B3.1
Answers
B3.1 1 Functional foods
Students’ Book pages
1 A food that contains an added ingredient that promotes good
health. The ingredient is not normally found in that food.
2 Prebiotics contain oligosaccharides which are food for
beneficial bacteria in our gut. Probiotics contain the
beneficial bacteria themselves.
3 They are food for the beneficial bacteria which live in the
human gut.
4 The foods reduce the level of cholesterol in the blood.
Raised cholesterol levels increase the risk of heart disease.
5 Opinions might include: the doubts expressed about the
benefits claimed for functional food; that functional foods
should be tested for the benefits claimed before they can be
marketed as functional foods; that many of the naturally
occurring ingredients of a balanced diet are those that are
added to foods to make them functional.
Summary exercise
functional, prebiotics, oligosaccharides, bacteria, fermentation,
cholesterol, heart disease
Higher questions
1 The health benefit claimed should be independent of all
other variables (e.g. other benefits which may work together
with the benefit in question). The food to be tested should be
available to two groups of volunteers standardised for age,
gender and metabolic functions. The volunteers in one group
take in a certain mass of food containing the functional
ingredient for a certain time. The same happens in the other
group, except the food does not contain the functional
ingredient. Each group is monitored to measure any health
benefit. In practice, to control all variables other than the one
under investigation (health benefit) is difficult.
2 Student’s own answer.
Extension questions
1 a kills cancer cells;
b loss of bone density (sometimes called ‘thinning of
bones’);
c by undertaking clinical trials which compare the health
(incidence of cancer, development of osteoporosis) of
people eating prebiotics compared with people who are
eating a placebo (not a prebiotic).
3 Yoghurt is a probiotic food which contains some of the ‘good’
bacteria that might have been killed in the gut of a person
taking antibiotics long term.
Worksheet B3.1 1a
1 Slicing increases the surface area available on which yeast
enzymes can catalyse fermentation reactions. The rate of
fermentation increases. Boiling kills microorganisms which
interfere with the fermentation reactions.
2 a Anaerobic respiration;
b ethanol and carbon dioxide
yeast
c sugar  ethanol  carbon dioxide
3 The components of a mixture each have different boiling
points. Careful control of temperature allows each
component to be boiled and vaporised separately. In each
case the vapour is cooled and the distillate collected as a
fraction separate from the other liquids in the mixture.
5 The liquid which distils at 78 °C and is collected.
7 No – the purity of the product is not guaranteed.
Worksheet B3.1 1b
The students’ responses should be based on definitions of the
words in the reverseword.
B3.1 2 Making yoghurt and
soy sauce
Students’ Book pages
1 Microorganisms breaking down large molecules to produce
different substances, usually under anaerobic conditions.
2 Lactobacillus.
3 a To kill bacteria which might spoil the product;
b to mix up the ingredients;
c to promote the activity of Lactobacillus bacteria.
4 To slow the multiplication of Lactobacillus bacteria left over
after the yoghurt has been made.
5 Aspergillus, Lactobacillus and yeast.
6 a To remove sediment suspended in the liquid;
b to kill bacteria which would spoil the product;
c to allow its flavours to develop.
2 Students should read the information on the label of each
food they choose. Prebiotics contain oligosaccharides which
promote an increase in the numbers of ‘good’ bacteria in the
gut. Probiotics contain the ‘good’ bacteria themselves.
34
Extension Units Science Teacher’s Guide
© Edexcel Limited 2007
Answers  continued
B3.1
7 Diagrams should have the following steps:
a homogenisation; sterilisation; starter culture added;
fermentation; raw yoghurt; cooling; flavourings (optional);
packaged.
b soya beans cooked; mixed with ground, roasted wheat;
Aspergillus mould added; spread on warm, shallow trays;
aerated; brine added; yeasts and Lactobacillus bacteria
added; raw soy sauce drained from mixture; filtration;
boiling; cooling; filtration; pasteurisation; stored; bottled.
Summary exercise
lactic acid, fermentation, coagulates, lactose, cooled, natural
Higher questions
1 a Proteases;
b carbohydrases.
5 Because enzymes produced by the mould digest proteins
and carbohydrates.
proteins
proteases

amino acids
carbohydrases
carbohydrates

sugars
6 Gives soy sauce its salty taste and helps to preserve the
product.
7 Lactobacillus.
8 Yeast ferments sugar at low levels of oxygen (anaerobic
conditions). Mould enzymes catalyse the breakdown of
proteins and carbohydrates in the mixture of cooked soya
beans and ground roasted wheat.
Worksheet B3.1 2c
2 a Amino acids;
b sugars;
Across: 4 homogenised, 5 lactate, 7 lactose, 8 Aspergillus
Down:1 Lactobacillus bulgaricus, 2 brine, 3 amino acids, 6
flavours
3 Aspergillus mould.
Extension questions
1 a The oxidation of sugar (glucose) by cells, releasing
energy;
b glucose (sugar)  alcohol (ethanol)  carbon dioxide.
