Practise Human defence systems. 14 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Give two ways the skin helps to defend the body against pathogens.
It is a barrier; it produces antimicrobial secretions.
Some bacteria produce toxins. Name the substance produced by white blood cells that counteracts toxins.
Antitoxins
Pathogens can enter the body through the nose and mouth. Name the acid produced in the stomach.
Hydrochloric acid
The body has physical, chemical and cellular defences against pathogens. Name the acid produced in the stomach that kills pathogens.
Hydrochloric acid
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
The human body has several ways of stopping pathogens from entering it.
(a) Which part of the body produces an acid that kills pathogens? Tick (✓) one box.[1]
Nose
Skin
Stomach
Trachea
(b) Give two ways the skin helps to defend the body against pathogens.[2]
(c) The nose contains hairs and mucus. How do these help to defend the body?[1]
(d) Name the type of blood cell that helps to destroy pathogens that get into the body.[1]
Show the answer and mark scheme
(a)Answer: Stomach
(b)Answer: It is a barrier; it produces antimicrobial secretions.
it is a barrier (to pathogens)
it produces antimicrobial secretions (that kill pathogens)
scabs form over cuts to seal them
(c)
they trap particles that may contain pathogens
(d)Answer: White blood cells
white blood cell
Question 2Medium7 marks
The trachea and bronchi are lined with cells that help to stop pathogens reaching the lungs.
(a) Describe how the cells lining the trachea and bronchi stop pathogens reaching the lungs.[3]
(b) Chemicals in tobacco smoke stop cilia moving. Explain why smokers are more likely than non-smokers to get chest infections.[2]
(c) Explain how the stomach helps to defend the body against pathogens.[2]
Show the answer and mark scheme
(a)
(some cells) produce mucus
mucus traps pathogens / particles
cilia move / waft the mucus up to the throat, where it is swallowed
(b)
mucus (and trapped pathogens) is not moved out of the airways / builds up
(so) pathogens reach the lungs / stay in the airways and cause infection
(c)
the stomach produces (hydrochloric) acid
(the acid) kills pathogens (in food / drink / swallowed mucus)
Question 3Hard9 marks
Cystic fibrosis is an inherited disorder. People with cystic fibrosis produce very thick, sticky mucus in their airways. Cilia cannot move this mucus easily.
(a) Explain why people with cystic fibrosis get more lung infections than other people.[3]
(b) A physiotherapist claps on the chest and back of a person with cystic fibrosis to loosen the mucus, which the person then coughs up. Explain how this reduces the chance of infection.[2]
(c) In a study, 40 people with cystic fibrosis had a mean of 5.5 chest infections per year before they started daily physiotherapy and a mean of 3.3 chest infections per year afterwards. Calculate the percentage decrease in the mean number of chest infections.[2]
(d) Some people with cystic fibrosis take antibiotics every day, even when they do not have an infection. Suggest one advantage and one disadvantage of this.[2]
Show the answer and mark scheme
(a)
the mucus traps pathogens
the mucus is not moved out of the airways (by the cilia) / stays in the lungs
(so) pathogens stay in the lungs and reproduce / cause infection
warm, moist mucus is a good place for bacteria to grow
(b)
it removes mucus containing trapped pathogens from the lungs
(so) fewer pathogens remain to reproduce / cause infection
(c)Answer: 40%
(5.5 − 3.3) ÷ 5.5 × 100
40 (%)
(d)
advantage: kills bacteria before they can cause an infection
disadvantage: bacteria may become resistant to the antibiotic / the antibiotic may not work when it is needed / side effects