AQA GCSE Biology: Infection and response — Practice Questions & Answers
How pathogens cause communicable disease, how the human body defends itself, and how we prevent and treat illness using vaccination, antibiotics and monoclonal antibodies, plus plant disease and defences.
750 practice questions available for this topic — here are 10 with full answers and explanations.
What name is given to microorganisms that cause infectious disease?
Antibodies
Pathogens
Antigens
Antitoxins
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WhyPathogens are microorganisms (bacteria, viruses, fungi or protists) that cause communicable (infectious) disease. They can be passed from one organism to another.
2Multiple choice · Easy
Which type of pathogen causes measles?
Bacterium
Fungus
Virus
Protist
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WhyMeasles is a viral disease. It is spread by inhalation of droplets from sneezes and coughs, and can be fatal if complications arise. Most young children are vaccinated against it.
3Multiple choice · Easy
How do bacteria typically make us feel ill?
By living inside cells and bursting them open
By producing toxins that damage tissues
By digesting the skin's surface
By blocking the windpipe with spores
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WhyBacteria may produce toxins (poisons) that damage tissues and make us feel ill. Viruses, by contrast, reproduce inside cells and cause cell damage as they burst out.
4Multiple choice · Easy
Which disease is caused by a protist and spread by mosquitoes?
Salmonella food poisoning
Malaria
Measles
Gonorrhoea
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WhyMalaria is caused by a protist. The mosquito acts as a vector, carrying the pathogen from person to person. Spread can be reduced by preventing mosquitoes from breeding and using mosquito nets.
5Multiple choice · Medium
Salmonella food poisoning is caused by bacteria. How can its spread be prevented in the UK?
Vaccinating poultry against Salmonella
Using mosquito nets
Spraying crops with fungicide
Taking antiviral drugs
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WhyIn the UK, poultry are vaccinated against Salmonella to control the spread. Symptoms (fever, cramps, vomiting, diarrhoea) are caused by toxins released by the bacteria, which are ingested in food prepared in unhygienic conditions.
6Multiple choice · Medium
Gonorrhoea is a sexually transmitted disease. Which statements correctly describe its cause and control?
Caused by a virus; controlled by vaccination
Caused by a bacterium; controlled by antibiotics and condoms
Caused by a protist; controlled by mosquito nets
Caused by a fungus; controlled by fungicides
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WhyGonorrhoea is a bacterial STD with symptoms of a thick yellow/green discharge and pain on urinating. It was once easily treated with antibiotics such as penicillin, but many resistant strains have appeared. Spread is controlled by treatment with antibiotics and use of barrier contraception (condoms).
7Multiple choice · Medium
Tobacco mosaic virus (TMV) affects plants. What is its main effect?
It causes black spots ringed with yellow on leaves
It gives leaves a mosaic discolouration that reduces photosynthesis
It causes the roots to rot and die
It makes the plant produce excess chlorophyll
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WhyTMV is a widespread plant pathogen affecting many species including tomatoes. It causes a mosaic pattern of discolouration on the leaves, which reduces the amount of chlorophyll available, so photosynthesis and therefore growth are affected.
8Multiple choice · Medium
Rose black spot is a disease of plants. Which type of pathogen causes it and how does it spread?
A virus, spread by insects
A fungus, spread by water and wind
A bacterium, spread by soil
A protist, spread by mosquitoes
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WhyRose black spot is a fungal disease causing purple or black spots on leaves, which often turn yellow and drop early. This reduces photosynthesis and growth. The fungus spreads in the environment by water and wind, and can be treated with fungicides or by removing affected leaves.
9Multiple choice · Medium
HIV initially causes flu-like symptoms. What does HIV eventually attack if it is not controlled by antiretroviral drugs?
The red blood cells
The body's immune cells
The nerve cells in the brain
The cells lining the stomach
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WhyHIV attacks and damages the body's immune cells. When the immune system is badly damaged it can no longer deal with other infections or cancers, and the patient is described as having late-stage HIV infection (AIDS). HIV is spread by sexual contact or exchange of body fluids such as blood.
10Multiple choice · Medium
Which of the following is a non-specific first line of defence against pathogens?
Antibody production by white blood cells
The skin acting as a physical barrier
Phagocytosis of bacteria
Production of antitoxins
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WhyThe skin, nose, trachea, bronchi and stomach form non-specific defences that try to stop pathogens entering in the first place. The skin acts as a physical barrier and also secretes antimicrobial substances. White blood cells are part of the body's response after pathogens get in.
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Pathogen: A microorganism that causes an infectious disease. Pathogens can be viruses, bacteria, protists or fungi, and may infect animals or plants.
Infectious disease: An illness caused by a pathogen that can be passed from one organism to another.
Communicable disease: A disease that can be spread between individuals because it is caused by a pathogen; another name for an infectious disease.
Non-communicable disease: A disease that cannot be passed between individuals and is not caused by a pathogen, such as heart disease or cancer.
Microorganism: An organism too small to see without a microscope, such as a bacterium, virus, protist or fungus.
Virus: A very small pathogen that can only reproduce by entering a living host cell, taking it over and making copies of itself, which damages or destroys the cell.
Bacterium: A single-celled microorganism that can reproduce rapidly inside the body and may release toxins that damage tissues and cause illness.
Bacteria: The plural of bacterium; microorganisms, some of which act as pathogens by multiplying quickly and producing harmful toxins.