AQA A Level Biology

Topic Questions

2.6 Vaccines, Disease & Monoclonal Antibodies

1a3 marks

Figure 1 below shows the effect of vaccination followed by infection with the same pathogen on antibody concentration in the blood. 

Figure 1

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Explain why the vaccine causes an increase in antibody concentration.

1b2 marks

Figure 2 shows that when the individual is infected with the same pathogen a few months later, their antibody concentration increases more quickly. Explain why this is the case.

1c1 mark

For a vaccination programme to eradicate a disease, enough people need to be vaccinated that the disease can no longer spread. State the name given to this level of immunity.

1d2 marks

It can be difficult to reach the level of vaccination described in part c) above because some people are concerned about the use of vaccines. Give two reasons why people might have concerns around vaccination. 

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2a3 marks

Table 1 below contains information about different types of immunity. 

Table 1

Type of immunity

Production of antibodies

Presence of memory cells

Example of how it can be gained

Natural, passive

No

 

Across the placenta during pregnancy

Acquired, passive

 

No

An injection of antibodies

Natural, active

Yes

   

Acquired, active

 

Yes

Being vaccinated

Use your knowledge of immunity to fill in the gaps in Table 1 above.

2b1 mark

Use the information in Table 1 to suggest why babies need to be vaccinated from 8 weeks old.

2c2 marks

When an individual is vaccinated, they can remain susceptible to a disease for a few weeks afterwards. State why this is the case. 

2d2 marks

Tetanus is a bacterial infection gained from contact between the blood and soil-dwelling bacteria Clostridium tetani. An individual who had not been vaccinated against tetanus received a cut from a garden fork and it was suggested that they should go to the hospital for an injection of tetanus antibodies. State how this injection would protect them against tetanus.

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3a2 marks

Figure 1 below shows rates of MMR vaccine uptake and autism cases in children.

Figure 1

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Calculate the percentage decrease in children vaccinated with the MMR vaccine between 1990 and 1994.

3b2 marks

Suggest two reasons why there might have been a decrease in the percentage of children receiving the MMR vaccine during the early 1990s.

3c2 marks

During the mid-1990s a scientist proposed a causal link between the MMR vaccine and autism in children. The graph shown in Figure 1 is only part of the evidence against this scientist’s theory. State how the data in Figure 1 helps to disprove the link between the MMR vaccine and autism.

3d2 marks

The study carried out by the scientist mentioned in part c) involved 12 children with autism. Suggest why data gained from this study might be considered invalid.

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4a3 marks

Figure 1 below shows a representation of the Human Immunodeficiency Virus (HIV).

Figure 1

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Identify the structures labelled A-C on Figure 1

4b2 marks

Name the enzyme labelled enzyme X in Figure 1 and state its role.

4c2 marks

Figure 2 shows three stages of the process during which HIV infects Helper T cells.

Figure 2

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Describe the events that take place in order for step 2 in Figure 2 to progress on to step 3.

4d2 marks

State how the events shown in Figure 2 lead to the development of AIDS. 

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5a1 mark

Figure 1 below shows an example of a test used to diagnose HIV infection.

Figure 1

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Name the type of test shown in Figure 1.

5b2 marks

State why antibodies are present in the patient blood sample in Figure 1 and explain why they bind to the test plate when the sample is added to it.

5c2 marks

State what a positive test result would look like in the test shown in Figure 1. Explain how this result would occur.  

5d2 marks

Monoclonal antibodies can be used to deliver cancer drugs to a tumour. State why monoclonal antibodies are so useful in this type of treatment.

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1a3 marks

Figure 1 shows the progress of infection when damaged human skin comes into contact with Human Papillomavirus, or HPV.

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It can be 6-12 months before HPV antibodies can be detected in the blood of an individual with a HPV infection.  Use Figure 1 to suggest why this is.

1b3 marks

There is a vaccination for HPV which is routinely given to teenage girls, as it is thought to offer future protection against cervical cancer. The standard procedure is for each girl to receive three doses of the vaccine for full immunity, although there is some discussion  about the optimum number of doses. Figure 2  below shows antibody production after different doses of HPV vaccine in teenage girls.

Figure 2

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A student concluded from Figure 2 that it didn’t matter whether girls were given two  doses of vaccine or three. Evaluate this conclusion.

