Exam questions · Biology
Health and Communicable Disease
- 15 exam questions
- 47 marks
- 16 quick checks
Health and Disease
Just this lesson-
1 Describe [2 marks]
Describe the difference between a communicable disease and a non-communicable disease.
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Model answer
A communicable disease is caused by a pathogen and can be passed from one person to another, but a non-communicable disease is not caused by a pathogen and cannot be passed on.
Mark scheme
- A communicable disease is caused by a pathogen and can be passed on — 1 mark
- A non-communicable disease is not caused by a pathogen and cannot be passed on — 1 mark
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2 Name [3 marks]
Name the type of disease that each of these is: scurvy, cystic fibrosis and depression.
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Model answer
Scurvy is a deficiency disease. Cystic fibrosis is an inherited disorder. Depression is a mental illness.
Mark scheme
- Scurvy: deficiency disease — 1 mark
- Cystic fibrosis: inherited disorder — 1 mark
- Depression: mental illness — 1 mark
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3 Explain [3 marks]
People who have HIV are more likely to get tuberculosis (TB). Explain why.
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Model answer
HIV infects and damages the white blood cells, so the immune system becomes weak. The immune system can then no longer control the bacteria that cause TB, so they multiply, and the person is more likely to develop active tuberculosis.
Mark scheme
- HIV damages the white blood cells and the immune system — 1 mark
- The immune system cannot control the TB bacteria — 1 mark
- So tuberculosis is more likely to develop — 1 mark
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4 Explain [3 marks]
Cervical cancer is a non-communicable disease, but it can be linked to HPV infection. Explain how a virus can lead to a non-communicable disease.
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Model answer
HPV infects the cells of the cervix and can change their DNA. These cells then divide in an uncontrolled way and form a tumour, which is cervical cancer. The cancer itself cannot be passed on, so it is non-communicable, even though the virus that triggered it can be.
Mark scheme
- HPV infects the cells of the cervix and changes their DNA — 1 mark
- The cells divide in an uncontrolled way, forming a tumour — 1 mark
- The cancer cannot be passed on, so it is non-communicable — 1 mark
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5 Calculate [3 marks]
Source: In one year a country had 120 000 deaths. Of these, 18 000 were caused by communicable diseases and 96 000 were caused by non-communicable diseases. The rest were caused by injuries. Calculate the percentage of the deaths that were caused by communicable diseases, the percentage caused by non-communicable diseases, and the percentage caused by injuries.
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Model answer
Communicable: \(\frac{18000}{120000} \times 100 = 15\%\). Non-communicable: \(\frac{96000}{120000} \times 100 = 80\%\). Injuries: \(120000 - 18000 - 96000 = 6000\), and \(\frac{6000}{120000} \times 100 = 5\%\).
Mark scheme
- 15% from communicable diseases — 1 mark
- 80% from non-communicable diseases — 1 mark
- 5% from injuries — 1 mark
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6 Explain [2 marks]
A child lives on a diet that is very low in protein and vitamins and gets many infections. Explain why a poor diet can make infections more likely.
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Model answer
Without enough protein, vitamins and minerals, the body cannot make enough healthy white blood cells and antibodies, so the immune system is weaker. The pathogens are then not killed as quickly, so the child is more likely to get infections.
Mark scheme
- A poor diet means that the body cannot make enough white blood cells or antibodies — 1 mark
- The immune system is weaker, so infections are more likely — 1 mark
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7 Describe [3 marks]
Describe how a person's mental health and physical health can affect each other.
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Model answer
Long-term physical illness or pain can cause depression or anxiety, which lowers mental health. Stress and mental illness can weaken the immune system, so that a person is more likely to get infections. A person with poor mental health may also not eat well or exercise, which lowers their physical health.
Mark scheme
- Physical illness can cause poor mental health — 1 mark
- Stress or mental illness can weaken the immune system — 1 mark
- Poor mental health can lead to poor diet or exercise, lowering physical health — 1 mark
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8 Discuss [6 marks]
Discuss how different types of disease can interact with one another and with a person's health.
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Model answer
Different types of disease are linked. HIV is a communicable disease that damages the immune system, so a person with HIV is more likely to get another communicable disease, such as tuberculosis, because the TB bacteria are not controlled. A communicable disease can also lead to a non-communicable disease. HPV infection can change the cells of the cervix so that they divide in an uncontrolled way, which causes cervical cancer. A deficiency disease or a poor diet can lower the immune system, which makes infections more likely. Physical and mental health are also linked, because a long-term physical illness can lead to depression, and stress can weaken the immune system. All of these interactions lower a person's overall health.
Mark scheme
- Level 3 (5 to 6 marks): several interactions between different types of disease are explained with accurate examples, including the effect on the immune system — A clear, well-structured explanation using correct terms
- Level 2 (3 to 4 marks): two interactions are described, with some explanation — Some reasoning, but links are not fully developed
- Level 1 (1 to 2 marks): one example is named with little explanation — Simple statements
- Possible points: HIV and TB; HPV and cervical cancer; immune deficiency; poor diet and infection; physical and mental health — Content that can earn credit at any level
Quick check
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1
Which of these is a communicable disease?
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B: Tuberculosis
Tuberculosis is caused by a bacterium and can be passed on, so it is communicable.
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2
Which of these is a deficiency disease?
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D: Scurvy
Scurvy is caused by a lack of vitamin C in the diet.
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3
How is cystic fibrosis passed on?
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A: It is inherited from parents
It is an inherited disorder caused by faulty alleles that are passed from parents to children.
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4
Why are people with HIV more likely to get tuberculosis?
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C: HIV weakens the immune system
HIV damages the immune system, so the TB bacteria are not controlled.
