* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Answers to revision questions
Survey
Document related concepts
History of genetic engineering wikipedia , lookup
Fetal origins hypothesis wikipedia , lookup
Medical genetics wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Neuronal ceroid lipofuscinosis wikipedia , lookup
Microevolution wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Genome (book) wikipedia , lookup
Preimplantation genetic diagnosis wikipedia , lookup
Epigenetics of neurodegenerative diseases wikipedia , lookup
Transcript
AS Science in Society – Answers to revision questions Answers to revision questions Suggested answers are given in italics. Each bullet point represents one point for one mark. Where several points are given these are alternatives. The examiners comments are given below the bullet points in normal type. 3.1.1 Germ theory of disease and 3.1.2 Infectious disease 1. Comments by an examiner on how to rewrite the statements so that they will get marks. a) Bacteria can become resistant to antibiotics if they are exposed too often. Bacteria do not have an immune system. Antibiotics do not change individual bacteria, they select for the most resistant in the population. b) True for antibodies which help prevent disease as part of the immune system. Not true for antibiotics which cure some diseases. c) Better housing helps prevent airborne and water borne infectious diseases. d) Antibiotics only cure the infectious diseases that are caused by bacteria, They have no effect on viruses. e) Nothing is completely safe. We should make sure that they are as safe as possible. Vaccines are much safer than the disease they prevent. f) The most significant difference between viruses and bacteria is that viruses are not independent living organisms. They have to live inside a cell and use the cell processes to reproduce. g) All of the following diseases can be prevented by immunisation; measles, smallpox, TB, hepatitis. There are still no vaccines for HIV and malaria . h) The following diseases can be prevented by clean water; cholera, hepatitis, dysentery. Chickenpox, anthrax and TB are not waterborne . 2. a) No change between 1994 and 1998. Decline from 2000 to 2006. May have levelled out again from 2006 You will get a mark for each of the points above. Note that you must describe the different periods separately and give dates. A general ‘deaths have gone down’ would not score marks. Page 1 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions b) 1994 The range of uncertainty is 55 in this year. Subtract the lowest possible value from the highest possible value to find the range within which the rue value is expected to lie. c) The ranges of uncertainty for the two years overlap. the range indicates that it is known that the 2004 value is between 32 and 60, which includes the 2006 value of 37 2006 range of 24 – 52, includes the 2004 value of 45 Any 2 points d) War poor health services / lack of accurate diagnosis poor transport links 3.1.3 Transport issues 1. a) different chemical elements combined in a fixed ratio The terms element and fixed ratio are both essential here. Make sure you understand the difference between a mixture which can have different substances in any proportion. A compound always has the same elements in the same ratio. If the ratios are different it is a different compound. b) Hydrocarbon + oxygen carbon dioxide + water You must include the oxygen, without it there is no reaction. 2. a) 11.2 x100 = 32% 35 Remember the starting value, in this case the energy of petrol itself, goes on the bottom. b) It is released as heat It heats the air/ the car/ the road Remember energy is not destroyed it is just spread out. Page 2 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions 3. a) Athens, London, Barcelona, Birmingham Confidence interval depends on the spread of values. It tells us that there is a 95% probability that the true value of the mean lies within these limits. For all of these the confidence interval (could call it error bar) does not extend past 0. There is a 95% probability that the true mean is >0. b) The confidence interval includes negative values although the mean is greater than 0. There is therefore a probability that the true mean is negative, the death rate could actually decrease. c) Other pollutants could have a strong effect on death rate the data from the pollution monitoring stations may not be accurate health data may not be accurate the ozone level may always be very high so an increase of 10μg/m3 would have less effect d) No. We have a correlation but we need a causative mechanism to conclude causation. e) wider range of data smaller sample size 3.1.4 Medicines and 3.1.5 Ethical issues in medicine 1. a) the patients do not know which group they are in the medical staff do not know which patient is in which group Of course a controller who is not involved with the patients in any way knows who is in which group b) it reduces the effect of patient expectations on the reported outcome it prevents the expectations of medical staff influencing the way they treat patients the placebo effect is the same for both groups so the difference is likely to be due to the drug There is no placebo in this trial but patient expectations on which drug is better could still affect their outcomes in a way similar to the placebo effect. Page 3 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions c) it is important that the two groups are as equal as possible, on average, apart from the different drugs we do not know all the other variables that might be important randomly selected groups