Key term
OCR GCSE Biology A J247
Cell Level Systems
Topic overviewMicroscopy, and sub-cellular structuresDNA structure: polymer, double helix and nucleotidesProtein synthesis and the triplet codeEnzyme 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 mutationsHow genetic variants influence phenotypeAsexual 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, and evidence for environmental changeFood 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 defencesDetecting plant disease; white blood cells and plateletsNon-specific defences and the immune systemMonoclonal antibodies and their usesVaccines, 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 brainInvestigating and treating the brainHormonal coordination, thyroxine and adrenalineHormones in reproduction and the menstrual cycleContraception and treating infertilityPlant hormones and their commercial usesHomeostasis, and the skin in temperature controlInsulin and glucagon in blood sugar controlType 1 and type 2 diabetesOsmotic changes in body fluids, and the kidneysThe kidney tubule and the effect of ADHResponding to temperature and osmotic challenges
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
Food security, agricultural and biotechnological solutions
- 3 things to know
- Paper 4
Overview
What food security is and how population growth, changing diets, new pests, uniform crops, environmental change and input costs threaten it, sustainable food production, hydroponics, biological control and its risks, fertilisers and pesticides, genetically modified crops and animals, and biotechnology such as mycoprotein grown in sterile industrial vessels under controlled conditions.
What you need to know
Answer each one before you reveal it.
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Key term
Explain how changing diets in wealthier countries can reduce food security in poorer ones.
Key term
Explain why a field of a single crop variety is especially vulnerable to a new pathogen.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by food security?
Model answer
Having enough safe and affordable food available at all times to feed a population.
- 2
Explain how a rising human population threatens food security.
Model answer
More people must be fed from a limited area of farmland, so demand rises faster than production and the food available per person falls.
- 3
Explain how changing diets in wealthier countries can reduce food security in poorer ones.
Model answer
Wealthier populations eat more meat and imported produce, so land and crops abroad are used to feed livestock or for export rather than feeding local people.
- 4
How can a new pest arriving in a country reduce food security?
Model answer
It can destroy a large share of a crop before an effective control is found, cutting yields and raising prices.
- 5
Explain why a field of a single crop variety is especially vulnerable to a new pathogen.
Model answer
All the plants are genetically very similar, so a pathogen able to infect one can infect the whole crop.
- 6
Explain how environmental change threatens the food supply.
Model answer
Drought, flooding and changed temperatures lower yields and can make land unusable for the crops that were grown there.
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