In the earlier two-kingdom classification system, Chlamydomonas (having a cell wall) and Amoeba (lacking a cell wall) were placed in separate kingdoms. However, in R.H. Whittaker's five-kingdom classification, they are placed together in Kingdom Protista. Which of the following criteria proposed by Whittaker primarily justify bringing these two organisms together into the same kingdom?

Step-by-step solution

In the earlier classification systems, Chlamydomonas was placed with plants (due to the presence of a cell wall) and Amoeba was placed with animals (due to the absence of a cell wall). Whittaker's five-kingdom classification groups organisms based on specific criteria such as cell structure, body organisation, mode of nutrition, reproduction, and phylogenetic relationships. Kingdom Protista was created exclusively for all single-celled (unicellular) eukaryotes. Both Chlamydomonas and Amoeba share a eukaryotic cell