The taxon species may be defined by reproductive isolation and

Answer;

Morphology

The taxon species may be defined by reproductive isolation and morphology

Explanation;A taxon is a group of one or more populations of an organism. Morphology is the form or the appearance of a particular organism, while reproductive isolation is the separation of organisms by some type of barrier. Reproductive isolation is a type of mechanisms that prevent two or more organisms or populations from exchanging genes through reproduction. This occurs when two organisms or species are separated for too long such that they can no longer reproduce with each other due to different adaptation and changes in the environment.Morphology and reproduction isolation may be defining characteristics of taxon of species.

The answer is joseph is observing the colour of the reaction mixture to see whether proteins are present in the given solution.

An egg, or a sack of flour