Process
Edexcel AS-Level Biology A 9BN0
Lifestyle, Health and Risk
Topic overviewWater and the carbohydratesCondensation, hydrolysis and glycosidic bondsLipids, food tests and unitsThe cardiac cycle and the structure of the heartArteries, veins and capillariesCore practical: caffeine and the heart rate of DaphniaThe blood clotting cascadeThrombus, embolus and their consequencesAtherosclerosis and the risk factors for CVDTreatments for CVD, and cholesterol transportBMI, waist-to-hip ratio and energy balanceCore practical 2: the vitamin C content of food and drinkCorrelation, causation and the design of health studiesRisk perception, and handling quantitative data
Genes and Health
Topic overviewGas exchange surfaces and Fick's LawThe fluid mosaic model of the cell membraneOsmosis, diffusion and active transportSurface area and volume calculationsThe structure of DNA and RNATranscriptionTranslation and the genetic codeAmino acids and the levels of protein structureGlobular and fibrous proteins: haemoglobin and collagenAlternative splicing and tissue-specific proteinsEnzyme specificity, the active site and activation energyRates of reaction, Vmax and Core Practical 4Semi-conservative replication and Meselson-StahlTypes of mutation and the CFTR geneAlleles, genotype and monohybrid inheritancePedigree diagrams and the inheritance of cystic fibrosisThe effects of cystic fibrosis, and the chi-squared testPrenatal genetic testing: PGD, amniocentesis and CVSThe ethics of genetic screening
Voice of the Genome
Topic overviewProkaryotic cellsEukaryotic organelles and their functionsIdentifying organelles in an electron micrographProtein secretion, and levels of organisationMicroscopy: the graticule, magnification and standard formThe cell cycle and the stages of mitosisCore practical: the root tip squashMeiosis, linkage and sex linkageThe structure of sperm and egg cellsFertilisation: the acrosome and cortical reactionsTotipotency, pluripotency and sources of stem cellsThe ethics and risks of stem cell therapyDifferential gene expression and specialisationThe lac operonEpigenetics: DNA methylation and histone modificationPolygenic inheritance, continuous variation and statistics
Biodiversity and Natural Resources
Topic overviewBiodiversity, species richness and the index of diversityNiches and the three kinds of adaptationNatural selection and evolutionThe Hardy-Weinberg equation and its assumptionsReproductive isolation and speciationClassificationThe plant cell wall, chloroplast and amyloplastThe vacuole, plasmodesmata, pits and middle lamellaPlant cells in the electron microscopeStarch and celluloseLignin, xylem vessels and sclerenchyma fibresIdentifying plant tissues under the microscopeThe structure of xylem, phloem and sclerenchymaWater and the mineral nutrition of plantsCore practical: investigating mineral deficiencyCore practical: the tensile strength of plant fibresDrug development from Withering to modern trialsGrowing bacteria and aseptic techniqueCore practical: the antimicrobial properties of plantsSustainability and Conservation
Biodiversity and Natural Resources
- 20 subtopics
- 60 things to know
- Papers 1, 2 and 3
What Biodiversity and Natural Resources covers
Covers the variety of life and how it arises: measuring biodiversity, natural selection and speciation, classification, the structure and uses of plant tissues, and the testing of drugs and antimicrobials.
Where it is assessed
Papers 1, 2 and 3
Core content, examined on every paper.
Check the Pearson Edexcel specification ↗The 20 subtopics
Each one has its own page. Edexcel AS Biology A students sit this topic in the first year.
