Year 7 Biology

Content Checklist: Classification

  • Classification is the process of putting things into groups.
  • Biologists classify living things.
  • Taxonomy is the grouping and naming organisms.
  • Dichotomous keys help classify by giving 2 choices.
  • Keys are written or branching.
  • Best features for classifying are easy to observe and measure and do not change e.g. structures, not size colour or shape.
  • Species are given a two-part name, the genus and species.
  • Reasons for classifying - identification and communication.
  • The 5 Kingdoms are Animal, Plant, Fungi, Protist, Monera.
  • Classifying uses a hierarchical system - kingdom, phylum, class, order, family, genus, species.
  • Grouping organisms is based on similarities and differences.
  • Fungi are decomposers, they can’t make their own food e.g. mushrooms and yeast.
  • Protists are 1-celled organisms e.g. protozoa and algae.
  • Monera have cells with no nucleus e.g. bacteria.
  • All organisms are made of cells.
  • Vertebrates have a backbone, invertebrates don’t.
  • Arthropods have an exoskeleton.
  • Chordates have an internal skeleton, an endoskeleton.
  • Chordates are fish, birds, reptiles, mammals or amphibians.
  • Mammals are placentals, monotremes or marsupials.


Historical Background and Foundations

The pioneer of taxonomy, and of many sciences, was the Greek philosopher Aristotle (384–322 BC). He sought to catalog all known species of animal into higher categories, some of which are still used. His approach was distinctive in its methodology and its ambition. He recognized that not every species could be identified by a single distinguishing feature or characteristic. This permitted him to correctly classify problematic creatures such as the bat, with its anomalous ability to fly among otherwise mammalian features. Aristotle's disciple Theophrastus (c.372–287 BC) extended this method to plants.

Aberdein, A. (2009). Biology: Classification Systems. In K. L. Lerner & B. W. Lerner (Eds.), In Context Series. Scientific Thought: In Context (Vol. 1, pp. 167-176). Detroit, MI: Gale. Retrieved from

How are Organisms Classified?

What is Classification?

Classification is a method of organizing plants and animals into categories based on their appearance and the natural relationships between them. Also called scientific classification, it is science's way of identifying and grouping living things. The classification of organisms is a science called taxonomy, or systematics.

The Benefits of Classification

In the life sciences, the need to organize is very important and extremely useful. Classification helps biologists keep track of living things and to study their differences and similarities. It also shows biologists how living things are related to one another through evolution (the process by which living things change over generations). Classifying also saves time and effort. There are many possible ways to classify life: appearance, behavior, evolutionary history, or life development from fertilization to adulthood. The modern classification system is considered a natural system since it represents genuine relationships between organisms. In this natural system, the more closely organisms are related to each other, the more features they have in common. This system is also hierarchical, meaning that its categories are grouped according to size in a series of successively larger ranks.

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