B3.1 3 More on
microorganisms and food
2 a Aerobic respiration occurs in the presence of oxygen;
anaerobic respiration occurs in the absence of oxygen;
b ethanol  oxygen  ethanoic acid (acetic acid)
c CH3CH2OH  O2  CH3COOH  H2O
Students’ Book pages
Worksheet B3.1 2a
3 Students should use the Internet to search for relevant
information.
4 a The presence of lactic acid;
b the antibiotic kills lactic acid bacteria.
5 The starter culture contained lactic acid bacteria.
6 To ensure that microorganisms do not contaminate and spoil
the product.
7 So that the events observed in container A can be
compared.
Worksheet B3.1 2b
1 F
A
G
B
C
H
E
D
2 The sauce is rich in amino acids which combine to form
proteins.
3 To kill microorganisms that might contaminate the product
on the surface of the beans.
4 Aspergillus.
© Edexcel Limited 2007
1 Rennet obtained from the stomach tissue of slaughtered
calves.
2 Organisms into whose genetic material genes from a
different species have been inserted.
3 Because it is not made by GM organisms even though the
enzyme (chymosin) used to make it is.
4 Gelatine is made from animal bones. Vegetarians do not
eat meat. Carrageen extract is made from the seaweed
carrageen.
5 Monosodium glutamate. It is a flavour enhancer.
6 a Corynebacterium glutamicum;
b Acetobacter.
7 Aspergillus niger.
8 It enhances flavour and prevents the breakdown of vitamin
C.
9 It is sweeter than glucose.
10 Points should include: that microorganisms are specific in
their activities, so the product is not contaminated by
unwanted substances; the activities of microorganisms can
be controlled by alterations in temperature, pH etc.;
microorganisms can be cultured in fermenters and product
can be extracted from the culture.
Extension Units Science Teacher’s Guide
35
B3.1
Answers  continued
Summary exercise
6 From bacteria cultured in fermenters.
protein, chymosin, cheese, gelling, carrageen, glutamic acid,
invertase, fructose, yeast
7 Temperature/pH/co-factors.
Worksheet B3.1 3c
Higher questions
1 Algae may be single-celled (e.g. Pleurococcus), form
filaments (e.g. Spirogyra) or be made up of branched, flat
fronds secured to a firm surface by a holdfast at the end of a
short stalk-like structure.
1 a Lactose;
b lactic acid.
2 The curds separate from the whey.
3 Lactic acid is present.
2
Moulds
Yeasts
Formed of thread-like hyphae,
which spread over the surface
on which the mould is growing
Do not grow hyphae but live
as single cells
Some of the hyphae carry
capsules which contain spores
Spore capsules absent
Extension questions
5 a Because it is not made using GM microorganisms even
though the enzyme used in its production is made by GM
organisms;
b many people object to eating GM food.
B3.1 4 Eating well
1 The shape of a molecule of monosodium glutamate (MSG)
is different from the shape of a molecule of glutamic acid.
The body’s immune system recognises MSG as a molecule
not normally found in the body and responds to it resulting in
an allergic reaction.
Students’ Book pages
2 Points could include: alkali; treatment; drying; high
temperature; washing; purifying;
2 Milk and milk products, meat and alternatives (e.g. fish,
pulses), fruits and vegetables, bread and cereals.
3 Points could include: restriction enzyme; plasmid; identifying
gene; fermenter.
3 Body mass (kg)/(body height)2(m)2.
Worksheet B3.1 3a
1 Amino acids.
2 Enzymes, hormones, muscles consist of proteins.
3 Protease enzymes which catalyse the breakdown of
proteins.
4 Protein.
5 Less cloudy/clear.
Next Lesson
4 Amino acids are produced. These are absorbed by the
microbes and used to make proteins.
5 Washing liquid/powder – where proteins are digested as part
of the process of making product.
36
4 a An enzyme;
b promotes coagulation of milk.
Extension Units Science Teacher’s Guide
1 When it consists of a mixture of foods selected from each of
the four food groups in the correct proportions for good
health.
4 Points should include: BMI  20  underweight compared
with height; BMI 20–25  body mass/height ratio ideal for
maintaining good health; BMI 25–30  overweight compared
with height but unlikely to cause health problems; BMI  30 
obese compared with height with increased risk of the
development of obesity-related diseases.
5 The writing should include how to develop a programme of
eating a balanced diet which contains nutrients in the right
proportions for good health. Advice might include that the
input of energy should not exceed the person’s energy
requirements and that fibre promotes the movement of food
through the gut. Evidence that obesity increases the risk of
developing weight-related diseases should be presented.
Summary exercise
diet, 4, balanced diet, fibre, vitamin C, calcium (or vitamin D),
vitamin D (or calcium), BMI
© Edexcel Limited 2007
B3.1
Answers  continued
7 Problems might include: greater risk of developing heart
disease, arthritis, diabetes, etc. Use the Internet to search
for relevant information.
