TB Questions

Q1. Human diseases can be caused by many different types of organism, such as bacteria and viruses.

(a)  Give two differences between the genetic material of bacteria and viruses.
(2)
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(b)  Tuberculosis (TB) is caused when droplets, containing the bacterium Mycobacterium tuberculosis, are inhaled into the lungs.

In the lungs, large numbers of the bacterium are formed rapidly. These can be ingested by macrophages. Eventually, tubercles (tissue masses), containing dormant bacteria inside macrophages, may form.

(i)  Describe how macrophages ingest the bacteria.
(2)
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(ii)  Suggest why treatment with antibiotics may not be effective against the dormant bacteria in the tubercles.
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(iii)  TB can be prevented by vaccination. Explain how a person can develop artificial active immunity following vaccination.
(3)
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(c)  In a person with TB, the dormant bacteria in tubercles may be activated after several years. The bacteria multiply rapidly, resulting in severe lung damage.

The bacteria are released from the tubercles. These bacteria can inhibit the activity of T cells and infect other organs.

Explain why the activity of these bacteria and the inhibition of T cells means that a person may quickly develop severe symptoms leading to death.
(4)
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(Total for Question = 13 marks)

Q2. The human immunodeficiency virus (HIV), causes acquired immunodeficiency syndrome (AIDS).

(ii)  Explain why the destruction of T helper cells causes the symptoms of AIDS.
(4)
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Q3. Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis.
(a)  Describe how M. tuberculosis bacteria evade the immune system.
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(Total for question = 2 marks)

Q4.
 
Tuberculosis (TB) is a disease that affects the lungs. It is caused by the bacterium Mycobacterium tuberculosis. When these bacteria enter the body an immune response is triggered.
The Human Immunodeficiency Virus (HIV) affects the immune system. People infected with HIV are more likely to develop TB.
A study investigated the relationship between TB infections and HIV status.
In 2008, the number of people in the world estimated to have TB was 9.4 million.
The table shows the percentage of these people who were either HIV positive or HIV negative. The estimated number of deaths due to TB is also shown in the table.

(i)  Calculate the percentage of TB patients infected with HIV who died of TB.
(2)

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(ii)  Describe the effect of HIV on the number of deaths from TB.
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* (iii)  There are increased numbers of deaths from TB as a result of HIV infection.
The table shows data for deaths worldwide from HIV and TB in 2016.

Treatment of HIV with anti-viral drugs has reduced the incidence of TB associated with HIV infection.
The replication of HIV reduces the T-helper cell count. These anti-viral drugs reduce the replication of the virus in the body.
The graph shows the effect of this on the incidence of TB.

Explain the effect of using anti-viral drugs to treat HIV on the number of deaths from TB.
(6)

Q5.
 
Ebola haemorrhagic fever is a life-threatening disease caused by the Ebola virus.
(a)  Explain why antibiotics are not used to treat Ebola haemorrhagic fever.
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(b)  Some of the blood plasma of individuals who have survived infection with Ebola can be collected. This can be used in the treatment of individuals currently infected with Ebola.
Explain why the blood plasma from survivors can be used to treat new cases of Ebola infection.
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(c)  A study of the 2014 Ebola outbreak in Sierra Leone found that the Ebola virus was evolving rapidly.
Explain why the evolution of the virus might reduce the effectiveness of any vaccine being developed.
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(Total for question = 9 marks)

Mark Scheme

Q1.

Q2.

 

Q3.

 

Q4.

 

Q5.