OxfordAQA International A Level Biology
OxfordAQA International A Level Biology 3.1.10 Species and Taxonomy Exam Questions
Free OxfordAQA International A Level Biology revision for 3.1.10 Species and Taxonomy: what you need to know, common mistakes and exam-style questions with answers. Covers the species concept, binomial naming, the taxonomic hierarchy and molecular evidence for relationships between species.
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About OxfordAQA International A Level Biology 3.1.10 Species and Taxonomy
Species and taxonomy in Unit 1 asks how biologists define and name species and how they classify them. You need to know the definition of a species as the largest group able to interbreed and produce fertile offspring, use the binomial system, and recall the hierarchy of domain, kingdom, phylum, class, order, family, genus and species. You also need to evaluate why species can be hard to define, and explain how immunological comparisons and genome sequencing help clarify evolutionary relationships. This topic links to genetic diversity, biodiversity and speciation in Unit 3. Typical questions involve placing organisms into taxa or interpreting molecular data.
What you need to know
- Species A species is the basic unit of classification: the largest group of organisms able to interbreed and produce fertile offspring.
- Binomial naming Each species has a two-part scientific name: genus then species, for example Homo sapiens. The genus begins with a capital letter and the species name with a lower case letter.
- Taxonomic hierarchy The hierarchy is domain, kingdom, phylum, class, order, family, genus, species. Each level is a taxon, and groups within each taxon do not overlap.
- Problems defining species The interbreeding definition cannot be applied to fossils, organisms that reproduce asexually, or populations that are separated geographically. Some different species can produce fertile hybrids.
- Molecular evidence Genome sequencing compares base sequences directly. Immunological comparisons use antibodies against proteins of one species; the more precipitate formed with another species' protein, the more closely related they are.
Common mistakes in 3.1.10 Species and Taxonomy
- Writing the species name with a capital letter. Only the genus is capitalised, as in Panthera leo.
- Defining a species as organisms that can breed together. They must be able to produce fertile offspring.
- Getting the order of taxa wrong. A useful order is domain, kingdom, phylum, class, order, family, genus, species.
- Saying more precipitate in an immunological test means less related. More precipitate means more similar proteins, so the species are more closely related.
Try three 3.1.10 Species and Taxonomy exam-style questions
1. Give the two-part scientific name for a species and explain what each part shows. (2 marks)
Show the mark scheme answer
First part is the genus; second part is the species.
2. Explain why it can be difficult to use the ability to produce fertile offspring to decide whether two organisms belong to the same species. (2 marks)
Show the mark scheme answer
Organisms may reproduce asexually / be extinct / only known from fossils; may be geographically separated so cannot be observed breeding; some species form fertile hybrids. (Any 2)
3. Explain how comparing the base sequence of a gene can show how closely related two species are. (2 marks)
Show the mark scheme answer
More closely related species have more similar base sequences; because they share a more recent common ancestor and fewer mutations have accumulated.
3.1.10 Species and Taxonomy FAQs
What does OxfordAQA International A Level Biology 3.1.10 Species and Taxonomy cover?
It covers the species concept, binomial naming, the taxonomic hierarchy and molecular evidence for relationships between species.
Which unit is 3.1.10 Species and Taxonomy examined in?
It is part of Unit 1, The diversity of living organisms, which is examined at International AS. The Unit 5 synoptic paper at A2 can also draw on this content.
What is a taxon?
A taxon is any group within the classification hierarchy, such as a phylum or a genus. Organisms are grouped into taxa based on shared features and evolutionary relationships.