Higher questions
1
Nutrient
Deficiency disease
vitamin A
infections; poor vision in dim light
vitamin D
rickets (soft bones) in children; brittle bones in
adults
vitamin E
poorly understood in humans but causes sterility
in rats
vitamin K
spontaneous bleeding; long healing time
vitamin B1
beri-beri; nervous disorders
calcium
rickets (soft bones)
sodium
cramp
iron
anaemia
iodine
sluggish body chemistry
zinc
poor healing (skin complaints)
2 Reasons and explanations might include:
Reason
Explanation
watching a lot of television
lack of exercise
overeating
food is easily available
Extension questions
1 BMI  35.9. Obese (BMI above 30).
2 Their high BMI is not due to excess fat, but because
proportionately they are more muscular/producing more
protein. Protein is denser than fat, giving a high BMI.
Worksheet B3.1 4b
1 Putrid gums.
B3.1 5 Feeding the world
Students’ Book pages
1 By crossing two existing varieties, each with desirable
characteristics. Crossing concentrates the desirable
characteristics of each existing variety into the new hybrid
variety. Or the genes controlling desirable characteristics
can be inserted into existing varieties (genetic engineering).
2 The offspring of a cross between two closely related species
or varieties.
3 Desirable characteristics might include resistance to
disease, high yield, resistance to pests, shape/colour of fruit,
etc.
4 The insertion of genes from one species into the genetic
material of a different species.
5 Advantages include:
 Organisms used to make SCP are fast growing.
 SCP has a high protein, vitamin and mineral content.
6 SCP can be grown in large quantities in fermenters; the
fermenters take up little space; the conditions inside the
fermenters are controlled and independent of the weather.
Disadvantage: people might be reluctant to eat SCP.
2 B is too thin; C, E and F are too fat.
7 Student’s explanation might include:
 High yield crops can be quickly produced, e.g. rice.
 More people eat rice than any other crop.
 GM crops resistant to herbicides and insect attack reduce
the need for herbicides and insecticides.
 The impact of farming on the environment is reduced.
 Growing SCP reduces the amount of land needed for
growing crops and raising livestock.
3 Some people have a ‘weight problem’. Others are unhappy
with their looks.
Summary exercise
Worksheet B3.1 4a
1 Answers to nearest whole number: A 27; B 18; C 35; D 25; E
34; F 32.
4 Students should be clear that the rapid loss of weight at the
start of a slimming course is usually due to loss of water and
not body mass. Use the Internet to search for relevant
information.
5 Students should produce a balanced answer which shows
how the media and celebrity culture affect people’s
perceptions of themselves.
breeding, hybrid, fermenters, microorganisms, protein, vitamin
(or mineral), mineral (or vitamin)
Higher questions
1 Offspring are clones of their parent. The favourable
characteristics of the parent are therefore preserved
generation upon generation.
6 Students should use the Internet to search for relevant
information.
© Edexcel Limited 2007
Extension Units Science Teacher’s Guide
37
B3.1
Answers  continued
2 a Reasons might include low rainfall, civil unrest and so on.
b In the first case, development of drought tolerant crops
through biotechnology would help to overcome the
problem. A biotechnological solution to the problem in the
second case is unlikely. Students should aim to make
their decisions case-by-case.
4 A substance produced by Bacillus thuringiensis which
inhibits feeding in the juvenile (larval) stages of some
insects.
Extension questions
5 Refer to the diagram on page 21 of the Students’ Book for
the idea.
1 Students will need to visit their local supermarket and be
able to recognise the brand names of foods made from SCP.
Summary exercise
2 Students should be guided to itemise the different
components of a strategy which meets the needs of a
balanced diet.
Worksheet B3.1 5a
1 To prevent contamination of the nutrient solution inside the
fermenter.
2 Examples are: glucose syrup, fruit pulp, waste from paper
making, agricultural waste, sewage, etc.
3 Cools the fermenter.
4 So that enzyme activity remains at its optimum.
5 It is sterilised.
6 The inner surface should be smooth.
7 pH concentration/volume of nutrient solution/hygiene/oxygen
levels in the nutrient solution.
8 Refer to Worksheet 3.1 2b.
Worksheet B3.1 5b
Students should write clearly and follow a logical train of
thought.
B3.1 6 Genetically modified
plants
Students’ Book pages
1 A chemical which kills weeds (unwanted plants).
2 The gene controlling herbicide resistance is isolated and
inserted into the Ti plasmid of Agrobacterium tumefaciens.
The crop plant to be made herbicide resistant is infected with
GM Agrobacterium tumefaciens. A crown gall develops.
Pieces of tissue are cut from the crown gall, cultured and
grown into plantlets. The plantlets are herbicide resistant.
They are planted and grow into mature plants.
38
3 They also kill beneficial insects. Pests develop resistance to
the insecticides.
Extension Units Science Teacher’s Guide
weeds, non-resistant, harming, vector, DNA, crown gall,
genetically modified
Higher questions
1 Refer to page 18 of the Students’ Book for the relevant
information.
2 Refer to page 21 of the Students’ Book for the relevant
information.
Extension questions
1 Answers should include an understanding that the Ti
plasmid of Agrobacterium causes the development of crown
galls in plant tissue infected with Agrobacterium, that it can
be genetically engineered with desirable genes and that the
engineered plasmid inside Agrobacterium will cause crown
gall formation in infected plant tissue. Pieces cut from the
crown gall and cultured will develop into plantlets, each
containing the desirable gene(s) engineered into the Ti
plasmid.