are likely to be matched on other variables. medical staff might make choices based on some patient characteristic for example they might think the new drug is better and put the patients who are worse into that group/ or do the opposite It is very rare for researchers to assign patients to groups on the basis on known variables. Any matching is likely to introduce bias. d) high blood pressure is known as a significant risk factor it would be unethical to deny patients treatment that is known to be effective patients in the trial would be worse off than normal patients if they were given placebo trials may do harm because of unknown risks but it is unethical to cause known risks e) the risk of high blood pressure is so great, death or disability from stroke or heart attack, that the benefit of reducing it outweighs the discomfort of the side effects. f) g) h) negative results are as useful as positive ones it helps doctors know what to prescribe It might be tempting to assume that a new drug is better if it is not published others will not know the outcome and do the work again which would be a waste of resources a larger sample size means that the results are less likely to be due to chance in a small sample a result might be due to random variation in the groups larger SD means a greater spread of ages in the group You do not need to know how a SD is calculated but you do need to be able to recognise it ‘as an indication of the spread of values’ Page 4 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions 3. 1.6 Reproductive choices 1. a) Humans have about 30 000 genes. There are only 46 chromosomes each containing many genes b) Most diseases are caused by environmental factors though a few inherited diseases such as sickle cell or cystic fibrosis are caused by the genes we inherit. c) A mutation is change to a gene. Not all changes are harmful. Evolution would not happen without mutation. 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 if the allele is recessive. If it is dominant then the risk is 1 in 2. e) The term ‘designer baby’ means a baby that has been conceived by IVF with the characteristics that the parents want. This is what the term means but designer babies are still in the realm of science fiction. It is not possible to choose which of the parents’ genes a baby receives or even to test for the genes for many characteristics. f) PGD and IVF are not different terms for the same technique. PGD can only be done on an embryo conceived by IVF but most IVF embryos are not tested using PGD. g) IVF can be used to prevent the birth of babies with genetic diseases if the IVF embryo is then tested using PGD and embryos carrying alleles for a disease are then discarded . h) PGD can be used to identify an embryo with a genetic disease. It is not possible to use gene therapy on an embryo. Embryos found to be carrying a disease are discarded and only those without the disease alleles are implanted. i) Preimplantation genetic diagnosis, PGD, means that the egg and sperm are tested before conception. This is wrong. If the genes in an egg or sperm were tested they would be destroyed in the test. PGD takes one cell from a developing embryo, which does not affect the development. j) Amniocentesis can be used to prevent the birth of a baby with a genetic disease if it is followed by abortion of the affected fetus. Amioncentesis itself identifies the affected fetus. The parents then have to decide whether to have an abortion. Page 5 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions 2. A a) Use a utilitarian argument, the harm to the family from long term caring and the possible suffering of the disabled child could outweigh the harm of the abortion. b) The mother’s autonomy is important here. The mother may have a strong belief in the right to life and would refuse an abortion even if the child did have Down syndrome. c) This would involve the ill child’s right to life or a utilitarian argument for overall benefit. d) They could use a utilitarian argument to defend their restriction. IVF is expensive and the same money could pay to help a greater number of people with other health problems. 2.B a) The foetus’ right to life b) If the mother is considered as making the decision on her own behalf the only way to argue against her autonomy would be by using a utilitarian argument about the difficulty of bringing up a handicapped child. However she is in effect also making a decision on behalf of the unborn child. Again hard to argue against its existence. c) The child they wish to conceive is being used as a means to an end. It goes against the autonomy of this child as a person in its own right. d) This decision does not ensure justice, couples who can afford to will be able to pay for several rounds of IVF and greatly increase their chance of having a child. It is not justice if some couples are unable to have children because they cannot afford the medical treatment they need. 3.1.7 Radiation a) More neutrons b) same number of protons c) 2 half lives 60 years d) isotopes taken up by plants/small creatures in sea eaten by fish fish contaminated with radioactive isotopes long half life means isotopes remain in food chain Page 6 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges AS Science in Society – Answers to revision questions e) radiation/ βemissions cause mutations in DNA cells reproduce uncontrollably f) Sieverts measure the amount of damage to the body different types of radiation cause different amounts of damage g) 20 in 20 000 cases 1 in 1000 risk Page 7 ©The Nuffield Foundation, 2011 Copies may be made for UK in schools and colleges