Tuesday 4 January 2011

MYRSFO: AS Biology

After the somewhat vague and bewildering GCSE specifications, we settle down a little with the post-compulsory qualifications. A-Level is divided into two: AS and A2. It seems natural to stick with this division here, and to go with AS Biology first.

Unit BIOL 2
  • Candidates should be able to analyse and interpret data relating to interspecific and intraspecific variation
  • Candidates should appreciate the tentative nature of any conclusions that can be drawn relating to the causes of variation
  • The principles and importance of taxonomy
  • Classification systems consist of a hierarchy in which groups are contained within larger composite groups and there is no overlap
  • The phylogenetic groups are based on patterns of evolutionary history
  • A species may be defined in terms of observable similarities and the ability to produce fertile offspring
  • One hierarchy comprises Kingdom, Phylum, Class, Order, Family, Genus, Species
  • Candidates should be able to appreciate the difficulties of defining species and the tentative nature of classifying organisms as distinct species
  • Courtship behaviour as a necessary precursor to successful mating. The role of courtship in species recognition
  • An index of diversity describes the relationship between the number of species and the number of individuals in a community

Unit AS.2
Students should be able to:
  • Understand that organisms are adapted to their environment
  • Understand that ecological factors have an influence on the distribution of organisms
  • Understand the role of selection in maintaining the adaptiveness of populations of organisms in their environment
  • Understand that biodiversity involves variation among living organisms at all levels of biological organisation
  • Measure species diversity and appreciate that genetic diversity can be measured
  • Understand the principle of taxonomy
  • Understand the concept of the species
  • Understand the other taxa within which species can be grouped
  • Understand phylogenetic taxonomy as a means of classifying sets of species according to ancestral relationships
  • Appreciate the five kingdom system of classification

Unit 2
Students will be assessed on their ability to:
  • Explain the terms biodiversity and endemism and describe how biodiversity can be measured within a habitat using species richness and within a species using genetic diversity, e.g. variety of alleles in a gene pool
  • Describe the concept of niche and discuss examples of adaptation of organisms to their environment (behavioural, physiological and anatomical)
  • Describe how natural selection can lead to adaptation and evolution
  • Discuss the process and importance of critical evaluation of new data by the scientific community, which leads to new taxonomic groupings (i.e. three domains based on molecular phylogeny)
  • Discuss and evaluate the methods used by zoos and seedbanks in the conservation of endangered species and their genetic diversity (e.g. scientific research, captive breeding programmes, reintroduction programmes and education)

Unit F212
Candidates should be able to:
  • define the terms species, habitat and biodiversity
  • explain how biodiversity may be considered at different levels; habitat, species and genetic
  • define the terms classification, phylogeny and taxonomy
  • explain the relationship between classification and phylogeny
  • outline the binomial system of nomenclature and the use of scientific (Latin) names for species
  • discuss the fact that classification systems were based originally on observable features but more recent approaches draw on a wider range of evidence to clarify relationships between organisms, including molecular evidence
  • define the term variation
  • discuss the fact that variation occurs within as well as between species
  • describe the differences between continuous and discontinuous variation, using examples of a range of characteristics found in plants, animals and microorganisms
  • explain both genetic and environmental causes of variation
  • outline the behavioural, physiological and anatomical (structural) adaptations of organisms to their environments
  • explain the consequences of the four observations made by Darwin in proposing his theory of natural selection
  • define the term speciation
  • discuss the evidence supporting the theory of evolution, with reference to fossil, DNA and molecular evidence
  • outline how variation, adaptation and selection are major components of evolution
  • discuss why the evolution of pesticide resistance in insects and drug resistance in microorganisms has implications for humans

Unit BY2
All organisms are related through their evolutionary history:
  • Biodiversity is the number of different organisms on the planet. Biodiversity varies spatially and over time
  • Biodiversity has been generated through natural selection and adaptation over millions of years. Adaptive radiation e.g. Darwin’s finches on the Galapagos
  • Organisms are classified into groups based on their evolutionary relationships. Classification places organisms into discrete and hierarchical groups with other closely related species. The need for classification and its tentative nature. Characteristic features of Kingdoms: Prokaryotae, Protoctista, Plantae, Fungi, Animalia
  • Animal biodiversity is classified into over 20 major phyla and several minor ones with each phylum containing organisms based on a basic blueprint. Basic features of: Annelids, Arthropods, Chordates. Arthropods are subdivided into four groups (details not required). Some phyla contain many more species than others
  • Physical features and biochemical methods can be used to assess the relatedness of organisms. DNA ‘genetic fingerprinting’ and enzyme studies show relatedness without the problem of morphological convergence
  • All organisms are named according to the Binomial system. The species concept
At AS, OCR seems to be the most comprehensive (although many of the exam boards make up for it at A2). AS is mostly concerned with biodiversity and natural selection - more complex ideas of speciation are to be left until A2. Some boards mention phylogenies (morphological and molecular) at this stage, but you'll find others wait to A2. I particularly like WJEC's statement for the module, that "all organisms are related through their evolutionary history".


  1. I know this is possibly not strictly relevant to me as I'm writing grants for an entirely different country and have no idea if I'll ever write a grant in the UK, but I'm finding this really interesting.


  2. I'm really glad this is proving interesting - it's rather dry at the best of times listing assessment criteria for specifications, but thank you :).


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