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
Maintaining biodiversity, and evidence for environmental change
- 3 things to know
- Paper 4
Overview
The benefits of high biodiversity and why it makes an ecosystem stable, why international agreements and monitoring conservation schemes are hard, ecotourism and how it helps or harms a habitat, the factors that change where species are found, lichens and mayfly larvae as indicators of air and water quality, the effects of sewage, drought and rising carbon dioxide, and why distribution data needs many years and does not prove cause.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain why high biodiversity makes an ecosystem more stable.
Key term
Why is it difficult to reach international agreements on conservation?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Give two benefits to people of maintaining high biodiversity.
Model answer
A wide range of species provides food, medicines and materials, and stable ecosystems continue to supply clean water, pollination and fertile soil.
- 2
Explain why high biodiversity makes an ecosystem more stable.
Model answer
Many species carry out similar roles, so if one declines others can replace it and the ecosystem continues to function.
- 3
Why is it difficult to reach international agreements on conservation?
Model answer
Countries have different priorities and levels of wealth, and a government may be unwilling to limit farming, logging or industry that its economy depends on.
- 4
Why is monitoring essential once a conservation scheme has begun?
Model answer
Without repeated surveys there is no evidence of whether the population is recovering, so the scheme cannot be judged or improved.
- 5
Give two reasons why monitoring a conservation scheme is hard to do well.
Model answer
Surveys of large or remote areas are expensive and need trained staff, and populations must be counted over many years before a trend is clear.
- 6
What is ecotourism?
Model answer
Tourism that lets visitors see wildlife in its natural habitat while limiting damage to that habitat and returning money to local people.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Global Challenges, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.