1c4 marks

HPV vaccines provide protection against cancer by preventing the virus from causing mutations in infected cells. Current medical advances in vaccine technology mean that researchers hope that it will soon be possible to vaccinate people against cancer cells themselves. 

Figure 3 shows some of the changes that can take place when a cell becomes cancerous. 

Figure 3

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Use Figure 3 to suggest how a vaccine could be effective against the development of cancer. 

1d2 marks

Although it is hoped that cancer vaccination might one day be preventative, currently it is being trialled for the treatment of existing cancers rather than for prevention. 

Suggest why these types of therapeutic vaccine could be seen as preferable to more traditional cancer treatments such as chemotherapy.

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2a2 marks

Figure 1 below shows the structure of the human immunodeficiency virus (HIV).

Figure 1

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Suggest the functions of the following HIV components:

Glycoprotein ___________________

Reverse transcriptase __________________

2b3 marks

Figure 2 shows some of the changes that take place in the blood after infection by HIV.

Figure 2

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Use information in Figure 2 to explain the changes in HIV RNA copies in the plasma  during the first 14 weeks after infection.

2c2 marks

Use Figure 2 to explain why those infected with HIV experience an asymptomatic period  (period without symptoms) between 2-10 years. 

2d4 marks

Use Figure 2 and your own knowledge to explain how infection with HIV eventually  leads to the development of AIDS.

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3a2 marks

Figure 1 below shows the events that take place during the progression of a vaccination programme.

Figure 1

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Suggest what the ‘adverse events’ labelled in Figure 1 might be. 

3b4 marks

Suggest an explanation for the events seen in stage 3 of the vaccination programme in Figure 1.

3c3 marks

Towards the end of stage 4 in Figure 1, the disease incidence drops to zero. Explain what needs to happen within the vaccination programme to reach a disease incidence of zero.

3d3 marks

Table 1 shows the herd immunity thresholds for several different diseases.

Table 1

Disease

Herd immunity threshold (%)

Smallpox

80-85

Measles

92-94

Polio

75-92

SARS

50-75

SARS-CoV-2 (COVID-19)

82.5

Of the diseases listed in Table 1, only smallpox has been fully eradicated. Use information in Table 1 and your own knowledge to suggest why this is the case.

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4a3 marks

SARS-CoV-2 is the virus that causes COVID-19 disease. Figure 1 below shows the structure of a rapid lateral flow test strip used to test for the presence of SARS-CoV-2 antigens in a person’s nose and throat cells. This kind of test can be carried out at home in around 20 minutes.

Figure 1

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Describe and explain the contents of the section labelled ‘conjugate pad’ in Figure 1

4b2 marks

Explain the function of the control line on the test shown in Figure 1.

4c3 marks

Figure 2 below compares the sensitivity of the lateral flow test shown in Figure 1 with  another test called the PCR test at different stages during an infection.  PCR tests are carried out in a laboratory and results can take a few days to be returned. 

Figure 2

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A researcher concluded from Figure 2 that PCR tests should be used rather than lateral flow tests. Use this information and detail provided in part a) above to evaluate this conclusion.

4d2 marks

The PCR test involves amplifying the genetic material in a swab sample before testing for viral RNA. Use this information and detail provided in part a) above to suggest an explanation for the sensitivity difference between the two tests shown in Figure 2.

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5a4 marks

A method for the diagnosis of HIV is outlined in Figure 1 below

Figure 1

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 Explain how the test in Figure 1 gives a positive result if a patient has an HIV infection.

5b2 marks

An important process is missing from the description in Figure 1. Describe the missing  process and explain why it is essential.

5c3 marks

HIV infects human cells by binding to a cell surface receptor called CD4. This binding causes a shape change in the viral surface glycoproteins, enabling the virus to enter the host cell. 

A new treatment for HIV involves a monoclonal antibody called Ibalizumab, the action of which is shown in Figure 2 below.

Figure 2

10

Suggest how Ibalizumab works as a treatment for HIV.

5d3 marks

A trial looking at the efficacy of Ibalizumab investigated its impact on CD4 cell (also  known as helper T cell) count after 25 weeks of treatment. The results are shown in Figure 3 and include the standard deviations for each group of patients. 