- Biodiversity, species richness and the index of diversityRecall questions on endemism, species richness, the heterozygosity index and the index of diversity, and on what each measures.Open →
- Niches and the three kinds of adaptationRecall questions on what a niche includes, and on behavioural, physiological and anatomical adaptations.Open →
- Natural selection and evolutionRecall questions on variation, selective advantage, and how natural selection changes allele frequencies over time.Open →
- The Hardy-Weinberg equation and its assumptionsRecall questions on the two Hardy-Weinberg equations, what each term represents, the assumptions the model makes, and how it is used to test for evolution.Open →
- Reproductive isolation and speciationRecall questions on how isolation stops gene flow, and on how accumulated differences produce a new species.Open →
- ClassificationRecall questions on classifying organisms by phenotype and genotype, how scientists scrutinise new data, molecular phylogeny and Woese’s three domains, the taxonomic ranks, the biological and morphological species concepts and their limits, and the use of DNA evidence.Open →
- The plant cell wall, chloroplast and amyloplastRecall questions on cellulose in the cell wall, the membranes, thylakoids, grana and stroma of the chloroplast, and the role of amyloplasts.Open →
- The vacuole, plasmodesmata, pits and middle lamellaRecall questions on turgor and the tonoplast, and on plasmodesmata, pits and the middle lamella.Open →
- Plant cells in the electron microscopeRecall questions on how each plant structure appears in an electron micrograph.Open →
- Starch and celluloseRecall questions on amylose and amylopectin, how alpha and beta glucose differ, and why cellulose microfibrils are strong.Open →
- Lignin, xylem vessels and sclerenchyma fibresRecall questions on secondary thickening, the patterns of lignin deposition, and the structure and function of xylem vessels and sclerenchyma.Open →
- Identifying plant tissues under the microscopeRecall questions on recognising xylem, phloem and sclerenchyma, and on the arrangement of vascular bundles.Open →
- The structure of xylem, phloem and sclerenchymaRecall questions on which of these cells are living at maturity, their wall composition, and what each transports or supports.Open →
- Water and the mineral nutrition of plantsRecall questions on the roles of water in a plant, and on the functions and deficiency symptoms of nitrate, calcium and magnesium.Open →
- Core practical: investigating mineral deficiencyRecall questions on preparing deficient culture solutions, the variables controlled, and the observations recorded.Open →
- Core practical: the tensile strength of plant fibresRecall questions on the method, the tensile strength formula, and the variables that must be controlled.Open →
- Drug development from Withering to modern trialsRecall questions on William Withering and digitalis, placebos and double blind design, and the three phases of a modern trial.Open →
- Growing bacteria and aseptic techniqueRecall questions on the conditions bacteria need, obligate and facultative anaerobes, and the steps of aseptic technique.Open →
- Core practical: the antimicrobial properties of plantsRecall questions on the filter paper disc method, the zone of inhibition, controls, and laboratory safety rules.Open →
- Sustainability and ConservationRecall questions on seed banks, captive breeding and other conservation methods, and on what makes resource use sustainable.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
What does aseptic technique require?
Key term
What three components are included in the definition of biodiversity?
Numbers
State the formula for calculating the heterozygosity index (H).
Key term
Give an example of what would classify as a behavioural adaptation.
Key term
What are anatomical adaptations?
Evaluation
Why are individuals with advantageous traits more likely to contribute to the next generation?
Evaluation
State the Hardy-Weinberg equation for genotype frequencies.
Key term
In the Hardy-Weinberg equation, what does q represent?
Key term
What is the eventual outcome when isolated populations accumulate sufficient genetic differences?
Key term
What is classification in biology?
Key term
What is molecular phylogeny?
Key term
What are plasmodesmata?
Key term
Define pits in plant cell walls.
Key term
Describe the appearance of the vacuole in an electron micrograph.
Numbers
Describe the structure of amylopectin, including the types of glycosidic bonds present and where they occur.
Key term
What type of bond forms between adjacent parallel cellulose chains, and which groups are involved?
Evaluation
Define secondary thickening in plant cells.
Key term
What are sclerenchyma fibres and what do their secondary cell walls contain?
Key term
Describe the arrangement of vascular bundles in a dicotyledonous stem.
Key term
What substances do xylem vessels transport and in which direction?
Process
What structures are found at the end walls of phloem sieve tube elements and what is their function?
Key term
Describe the symptoms of nitrate deficiency in plants.
Key term
Describe the symptoms of magnesium deficiency in plants and explain why older leaves are affected first.
Key term
How are fibres isolated for tensile strength testing?
Numbers
State the formula for calculating tensile strength.
Process
What is aseptic technique?
Process
Describe how filter paper discs are used to investigate the antimicrobial properties of plant extracts.
Key term
Name two types of growth media used in microbiological aseptic techniques.
Process
How can plant fibres contribute to sustainability in terms of replacing conventional plastics?
Process
What happens to most plant-derived materials at the end of their useful life?
Key term
Why does variation exist within a population?
Key term
Define reproductive isolation.
Key term
What is the primary structural component of plant cell walls, and how is it arranged?