2 a Answers should include the idea that:
 restriction enzymes catalyse the breakdown of DNA
into different fragments
 there are many different restriction enzymes
 each restriction enzyme cuts DNA at a particular
recognition site, which is different for each enzyme.
b DNA ligase seals the ends of the desirable gene into its
plasmid vector.
Worksheet B3.1 6a
1 EHGCFBDA
2 A growth of cancerous plant tissue.
3 A crown gall is produced as a result of infection with
Agrobacterium tumefaciens.
4 Because the engineered Ti plasmid is inserted into an
Agrobacterium cell which is then cultured in a fermenter. The
Agrobacterium cells, each with its modified Ti plasmid, are
then used to infect plants, which then develop crown galls.
5 The crops are not killed by the herbicides used to control
weeds.
© Edexcel Limited 2007
B3.1
Answers  continued
Worksheet B3.1 6b
Extension questions
Students should write clearly and follow a logical train of
thought.
1 Refer to pages 22–23 of the Students’ Book and pages 18–
19 of the Copymaster file for relevant information. Students
should also use the Internet to help them research relevant
examples.
B3.1 7 Should GM crops
worry us?
Students’ Book pages
1 Conventional methods may not be able to keep up with
demand for food as the world’s population continues to
grow.
Climate change may alter the growing conditions. Crops
genetically modified to grow in the new environments may
need to be developed. Accept other suitable suggestions.
2 Industrial goals include maximising financial returns on
investments. Maximising financial returns includes seeking
new markets and selling more product. Scientific goals are
different. Ideas and experimentation leading to new
discoveries are part of the process.
3 Would growing GM crops:
 affect the quality of the food we eat?
 affect wildlife?
 lead to the development of herbicide resistant weeds?
4 Benefits include:
 enabling crops to grow in conditions (e.g. rainfall) where
the non-GM equivalent is unable to grow
 reducing the volume of pesticides sprayed on crops
 resisting disease-causing microorganisms
 enabling crops to produce their own fertiliser.
5 Possibly. GM crops might be able to grow in environments
where growth of non-GM equivalents, at present, is difficult
or impossible. Improved yields. Improved resistance to
disease/insect attack.
Summary exercise
industry, doubts, pollen, wildlife / health (these two either order),
food production, insecticides, balance
Higher questions
1 Refer to page 22 of the Students’ Book for the relevant
information.
2 Students should first establish a position which reflects their
views on the rights/advantages and wrongs/disadvantages
of growing GM crops. A balanced understanding of the
issues will then instruct their answer.
© Edexcel Limited 2007
2 Refer to pages 22–23 of the Students’ Book and pages 18–
19 of the Copymaster file for relevant information. Students
should also use the Internet to help them research relevant
examples.
Worksheet B3.1 7a
1 It is a feeding inhibitor.
2 Bacillus thuringiensis lives in the soil. Different species of
soil bacteria compete with each other for resources in short
supply. Producing toxin eliminates some of the opposition.
3 The toxin is species specific and therefore does not affect
beneficial insects. Farmers do not have to spray their crops
with poisonous chemicals.
4 Controls the synthesis of a protein or part of a protein.
5 Genetic engineering.
6 a Mitosis;
b clone;
7 Because the gene which controls the synthesis of toxin has
been inserted into their genetic material.
8 Because they are uncertain about the benefits of the science
and worried about the consequences of its use.
Worksheet B3.1 7b
1 Students should label the axis of the bar chart appropriately.
2 Cambridgeshire.
3 Lincolnshire.
4 Kent 12 000; Lincolnshire 22 000; Sussex 28 250; Cornwall
0; Devon 0; South Yorkshire 43 430; Essex 17 940;
Cambridgeshire 51 520.
5 More on the non-GM crop.
B3.1 8 Genetically
engineered insulin
Students’ Book pages
1 Pancreas.
Extension Units Science Teacher’s Guide
39
Answers  continued
B3.1
2 A large container in which cells quickly multiply. The
fermenter is filled with nutrient solution, which provides the
cells with all the nutrients they need to multiply and grow.
The conditions inside the fermenter are controlled to
maximise the growth of cells.
3 The bacteria produce large quantities of insulin reliably and
cheaply.
3 Bioinformatics involves the use of computers to match the
base sequences of the genome with the proteins for which
they code.
4 To show where the proteins coded for by our genes are
normally found in the cell.
4 The insulin produced is chemically the same as human
insulin produced naturally. This reduces the risk of allergic
reactions in people taking insulin to treat type 1 diabetes.
5 The original aim of sequencing human DNA has been
achieved. Continuing work includes the Cancer Genome
Project, which studies how variations in the base sequence
of genes might increase the risk of the development of
different cancers.
5 Students should refer to the diagram on page 21 of the
Students’ Book for guidance.
