Key term
Edexcel AS-Level Biology B 9BI0
Biological Molecules
Topic overviewMonosaccharides, disaccharides and polysaccharidesGlycosidic bonds and condensation reactionsStarch, glycogen and cellulose structureTriglycerides and phospholipidsSaturated and unsaturated fats and lipid propertiesAmino acid structure and the peptide bondPrimary, secondary, tertiary and quaternary structureFibrous and globular proteinsThe structure of DNADNA replication and gene mutationsThe structure of RNATranscription and translationEnzymes as globular proteinsFactors affecting enzyme activityMeasuring the rate of enzyme activityUnits, uncertainty and experimental errorEnzyme inhibitionInorganic ionsThe properties of water
Cells, Viruses and Reproduction of Living Things
Topic overviewCell theory and eukaryotic cell structureProkaryotic cells and Gram stainingMicroscopy, magnification and resolutionSignificant figures, estimates and mathematical symbolsVirus structure and classificationThe lytic cycle and latencyTreating viral disease and the ethics of untested drugsThe cell cycle and its regulationMitosis and the behaviour of chromosomesMitosis in growth, repair and root tip squashesMeiosis, genetic variation and chromosome mutationsGametogenesis in mammalsFertilisation and early embryo developmentPollen and embryo sac formationDouble fertilisation in flowering plantsInvestigating pollen tube growth
Classification and Biodiversity
Exchange and Transport
Topic overviewSurface area to volume ratioThe fluid mosaic modelDiffusion, osmosis and facilitated diffusionActive transport, endocytosis and exocytosisGas exchange in insects, fish and mammalsDissecting the insect gas exchange systemGas exchange in flowering plantsThe structure of the heart and blood vesselsThe double circulatory systemThe cardiac cycleMyogenic stimulation and ECG tracesThe composition of bloodThe functions of blood and clottingAtherosclerosis and its risk factorsHaemoglobin and the Bohr effectOxygen dissociation curvesFormation of tissue fluidThe lymphatic systemXylem and phloem structureApoplastic and symplastic pathwaysThe cohesion-tension theoryMeasuring transpiration with a potometerTranslocation and the mass flow hypothesis
Classification and Biodiversity
- 8 subtopics
- 22 things to know
- Papers 1, 2 and 3
What Classification and Biodiversity covers
How organisms are classified and why the scheme changes as evidence changes, natural selection and how new species arise, how biodiversity is measured, and the case for conserving it.
Where it is assessed
Papers 1, 2 and 3
Examined on every paper.
Check the Pearson Edexcel specification ↗The 8 subtopics
Each one has its own page. Edexcel AS Biology B students sit this topic in the first year.
- The hierarchy of classificationRecall questions on the eight ranks of the classification hierarchy in order from domain to species, and on which rank is the most inclusive and which the most specific.Open →
- Defining a speciesRecall questions on the biological species concept and its limitations for asexual, extinct and hybridising organisms.Open →
- DNA sequencing and molecular phylogenyRecall questions on how gel electrophoresis separates fragments and distinguishes species, how DNA sequencing reveals differences in base sequence and evolutionary relationships, and the role of bioinformatics in classification.Open →
- Five kingdoms, three domains and peer reviewRecall questions on how journals, peer review and conferences validate new evidence, the five kingdoms, the three domains of Archaea, Bacteria and Eukarya, the ribosomal RNA evidence behind them, and how Archaea differ from Bacteria.Open →
- Natural selection, adaptation and drug resistanceRecall questions on adaptation and how natural selection changes allele frequency, niches and physiological, behavioural and anatomical adaptations, and how mutation and selection produce drug resistance in pathogens and an evolutionary race with medicines.Open →
- Allopatric and sympatric speciationRecall questions on geographical and reproductive isolation, the mechanisms of each, and how isolation leads to a new species.Open →
- Measuring biodiversityRecall questions on measuring species diversity in a habitat with the index of diversity, what N and n stand for, calculating and interpreting D step by step, and assessing genetic diversity from the variety of alleles in a gene pool.Open →
- Conservation and its ethical caseRecall questions on the ethical and economic case for biodiversity and ecosystem services, and on in-situ and ex-situ conservation in zoos, seed banks, nature reserves and national parks, with the strengths and limitations of each.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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How can gel electrophoresis help determine evolutionary relationships between species?
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How does DNA sequencing help determine evolutionary relationships?
Evaluation
How do scientific journals, peer review and scientific conferences help validate evidence for evolution?
Evaluation
What role do environmental pressures play in natural selection?
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What is an anatomical adaptation, and how does it differ from a behavioural adaptation?
Numbers
In Simpson's index of diversity, what do N and n represent, and what does a higher value indicate?
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Why was the three-domain model proposed instead of keeping all prokaryotes in one kingdom?
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What accumulates between populations during sympatric speciation?
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What is the source of variation that allows pathogens to evolve resistance to medicines?
Numbers
State the formula for Simpson's Index of Diversity.
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How can in-situ conservation lead to conflict with local human populations?
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How is a species traditionally defined?
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How does gel electrophoresis separate DNA or protein fragments?
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State an ethical reason for maintaining biodiversity.
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Why does hybridisation between distinct species pose a problem for the biological species definition?
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During gel electrophoresis, which DNA fragments travel further through the gel?
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What is peer review?
Evaluation
How does the frequency of advantageous alleles change over generations during natural selection?
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What is an adaptation?
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What does the index of diversity measure in a habitat?
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What is the economic justification for maintaining biodiversity?
Take Classification and Biodiversity 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: distribution of individuals among the species present.
Natural selection vs Artificial selection
Natural selection: differential survival and reproduction caused by inherited variation. Artificial selection: human-directed breeding for chosen inherited characteristics.
Homologous structures vs Analogous structures
Homologous structures: features sharing ancestry despite possibly different functions. Analogous structures: features sharing function but arising independently.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the first (highest) level in the eight-level classification hierarchy?
Model answer
Domain.
- 2
What is the second level in the classification hierarchy, immediately below domain?
Model answer
Kingdom.
- 3
What taxonomic level comes immediately below kingdom in the classification hierarchy?
Model answer
Phylum.
- 4
What is the fourth level in the classification hierarchy, positioned between phylum and order?
Model answer
Class.
- 5
What taxonomic rank comes immediately below class in the classification hierarchy?
Model answer
Order.
- 6
What is the sixth level in the classification hierarchy, positioned between order and genus?
Model answer
Family.
What is inside Levo
Six ways to work the same material.
Classification and Biodiversity revision questions
- Is Classification and Biodiversity examined at AS in Edexcel Biology B?
- 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 Classification and Biodiversity cover in Edexcel AS-Level Biology B?
- 8 subtopics: the hierarchy of classification, defining a species, dna sequencing and molecular phylogeny, five kingdoms, three domains and peer review, natural selection, adaptation and drug resistance, allopatric and sympatric speciation, measuring biodiversity and conservation and its ethical case. Each one has its own page with questions and model answers.
- How is Classification and Biodiversity organised?
- By the Edexcel 9BI0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Classification and Biodiversity, 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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