Figure 3

11

State and explain what can be concluded about the efficacy of Ibalizumab from the results shown in Figure 3.

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1a2 marks

Pulmonary tuberculosis (TB) is a contagious bacterial infection that involves the lungs.Pulmonary TB is caused by the bacterium Mycobacterium tuberculosis.

In the UK, children are vaccinated against this disease. What is a vaccine?

1b6 marks

Describe how vaccination can lead to protection against pulmonary tuberculosis.

1c2 marks

The MMR vaccine is a vaccine against measles, mumps, and rubella (Germa measles). A child was given the vaccine but it took over a week for any antibodies to appear in the child’s blood. Explain why.

1d1 mark

Sometime after the first MMR vaccination, the child in part c) was given a second dose of the vaccine as a ‘booster’. Immediately after this second vaccination, the concentration of antibodies in the child’s blood increased. Explain why.

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2a2 marks

Pertuzumab is a monoclonal antibody used to treat breast cancer. This monoclonalantibody has a radioactive substance attached to it.

What is the advantage of having a radioactive substance attached to the antibody, rather than injecting the radioactive substance directly?

2b2 marks

The monoclonal antibody in part a) only binds to cancer cells. Why does it do this and not bind to other cells in the body?

2c2 marks

A small number of patients who are given the monoclonal antibody in part a) have an immune response to it. Explain why.

2d2 marks

An intravenous drip is used to deliver the monoclonal antibody in part a) directly into vein of a patient. Suggest why it is not given as a drug for the patient to swallow.

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3a1 mark

Warts are growths on the skin caused by an infection with human papillomavirus. A  medical researcher vaccinated a group of adult patients against human papillomavirus. He gave each patient two doses of vaccine, 5 months apart. The researcher tested three samples of blood from each of the patients:

Sample 1: taken 3 week before the first dose of vaccine

Sample 2: taken 3 weeks after the first dose of vaccine

Sample 3: taken 3 weeks after the second dose of vaccine

He measured the concentration of antibodies against human papillomavirus in the
patients’ blood each time. The results are shown in the graph in Figure 1:

Figure 1

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Calculate the percentage increase in the mean concentration of antibodies in blood between samples 2 and 3.

3b2 marks

In a trial for a new, improved version of the vaccine in part a), a doctor gave the new vaccine to a group of adult volunteers. The doctor followed the same procedure as in part a), each volunteer was given two doses of vaccine, 5 months apart. As in part a), the doctor tested three samples of blood from each of the patients. Suggest two factors the doctor should have considered when selecting adult volunteers for this trial.

3c4 marks

In the graph in Figure 1 there are clear differences between the mean concentrations of antibodies in the three blood samples. Explain these differences.

3d1 mark

Give one way in which a pathogen can cause disease when it enters the body of a host organism.

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4a4 marks

Contrast active immunity and passive immunity. 

4b1 mark

When a person is bitten by a venomous spider called a Black Widow spider, the spider injects a toxin into the blood. Antivenin is injected as treatment to spider bites. Antivenin contains antibodies against the toxin. This treatment is an example of passive immunity.

Explain how the antivenin cures a person who has been bitten.

4c1 mark

In order to cure someone who has been bitten by a black widow spider (see part b), explain why it is essential to use passive immunity, rather than active immunity.

4d3 marks

The antivenin described in part b) is produced by injecting the venom from black widow spiders into horses, which then produce antibodies against the venom. However, some patients have a life-threatening reaction to this horse-made antivenin. A new form of antivenin has been produced by the same process, but using sheep instead of horses. 

Suggest why this new form of antivenin causes fewer reactions in people than that produced using horses.

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5a2 marks

The diagram in Figure 1 shows a human immunodeficiency virus (HIV).

Figure 1

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Name structure B and structure E in Figure 1.

5b2 marks

Name structure C in Figure 1 and state its function in this virus.

5c4 marks

After HIV has infected a T cell, new HIV viruses are produced. Describe how.

 

5d2 marks

When the new HIV viruses are released from the T cell (see part c), the T cell bursts/lyses and is destroyed. This destruction of T cells is very dangerous and could eventually cause the death of someone infected with HIV. Explain why.

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