Summary exercise
Summary exercise
hormone, sugar, genetically engineered, gene, fermenters,
release, separated
genetic code, amino acid, order, genome, genomics,
bioinformatics, genes
Higher questions
1 Control the synthesis of protein.
Higher questions
1 B
A
E
D
C
F
2 Human genes control the synthesis of proteins in the human
body. If the proteins are useful medicines then patients are
unlikely to suffer adverse reactions because the medicines
are of human origin. The need for the animal testing of such
new medicines is therefore reduced.
Extension questions
2 Students should use the Internet to search for relevant
information.
3 Genomics is the process where the sequence of bases in an
organism’s DNA is identified. Bioinformatics aims to discover
the functional significance of a sequence.
Extension questions
1 5.
1 Populations of bacteria always contain a few individuals with
genes that make them resistant to antibiotics. These
individuals survive and reproduce. The new generation
inherits the genes which cause resistance to antibiotics.
Resistance develops rapidly in bacteria because they
reproduce rapidly.
2 Students should use the Internet to obtain the relevant
information.
2 Students should use the Internet to obtain the relevant
information.
Labels are clockwise from top right: cell, DNA, gene, nucleus,
chromosome.
Worksheet B3.1 8a
Worksheet B3.1 9b
B4, E2, C1, A5, D3
1 Helical, two stranded, the strands are joined by the bases,
the bases pair A-T G-C T-A C-G, each turn of the helix
through 360o carries 10 base pairs.
B3.1 9 Genomics
Worksheet B3.1 9a
Microscope, chromosomes, nucleus, divide, DNA, code,
proteins, genes, 30 000, Human Genome.
2 10.
Students’ Book pages
4 James Watson, Francis Crick, Morris Wilkins.
1 A gene is a length of DNA. It controls the synthesis of a
protein or part of a protein.
5 Franklin died in 1957. The Nobel Prize for the discovery was
awarded in 1962. Nobel Prizes are not awarded
posthumously.
2 All of the genetic material contained in the nucleus of a cell.
40
Extension Units Science Teacher’s Guide
© Edexcel Limited 2007
B3.1
Answers  continued
B3.1 10 Genomic medicine
Worksheet B3.1 10b
Students’ Book pages
Across: 2 replicate or duplicate, 4 pharmacogenomics, 6
asthma,
7 human genome
1 A response to the drug in the patient which is as bad as, or
worse than, the illness it is supposed to treat.
Down: 1 adverse, 3 liver, 4 pharmacology 5 mutation
2 The combination of our understanding of how the human
genome affects an individual’s response to particular drugs
and how the drug can be tailored to maximise its effect in the
light of the response.
B3.1 11 Medicinal plants
3 Because the slight differences between genomes affects the
response of individuals to particular drugs.
1 Experience of the successful treatment of disease using
plants and animals has passed from generation to
generation.
4 Pharmacogenomics matches the design of a drug to an
individual’s genome, which affects the individual’s response
to the drug and helps to maximise its effect.
Summary exercise
pharmacology, personalising, pharmacogenomics, guesswork,
adverse
Higher questions
1 a An unintentional and often unwanted effect of a drug;
b e.g. aspirin; disadvantageous: irritation of/bleeding from
the gut;
c refer to pages 28–29 of the Students’ Book for relevant
information.
2 Bioinformatics involves the use of powerful computers which
help to match the base sequences of the genome with the
proteins for which they code. Pharmacogenomics refers to
the tailoring of drug treatments to the genetic make up of the
patient.
Extension questions
1 Students should give a balanced account which offsets costs
(different types of a particular drug, each with a limited
market) against possible savings (more efficient treatments).
2 The doctor might be able to identify genetic markers which
predispose an individual to certain health problems. Action
could then be taken to help stop problems developing. A
selection of drugs which minimise adverse reactions would
be possible.
Worksheet B3.1 10a
A–2, B–4, C–3, D–1
Students’ Book pages
2 The application of scientific methods to traditional medicine
has improved our understanding of how successful
treatments work and has suggested new approaches to the
sourcing of treatments for diseases from plant and animal
products.
3 Curare is a muscle relaxant which makes it easier to control
the breathing of patients undergoing surgery.
4 a Cocaine; morphine;
b digitalis.
5 Cancer.
6 The substances are extracted from plants and made up into
medicines and drugs. Examples include vinblastine and
vincristine.
Summary exercise
trial and error, traditional medicine, curare, Strychnos,
rainforest, surgery, rosy periwinkle, vincristine, cancer
Higher questions
1 Yes. At high concentrations substances may be poisonous.
At low concentrations the same substance may help to treat
disease.
2 Students’ answers might include: rare plants with medicinal
value are conserved; synthesis of the drug may be cheaper
than extracting it; supplies of the synthesised drug are
reliable.
Extension questions
1 The chemical structures of drugs affect their efficiency in
treating disease. It is possible to alter the structure,
increasing the drug’s efficiency.
2 Students should use the Internet to search for information
which supports pages 30–31 of the Students’ Book and
pages 26–27 of the Copymaster file.
© Edexcel Limited 2007
Extension Units Science Teacher’s Guide
41
B3.1
Answers  continued
2 Students should use the Internet to search for relevant
information using the references given as a starting point.
2 Populations of Plasmodium always contain a few individuals
with genes which make them resistant to antimalarial drugs.
