Topic study hub
Communicable diseases
Study communicable diseases in AQA GCSE Biology 8461 using approved subtopics and learning objectives from the official specification structure.
72
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaGcseBiologyInfection and response
Choose a revision tool
Start revising Communicable diseases
Syllabus checklist
What you need to know
72 objective pages available
Communicable (infectious) diseases9 objectives
- Define pathogens as microorganisms that cause infectious disease.
- State that pathogens may be viruses, bacteria, protists or fungi.
- Explain that pathogens may infect plants or animals.
- Explain that pathogens can spread by direct contact, by water or by air.
- Explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
- Explain how the spread of diseases can be reduced or prevented.
- Explain that bacteria and viruses may reproduce rapidly inside the body.
- Explain that bacteria may produce toxins that damage tissues and make us feel ill.
- Explain that viruses live and reproduce inside cells, causing cell damage.
Viral diseases9 objectives
- Describe measles as a viral disease that causes fever and a red skin rash.
- Explain that measles is a serious illness that can be fatal if complications arise.
- Explain why most young children are vaccinated against measles.
- Explain that the measles virus is spread by inhalation of droplets from coughs and sneezes.
- Describe HIV as a viral disease that initially causes a flu-like illness.
- Explain that HIV attacks the body's immune cells and can lead to late-stage infection or AIDS if not controlled.
- Explain that HIV is spread by sexual contact or exchange of body fluids such as blood when needles are shared.
- Describe tobacco mosaic virus as a widespread plant pathogen that affects many species including tomatoes.
- Explain that tobacco mosaic virus causes a mosaic pattern of leaf discolouration that reduces photosynthesis and plant growth.
Bacterial diseases8 objectives
- Explain that salmonella food poisoning is spread by bacteria ingested in food or on food prepared in unhygienic conditions.
- Explain that poultry are vaccinated against salmonella in the UK to control the spread.
- Describe salmonella symptoms including fever, abdominal cramps, vomiting and diarrhoea.
- Explain that salmonella symptoms are caused by the bacteria and the toxins they secrete.
- Describe gonorrhoea as a sexually transmitted bacterial disease with pain on urinating and a thick yellow or green discharge.
- Explain that gonorrhoea was once easily treated with penicillin but resistant strains are now common.
- Explain that gonorrhoea is spread by sexual contact.
- Explain that the spread of gonorrhoea can be controlled by treatment with antibiotics or the use of barrier contraception such as condoms.
Fungal diseases5 objectives
- Identify rose black spot as a fungal disease of plants.
- Describe rose black spot as causing purple or black spots on leaves.
- Explain that infected leaves often turn yellow and fall early.
- Explain that rose black spot reduces photosynthesis and affects plant growth.
- Explain that rose black spot spreads by water or wind and can be treated with fungicides or by removing and destroying affected leaves.
Protist diseases5 objectives
- State that the pathogens that cause malaria are protists.
- Explain that the malarial protist has a life cycle that includes the mosquito.
- Describe malaria as causing recurrent episodes of fever.
- Explain that malaria can be fatal.
- Explain that malaria is controlled by preventing mosquitos from breeding and by using mosquito nets to avoid bites.
Human defence systems9 objectives
- Describe the skin as a non-specific defence system against pathogens.
- Describe the nose as a non-specific defence system against pathogens.
- Describe the trachea and bronchi as non-specific defence systems against pathogens.
- Describe the stomach as a non-specific defence system against pathogens.
- Explain the role of the immune system in the defence against disease.
- Explain that if a pathogen enters the body the immune system tries to destroy it.
- Explain how white blood cells defend against pathogens by phagocytosis.
- Explain how white blood cells defend against pathogens by producing antibodies.
- Explain how white blood cells defend against pathogens by producing antitoxins.
Vaccination5 objectives
- Explain how vaccination can prevent illness in an individual.
- Explain how vaccinating a large proportion of the population reduces the spread of pathogens.
- Explain that vaccination introduces small quantities of dead or inactive pathogen into the body.
- Explain that vaccination stimulates white blood cells to produce antibodies and enables a faster response if the pathogen re-enters the body.
- Evaluate the global use of vaccination in the prevention of disease.
Antibiotics and painkillers8 objectives
- Explain the use of antibiotics and other medicines in treating disease.
- Explain that antibiotics such as penicillin help to cure bacterial disease by killing infective bacteria inside the body.
- Explain why specific bacteria should be treated by specific antibiotics.
- Explain how antibiotics have greatly reduced deaths from infectious bacterial diseases.
- Explain why the emergence of antibiotic-resistant strains is a major concern.
- Explain that antibiotics cannot kill viral pathogens.
- Explain that painkillers and other medicines treat the symptoms of disease but do not kill pathogens.
- Explain why it is difficult to develop drugs that kill viruses without also damaging body tissues.
Discovery and development of drugs14 objectives
- Describe the process of discovery and development of new medicines, including preclinical and clinical testing.
- Explain that traditional drugs were extracted from plants and microorganisms.
- Recall that the heart drug digitalis originates from foxgloves.
- Recall that the painkiller aspirin originates from willow.
- Recall that penicillin was discovered by Alexander Fleming from the Penicillium mould.
- Explain that most new drugs are synthesised by chemists in the pharmaceutical industry.
- Explain that a new drug may still start from a chemical extracted from a plant.
- Explain that new drugs must be tested to show that they are safe and effective.
- Explain that new drugs are tested for toxicity, efficacy and dose.
- Describe preclinical testing using cells, tissues and live animals.
- Describe clinical trials using healthy volunteers and patients.
- Explain that clinical trials begin with very low doses and then move to the optimum dose if the drug is shown to be safe.
- Explain what is meant by a double blind trial and the use of a placebo.
- Explain that the results of testing and trials are published only after scrutiny by peer review.
Key terms
pathogensinfectious diseaseinfectious diseasesinfectiontransmissiondisease preventiontransmission routesbacteriavirusestoxinscell damagemeasles
Exam tips
- Understand Pathogen Definition: Use memorize the definition of pathogens as microorganisms that cause infectious diseases. Use flashcards to reinforce this concept. Link your answer to Communicable (infectious) diseases in Communicable diseases, and keep the biology specific to infectious. Link your answer to Communicable (infectious) diseases in Communicable diseases, and keep the biology specific to infectious.
- Know Your Pathogens: Use create flashcards for each type of pathogen: viruses, bacteria, protists, and fungi, including their characteristics. Link your answer to Communicable (infectious) diseases in Communicable diseases, and keep the biology specific to state. Link your answer to Communicable (infectious) diseases in Communicable diseases, and keep the biology specific to state.
Common mistakes
- Misunderstanding Pathogens: Remember that pathogens are the microorganisms (like bacteria, viruses, fungi, or protists) that lead to infectious diseases. Focus on the definition of pathogens as the cause, not the effect.
- Misidentifying Pathogen Types: To fix this, students should create a chart listing the four types of pathogens (viruses, bacteria, protists, fungi) and include examples of each to reinforce their understanding.
Practice preview
Continue by objective
Objectives are grouped by subtopic so students can jump straight to the exact skill they want to revise.
Related topics