Communicable diseases revision notes

Communicable diseases is part of Infection and response in AQA GCSE Biology 8461. This revision note keeps revision tied to the approved curriculum so students can move from broad understanding into precise exam-ready explanations without drifting away from the specification.

Across 9 subtopics, the topic covers 72 approved learning objectives. Students should revise the language of each objective, identify the biological process or example it refers to, and then practise explaining the idea clearly in context.

Communicable (infectious) diseases is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include infectious, state, that, pathogens, viruses, and bacteria. Important terminology includes pathogens, infectious disease, infectious diseases, and infection. A helpful exam reminder is to memorize the definition of pathogens as microorganisms that cause infectious diseases. Use flashcards to reinforce this concept.

Viral diseases is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include viral, that, measles, serious, illness, and fatal. Important terminology includes measles, viral disease, complications, and vaccination. A helpful exam reminder is to when studying measles, remember to clearly describe its symptoms, specifically the fever and red skin rash.

Bacterial diseases is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include that, salmonella, food, poisoning, and spread. Important terminology includes salmonella food poisoning, spread, vaccination, salmonella, salmonella symptoms, and food poisoning. A helpful exam reminder is to focus on explaining how salmonella food poisoning is spread through food that is either contaminated or prepared in unhygienic conditions.

Fungal diseases is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include fungal, rose, black, spot, causing, and purple. Important terminology includes rose black spot, fungal disease, leaf infection, infected leaves, and yellowing. A helpful exam reminder is to familiarize yourself with the specific characteristics of rose black spot, including its appearance and effects on plants.

Protist diseases is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include protist, malaria, causing, recurrent, and episodes. Important terminology includes malaria, protist, malarial protist, mosquito life cycle, and recurrent episodes. A helpful exam reminder is to memorize that malaria is caused by protists and be able to identify them in exam questions.

Human defence systems is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include defence and systems. Important terminology includes skin, non-specific defence, non-specific defence system, nose, trachea, and bronchi. A helpful exam reminder is to memorize the structure and function of the skin as a barrier against pathogens, focusing on its role in the immune response.

Vaccination is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include vaccination, vaccinating, large, proportion, population, and reduces. Important terminology includes vaccination, immune response, herd immunity, pathogen spread reduction, and pathogen. A helpful exam reminder is to study how vaccinations introduce dead or inactive pathogens to stimulate the immune response.

Antibiotics and painkillers is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include antibiotics, diseases, and emergence. Important terminology includes antibiotics, painkillers, penicillin, specific antibiotics, and bacterial infection. A helpful exam reminder is to make sure to explain how antibiotics work specifically against bacterial infections, including examples like penicillin.

Discovery and development of drugs is a core part of Communicable diseases. Students should understand that 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. Useful keywords here include discovery, development, drugs, recall, that, and heart. Important terminology includes preclinical testing, clinical testing, traditional drugs, extraction, digitalis, and foxgloves. A helpful exam reminder is to create a flowchart outlining the stages of drug discovery and development, including preclinical and clinical testing.

When revising Communicable diseases, students should move beyond memorising isolated facts. Strong answers link the biology to the right subtopic, use precise scientific vocabulary, and explain why a symptom, treatment, defence, or investigative method matters in the wider topic.

A reliable revision routine is to read the subtopic summary, learn the key terms, answer practice questions, and then check whether the explanation still matches the approved learning objective. This prevents vague answers and helps students build confidence with both short recall questions and longer written responses.