These individuals survive and reproduce. The new
generation inherits the genes which cause resistance to
antimalarials. Resistance to the drugs develops over the
generations.
Worksheet B3.1 11b
Extension questions
1 Products include: nuts, rubber, medicines, timber.
1 and 2Students should use the Internet to search for relevant
information.
Worksheet B3.1 11a
1 Extracting substances from plants and observing the effects
of the substances given to people who are ill.
2 Farming (quarrying, water resources).
3 The products sourced from plants and animals are not used
faster than the plants and animals can renew themselves.
B3.1 12 Aspirin and quinine
Students’ Book pages
Worksheet B3.1 12a
1 Students should use the information provided to produce a
historical sequence.
2 From the Latin name Salix for the willow tree.
3 Aspirin ‘thins’ the blood and therefore reduces the risk of
blood clots forming, triggering another heart attack.
1 The substance which is effective in relieving the medical
problems experienced, e.g. relieves pain; reduces fever.
4 Aspirin: irritation of/bleeding from the gut. Paracetamol: liver
damage.
2 Salicin.
5 By taking the drug with meals.
4 Because it not only relieves pain, but also reduces the risk of
heart attack, swelling in joints and fever.
6 a Paracetamol – aspirin can cause bleeding;
b paracetamol – alcohol makes the gut more vulnerable to
the effects of aspirin;
c aspirin – people suffering from a bad cold/flu develop a
high body temperature. Aspirin reduces body
temperature.
5 a Plasmodium;
b Anopheles.
Worksheet B3.1 12b
3 It is more effective than salicin as a painkiller. However, it
irritates the lining of the stomach and intestines and may
cause bleeding.
6 Something that transfers something else from one place to
another, e.g. Anopheles is the mosquito vector which
transfers Plasmodium from a person infected with the
parasite to another person.
Each clue should have a clear link to the term to which it refers.
B3.1 13 Artemisinin and taxol
7 Quinine.
8 The substances which are the active ingredients in
traditional medicines are often the starting points for the
development of new drugs which are more effective than the
original substances themselves.
Summary exercise
willow, painkiller, gut, bleeding, aspirin, anti-inflammatory,
Cinchona, Plasmodium, chloroquine, resistance
Higher questions
1 Plasmodium (the malaria parasite) is resistant to
chloroquine.
Students’ Book pages
1 Malaria; cancer.
2 Genetically engineering the gene which controls the
synthesis of a substance similar to artemisinin into yeast
cells means that the cells will be able to synthesise the
substance on a large scale. The substance can be
converted into artemisinin.
3 It stops cells from dividing.
4 Cells are cultured in conditions which maximise the rate of
cell division and growth. The more cells there are producing
taxol, the more taxol is produced.
5 Student’s answer should include descriptions of advances in
cell cultures (taxol) and genetic modification of cells with
genes that control the synthesis of substances which are
effective drugs (artemisinin).
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Extension Units Science Teacher’s Guide
© Edexcel Limited 2007
B3.1
Answers  continued
Summary exercise
B3.1 14 Stem cell research
parasite, malaria, vector, transmission, yew, dividing, cancer
Higher questions
1 Refer to Figure B on page 24 of the Students’ Book to give
the idea.
Students’ Book pages
1 Division of the nucleus of a parent into two, followed by
division of the cell into two daughter cells. The daughter cells
are genetically identical to each other and the parent cell.
2 Demand outstrips supply of the drug.
2 Unspecialised cells.
Extension questions
1 Students should understand the links between the causes,
transmission and prevention of malaria. The stages on which
antimalarial drugs act should be defined. Attention should be
drawn to the latest developments in the search for an
antimalarial vaccine and the breeding of GM mosquito
vectors in which malaria parasites cannot survive.
2 Cancer develops as a result of uncontrolled mitosis.
Preventing mitosis prevents cancerous growths from
developing.
Worksheet B3.1 13a
1 Red blood cells (also liver cells).
2 When blood cells infected with Plasmodium parasites burst,
the toxins released cause an allergic reaction which results
in raised body temperature.
3 Quinine, chloroquine, mepacrine, artemisinin. Students
should search the Internet for information about
antimalarials.
4 Populations of Plasmodium always contain a few individuals
with genes that make them resistant to antimalarials. These
individuals are more likely to survive and reproduce. The
new generation inherits the genes which cause resistance.
Resistance develops in Plasmodium. The antimalarials act
as agents of natural selection.
5 The closed nature of communist China before the 1980s
prevented the free exchange of information between China
and the rest of the world. With the liberalisation of the
economy (and to some extent of society in general), the
exchange of information increased.
6 Plasmodium has not developed resistance to artemisinin –
yet. If Plasmodium develops resistance to the other drugs in
ACT, then the artemisinin component controls it.
Worksheet B3.1 13b
3 The process where unspecialised stem cells divide and
develop into specialised cells (the cells become different
from one another).
4 Yes – adult stem cells from bone marrow are used to treat
blood disorders, e.g. leukaemia.
5 Using stem cells to repair damage to tissues caused by
disease and the processes of aging.
