Disease, Defence & Treatment (WJEC GCSE Science (Double Award): Biology): Exam Questions

Image 5 shows surgery on a patient with heart disease caused by a faulty gene.

Image 5

After surgery, it is important that wounds are sealed.

Explain why wounds must be sealed.

Patients are given antibiotics after surgery.

State the name of one antibiotic and the reason why antibiotics are given to patients.

Antibiotic ........................................................................................

Reason ..........................................................................................

Complete the table by writing true or false against each of the following pairs of statements about antibiotics and vaccines.

Smallpox was an infectious disease caused by a virus. An estimated 300 million people worldwide died from smallpox during the 20th Century. The last naturally occurring case was diagnosed in October 1977 and the World Health Organization certified the global eradication of the disease in 1980.

The global eradication was considered to have occurred because the smallpox vaccine was very effective and the programme of vaccination was thorough and worldwide.

However, some authorities dispute the claim that eradication was due to vaccination. They stated that deaths from smallpox were already decreasing in unvaccinated populations and that only 10% of the World's population were vaccinated.

Graphs 8.1, 8.2, 8.3 and 8.4 show data for four diseases that caused deaths in the UK in the 19th and 20th Centuries. They also show the dates at which vaccines for three of these diseases were introduced.

Note: Mandatory vaccination enforced means that by law people had to be vaccinated against smallpox.

Mandatory vaccination repealed means that people were no longer legally required to be vaccinated against smallpox.

Using only the information in Graphs 8.1, 8.2, 8.3 and 8.4, explain how they could be used as evidence both for and against the use of vaccination.

MMR is a safe and effective vaccine that protects against measles, mumps and rubella. These diseases are caused by viruses.

• The full course of MMR vaccination requires two doses; a child has the first injection at the age of one year and the second at three years.

• If the child comes into contact with any of these viruses in the future, lymphocytes in the blood will rapidly cause the destruction of these viruses and the child will not become ill.

• A small number of children may get minor side effects due to the vaccine.

Use this information and your own knowledge to complete the following table by writing True or False against each statement.

Predict what would happen to the number of cases of measles, mumps and rubella if fewer children were given the MMR vaccine.

Graph 5.1 shows the percentage of children receiving the MMR vaccine in the UK between 1989 and 2018. It is the target of any UK vaccination programme to get at least 95% of children vaccinated.

In 1998, a report was published which claimed that there was a link between the MMR vaccine and a condition called autism. The report was later shown to be completely untrue.

Graph 5.1

(i) State the year the percentage of children receiving the MMR vaccine was closest to the UK target.

...................................................................................................

[1]

(ii) State a conclusion that could be made about the success of the MMR vaccination programme between 1990 and 1993.

[1]

(iii) The percentage of children vaccinated decreased after the report was published. Suggest the reason for this.

[1]

Image 8.1 shows the structure of a bacterium and a virus.

Image 8.1

Use all the information given to describe the similarities and differences between the structure of the bacterium and the virus.

The diagram shows a pathogen that causes an infectious disease.

(i) State the type of pathogen shown above.

.................................................................................................................................

[1]

(ii) Sudden changes to a gene cause changes to the antigens on the coat of the pathogen.

State the term for a sudden change to a gene.

.................................................................................................................................

[1]

State one way by which pathogens are spread between people.

The following statements (1–6) describe how the body responds when it is invaded by pathogens. The statements are not in the correct order.

1. The pathogens have foreign antigens

2. Pathogens enter the blood

3. They respond by releasing antibodies to the antigens

4. The antibodies attach to the pathogen

5. The antigens are recognised as foreign by lymphocytes

6. The attached antibodies help phagocytes destroy the pathogen

Complete the sequence to put the statements in the correct order.

.............. .........1..... .............. ........3...... .............. ..............

Image 5.1 shows a white blood cell which is ingesting micro-organisms in the bloodstream of a person.

Image 5.1

(i) State the type of white blood cell shown.

...................................................................................................

[1]

(ii) Suggest what will happen to the micro-organisms after they have been ingested by the white blood cell.

[1]

A person was vaccinated against an infectious disease caused by a virus. Graph 5.2 shows the concentration of antibodies in the blood of the person over the next 90 days.

Graph 5.2

(i) Explain the increase in antibody concentration over the first 20 days.

[3]

(ii) Give two possible reasons that could account for the increase in antibody concentration from point X on Graph 5.2.

1.

2.

