CAIE IGCSE Biology 10.1 Diseases and Immunity Questions

Practise disease and immunity questions on pathogen transmission, body defences, disease control, vaccination, passive immunity and cholera toxin effects.

Exam points

define a pathogen and transmissible disease, distinguishing pathogen cause from host-to-host passage
identify skin, nasal hairs, mucus, stomach acid and white-cell actions as barriers or defences
explain how clean water, sewage treatment, hygiene, food preparation and waste disposal interrupt spread
match pathogen antigens with complementary antibody shapes and explain immune recognition
explain antibody binding by neutralising pathogens or marking them for phagocyte destruction
distinguish active immunity after infection or vaccination from passive antibody transfer
sequence vaccination from weakened pathogen or antigen through lymphocytes, antibodies and memory cells
interpret vaccination data by comparing cases in vaccinated and unvaccinated groups
identify passive immunity from placental, breast-milk or injected ready-made antibodies
explain why passive immunity is temporary when antibodies decline and memory cells are absent
trace cholera toxin from chloride secretion to lower water potential and osmotic water movement
link cholera osmotic water loss to diarrhoea, dehydration and loss of body ions

Covered syllabus points

10.1.1—Pathogen as a disease-causing organism 10.1.2—Transmissible disease as a disease 10.1.3—Pathogen is transmitted: (a) by direct 10.1.4—Body defences 10.1.5—Controlling disease spread 10.1.6—Active immunity as defence against 10.1.7—Each pathogen has its own antigens 10.1.8—Antibodies as proteins that bind 10.1.9—Specific antibodies have complementary 10.1.10—Active immunity is gained after 10.1.11—Process of vaccination: (a) weakened 10.1.12—Role of vaccination in controlling 10.1.13—Passive immunity is a short-term 10.1.14—Importance of breast-feeding 10.1.15—Memory cells are not produced 10.1.16—Cholera as a disease caused 10.1.17—Cholera bacterium produces a toxin

[Maximum number: 1]

Campylobacter is a bacterium that can cause food poisoning.

Which word describes Campylobacter?

antibody

disease

pathogen

symptom

[Maximum number: 2]

Rubella and kwashiorkor are two diseases that affect children.

Rubella is a transmissible disease and kwashiorkor is a non-transmissible disease.

Define the term transmissible disease.

[Maximum number: 1]

By which route would an HIV infection not be transmissible?

blood

saliva

sharing needles for injections

semen

[Maximum number: 2]

Fig. 6.1 is a diagram of the virus that causes measles.

Fig. 6.1

Viruses and some bacteria are pathogenic. Diseases caused by pathogens are transmissible.

The body has barriers to defend itself against pathogens.

State two mechanical barriers of the body.

[Maximum number: 1]

These actions may be important in controlling the spread of disease.

1 washing hands after going to the toilet
2 disposing of waste frequently
3 using separate cutting boards for meat and salad
4 disposing of raw sewage into a river

Which would help control the spread of disease?

1, 2, 3 and 4

1, 2 and 3 only

2 and 3 only

4 only

[Maximum number: 1]

Which row describes active immunity?

depends on

phagocytes

memory cells are

produced

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[Maximum number: 1]

The immune system recognises pathogens and attacks them.
Which feature of pathogens triggers this response?

antibodies

antibiotics

antigens

memory cells

[Maximum number: 4]

Fig. 6.1 is a diagram of the virus that causes measles.

Fig. 6.1

Some white blood cells produce antibodies as part of the body's defence against pathogens.

Describe the role of antibodies in defence of the body.

[Maximum number: 1]

The sequence of amino acids in antibodies enables them to complete which function?

bind to a specific antigen

bind to all pathogens

perform phagocytosis

confer passive immunity for all diseases

[Maximum number: 4]

Cholera is a transmissible disease.

(a)

A study was designed to test the effectiveness of a cholera vaccine in an area where outbreaks of cholera occur frequently.

The doctors gave some people in this area the new vaccine.

[ 4 ]

(i)

Explain why the people were not protected from cholera immediately after receiving the vaccine.

[ 3 ]

(ii)

The doctors ensured that the people who received the new vaccine had not had cholera before.

Suggest why.

[ 1 ]

(b)

Explain how cholera causes diarrhoea.

[ 4 ]

(c)

Describe how diarrhoea is treated.

[ 2 ]

[Maximum number: 1]

Cholera is a transmissible disease.

A study was designed to test the effectiveness of a cholera vaccine in an area where outbreaks of cholera occur frequently.

The doctors gave some people in this area the new vaccine.

Suggest what the cholera vaccine must contain to be effective.

[Maximum number: 2]

Cholera is a transmissible disease.

A study was designed to test the effectiveness of a cholera vaccine in an area where outbreaks of cholera occur frequently.

The doctors gave some people in this area the new vaccine.

There was an outbreak of cholera in the area two months after the new vaccine was given.

The people who had symptoms of cholera were monitored in hospital for two days.
Some of the infected people had received the new vaccine and others had not received the vaccine.

The results are shown in Fig. 4.1.

Fig. 4.1

Using the information in Fig. 4.1, discuss how effective the vaccine was at preventing the symptoms of cholera.

[Maximum number: 5]

(a)

During pregnancy, antibodies are acquired by the fetus from the mother.

State the organ the antibodies cross to reach the fetus.

[ 1 ]

(b)

A baby was breastfed for six months. The concentration of antibodies in the baby's blood obtained from breast milk and the concentration of antibodies made by the baby itself were measured.

Fig. 6.1 shows the results.

Key: antibodies acquired by the baby from the mother
---- antibodies produced by the baby

[ 4 ]

(i)

Complete the sentences to describe the changes in antibody concentration in the baby.

After birth the concentration of antibodies acquired from the mother decreases rapidly to 0 arbitrary units at ______ months.

Antibodies start being produced by cells called ______ in the baby immediately after birth.

The total concentration of antibodies in the baby from both sources is ______ arbitrary units at 4 months.

The concentration of antibodies acquired from the mother and the concentration of antibodies produced by the baby are the same at ______ months.

[ 4 ]

[Maximum number: 2]

A baby was breastfed for six months. The concentration of antibodies in the baby's blood obtained from breast milk and the concentration of antibodies made by the baby itself were measured.

Fig. 6.1 shows the results.

Key: antibodies acquired by the baby from the mother
---- antibodies produced by the baby

Describe the benefits of breastfeeding a baby for the first six months of life.

[Maximum number: 2]

Meningitis is a transmissible disease. One form of the disease is caused by the bacterium Neisseria meningitidis.

People who have meningitis are treated with injections of antibodies to give them passive immunity.

Explain why passive immunity does not give long-term protection against diseases, such as meningitis.

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Covered syllabus points

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Question 10

Question (a)

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