AC9S7U01 • Homework
Biological Classification and Dichotomous Keys
Use scientific vocabulary, observable evidence and clear reasoning. Where First Nations Australian knowledge is discussed, use respectful, place-aware language and avoid treating diverse knowledge systems as one national system.
Part A — 2-mark questions
- State two reasons why scientists classify living things. (2)
- List two observable features that could be used to classify animals. (2)
- Explain what a dichotomous key is used for. (2)
- Write the two most specific levels of the Linnaean hierarchy. (2)
- Describe one way improvements in microscopy changed biological classification. (2)
Part B — 5-mark questions
- Explain how to create a dichotomous key for a group of organisms. Include how you would choose features, write paired statements and test the finished key. (5)
- Compare contemporary Western scientific classification with First Nations Australian classification knowledge. Give at least three differences or contrasts, and explain why First Nations systems should be described as diverse and place-based. (5)
- Describe the Linnaean hierarchical classification system from kingdom to species and explain why a nested hierarchy is useful for scientists. (5)
- Explain how students could use a provided dichotomous key during fieldwork to identify an unfamiliar organism. Include observations, following the key and checking the final identification. (5)
- Discuss how improved microscopy changed classification. Include examples of new evidence that became available and explain why classifications may be revised when new evidence is found. (5)
Part C — Enrichment
11. Classification systems change with evidence and purpose. Analyse how biological classification has changed from relying mainly on visible features to using microscopic evidence and, as an extension, molecular evidence. Compare this with First Nations Australian classification knowledge that may organise living things through relationships with Country/Place, season, behaviour and cultural significance. Explain why different systems can be valuable for different purposes without ranking one as inherently superior.
Answer guide
1
Any two valid reasons: identification, organisation of biodiversity, communication, comparison, supporting research or conservation.
2
Examples include body covering, number/type of limbs, presence of backbone, symmetry or reproductive structures.
3
It identifies an organism by following a sequence of paired, contrasting choices based on observable features.
4
Genus and species.
5
Microscopy revealed cells, microorganisms and internal cell structures, giving scientists new evidence for grouping organisms.
6
List features, choose a clear observable split, write two mutually exclusive statements, repeat within groups, ensure every organism has one path, then test and revise ambiguous steps.
7
Western scientific classification commonly uses standardised nested taxonomic ranks and scientific naming. First Nations Australian systems are diverse and may organise living things according to locally meaningful ecological, seasonal, relational and cultural knowledge connected to particular Peoples and Country/Place. Specific examples require reliable local/community sources.
8
Kingdom → Phylum → Class → Order → Family → Genus → Species. The hierarchy organises biodiversity into nested groups and supports consistent identification and communication.
9
Observe the specimen carefully, begin at the first paired choice, select the matching statement at each step, follow the directions to an identification, then check the identified organism against recorded features.
10
Better microscopes revealed previously unseen microorganisms and cellular features. New evidence sometimes showed that old groupings did not reflect important biological differences, so classifications were revised.
11
Strong responses explain evidence-driven change in scientific classification, distinguish required microscopy content from molecular extension, accurately describe the nested Western system, treat First Nations knowledge as diverse/place-based, and compare purposes respectfully without inventing cultural details.