AQA A Level Biology

Revision Notes

2.1.1 The Cell Theory

The Cell Theory

  • Until microscopes became powerful enough to view individual cells, no-one knew for certain what living organisms were made from
  • A scientist called Robert Hooke is thought to be the first person to view cells (including single-celled microorganisms) and Hooke also came up with the term “cells” to describe these newly discovered structures
  • Matthias Schleiden and Theodor Schwann were two other scientists who studied animal and plant cells
    • In 1837, they came up with the idea that all living organisms are made of cells
    • This idea is known as ‘cell theory’
    • The cell theory is a unifying concept in biology (it is universally accepted)
  • The cell theory includes three main ideas:
    • All living organisms are made up of one or more cells
    • Cells are the basic functional unit (i.e. the basic unit of structure and organisation) in living organisms
    • New cells are produced from pre-existing cells

Exam Tip

Don’t worry about learning the name of the scientists described above or when the cell theory was first described. You just need to know the three main components of the cell theory and that the theory is accepted by all scientists!


Alistair graduated from Oxford University in 2014 with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems and Societies.

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