Syllabus Edition

First teaching 2023

First exams 2025

|

Infectious Diseases (CIE AS Biology)

Exam Questions

2 hours41 questions
1a
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1 mark

Identify the pathogen which causes cholera.

1b
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2 marks

There is a high risk of cholera outbreaks occurring after natural disasters such as earthquakes, hurricanes and floods.

Explain why this would be the case.

1c
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4 marks

Cholera is an infectious disease. Table 1 shows some information about three other infectious diseases.

Table 1

Infectious disease Name of causative organism(s) Type of causative organism Main mode of transmission
HIV/AIDS Human immunodeficiency virus (HIV) Virus  
Tuberculosis Mycobacterium tuberculosis Bacterium  
  Plasmodium   Feeding/sucking blood by Anopheles mosquito

Complete the missing information in Table 1.

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2a
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1 mark

Infectious diseases are caused by pathogens and are transmissible.

State what is meant by the term transmissible.

2b
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2 marks

Tuberculosis (TB) is an example of an infections disease.

Give two further examples of infectious diseases.

2c
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1 mark

Give the name of the pathogen that cause TB in humans.

2d
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3 marks

Describe the method of transmission of TB from an infected to an uninfected person.

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3a
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3 marks

Malaria is an infectious disease that is spread by an insect vector.

(i)

Define the term vector.

[2]

(ii)

State the specific type of organism that acts as a vector for the spread of malaria.

[1]

3b
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2 marks

Other than the vector mentioned at part (a)(ii), identify two possible methods of transmission of malaria.

3c
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2 marks

One of the ways to reduce the spread of malaria is to avoid being bitten by the insect vector mentioned at part (a)(ii).

State two ways in which this can be achieved.

3d
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1 mark

Despite global efforts to eradicate malaria, there are still countries where the disease is prevalent.

Give one reason why malaria has not been eradicated globally.

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4a
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2 marks

HIV is a disease caused by a viral pathogen.

Identify two diseases caused by bacterial pathogens.

4b
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2 marks

Give two methods that may prevent the transmission of HIV.

4c
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2 marks

Explain why antibiotics would not be given as a treatment for HIV

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5a
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1 mark

Cholera is caused by a bacterial pathogen that infects the small intestines causing excess water to move into the lumen of the intestines from the surrounding cells and bloodstream.

Name one symptom of cholera.

5b
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1 mark

Explain why boiling water will help to reduce the likelihood of cholera infection.

5c
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1 mark

The last reported case of locally acquired cholera in the UK was in 1893.

Suggest why it would not be worthwhile vaccinating against cholera in the UK.

5d
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2 marks

Chlorinated water is available in mainline piped water in the UK. 

Explain how this has contributed to the eradication of cholera in the UK.

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1a4 marks

Tuberculosis (TB) is an example of an infectious disease.

Explain why TB can be considered an infectious disease.

1b3 marks

Table 1 below shows the number of TB cases reported during one year in three different countries.

Table 1

Country Number of cases

Number of cases per

100 000 population

Germany 3000 4
India 2 100 000 182
South Africa 450 000 975

Use Table 1 to explain why it is advantageous to provide data on the number of cases per 100 000 population rather than only stating the total number of cases.

1c3 marks

Outline why TB has a greater chance of being fatal in people who already have HIV/AIDS compared to people who do not have HIV/AIDS.

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2a3 marks

Describe the transmission of malaria from an infected person to an uninfected person.

2b2 marks

Fig. 1 below is a drawing of an electron micrograph showing a red blood cell of someone infected with malaria.

10-1-fig-4-1Fig. 1

From Fig. 1, identify two features that show the malarial parasite is eukaryotic.

2c4 marks

The presence of malarial parasites in red blood cells can have various negative effects on the human body.

Use the Fig. 1 and your own knowledge to outline some of these effects.

