Which of Following Is a Main Idea of the Cell Theory?


Jane Flores

The Cell Theory is one of the most fundamental concepts in biology. It is a set of principles that explains the structure, function, and behavior of cells.

The theory was first proposed by three scientists – Matthias Schleiden, Theodor Schwann, and Rudolf Virchow – in the 19th century. It has since undergone many modifications and revisions but remains a cornerstone of modern biology.

What is the Cell Theory?

The Cell Theory comprises three main ideas:

  • All living organisms are made up of one or more cells.
  • The cell is the basic unit of life.
  • All cells arise from pre-existing cells.

Idea #1: All living organisms are made up of one or more cells

This idea means that everything that is alive – from the tiniest bacterium to the largest mammal – is composed of at least one cell. Cells are the building blocks of life, and they carry out all the functions required for an organism to survive and reproduce.

Idea #2: The cell is the basic unit of life

This idea means that cells are the smallest structural and functional units of living things. They are capable of performing all the tasks necessary to sustain life, such as obtaining nutrients, producing energy, and eliminating waste. Every organism on Earth, no matter how complex, began as a single cell.

Idea #3: All cells arise from pre-existing cells

This idea means that new cells can only be formed by division from existing cells. This principle is known as biogenesis and stands in contrast to spontaneous generation – an outdated theory that suggested life could arise spontaneously from non-living matter.


In summary, the Cell Theory states that all living things are composed of cells, cells are the basic unit of life, and new cells can only arise from pre-existing cells. These fundamental ideas have revolutionized our understanding of biology and continue to guide research in the field today.


– Alberts, B. (2014). Molecular biology of the cell. Garland Science. – Campbell, N. A., & Reece, J. B.

(2005). Biology. Benjamin Cummings. – Lodish, H., Berk, A., & Zipursky, S. L. (2000). Molecular cell biology. W.H. Freeman.