[2]

(iii) State the name of the cell that is responsible for the very rapid antibody production between days 45 and 65.

...................................................................................................

[1]

(iv) State the scientific term which could be used to describe this person in relation to the virus after day 65.

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[1]

MMR is a 3-in-1 vaccine that protects people against measles, mumps and rubella. Children should be fully vaccinated against these three diseases by school age.

In 1998, a British doctor published the results of his research in a medical journal. His work stated that there was a link between the MMR vaccine and a condition called autism. The General Medical Council found the work published by the doctor to be “dishonest” and the doctor was struck off the UK medical register. Unfortunately, before the work was discredited, it had been picked up by the media and spread across the World.

Graph 5.3 shows the percentage of school-age children who had received the MMR vaccine in England and Wales between 1996 and 2010.

Graph 5.3

(i) From Graph 5.3, state the effect the published work linking MMR vaccination with autism had on the percentage of children receiving the MMR vaccine.

[1]

(ii) Sketch a single line on Graph 5.3, extending between 1996 and 2010, to show the effect the published work linking MMR vaccination with autism would have had on the number of cases of measles in England and Wales. No labels or numbers are required.

[2]

The diagram shows a bacterial cell.

Label structures A, B and C on the diagram above.

A ..........................................................

B ...........................................................

C ..........................................................

Carys wanted to investigate the effect of an antibiotic on bacterial growth. She set up the experiment shown below with test tubes containing increasing concentrations of an antibiotic and inoculated each test tube with a fixed volume of nutrient broth containing a known concentration of bacteria.

The tubes were incubated at 25 °C for two days. The cloudier the solution becomes the more bacteria present. A clear sample means there is no bacterial growth.

(i) Explain the result observed in tubes 4–6.

[1]

(ii) Suggest the minimum concentration of antibiotic that would be effective against the bacterium.

minimum concentration = ........................... µg/cm³

[1]

(iii) Suggest how Carys could improve her experiment so that she could obtain a more accurate value for the minimum concentration of antibiotic needed to be effective against the bacterium.

[2]

Thalidomide is a medical drug that caused unexpected damage to foetuses in the 1950s and 1960s. It was used for easing morning sickness in pregnant women, although it had not been fully tested.

As a result of the damage to foetuses, the drug was banned. Drug testing was also made more thorough.

Thalidomide has since been used as a treatment for bone cancer. However, its use is heavily regulated to prevent a repeat of the problems it caused last century.

With thalidomide came the widespread recognition that differences in sensitivity to drugs between species required consideration. Many scientists report that animals are good predictors of how humans will respond to drugs and that current testing procedures would have identified the dangers of thalidomide and the side effects would have been avoided.

Despite this, there is evidence that animal tests cannot predict how humans will respond to a drug. In 1990, six different drugs were trialled in humans and in animals. The results showed that animals and humans had 22 common side effects (true positives). There were 48 side effects in animals which did not occur in humans (false positives). There were also 20 side effects in humans that did not occur in animals (false negatives).

The sensitivity of the animal tests is calculated using the formula:

$\text{Sensitivity}=\frac{\text{TP}}{\text{TP}+\text{FN}}\times 100$

TP = true positives

FN = false negatives

Calculate the sensitivity of the animal tests in the trial carried out in 1990.

Sensitivity = ....................................... %

Use only the information in the passage to answer the following questions.

(i) Evaluate the arguments for and against the use of animals in drug testing.

[2]

(ii) State how the thalidomide problem has had one positive outcome on the development of new drugs.

[1]

(iii) State why the ban on thalidomide was removed.

[1]

The photograph shows bacteria called E. coli.

Bacteria such as E. coli can be pathogens.

(i) State the meaning of the term pathogen.

[1]

(ii) Describe two ways in which pathogens are spread from person to person.

[2]

Bacterial infections may be treated by antibiotics.

(i) State the name of one antibiotic.

.................................................................................

[1]

(ii) Which one of the following results from the over use of antibiotics?

Underline the correct answer.

People become immune to antibiotics

People become resistant to antibiotics

Bacteria become immune to antibiotics

Bacteria become resistant to antibiotics

[1]

The diagram below shows how a lymphocyte responds to the presence of antigens in the body.

Explain how the body responds to a foreign antigen the first time it is encountered and why the response is faster when the same antigen is encountered a second time.

Measles is a communicable disease. The diagram shows two populations of people, during an outbreak of the measles virus.

Using only the diagram above, explain the advantage of a vaccination programme.