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5
What is the link between HPV and cervical cancer?
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B: HPV can lead to cervical cancer
HPV can change the cells of the cervix so that they divide in an uncontrolled way.
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6
Which statement about cancer is correct?
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D: Most cancers cannot be passed from person to person
Cancer is caused by changes to cells that lead to uncontrolled division, and it cannot be caught from another person.
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7
In a country, 8 000 of 50 000 deaths are caused by communicable diseases. What percentage is this?
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A: 16%
8 000 divided by 50 000 is 0.16, which is 16%.
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8
Which of these would NOT lead to an immune deficiency?
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C: A balanced diet
A healthy balanced diet helps the body to make white blood cells. The other three weaken the immune system.
How Communicable Diseases Spread
Just this lesson-
1 Name [4 marks]
Name the four types of pathogen that cause communicable diseases.
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Model answer
Viruses, bacteria, protists and fungi.
Mark scheme
- Viruses — 1 mark
- Bacteria — 1 mark
- Protists — 1 mark
- Fungi — 1 mark
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2 Describe [3 marks]
Describe three ways in which a communicable disease can be spread from one person to another.
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Model answer
Pathogens can pass by direct contact, such as through blood or sexual contact. They can be breathed in as droplets that are released when an infected person coughs or sneezes. They can be spread in contaminated food or water that is swallowed.
Mark scheme
- Direct contact (touch, blood or body fluids) — 1 mark
- In the air in droplets from coughs and sneezes — 1 mark
- In contaminated water or food that is taken in (accept vectors) — 1 mark
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3 Explain [3 marks]
Malaria is caused by a protist. Explain how the disease is spread from one person to another.
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Model answer
The protist is carried by a vector, which is the female Anopheles mosquito. The mosquito feeds on the blood of an infected person and takes up the protist. When it bites another person, it passes the protist into that person's blood, so that the disease is spread. The mosquito is not harmed by the protist.
Mark scheme
- The mosquito is a vector that carries the pathogen — 1 mark
- It takes up the protist when it feeds on an infected person — 1 mark
- It passes it into the blood of another person when it bites — 1 mark
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4 Explain [3 marks]
After flooding in a town, there is an outbreak of cholera. Explain how the flooding may have caused the outbreak.
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Model answer
The flood water can mix sewage with the supply of drinking water, so that the water is contaminated with the bacteria that cause cholera. People who drink the water take the bacteria into their gut. The bacteria reproduce and release toxins, which cause the disease, and it spreads rapidly to many people who use the same water.
Mark scheme
- Sewage mixes with the drinking water, so it contains the cholera bacteria — 1 mark
- People who drink the water take in the bacteria — 1 mark
- The disease spreads quickly, because many people use the same supply — 1 mark
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5 Describe [3 marks]
Tobacco mosaic virus infects tobacco plants. Describe two ways in which a plant virus can be spread from one plant to another.
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Model answer
The virus can be passed in the sap on the hands or tools of workers who touch an infected plant and then a healthy plant. It can also be carried by insects, such as aphids, that feed on an infected plant and then on healthy plants. It can also pass by direct contact between leaves.
Mark scheme
- Spread by contact with infected plants or sap, on hands or tools — 1 mark
- Spread by insect vectors such as aphids — 1 mark
- Development of one of the methods, such as that the vector feeds on the sap — 1 mark
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6 Calculate [3 marks]
A single bacterium divides once every 30 minutes. Calculate the number of bacteria that could be produced from a single bacterium after 4 hours. Give your answer in standard form.
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Model answer
4 hours is 240 minutes, and \(240 \div 30 = 8\) divisions. The number of bacteria is \(2^8 = 256\), which is \(2.56 \times 10^2\) in standard form.
Mark scheme
- 8 divisions — 1 mark
- \(2^8 = 256\) — 1 mark
- \(2.56 \times 10^2\) — 1 mark
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7 Calculate [3 marks]
Source: A town has a population of 40 000. A random sample of 500 people was tested for an infection, and 30 of the people had the infection. Estimate the number of people in the town who have the infection, and give one reason why the estimate may not be accurate.
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Model answer
\(\frac{30}{500} = 0.06\), and \(0.06 \times 40\,000 = 2400\) people. The estimate may not be accurate because the sample is small and may not be representative of the whole town.
Mark scheme
- \(30 \div 500 = 0.06\) — 1 mark
- 2400 people — 1 mark
- A reason, such as that the sample may not be representative or is small — 1 mark
Quick check
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1
Which type of pathogen has hyphae and spores?
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C: Fungi
Fungi are made of threads called hyphae and they reproduce by spores.
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2
How does the flu virus spread?
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A: In droplets in the air
Droplets from coughs and sneezes contain the virus and are breathed in by other people.
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3
What is a vector?
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D: An organism that carries a pathogen between hosts
A vector carries a pathogen from one host to another without being affected by it.
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4
Which disease is spread in contaminated drinking water?
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B: Cholera
Cholera is caused by bacteria that spread in water contaminated with sewage.
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5
How do the spores of barley powdery mildew mainly spread?
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C: On the wind
Fungal spores are very light and are carried on the wind.
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6
Which of these protists causes malaria?
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A: A single-celled organism with a nucleus
Malaria is caused by a protist, carried by Anopheles mosquitoes.
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7
One bacterium divides every 20 minutes. How many bacteria are there after 2 hours?
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D: 64
2 hours is 6 divisions, and 2 to the power 6 is 64.
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8
In a sample of 100 people, 8 have a disease. About how many in a population of 5 000 would have it?
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B: 400
8 divided by 100 is 0.08, and 0.08 multiplied by 5 000 is 400.