Final answer:
Peter's statement that 'Organisms can be made up of one or more cells' is correct. Organisms are categorized into unicellular (single-celled) and multicellular (multi-celled with specialized cells forming tissues and organs) based on their cellular structure.
Step-by-step explanation:
Peter is correct in the discussion, and here's why: Organisms can indeed be made up of one or multiple cells. The cell theory serves as a fundamental principle in biology, asserting that all living things are composed of cells. These cells are the structural unit of living organisms and can proliferate through the division of pre-existing cells.
We divide organisms into two primary categories based on their cellular structure: unicellular organisms and multicellular organisms. Unicellular organisms are composed of a single cell that performs all life functions. In contrast, multicellular organisms consist of numerous cells that often specialize to perform specific functions and are organized into tissues, organs, and organ systems.
Examples of unicellular organisms include bacteria and many types of algae, where each single cell represents a complete individual organism capable of performing all necessary life processes. On the other hand, animals, plants, and fungi are examples of multicellular organisms, where cells are specialized and work together to ensure the survival of the whole organism. This specialization and the division of labor among different cell types afford multicellular organisms various advantages over their unicellular counterparts.