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3a
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3 marks

Fig. 1 shows the human gas exchange system.

fig1-1-qp-octnov-2018-9700-21

Fig. 1

Name the structures labelled A, B, and C in Fig. 1.

3b
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1 mark

Tuberculosis (TB) is an infectious disease that attacks the lungs.

Suggest one symptom which may be experienced by an infected individual as a result of lung damage.

3c
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1 mark

Malaria is an infectious disease.

Name the pathogen that causes malaria.

3d
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3 marks

There are a number of vaccines being developed to help control the spread of malaria.

Explain why vaccination programmes have not been able to eradicate malaria.

3e
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4 marks

Fig. 2 shows the distribution of malaria in the Americas in 2012.

fig1-2-qp-octnov-2018-9700-21

Fig. 2

Suggest the factors, other than lack of vaccines, that could be restricting the distribution of malaria to area P.

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4a2 marks

Fig.1 shows three stages of the process during which HIV infects Helper T-Cells.

f-7esBdi_4

Fig. 1

After stage 2, the single-stranded RNA from the virus must be converted into double-stranded DNA. The host cell uses this DNA to produce viral proteins which are assembled into new HIV particles, as shown in stage 3.

(i)
Identify the enzyme that would be used to produce the double-stranded DNA after stage 2.
[1]
(ii)
Name the two processes used by the host cell to produce viral proteins.
[1]
4b2 marks

Using Fig.1 and your own knowledge, explain why HIV only infects specific cells in the host.

4c3 marks

Fig. 2 gives information about the number of people living with HIV and the number of deaths of individuals who are HIV positive, between 1981 and 2009

6-2-4a-hiv-graph---sq

Fig.2

Describe what the data shows.

4d3 marks

Suggest reasons for the trend in the deaths of people with HIV from 1995 as shown in the data in Fig. 2

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5a3 marks

Cholera is a transmissible disease.

Describe how cholera is transmitted between people.

5b3 marks

Describe three methods which could be used in the prevention and control of cholera.

5c2 marks

When food contaminated with V.cholerae reaches the digestive system, the bacteria attach to the wall of the small intestine. Toxins produced by the bacteria trigger the release of chloride ions into the lumen of the small intestine, this increases the solute concentration in the lumen.

One of the first symptoms that might be observed in an infected individual is diarrhoea.

Explain how infection with V.cholerae results in diarrhoea.

5d2 marks

Suggest why untreated cholera may become life-threatening.

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1a
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2 marks

Pulmonary tuberculosis (TB) is a contagious bacterial infection that involves the lungs. In the UK, children are vaccinated against this disease.

Discuss the importance of a vaccine in disease prevention and control.

1b
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4 marks

Describe how vaccination can lead to protection against pulmonary tuberculosis.

1c
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2 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 Fig. 1 below.

10-1-fig-5-1Fig. 1

Suggest how Ibalizumab works as a treatment for HIV.

1d
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2 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 Fig. 2 for each group of patients.

10-1-fig-5-2Fig. 2

State and explain what can be concluded about the efficacy of Ibalizumab from the results shown in Fig. 2.

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2a
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4 marks

The bacteria that cause tuberculosis (TB) can be found in many parts of the body including the lungs.

(i)
State the name of the bacterium that causes TB.
 [1]

(ii)

The presence of the pathogen in the lungs attracts phagocytes to the area of infection. The phagocytes release elastase, which digests elastin.

Many people with TB feel tired all the time.

Suggest and explain how the effect of phagocytes on tissues in the lungs leads to people feeling tired all the time.

[3]
2b
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5 marks

Discuss the biological factors and social factors that make TB a difficult disease to control.

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3a
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2 marks

Malaria is a disease that is caused by a parasite from the genus Plasmodium. The parasite has a complex life cycle that involves humans and the Anopheles mosquito. After transfer from mosquito to human, Plasmodium is transported to the liver where it infects liver cells, after which it leaves the liver cells and infects red blood cells.