6 Stem cells taken from the brain of a person suffering from
Parkinson’s would be cultured and encouraged to
differentiate into dopamine-producing cells. These cells are
transplanted into the brain of the same person. Reduced
levels of dopamine are the cause of the disease. The
transplanted cells would produce dopamine and relieve the
condition.
Summary exercise
mitosis, embryo, stem, unspecialised, differentiation, dopamine,
Parkinson’s disease, muscle
Higher questions
1 Embryonic stem cells may differentiate into any type of cell.
Adult stem cells may only differentiate into a limited number
of different types of cell.
2 Because embryonic stem cells can potentially differentiate
into many more types of cell than adult stem cells, their use
to treat a range of diseases is more flexible.
Extension questions
1 Answers should include the idea that the patterns of activity
of the sets of genes controlling differentiation varies between
the sets. Differentiation is the result.
2 Students should use the Internet to search for relevant
information. Accounts should be balanced, highlighting the
difficulties of developing new treatments as well as their
possible advantages.
1 Malaria, antimalarials, yeast, anti-cancer, oxygen.
3 Yew, taxol, anti-cancer, dividing, cell, cells, yew.
Worksheet B3.1 14b
Across: 2 differentiation, 3 muscles, 5 stem cells
Down: 1 mitosis, 4 fertilisation, 6 dopamine
© Edexcel Limited 2007
Extension Units Science Teacher’s Guide
43
Answers  continued
B3.1
B3.1 15 Girl or boy?
Worksheet B3.1 15a
Students’ Book pages
2 Students should support their views with evidence.
1 a X;
b Y;
c X; d X and Y.
2 Dad.
3 The fertilisation of eggs with sperm outside of the woman’s
body.
4 By testing embryonic cells to see which chromosomes are
present and choosing the combination wanted, or by sorting
sperm into X and Y and using one of the types of sperm to
fertilise an egg, producing the combination of sex
chromosomes wanted.
1 No – they’re not based on evidence as the result of
experiment.
3 a Nita and Sam possibly want a boy to help balance the
gender ratio in their family. Their wishes might be open to
the challenge that the reasons are superficial. Jill and
Steven’s choice is based on their wish to reduce the risk
of their children developing a genetic disorder. Many
people would support their choice; others might feel that
it is not morally right to interfere with natural processes.
b Students’ responses will depend on their answers to a.
Worksheet B3.1 15b
5 Depending on which sex is the most popular, the sex ratio of
50:50 boys/girls would be skewed in favour of the popular
choice.
1 (From top right moving clockwise) membrane surrounding
the nucleus, Y chromosome, X chromosome, cytoplasm, cell
surface membrane.
6 Babies selected for the characteristics parents want in their
children (e.g. eye colour, intelligence, etc.).
2 The presence of a Y chromosome.
7 Advantages: it enables parents to choose embryos which
are free of faulty genes that cause genetic disorders.
Disadvantages: it enables parents to choose embryos with
characteristics which may be trivial (curly hair/straight hair)
or which may be used to treat disorders/diseases in siblings
(the embryo, and therefore the child, may not be wanted for
its own sake).
3 Embryo – the hollow ball of cells formed by repeated
divisions following fertilisation of an egg. In vitro fertilisation
– eggs are taken from a woman and placed in a sterile Petri
dish with sperm. Designer baby – parents choose an embryo
with desirable characteristics. Eugenics – only couples with
‘desirable’ characteristics are allowed to have children.
B3.1 16 Ethical issues
Summary exercise
Y, X, genetic, skew, unethical, designer
Students’ Book pages
Higher questions
1 Students should carefully think of the consequences in each
case a–d before answering the question.
1 Duchenne muscular dystrophy (DMD) mostly occurs in boys.
The ability to choose a female embryo means there is less
risk of a family having a child that develops DMD.
2 Possibly. Dolly the sheep was a clone and died ‘young’ for a
sheep.
2 Refer to pages 38–39 of the Students’ Book for relevant
information.
Extension questions
1 Eugenics includes the idea that the human race can be
improved only by allowing couples with desirable
characteristics to have children – the selective breeding of
human beings. The eugenics programmes of the 1930s in
Nazi Germany makes the subject particularly controversial.
2 Students should use the Internet to search for relevant
information.
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Extension Units Science Teacher’s Guide
3 Embryonic stem cells are more versatile than adult stem
cells. However, using embryonic stem cells destroys the
embryos themselves. Some people believe that life begins at
conception and that destroying embryos is equivalent to
murder.
4 Students should think carefully and decide:
 what are the new reproductive technologies
 what is meant by ‘playing God’
 what is meant by ‘creating monsters’?
Students should use reasoned arguments based on
evidence, not emotional views based on unsupported
opinion.
© Edexcel Limited 2007
B3.1
Answers  continued
Summary exercise
sheep, mammal, cloned, designer, genetic, stem, morally
Higher questions
1 Deciding whether or not humans are uniquely different from
all other mammals is the issue central to the answer.
Students should aim to develop a balanced argument.
2 Students should have a clear understanding of the
difference between morals and ethics.
Extension questions
1 and 2 Students should use the Internet to search for
relevant information.
