03 Microorganisms and
disease FT
6
3
Microorganisms can cause disease.
(a) What actions of microorganisms produce the symptoms of infectious disease?
Write down two of these actions.
1
[2]
2
(b) In warm conditions, a bacterium can divide into two new bacteria every twenty minutes.
(i) A chef puts a cooked meal on a warm work surface.
A single bacterium is present on the food.
The meal was left for two hours.
Calculate how many bacteria would be present after this time.
Show your working.
answer =
[2]
(ii) The results of this type of calculation have important implications for chefs.
Use your answer to (b)(i) to explain why.
...................................................................................................................................... [2]
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(c) Robert Koch was a scientist who proved that bacteria can cause disease.
Read the article about Robert Koch and then answer the questions.
In 1890 Koch published his research into bacteria and disease.
He wanted to show that a particular type of bacteria was responsible for causing the disease
tuberculosis.
These were his findings.
1
He found the bacteria in all the organisms with the disease but not in healthy organisms.
2
He isolated the bacteria from an animal with the disease and grew the bacteria in a Petri dish.
3
He then introduced the bacteria into a healthy animal.
4
The healthy animal started to show symptoms of the disease.
5
He isolated the bacteria from the new diseased animal and checked to make sure it was the
same as the bacteria he had found in diseased animals at the start of his investigation.
Answer the questions by using the information provided.
(i) Which statement, 1, 2, 3, 4 or 5, describes a correlation?
[1]
statement
(ii) Do statements 1, 2, 3, and 4, when taken together, prove that the bacteria caused
tuberculosis?
Explain your answer.
...................................................................................................................................... [2]
(iii) For Koch’s ideas to have been accepted by the scientific community, what should other
scientists have done?
...................................................................................................................................... [2]
[Total: 11]
© B1B2B3 Jan OCR 2012
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8
3
This question is about disease.
(a) All infectious diseases have symptoms, although these depend on the particular disease.
What is the cause of these symptoms for most infectious diseases?
Put ticks (✓) in the boxes next to the two best answers.
the medicine taken to cure the disease
other microorganisms that take advantage of the situation
damage done to cells
the length of time that the illness lasts
toxins produced by the microorganism
people eating less food when they feel ill
[1]
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(b) The first time we come into contact with a disease-causing microorganism we may become ill.
Our immune system can protect us from getting ill if we are infected with the same
microorganism again.
Explain how our immune system does this.
The quality of written communication will be assessed in your answer.
.............................................................................................................................................. [6]
(c) Scientists regularly produce new drugs to fight disease.
Using drugs always carries a risk.
NICE is the official body that licenses new drugs.
NICE has licensed a new drug to treat cancer, even though scientists know that the drug
could cause the deaths of a small number of people.
Suggest why the new cancer drug has been licensed.
.............................................................................................................................................. [2]
B1B2B3 June 2012 OCR
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10
(d) Influenza is a serious disease.
Look at the table of data about influenza (flu). The fatality rate is the percentage of people
with the disease who die.
Type of flu
Date
Spanish flu
1918-20
Asian flu
1957-8
Hong Kong flu
2009 flu
Number of deaths
in millions
80
Fatality
rate (%)
Severity
index
2
5
1.25
0.13
2
1968-9
0.8
0.1
2
2009-10
0.018
0.03
not available
(i) Use the data in the table to suggest what may be indicated by the ‘severity index’.
...................................................................................................................................... [1]
(ii) Describe the correlation between the number of deaths and the fatality rate.
...................................................................................................................................... [1]
(iii) Spanish flu killed 80 million people worldwide between 1918 and 1920.
One hundred years earlier, Russian flu killed 1 million people worldwide.
Suggest two reasons why Russian flu killed fewer people worldwide than Spanish flu.
...................................................................................................................................... [2]
[Total: 13]
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5
Tony has pneumonia.
His doctor prescribes antibiotics.
(a) Suggest the type of microorganism that causes pneumonia.
.............................................................................................................................................. [1]
(b) The microorganism reproduces rapidly.
It divides into 2 every 20 minutes.
Starting with 1 microorganism, what is the maximum number that could be present in Tony’s
body after 2 hours?
You must show your working.
Put a tick (✓) in the box next to the correct answer.
32
64
128
256
[2]
(c) Suggest why it is important that Tony starts his course of treatment as soon as possible.
.............................................................................................................................................. [1]
(d) The doctor tells Tony to complete the course of treatment.
Explain why this is important.
.............................................................................................................................................. [2]
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(e) Tony recovers.
Several years later, Tony’s friend, Gordon, also catches pneumonia.
This time the antibiotic does not work.
The doctor decides to give Gordon two other antibiotics at the same time.
Gordon recovers.
Suggest why:
•
the original antibiotic did not work
•
using two other antibiotics was effective.
.............................................................................................................................................. [3]
[Total: 9]
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