, and that they present arguments both for and against the processes.

D Cloning humans Look for evidence of a good understanding of the ideas both for and against the process, and an awareness of technical difficulties, biological dilemmas and ethical problems



B1.12-4


Guidance IB1.12.8 To clone or not to clone?

Requirements (per student) • Presentation IB1.12.8 • Activity AB1.12.2

Teaching notes Students view the presentation and then complete Activity AB1.12.2 The cloning debate.

Slide 1: To clone or not to clone? Students are introduced to the idea that many species of animals have been cloned and that cloning can be used in very different ways. They are going to look at some of the decisions that need to made about this fast-developing technology. Emphasise, that in most of the examples described, it is adult cell cloning that is the basic technique.

Slide 2: Dolly the sheep Image of Dolly the sheep with her own first lamb, Bonnie. This reminds students that adult cell cloning is not easy. It took 277 eggs to produce 1 live lamb.

Slide 3: Cloned cattle Reminder that cattle are often cloned by embryo cloning (when a single embryo is split into lots of individual cells, which each develop into another embryo to be implanted in a surrogate mother cow). The cows on the slide were produced by the less common method of adult cell cloning.

Slide 4: The first dog clone The first dog to be cloned was produced in South Korea in 2005. The photo shows Snuppy the clone as a puppy alongside the original dog. The scientist who produced Snuppy was later disgraced because he faked evidence in work on human stem cells. However, DNA testing proved that Snuppy really was a clone.

Slide 5: Cloning pets 1 This slide shows CopyCat, the first cat to be cloned successfully, and Little Nicky, the first pet cat to be commercially cloned.

Slide 6: Cloning pets 2 This slide shows an American couple with the first commercially produced cloned pet dog – all £100,000 worth of him!

Slide 7: Cloning horses The first cloned horse, who was both daughter and identical clone of the mare who gave birth to her.

Slide 8: Cloning race horses? This image shows a foal who is a clone of a highly successful endurance champion who is a gelding. Race horses are often gelded, though if they then become extremely successful they cannot be used at stud. But if the gelded horse is cloned, the foal will be a stallion and can be used for breeding.

Slide 9: Cloning endangered species Scientists have tried to use cloning to increase the numbers of some of the most endangered species of animals. There was great excitement when Noah the baby gaur (a very rare breed of wild cattle) was born. Unfortunately, he died of infection within 2 days of birth. Cloning mouflon (rare wild sheep) has been more successful. But very few endangered animals have been cloned. One problem is that animals which are closely related but not the same species usually have to act as both egg donors and surrogate mothers.

Slide 10: Cloning extinct organisms This slide shows an almost perfect fossil of a baby mammoth found in the Siberian permafrost in 2007. Scientists think that it may one day be possible to clone extinct animals form DNA extracted from extremely well-preserved fossils like this one. Again one problem is that animals which are closely related but not the same species would have to act as both egg donors and surrogate mothers. Also the environment, food supply, habitat, etc of extinct animals no longer exists.

Slide 11: Cloning primates Cloning primates is proving much more difficult than cloning most other mammalian species, although early embryos and embryonic stem cells were produced in 2009.

Slide 12: Human clones The final slide simply raises the issue of human clones – not only whether it can be done (so far the answer is no although one or two maverick scientists claim to have tried) but whether it should be done.



B1.A-2


Guidance AB1.A.1 Huntington’s disease


• Activity sheet AB1.A.1

Teaching notes This activity introduces Huntington’s disease. It is supported by Section C in the Textbook.

Answers to questions 1 Both men and women can suffer from

Huntington’s disease. Only one parent needs to have the condition for it to be passed on to their children.

2 a Huntington’s disease is an inherited condition. Eileen thinks that David is more likely to have inherited the condition because he looks a lot like his dad.

b Sarah is just as likely as David to have inherited the condition from their dad. It has nothing to do with what other features they may have inherited.

c No – it’s a bit late. Symptoms of Huntington’s disease are usually noticed between ages 35 and 50 years.



B1.B-2


Guidance AB1.B.1 Embryo selection is here to stay


• Activity sheets AB1.B.1 • coloured pens/pencils

Teaching notes This activity recaps students’ understanding of embryo selection. Students should have met the terminology in an earlier lesson. However, there is sufficient guidance for students if they have not done so.

Answers to questions 1 Definition of IVF: Paragraph 4 ‘fertilise the egg

outside the woman’s body’. 2 Description of choosing embryos: Text with

diagrams at bottom of article. 3 Fact: In 1989 scientists found the gene for cystic

fibrosis. Speculation: some said we were close to a cure.

4 ‘This method throws away human beings.’ ‘Embryos are a group of cells. They aren’t conscious.’

5 eg Fact: ‘Fifteen years on we still don’t have one.’ eg Speculation: ‘Soon they’ll be offering embryo testing for features like eye colour or height.’ eg Opinion: ‘Couples that test the embryos for a disease gene are just giving their children a helping hand.’

6 The final sentence expresses a positive view of PGD suggesting that the author is in favour of its use.



B1.B-3


Guidance AB1.B.2 Inheriting gender


• Activity sheet AB1.B.2

Teaching notes This activity reinforces students’ understanding of gender determination.

Answers to questions 1

ovum

X X Sperm cell X XX XX

Y XY XY

2 a Reference to girls having two X chromosomes. A faulty recessive allele will not display its characteristic where there is a normal dominant allele present on the other X chromosome. Boys have only one X chromosome, so a faulty recessive allele will always be displayed.

b Haemophilia was recognised as an inherited disease which could be passed on from one generation of a family to the next.

c i Michael and Bob have haemophilia. ii Lesley and Melissa are carriers of

haemophilia. iii Sara, Leanne, and Kara may be carriers

of haemophilia. iv Darren, Mark, Peter, and James are not

affected by haemophilia.