Key term
AQA GCSE Combined Science Biology 8464
Bioenergetics
Cell Biology
Topic overviewEukaryotes and prokaryotesAnimal and plant cellsCell specialisation and differentiationMicroscopyChromosomes, mitosis and the cell cycleStem cells in embryos, adults and meristemsTherapeutic cloning, its risks, and cloning plantsDiffusion and the factors affecting its rateSurface area to volume ratio and exchange surfacesOsmosisActive transport
Ecology
Topic overviewLevels of organisation in an ecosystem, and what organisms needCompetition, interdependence and stable communitiesAbiotic factorsBiotic factorsAdaptationsProducers, food chains and sampling with quadrats and transectsPredators, prey and measuring population sizeHow materials are cycledWaste management and biodiversityLand use, deforestation and global warmingMaintaining biodiversity
Homeostasis and Response
Infection and Response
Inheritance, Variation and Evolution
Topic overviewSexual and asexual reproductionMeiosisDNA and the genomeGenetic terms, dominant and recessive allelesPunnett squares, probability and genetic crossesInherited disorders and sex determinationVariationEvolutionSelective breedingWhat genetic engineering is, and what it is used forGM crops, their risks, and the steps of the processEvidence for evolution, and extinctionFossilsResistant bacteriaClassification of living organisms
Organisation
Topic overviewLevels of organisation, and how enzymes workAmylase, proteases and lipasesBile, food tests and the effect of pH on amylaseThe heart, the lungs and double circulationThe pacemaker, the blood vessels and the bloodCoronary heart disease: a non-communicable diseaseHealth issuesRisk factors and causal mechanisms in diseaseSampling, correlation and interpreting risk dataCancerPlant tissues, and transpiration and its rateRoot hair cells, xylem, phloem and stomata
Infection and Response
Human defence systems
- 3 things to know
- Biology Paper 1
Overview
Non-specific defences of the skin, nose, trachea, bronchi and stomach, why damaged cilia cause chest infections, the specific immune response and immunity, and phagocytosis, antibodies and antitoxins produced by white blood cells.
What you need to know
Answer each one before you reveal it.
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Key term
What is a non-specific defence, how does the nose keep pathogens out, and why do damaged cilia lead to chest infections?
Key term
What is meant by a non-specific defence?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by a non-specific defence?
Model answer
A defence that acts against all pathogens rather than against one particular pathogen.
- 2
How does the skin defend the body against pathogens?
Model answer
It forms a barrier that pathogens cannot easily pass through, and it heals over cuts to close the barrier again.
- 3
How does the nose help to keep pathogens out of the body?
Model answer
Hairs and mucus in the nose trap particles and pathogens in the air breathed in.
- 4
Describe how the trachea and bronchi defend the lungs.
Model answer
They secrete mucus that traps pathogens, and cilia waft the mucus up to the throat where it is swallowed.
- 5
How does the stomach defend the body against pathogens?
Model answer
It produces hydrochloric acid, which kills pathogens that are swallowed in food or mucus.
- 6
Explain why someone whose cilia have been damaged suffers more chest infections.
Model answer
Mucus carrying trapped pathogens is no longer moved out of the airways, so pathogens stay in the lungs.
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