Once inside the red blood cells the parasite digests haemoglobin internally into a toxic form known as ferriprotoporphyrin IX (FP). The parasite then converts this FP into a non-toxic molecule called haemozoin. This process is referred to as 'sequestration' and the reaction is catalysed by the enzyme haem polymerase.

Fig. 1 shows the breakdown of haemoglobin inside the malaria parasite.

Haemoglobin space rightwards arrow with digestion on top FP space space rightwards arrow with sequestration on top Haemozoin space

Fig. 1

One of the symptoms during this stage of a malaria infection is fatigue.

Using the information provided, suggest a reason for this.

3b
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2 marks

Chloroquine is currently one of the most popular forms of treatment for malaria. Chloroquine works by inhibiting the action of haem polymerase.

Suggest how chloroquine may act as a treatment for malaria.

3c
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2 marks

The genetic material of the Plasmodium parasite contains genes involved with the production of several thousand potential antigens on its cell surface. 

Using the information provided, as well as your own knowledge, suggest two possible challenges that scientists face in the development of an effective malaria vaccine.

3d
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2 marks

The Anopheles mosquito serves as a vector for the Plasmodium parasite. Anopheles is prevalent in the tropical and subtropical parts of sub-Saharan Africa. Some scientists believe that global warming may have an effect on the occurrence of malaria.

Predict and explain a possible effect that an increase in global temperatures may have on the occurrence of malaria.

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4a2 marks

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

10-1-fig-1-1Fig. 1

Identify structure B and structure C in Fig. 1.

4b1 mark

Structure C plays a very important role in the virus represented by Fig. 1.

State the function of structure C in this virus.

4c2 marks

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

Explain why the destruction of T-helper cells could eventually cause the death of an HIV-positive person.

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5a
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3 marks

Viruses share common structural features. Some viruses, such as human immunodeficiency virus (HIV), also have an outer envelope as part of their structure.

Outline the key structural features of viruses.

5b
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7 marks

HIV can remain in a dormant state within infected immune system cells for many years. A person diagnosed as HIV‐positive (HIV+) has the virus but does not have symptoms of HIV/AIDS.

The chances of an HIV+ person developing HIV/AIDS can be greatly reduced with a drug treatment programme known as anti‐retroviral therapy (ART).

In 2010, the World Health Organization (WHO) published recommendations for the treatment of pregnant women living with HIV. This includes both HIV+ women and women who have developed HIV/AIDS.

The publication recommended that all pregnant and breastfeeding women living with HIV should be provided with ART.

Fig. 1 shows the number of pregnant women living with HIV, and the number of these receiving ART, between 2005 and 2013, in low and middle income countries.

fig4-1-qp-octnov-2018-9700-22
Fig. 1

(i)

From the data in Fig. 1, it can be calculated that 13% of pregnant women living with HIV received ART in 2005.

Calculate the percentage of pregnant women living with HIV that received ART in 2013.

[1]

(ii)
Describe the trends shown in Fig. 1.
[3]
(iii)
Suggest and explain the global importance of providing ART to all pregnant and breastfeeding women living with HIV.
[3]
5c
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5 marks

In a person who has been infected with HIV‐1, the most common strain of HIV, a sample of blood can be tested for the presence of the virus.
One test that can only be used in the early stages of infection involves a monoclonal antibody specific for p24, a structural protein present in the virus.

Fig. 2 is a flow chart outlining the steps in the production of anti‐HIV p24 monoclonal antibody.

fig4-2-qp-octnov-2018-9700-22
Fig. 2

(i)
State what is being injected into the mouse in step 1.
[1]
(ii)
Explain why several weeks, rather than several days, separates step 1 and step 2.
[1]
(iii)
State one feature of the myeloma mouse cells, used in step 3, that is essential for this production process.
[1]
(iv)
Name the fused cells formed in step 4.
[1]
(v)
Suggest why step 6 is necessary.
[1]

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