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

Strovimab is a monoclonal antibody that is used to treat coronavirus (COVID-19). In a randomised double-blind, placebo-controlled study, Strovimab was shown to reduce the risk of hospitalisation due to COVID-19 by 79%.

Image 7 shows a process for producing monoclonal antibodies.

Image 7

With reference to Image 7, state the names of the cells labelled:

A ..................................
B ..................................

Strovimab is manufactured using cells grown in a laboratory instead of a live mouse, as shown in Image 7.
Suggest one ethical advantage of using cells grown in a laboratory instead of using a live mouse.

State what is meant by the terms:

(i) double-blind;

[1]

(ii) placebo.

[1]

The 4CMenB vaccine was created to target a bacterium called Neisseria meningitidis, which causes a form of a disease called meningitis. The vaccine has also been found to reduce the rates of a sexually transmitted infection (STI) called gonorrhoea. Gonorrhoea is caused by a bacterium called Neisseria gonorrhoeae.

Explain how the 4CMenB vaccine causes the body to develop immunity against Neisseria meningitidis.

Use your knowledge of classification to suggest why the 4CMenB vaccine is also effective against gonorrhoea.

Gonorrhoea is symptomless in up to 50% of females and 10% of males. Left untreated, it can cause infertility in women.

Graph 10 shows the number of people in Australia diagnosed with gonorrhoea between 2010 and 2019.

Graph 10

In 2019, the 4CMenB vaccine was introduced in Australia for people between 17 and 20 years old and the probability of getting gonorrhoea was reduced by 33%. In a similar study in the US, the vaccine was introduced for 16 to 23-year-olds, reducing the probability of getting gonorrhoea by 40%.

(i) Compare the trends shown in Graph 10 for the number of males and females diagnosed with gonorrhoea between 2010 and 2019.

[2]

(ii) Suggest why it is more difficult to reduce the number of women with gonorrhoea compared with men.

[1]

(iii) Evaluate how the evidence provided shows that the 4CMenB vaccine could be effective against gonorrhoea worldwide.

[2]

State one other way, apart from vaccination, to prevent the spread of an STI.

Image 9.1 shows the structure of the human immuno-deficiency virus (HIV).

In some of the people who have an HIV infection, the virus can lead to the disease AIDS, which can be fatal.

Image 9.1

State two ways, visible in Image 9.1, in which the structure of HIV is different from other viruses

1...............................................
2..............................................

State how HIV is spread from one person to another and one measure which can be taken to reduce the spread.

In 2000, the United Nations set a target that 90% of people with HIV should be receiving treatment. This treatment should be effective at reducing the number of people developing AIDS.

By 2010, 97% of people with HIV in the UK were being treated with the anti-viral drug, HAART.

Graph 9.2 shows the results from investigations on the effectiveness of HAART.

Graph 9.2

Using the information provided on this page, give the evidence that by 2010 the UK had met the UN target by

(i) providing treatment to enough people;

[1]

(ii) providing treatment which was effective.

[1]

Graph 9.3 shows the percentages of people in different age groups in the UK who were known to be infected with HIV in 2017. The total number of infected people was 101610.

Graph 9.3

From the information given above calculate

(i) the percentage of people in the 25–34 age group,

[1]

(ii) the number of people in the 35–49 age group.

[2]

(iii) Most campaigns which encourage people to take treatment for HIV infections are targeted at those under 35. Some charities, however, say it would be more effective to target campaigns at older age groups.

Using the information in Graph 9.3, state one piece of evidence which supports the point of view of some charities.

[1]

In 2018–19, there was an outbreak of the Ebola virus disease in the Democratic Republic of the Congo (DRC). A double-blind clinical trial was carried out in four villages on 499 people infected with the Ebola virus. The purpose was to test the effectiveness of four potential treatments against the virus.

Table 9 shows the results halfway through the trial in August 2019.

Table 9

At the time of the trial, 1900 people out of 2831 confirmed cases of Ebola in other parts of the DRC had died of the disease. None of the 2831 people were part of the trial and so did not receive any of the four treatments above.

(i) Use the information given above to calculate the percentage of confirmed cases of Ebola who received no treatment and died of the disease. Give your answer to two significant figures.

[2]

Percentage = ..........................

(ii) The results shown in Table 9 convinced the scientists to stop using ZMapp and Remdesivir, and place all remaining patients on either REGN-EB3 or mAb-114.

Suggest why the scientists stopped using ZMapp and Remdesivir in August 2019 and placed all the remaining patients on either REGN-EB3 or mAb-114.

[1]

(iii) Explain the meaning and importance of double-blind trials.

[2]

(iv) This trial did not use a placebo. Suggest why a placebo could be considered unethical in this trial.

[1]

mAb-114 is a monoclonal antibody. It was developed using blood samples isolated from an Ebola survivor in 1995.

Outline the pre-clinical stages, in the correct sequence, which would have been carried out before the treatments could be used for clinical trials.
Describe how the monoclonal antibody mAb-114 could have been produced using lymphocytes from a sample of survivor’s blood.

Since 1985, approximately 100 different monoclonal antibodies have been developed and some are used in the treatment of breast cancer linked to the mutated HER2 gene. During chemotherapy a drug is attached to the monoclonal antibody to target these cancer cells directly.

Explain how the monoclonal antibody targets these cancer cells directly.

State two other uses of monoclonal antibodies.