Key term
OCR GCSE Biology A J247
Cell Level Systems
Topic overviewMicroscopy, and sub-cellular structuresDNA structure: polymer, double helix and nucleotidesEnzyme action, and investigating enzymesCellular respiration as an exothermic processAerobic and anaerobic respiration comparedSynthesis and breakdown of carbohydrates, proteins and lipidsPhotosynthesis: producers and the processPhotosynthesis as endothermic, and investigating itLimiting factors in photosynthesis
Community Level Systems
Genes, Inheritance and Selection
Topic overviewGenetic terms, and the genomeGenome, environment and mutationsAsexual and sexual reproduction comparedHaploid, diploid and meiosisSingle gene inheritance and Punnett squaresSex determination, multiple genes and Mendel's workVariation within a population, and classificationNatural selection and evolutionEvidence for evolution, and the work of Darwin and Wallace
Global Challenges
Topic overviewField investigations, and human impact on ecosystemsMaintaining biodiversity, monitoring conservation and ecotourismFood security, agricultural and biotechnological solutionsSelective breeding and genetic engineeringHealth, disease, and types of diseaseInteractions between diseases, and how they spreadReducing the spread of disease, and named examplesPhysical and chemical plant defencesWhite blood cells, antibodies and plateletsNon-specific defences and the immune systemVaccines, medicines and aseptic techniqueDeveloping new medicines, and non-communicable diseaseTreating cardiovascular disease, and lifestyle factorsCancer, and the use of stem cells in medicineGene technology in medicine, and the human genome
Organism Level Systems
Topic overviewThe nervous system and coordinated responsesThe reflex arcThe eye and its common defectsThe structure and function of the brainHormones and the endocrine glandsHormones in reproduction and the menstrual cycleMethods of contraceptionTropisms, auxin and the roles of plant hormonesHomeostasis, and the skin in temperature controlInsulin and the control of blood glucoseType 1 and type 2 diabetesOsmotic changes in body fluids, and the kidneysKidney structure and the parts of the tubule
Scaling Up
Topic overviewDiffusion, osmosis and active transportMitosis, the cell cycle and cell differentiationStem cells in animals and meristems in plantsSurface area to volume ratio and exchange surfacesThe circulatory system, the heart and blood vesselsRed blood cells and plasmaRoot hair cells, transpiration and translocationXylem and phloemFactors affecting water uptake, and the potometer
Global Challenges
Vaccines, medicines and aseptic technique
- 3 things to know
- Paper 2
Overview
What a vaccine contains and how it gives immunity, what antibiotics, antivirals, antiseptics and painkillers do and do not do, why drugs that kill viruses are hard to make, antibiotic resistance, aseptic technique with flamed loops, alcohol, autoclaves and taped dishes kept at 25 °C, and testing antiseptics with paper discs on a bacterial lawn, including calculating the area of clear zones.
What you need to know
Answer each one before you reveal it.
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Key term
Explain how being vaccinated makes a person immune to a disease.
Key term
Explain why it is difficult to develop a drug that kills a virus without harming the patient.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does a vaccine contain?
Model answer
A dead or weakened form of the pathogen, or just its antigens, so it cannot cause the disease.
- 2
Explain how being vaccinated makes a person immune to a disease.
Model answer
The antigens in the vaccine make lymphocytes produce antibodies and memory cells, so if the real pathogen enters later it is destroyed before it causes illness.
- 3
What do antibiotics do, and which type of pathogen do they have no effect on?
Model answer
They kill bacteria inside the body or stop them multiplying; they have no effect on viruses.
- 4
Explain why it is difficult to develop a drug that kills a virus without harming the patient.
Model answer
Viruses reproduce inside the body's own cells, so a substance that destroys them tends to damage those cells as well.
- 5
What do antiviral drugs do?
Model answer
They slow or stop a virus reproducing inside cells, which reduces the symptoms and can keep an infection under control for years.
- 6
What is an antiseptic and where is it used?
Model answer
A chemical that kills microorganisms or stops them growing, used outside the body on skin, wounds and surfaces.
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