IGCSE · Biology 0610 · Disease, gas exchange & respiration
Diseases & immunity: IGCSE Biology questions with answers
Free Diseases & immunity questions for IGCSE Biology (0610), part of Disease, gas exchange & respiration. Each question has the answer and the marking points an examiner would look for.
A child is given a first dose of a vaccine at week 0 and a second dose at week 6. The concentration of specific antibodies in the blood is measured.
(a)
Explain what is in a vaccine and why it does not cause the disease.
[2]
(b)
Describe and explain the difference between the antibody response after the first and after the second dose.
[4]
(c)
Explain why antibodies are specific to one pathogen.
[2]
(d)
A baby receives antibodies in breast milk. State the type of immunity this gives and why it is only short-term.
[2]
(e)
Explain why vaccinating a large proportion of a population protects people who are not vaccinated.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
Contains antigens / weakened or dead pathogen that cannot cause disease
antigens / dead or weakened pathogen B1 pathogen harmless / cannot reproduce B1
2
(b)
Second response faster, greater concentration and lasts longer; memory cells made after the first dose; they divide rapidly and produce antibodies quickly
second response faster B1 higher concentration of antibodies B1 memory cells formed after first dose B1 memory cells recognise antigen and divide rapidly B1
4
(c)
Each antibody has a shape complementary to one antigen
antibody shape complementary to specific antigen B1 different pathogens have different antigens B1
2
(d)
Passive immunity; no memory cells are made, antibodies are broken down
passive B1 no memory cells / antibodies broken down B1
2
(e)
Herd immunity: fewer people can carry or spread the pathogen, so transmission is reduced
fewer people can spread the pathogen B1 herd immunity / reduced chance of contact with infected person B1
2
Question 2Structured · 4 marksA* challenge
Cholera is caused by a bacterium in contaminated water.
(a)
Explain how cholera causes diarrhoea and dehydration.
[3]
(b)
State one way of preventing the spread of cholera.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
toxin; chloride ions secreted; water follows by osmosis
the bacterium produces a toxin B1 chloride ions are secreted into the small intestine B1 water moves out of the blood by osmosis, causing diarrhoea and dehydration B1
3
(b)
clean water; sewage treatment
clean water supply / sewage treatment / hygiene B1
1
Question 3Structured · 4 marks
Some diseases are transmissible and some are not.
(a)
Give one example of each type.
[2]
(b)
Explain the difference between active and passive immunity.
transmissible: e.g. influenza, cholera, HIV B1 non-transmissible: e.g. coronary heart disease, diabetes B1
2
(b)
own antibodies vs given antibodies
active: the body makes its own antibodies (long term, memory cells) B1 passive: antibodies are given (from mother/injection), short term B1
2
Question 4Structured · 12 marks
This question is about defence against disease.
(a)
State what is meant by a pathogen.
[1]
(b)
Describe how phagocytes protect the body.
[2]
(c)
Explain how lymphocytes protect the body against a specific pathogen.
[3]
(d)
Explain how vaccination provides long-term protection against a disease.
[4]
(e)
Explain why a vaccine against one disease does not protect against a different disease.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
disease-causing organism
a disease-causing organism B1
1
(b)
engulf pathogens; digest them
phagocytes engulf pathogens (phagocytosis) B1 and digest them with enzymes B1
2
(c)
produce antibodies; complementary to antigens; mark pathogens / cause them to clump
lymphocytes produce antibodies B1 antibodies are complementary in shape to antigens on the pathogen B1 they bind and lead to destruction of the pathogen (directly or by marking it for phagocytes) B1
3
(d)
weakened/dead pathogen or antigens; lymphocytes make antibodies; memory cells; faster larger secondary response
vaccine contains weakened / dead pathogen or its antigens B1 lymphocytes produce antibodies B1 memory cells are produced B1 on infection memory cells give a faster, larger antibody response before symptoms develop B1
4
(e)
antibodies are specific to one antigen shape
antibodies are specific B1 they are complementary only to the antigen of that pathogen B1
2
Question 5Structured · 4 marks
The spread of disease can be controlled.
(a)
Explain how each method reduces the spread of disease: hygienic food preparation; good personal hygiene; waste disposal.
[3]
(b)
Explain why antibodies are specific.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
kills/removes pathogens; stops transmission
food: prevents pathogens reaching food/kills them by cooking B1 hygiene: washing hands removes pathogens B1 waste disposal: removes breeding grounds for vectors/pathogens B1
3
(b)
shape complementary to antigen
each antibody has a shape that fits only one antigen B1
1
Question 6Structured · 11 marks
This question is about transmissible diseases.
(a)
State three ways in which pathogens can be transmitted.
[3]
(b)
Describe two of the body’s mechanical or chemical barriers to pathogens.
[2]
(c)
Explain why a clean water supply and good sewage treatment reduce the spread of cholera.
[2]
(d)
HIV is a sexually transmitted infection. Describe how HIV affects the immune system.
[2]
(e)
Suggest two ways the spread of HIV can be controlled.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
direct contact / body fluids; contaminated food or water; air droplets; vectors
Any 3 of: direct contact including body fluids; contaminated food or water; air (droplets); animal vectors B3
3
(b)
skin; hairs in nose; mucus; stomach acid
Any 2 of: skin; hairs in the nose; mucus (traps pathogens); stomach acid (kills pathogens) B2
2
(c)
pathogen spread in water contaminated with faeces; treatment removes or kills bacteria
cholera bacteria are spread in water contaminated by faeces B1 treatment kills / removes the bacteria before people drink the water B1
2
(d)
infects and destroys lymphocytes; fewer antibodies, more infections (AIDS)
HIV infects and destroys lymphocytes B1 fewer antibodies are made so the body cannot fight other infections (AIDS) B1
2
(e)
condoms; not sharing needles; screening blood; treatment of infected people
Any 2 of: use of condoms; not sharing needles; screening blood for transfusion; antiretroviral treatment B2
2
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