Key term
What are thylakoids in a chloroplast?
Key term
List six structures found in plant cells but absent in animal cells.
Key term
Compare the type of glucose and molecular orientation in starch versus cellulose.
Key term
In a mineral deficiency investigation, what type of culture solution is used as a control?
Key term
How are deficient solutions prepared for investigating plant mineral deficiencies?
Key term
What condition was William Withering attempting to treat with his foxglove preparation?
Key term
Define biodiversity.
Key term
Define the term niche in ecology.
Evaluation
What determines whether a variation confers a selective advantage?
Key term
In the Hardy-Weinberg equation, what does p represent?
Process
What is the first step in the process by which reproductive isolation leads to speciation?
Key term
What type of characteristics does classification use to group organisms based on observable features?
Key term
What are grana in chloroplasts?
Numbers
What proportion of a mature plant cell's volume can the vacuole occupy?
Key term
Name six structures that are common to both plant and animal cells.
Key term
What type of monomer makes up starch, and what type of bond joins these monomers together?
Key term
What is lignin and what properties does it confer to cell walls during secondary thickening?
Key term
Within a vascular bundle of a dicotyledonous stem, where is the xylem located relative to the phloem?
Key term
Name three types of elongated cells that are arranged in vascular bundles within the stem.
Key term
Name four types of biological molecules that require nitrate ions for their synthesis in plants.
Key term
What observations should be recorded during a mineral deficiency investigation?
Evaluation
Define tensile strength.
Key term
What is a double blind trial?
Key term
State one environmental requirement for bacterial growth relating to temperature.
Key term
Define the term zone of inhibition.
Key term
What sustainable products can be manufactured from plant starch?
Take Biodiversity and Natural Resources further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Species richness vs Species evenness
Species richness: number of different species present. Species evenness: relative distribution of individuals among species.
In situ conservation vs Ex situ conservation
In situ conservation: protection within the natural habitat. Ex situ conservation: protection outside the natural habitat.
Continuous variation vs Discontinuous variation
Continuous variation: phenotypes distributed across a range. Discontinuous variation: phenotypes falling into distinct categories.
Questions from this topic
Each one with the model answer underneath.
- 1
What has happened to the variety of life on Earth over time, and what is the current threat to this variety?
Model answer
It has grown enormously over evolutionary time, and human activity is now reducing it.
- 2
Define biodiversity.
Model answer
Biodiversity refers to the variety of living organisms in an area, including the variety of species, genetic variation within species, and variety of habitats and ecosystems.
- 3
What three components are included in the definition of biodiversity?
Model answer
1. Variety of species, 2. Genetic variation within species, 3. Variety of habitats and ecosystems.
- 4
What is meant by endemism?
Model answer
Endemism refers to a species being native to and restricted to a particular geographic area, found nowhere else naturally.
- 5
Define species richness.
Model answer
Species richness is the number of different species present in a habitat.
- 6
What does the heterozygosity index measure?
Model answer
The heterozygosity index measures genetic diversity within a species by indicating the proportion of individuals that are heterozygous for a particular gene.
What is inside Levo
Six ways to work the same material.
Biodiversity and Natural Resources revision questions
- Is Biodiversity and Natural Resources examined at AS in Edexcel Biology A?
- Yes. It sits in Papers 1, 2 and 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Biodiversity and Natural Resources cover in Edexcel AS-Level Biology A?
- 20 subtopics: biodiversity, species richness and the index of diversity, niches and the three kinds of adaptation, natural selection and evolution, the hardy-weinberg equation and its assumptions, reproductive isolation and speciation, classification, the plant cell wall, chloroplast and amyloplast, the vacuole, plasmodesmata, pits and middle lamella, plant cells in the electron microscope, starch and cellulose, lignin, xylem vessels and sclerenchyma fibres, identifying plant tissues under the microscope, the structure of xylem, phloem and sclerenchyma, water and the mineral nutrition of plants, core practical: investigating mineral deficiency, core practical: the tensile strength of plant fibres, drug development from withering to modern trials, growing bacteria and aseptic technique, core practical: the antimicrobial properties of plants and sustainability and conservation. Each one has its own page with questions and model answers.
- How is Biodiversity and Natural Resources organised?
- By the Edexcel 9BN0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Biodiversity and Natural Resources, 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.
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