AS Science in Society – Revision questions
Some revision questions
These questions have been written by an AQA examiner but they are not
necessarily the same style as the questions in the actual exam. They are
intended to help your revision by checking that you understand and can use
some key parts of the specification in a context.
3.1.1 Germ theory of disease and 3.1.2 Infectious
disease
1. Below are statements typical of exam answers that don’t get full marks
because they are WRONG or only partly true. Rewrite each to make it
true.
a) Bacteria become immune to antibiotics if they are exposed too often.
b) Antibiotics and antibodies both help prevent disease.
c) Infectious disease can be prevented by better housing.
d) Antibiotics cure infectious diseases.
e) We should make sure that vaccines are completely safe.
f) The most significant difference between viruses and bacteria is that
viruses are smaller.
g) Examples of diseases can be prevented by immunisation; measles,
smallpox, HIV, TB, malaria, hepatitis.
h) Examples of diseases that can be prevented by providing clean water;
cholera, TB, hepatitis, dysentery, chickenpox, anthrax.
2. Tuberculosis, TB, is a significant cause of death in many countries.
Figure 1 shows some data produced by the World Health Organisation for
Afghanistan.
Figure 1 Deaths due to tuberculosis among HIV-negative people (per 100
000 population)
1994
1996
1998
2000
2002
2004
2006
2008
66 (38-93)
66 (42-89)
66 (52-80)
59 (46-74)
51 (38-66)
45 (32-60)
37 (25-52)
37 (24-52)
a) Summarise the trend in deaths from TB in Afghanistan from 1994 – 2008
(2 marks)
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b) The figures in brackets show the uncertainty in the data. For which year
is the value shown the most uncertain?
(1 mark)
c) Explain why we cannot be sure that the drop shown between 2004 and
2006 represents a real change in the death rate.
(2 marks)
d) Suggest two reasons why there is so much uncertainty in the data.
(2 marks)
3.1.3 Transport issues
1. Petrol contains chemical compounds called hydrocarbons.
a) Explain the meaning of the word compounds in this sentence
b) Petrol burns in a car engine. Describe the chemical reaction that takes
place. You may use words, chemical symbols or a diagram.
2. One litre of petrol contains about 35 MJ of energy.
a) In normal use only about 11.2 MJ are actually used to move the car.
Calculate the efficiency of the car engine.
b) What has happened to the rest of the energy?
3. Researchers collected data on daily deaths from many European cities.
They also obtained data from the air pollution monitoring stations in each
city. Figure 1 shows the relationship between a 10μg/m3 increase in daily
ozone concentration and the change in death rate.
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Figure 1. Percentage increase in the total daily number of deaths and
their 95% confidence interval associated with an increase of 10 µg/m 3 in
the levels of 8-hour ozone, only for the summer period.
http://ajrccm.atsjournals.org/cgi/content/full/170/10/1080#FIG2
a) Name two of the cities for which there is the clearest clear evidence of a
correlation between increased ozone and increased death rate.
(1 mark)
b) Explain why we cannot be sure from these results that there is a
correlation between increased ozone and death rate in Budapest or
Stockholm.
(1 mark)
c) What other factors might make it difficult to determine a relationship
between increase in ozone and death rate in some cities?
(2 marks)
d) Can we conclude that ozone causes an increase in deaths? Explain your
answer.
(1 mark)
e) The confidence interval bars are much longer for some cities. What does
this suggest about the data from those cities?
(1 mark)
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3.1.4 Medicines and 3.1.5 Ethical issues in medicine
1. High blood pressure is an important risk factor for strokes and heart
attacks in older people. Several different drugs are available to reduce
blood pressure. One research project compared the effectiveness of two
different types of drug, a diuretic, type A and the much newer calcium
channel blocker, type B.
6321 patients with high blood pressure were recruited and assigned at
random to group A or group B. This was double-blind study. Group A
received the diuretic and group B the calcium blocker. They were
followed up regularly for four years.
a) What does double-blind mean in the context of a drug trial?
(2 marks)
b) Why does double-blind design increase confidence in the results of a
trial?
(2 marks)
c) Why is assigning patients at random to the two groups the best way of
reducing the chance of bias in the results, compared to a system where
medical staff make the choice?
(2 marks)
d) In this trial there was no placebo group. The new drug, type B was
compared against the previous standard treatment, type A. What are the
ethical reasons for this trial design?
(2 marks)
e) Some patients experienced side effects from both of the drugs. These
included dizziness and headache. Nearly all of them continued taking the
medicines. How might they have weighed up risks and benefits to make
this decision?
