What is the main aim of biological classification?
To organise organisms in a way that reflects their evolutionary history, rather than simply sorting them by appearance.
Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) · 1.2
Revise Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) specification point 1.2, Concept and uses of classification systems, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What is the main aim of biological classification?
To organise organisms in a way that reflects their evolutionary history, rather than simply sorting them by appearance.
What relationship is expected between organisms placed in the same classification group?
They are related by common ancestry.
What do groups nested within larger groups represent in biological classification?
Patterns of more recent and more distant evolutionary relationships.
Why can DNA base sequences provide evidence about organisms’ evolutionary relationships?
DNA carries inherited information that changes gradually over time.
Why do organisms with a more recent common ancestor usually have more similar DNA base sequences?
Fewer differences have built up since they diverged. Organisms with a more distant common ancestor usually have more DNA differences.
What should the groups formed using DNA sequence comparisons reflect?
The organisms’ evolutionary relationships—how closely related they are.
On what basis can organisms be placed in the same classification group?
They share identifiable features.
What role do differences in features play in classification?
They help distinguish one group of organisms from another.
What is a species?
A group of organisms that can reproduce with one another to produce fertile offspring.
What does it mean for offspring to be fertile?
They can themselves reproduce.
Why are similar visible features alone insufficient to identify organisms as members of the same species?
Species membership depends on the ability to reproduce with one another and produce fertile offspring, not simply on appearance.
What is the purpose of the binomial naming system?
To give each species an internationally agreed scientific name.
What do the two parts of a binomial scientific name identify, in order?
What is a dichotomous key?
A tool that identifies an organism through a sequence of choices between two contrasting descriptions of identifiable features.
In a dichotomous key, where does choosing the description that matches the organism lead?
To another pair of choices or to an identification.
What are the main steps in constructing a dichotomous key?