Open response questions
Extended open response questions require longer answers than structured questions that have fewer marks. Open response questions are usually worth six marks, but some are worth fewer marks.
It is wise to plan your answer first by making some notes. This will help you to include all the key points.
To gain full marks, you need to:
- support explanations using scientific knowledge and understanding
- use appropriate scientific words
- write clearly and link ideas in a logical way
- maintain a sustained line of reasoning
Open response questions often use these command words:
- Describe means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.
- Explain means you need to make something clear, or state the reasons for something happening.
- Compare means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y, and give a comparison. Do not just write about X only or Y only.
- Evaluate means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.
Open response questions may be synoptic questions, which bring together ideas from two or more topics. For example, a question about fertilisers could include ideas about covalent substances, acids and alkalis, chemical calculations and effects on the environment.
The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain full marks, but you do need to write in sentences, linking them logically and clearly.
This page contains AQA material which is reproduced by permission of AQA.
Sample question 1 - Foundation
Question
Every year, many patients need to have heart valve replacements.
Information is given below about two types of heart valve.
| Living human heart valve | Cow tissue heart valve |
| It has been used for transplants for more than 12 years | It has been used since 2011 |
| It can take many years to find a suitable human donor | It is made from the artery tissue of a cow |
| It is transplanted during an operation after a donor has been found | It is attached to a stent and inserted inside the existing faulty valve |
| During the operation, the patient's chest is opened and the old valve is removed before the new valve is transplanted | A doctor inserts the stent into a blood vessel in the leg and pushes it through the blood vessel to the heart |
| Living human heart valve | It has been used for transplants for more than 12 years |
|---|---|
| Cow tissue heart valve | It has been used since 2011 |
| Living human heart valve | It can take many years to find a suitable human donor |
|---|---|
| Cow tissue heart valve | It is made from the artery tissue of a cow |
| Living human heart valve | It is transplanted during an operation after a donor has been found |
|---|---|
| Cow tissue heart valve | It is attached to a stent and inserted inside the existing faulty valve |
| Living human heart valve | During the operation, the patient's chest is opened and the old valve is removed before the new valve is transplanted |
|---|---|
| Cow tissue heart valve | A doctor inserts the stent into a blood vessel in the leg and pushes it through the blood vessel to the heart |
A patient needs a heart valve replacement. A doctor recommends the use of a cow tissue heart valve.
Give the advantages and disadvantages of using a cow tissue heart valve compared with using a living human heart valve.
Use information from the table and your own knowledge in your answer. [6 marks]
Indicative content
Advantages of cow tissue valve:
- abundant supply of cows
- so shorter waiting time
- no need for tissue typing
- less invasive or shorter recovery time
- cheaper operation costs
- less operation / anaesthetic risks
Disadvantages of cow tissue valve:
- made from cow so possible objections on religious grounds
- new procedure so could be unknown risks
- risks of using a stent, eg blood clots, stent breaking or valve tearing
- not proven as a long term treatment
- may be rejected
Sample question 2 - Higher
Question
In-vitro fertilisation (IVF) treatment can be used to help women become pregnant.
IVF uses some of the hormones shown in the graph below.
Explain why IVF increases the chance of some women becoming pregnant. [6 marks]
Indicative content
Identification of hormones used in IVF:
- FSH
- LH
Role of hormones in IVF:
- FSH causes eggs to mature
- LH causes the eggs to be released
Effect of chance of effective pregnancy:
- high levels of hormones cause many eggs to be matured or released
- sperm and eggs are collected and the eggs are fertilised (so increased probability of fertilisation)
- fertilised egg cells are given time to develop into a small ball of cells
- some are transferred into the mother (uterus), to increase the probability of one successful implanting
Sample question 3 - Higher
Question
Huntington's disease is an inherited disorder that affects the nervous system.
It is caused by a dominant allele.
A man is heterozygous for Huntington's disease.
His partner is healthy and does not have the allele that causes Huntington's disease.
The couple want to have a child.
The couple visit a genetic counsellor who gives them the following options:
- adopt a child
- gamete donation – uses sperm from another man to fertilise the woman's eggs by in vitro fertilisation (IVF)
- conceive naturally
- use pre-implantation genetic diagnosis (PGD)
- Many embryos are produced by IVF using gametes from the man and woman.
- Embryos are tested for Huntington's disease and a healthy embryo is implanted into the woman's uterus.
- The risk of implanting an embryo with an allele for Huntington's disease is 0.2%.
- Costs the NHS about £11,000.
- Conceive naturally and use prenatal diagnosis (PND) once the woman becomes pregnant.
- A sample of the placenta is taken at 10 weeks of pregnancy or a sample of fluid is taken from around the developing baby at 16 weeks of pregnancy.
- The sample is tested for Huntington's allele.
- A 0.5 to 1.0% risk of miscarriage.
- About 1% of samples collected are unsuitable for testing.
- Costs the NHS about £600.
The couple decide they want to have a healthy baby that is their own biological offspring.
Evaluate the options.
Suggest which option would be best for the couple. [6 marks]
Indicative content
- Adoption / gamete donation unsuitable as offspring not biologically theirs.
- Natural conception too risky / only 50% chance of healthy offspring.
- Natural conception would cause worry whether baby would be healthy or not.
- Choice is between PGD and PND.
Positives of PGD:
- baby would be theirs
- results obtained at an early stage
- high chance baby would be healthy
- parents would have confidence of having a healthy baby from the start of pregnancy
- lower risk of miscarriage compared to PND
- PGD occurs before pregnancy / implantation
- PGD does not involve abortion so less trauma / less pain / ethical comparison
- spare healthy embryos may be used for research / medical treatment
Negatives of PGD:
- slight / 0.2% chance of misdiagnosed embryo
- expensive procedure
- cost to NHS of non-essential procedure
- unhealthy embryos might be destroyed
- large number of embryos produced so healthy embryos may be destroyed
- ethical issues of using embryos for research
- some people are opposed to IVF due to their religious beliefs
Positives of PND:
- natural conception less invasive for mother
- psychological benefit of producing child naturally
- 99% / high chance that result of test would be conclusive
Negatives of PND:
- sampling technique invasive to mother
- risk of miscarriage
- risk of infection
- a long wait before test can be carried out
- 50% chance baby will have allele for Huntington's disease
- parents will have a difficult decision to make if baby is unhealthy
- baby may be aborted
- ethical / religious issues of abortion