Worksheet B3.1 16b
1 Sheep A.
2 Because Dolly is a clone of her mother.
3 The number of chromosomes in the nucleus of the egg
before its removal is half the number of chromosomes in the
cell taken from the milk-producing tissue.
4 Students should refer to the information about producing
Dolly.
5 Responses might include the idea that the recombination of
male and female chromosomes in the fertilised egg results in
genetic variation. The discussion involves the advantages of
the diploid state compared with the haploid state. The
discussion is an advanced one. It is suggested that
feminist/political viewpoints are avoided on the basis that
these are subjective and formed on the basis of
unsubstantiated opinion of no biological relevance.
6 Student’s own answer.
7 The views expressed should be supported by evidence.
Students should be aware that it is not possible to draw
general conclusions from the evidence of one example.
B3.1 17 Questions
1 The Ti plasmid of Agrobacterium causes tumours in plants
infected with the bacterium. If the Ti plasmid is genetically
engineered with the gene which controls herbicide
resistance and the plant is infected with Agrobacterium
containing the genetically engineered plasmid, the cells of
the tumour which develops contain the plasmid with the
herbicide resistance gene in place. Pieces of tissue cut from
the tumour can be grown into plantlets (and then plants),
each resistant to herbicide.
© Edexcel Limited 2007
2 It produces a substance called insect crystal protein which
inhibits the larvae (young stages) of some insects from
feeding. The insects die.
3 A balanced diet consists of a mixture of foods taken from
each of the four basic food groups in proportions appropriate
for good health. Students should decide which food group
each item of each meal belongs to. They should base their
explanation on their assessment of which mixture best fits
the description of a balanced diet.
4 a Milk;
b Lactobacillus;
c to make sure that only Lactobacillus is present in the
milk. Other microorganisms would spoil the product
(yoghurt).
5 Genetic engineering methods can introduce new genes into
plants, producing new varieties which reproduce readily
within one generation. Traditional plant breeding
programmes take several generations to produce new
varieties which reproduce reliably.
6 a Sheep and humans are mammals. If a sheep can be
cloned then it should be possible to clone a human.
b The clone would not have parents; the clone could be
used as a source of spare parts for the person who gave
rise to the clone, for example.
c Unspecialised cells.
d Stem cells taken from the brain of a person suffering from
Parkinson’s would be cultured and encouraged to
differentiate into dopamine-producing cells. These cells
are transplanted into the brain of the same person.
Reduced levels of dopamine are the cause of the
disease. The transplanted cells would produce dopamine
and relieve the condition.
7 a A loop of yeast (or bacterial) DNA;
b restriction enzyme/restriction endonuclease;
c the fermenter contains a solution of all of the nutrients the
yeast cells need to reproduce and grow. The conditions
in the fermenter are controlled to maximise the
reproduction and growth of yeast cells;
d chymosin;
e the enzyme used to make non-vegetarian cheese is
sourced from animals.
8 a
b
c
d
To prevent them developing the symptoms of malaria;
quinine;
pharmacogenomics;
the insulin used to treat diabetes is produced by bacteria
genetically engineered with the human insulin gene. The
insulin produced is identical to human insulin, and so
people being treated with it are less likely to have allergic
reactions.
Extension Units Science Teacher’s Guide
45
B3.1
Answers  continued
9 a Taxol;
b it prevents cancer cells from dividing;
c the trees are scarce and an endangered species.
10 a Father’s sperm contains either an X chromosome or a
Y chromosome. Baby’s sex depends on which type of
sperm fertilises the egg (eggs always carry an X
chromosome). XX  girl, XY  boy.
b The Y chromosome is smaller than the X chromosome
and most of the genes it carries determine sex. Many
genetic disorders are the result of the activity of a
recessive allele/gene on some of the chromosomes. In
females, if a genetic disorder is carried on one of the X
chromosomes, then its partner X chromosome will
usually carry the normal gene which masks the effect of
the abnormal gene. Since the Y chromosome does not
carry genes other than those which determine sex, then
the absence of the normal partner gene means that the
abnormal gene is not masked. Its activities result in the
genetic disorder.
c By detecting the presence of genes which cause
genetic disorders.
d Genetic testing is carried out on embryos. Testing may
cause the embryo to abort (maximum 1% risk of all
tests).
11 a A mean  42 hours, B mean  18 hours, C mean  34
hours;
b B – takes the shortest period of time to complete the
fermentation;
c Yeast ferments the sugars in bread dough. During the
fermentation carbon dioxide is produced. The gas
‘raises’ (leavens) the dough. When baked, the bread
will have a lighter, ‘puffy’ texture compared with
unleavened bread.
12 a 1.5 million;
b Anopheles mosquito;
c i Cinchona tree;
ii it kills the Plasmodium parasite and lowers the body
temperature of the person suffering from malaria.
d ACT is used when Plasmodium develops resistance to
other antimalarials, especially chloroquine. The thinking
is that if Plasmodium develops resistance to one of the
drugs in the combination therapy, the other drugs in the
combination will still be effective and destroy the
parasite.
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Extension Units Science Teacher’s Guide
© Edexcel Limited 2007