Stomach Ulcers and Ebola

1. 1 State [2 marks]

   State the type of pathogen that causes (a) stomach ulcers and (b) Ebola.

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   Model answer

   (a) A bacterium (Helicobacter pylori). (b) A virus.

   Mark scheme

   • Bacterium — 1 mark
   • Virus — 1 mark
2. 2 State [2 marks]

   State how (a) Helicobacter pylori and (b) the Ebola virus are spread.

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   Model answer

   (a) By oral transmission, in contaminated food, water or saliva. (b) By contact with body fluids.

   Mark scheme

   • Oral transmission — 1 mark
   • Body fluids — 1 mark
3. 3 Explain [3 marks]

   Explain how Helicobacter pylori causes a stomach ulcer.

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   Model answer

   The bacteria live in the mucus lining of the stomach, and they damage the cells that make mucus. The lining is then not protected from the stomach acid and enzymes, which attack it and form an open sore, or ulcer.

   Mark scheme

   • Bacteria live in the mucus / damage the lining — 1 mark
   • Lining no longer protected from acid — 1 mark
   • Acid wears away the lining to form an ulcer — 1 mark
4. 4 Describe [3 marks]

   Describe the symptoms of Ebola.

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   Model answer

   Ebola causes a high fever, headache and muscle pain, and vomiting and diarrhoea. In severe cases it damages the blood vessels and causes internal and external bleeding, which is called a haemorrhagic fever.

   Mark scheme

   • Fever, headache, muscle pain — 1 mark
   • Vomiting and diarrhoea — 1 mark
   • Bleeding — 1 mark
5. 5 Explain [4 marks]

   Explain how the spread of Ebola can be reduced.

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   Model answer

   Infected people should be isolated, so that they cannot pass the virus on. Health workers should wear protective clothing to avoid contact with body fluids, and the people who have had contact with the sick should be traced and monitored. Bodies should be buried safely, and vaccination can protect health workers and contacts.

   Mark scheme

   • Isolation — 1 mark
   • Protective clothing — 1 mark
   • Contact tracing — 1 mark
   • Safe burials or vaccination — 1 mark
6. 6 Evaluate [6 marks]

   Explain how the work of Marshall and Warren changed the treatment of stomach ulcers, and why the scientific community was slow to accept their ideas.

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   Model answer

   Before the 1980s doctors thought that ulcers were caused by stress, spicy food and acid, and they were treated with antacids, which gave relief but often did not cure them. Marshall and Warren found Helicobacter bacteria in ulcers, and Marshall drank a culture of the bacteria and developed inflammation of the stomach, which showed it could cause disease. This led to treatment with antibiotics, which cured most ulcers. Many doctors were slow to accept it because it went against the established idea, and it was thought that bacteria could not survive in the acid of the stomach. The evidence had to be repeated and checked by others before it was accepted.

   Mark scheme

   • Old idea: stress, food and acid — 1 mark
   • Treatment was antacids — 1 mark
   • Marshall and Warren found the bacteria — 1 mark
   • Marshall's experiment — 1 mark
   • New treatment with antibiotics — 1 mark
   • Slow to accept, needed to be checked by others — 1 mark

Quick check

1. 1

   What causes most stomach ulcers?

   1. AStress
   2. BSpicy food
   3. CHelicobacter pylori
   4. DA virus
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   C: Helicobacter pylori

   Most ulcers are caused by the bacterium Helicobacter pylori.

2. 2

   How is Helicobacter pylori spread?

   1. ABy oral transmission
   2. BBy mosquito bites
   3. CBy blood transfusions only
   4. DBy airborne spores
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   A: By oral transmission

   It is spread by oral transmission, in food, water or saliva.

3. 3

   How is an ulcer caused by Helicobacter treated?

   1. AWith a vaccine
   2. BWith antiretroviral drugs
   3. CWith no treatment
   4. DWith antibiotics and a drug that reduces acid
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   D: With antibiotics and a drug that reduces acid

   A combination of antibiotics and an acid-reducing drug is used.

4. 4

   What type of pathogen causes Ebola?

   1. AA bacterium
   2. BA virus
   3. CA fungus
   4. DA protist
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   B: A virus

   Ebola is caused by a virus.

5. 5

   How is Ebola spread?

   1. ABy drinking water
   2. BBy mosquitoes
   3. CBy contact with body fluids
   4. DBy airborne spores
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   C: By contact with body fluids

   It is spread by contact with the body fluids of an infected person.

6. 6

   What does "haemorrhagic fever" mean?

   1. AA fever with bleeding
   2. BA fever with a rash
   3. CA fever with a cough
   4. DA fever with diarrhoea only
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   A: A fever with bleeding

   It is a fever together with bleeding, caused by damage to blood vessels.

7. 7

   Why do health workers wear protective clothing in an Ebola outbreak?

   1. ATo keep warm
   2. BTo protect patients from bacteria
   3. CTo prevent mosquitoes biting
   4. DTo avoid contact with infected body fluids
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   D: To avoid contact with infected body fluids

   It stops contact with body fluids that contain the virus.

8. 8

   Who proved that H. pylori causes stomach inflammation by drinking a culture of it?

   1. ARobin Warren
   2. BBarry Marshall
   3. CLouis Pasteur
   4. DEdward Jenner
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   B: Barry Marshall

   Barry Marshall drank a culture of the bacteria in 1984.

9. 9

   Why was the idea that bacteria cause ulcers difficult for doctors to accept at first?

   1. AIt was thought that bacteria could not survive in stomach acid
   2. BIt was published in a newspaper
   3. CMarshall had no qualifications
   4. DThe bacteria were too large to see
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   A: It was thought that bacteria could not survive in stomach acid

   It was thought that bacteria could not live in stomach acid, and the old idea of stress and acid was well established.