(1 mark)
f)
Figure 1 shows the rate of death for three monthly intervals in the two
groups.
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Figure 1 Death rate for patients taking either type A or type B drugs
for high blood pressure.
Key
.........
type A
death rate
_______ type B
Figure 3 shows that there is very little difference between the two drugs. Why
did they publish a negative result like this?
(2 marks)
g) This trial involved an unusually large number of patients. Why does this
increase our confidence in the results?
(1 mark)
h) The mean age of the patients taking part in the trial was 65. The spread
of ages is shown by the Standard Deviation of 6.5. In a different trial the
patients also had a mean age of 65 but a standard deviation of 8.2. What
does this tell us about the difference between the sample of patients in
the two trials?
3.1.6 Reproductive choices
1. Below are statements typical of exam answers that don’t get full marks
because they are WRONG or only partly true. Rewrite each to make it
true.
a) Humans have about 30 000 chromosomes
b) The genes we inherit determine what illnesses we will get
c) A mutation is damage to a gene
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d) If both parents carry a single gene/allele with a mutation for a genetic
disease the chance of each of their children inheriting the disease is 1 in
4.
e) The term ‘designer baby’ means a baby that has been conceived by IVF
with the characteristics that the parents want.
f)
PGD and IVF are different terms for the same technique
g) IVF is mainly used to prevent the birth of babies with genetic diseases
h) PGD can be used to identify an embryo with a genetic disease and
correct it using gene therapy
i)
Preimplantation genetic diagnosis, PGD, means that the egg and sperm
are tested before conception
j)
Amniocentesis can be used to prevent the birth of a baby with a genetic
disease.
2.
Many of the decisions about reproductive choices involve ethical issues
as well as medical ones. Some of the general ethical principles you might
use are shown in the box below. The headings are from the textbook
pages 65-67.
Balancing rights an example of a right is the right to life. Does this always
extend to a foetus?
Maximising the benefits a utilitarian approach considers the consequences
of a decision to maximise good outcomes or minimise bad ones.
Making decisions for yourself autonomy is an important part of the respect
due to individuals. Parents should have the right to make decisions
Ensuring justice is it fair, this might involve who has access to IVF
A
Which of the above principles could be used to justify each of the
following? Explain how you would use the principle to support the
decision.
B
Which of the above principles could be used to argue against each of the
following? Explain how you would use the principle to oppose the
decision.
a) The abortion of a foetus which is known to be severally disabled
b) A pregnant woman refuses to have amniocentesis to test her foetus for
possible Down syndrome.
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c) Parents want to have IVF and PGD to select an embryo specifically so
that the child born will be a suitable match to donate cells to save the life
of their existing ill child.
d) A health authority will only pay for one round of IVF for infertile couples
who cannot conceive naturally. They say this is due to shortage of funds.
3.1.7 Radiation
On 11 March 2011 the Fukushima Daiichi nuclear power site in Japan was hit
by an earthquake and then a huge tsunami and severely damaged . Although
the nuclear fission reaction was halted the reactor core continued to heat up
and radioisotopes have been released from the plant. The two most
dangerous isotopes are iodine-131 and caesium-137 .
Some of the characteristics of these isotopes are given in Figure 1.
iodine-131
caesium-137
Figure 1
half life
8 days
30 years
emission
β
βand γ
a) How is the composition of an atom of iodine-131 different from that of an
atom of the stable isotope iodine-127?
(1 mark)
b) How is it the same?
(1 mark)
c)
In one area near the power plant the radioactivity from caesium-137 is 4
MBq/m2 How long will it take for this to fall to a safe level of 1MBq/m2 ?
(2 marks)
d) After discharge from the power plant into the sea one scientist has
suggested that it will be many years before the fish will be safe to eat.
Explain the sequence of events that make fish a risk.
(3 marks)
e) Iodine concentrates in the thyroid gland and can cause cancer. Explain
the process by which this contamination with iodine-131 leads to cancer
in thyroid cells.
(2 marks)
f)
1 millisievert per year is the normal safe limit for radiation above normal
background levels. The Japanese government has plans to relax this
limit to 20millisieverts a year for school children in Fukushima district.
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What is the advantage of using sieverts as the unit in this case rather
than Bequerels as in question b)?
(1 mark)
g)
Exposure to each additional dose of 1mSv per year is estimated to
increase the annual risk of cancer by 1 in 20 000. What would be the
annual risk of cancer to these schoolchildren due to the Fukushima
nuclear waste if the limits were relaxed?
(1 mark)
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