Final answer:
Agar is a solidifying agent ideal for culture media due to its gel-forming ability upon cooling and its inert, non-nutritive nature, which does not interfere with organism growth.
Step-by-step explanation:
Two characteristics of agar that make it an ideal solidifying agent are that it gels on cooling and it is non-nutritive and inert. When agar is dissolved in hot water and then cooled, it polymerizes into a gel, which forms a solid medium upon cooling. This physical property is essential for tissue culture studies and bacteriological culture media, as it provides a stable platform for bacteria and other microorganisms to grow into observable colonies with distinct colonial morphologies. Additionally, because agar is an inert, non-nutritive substance, it does not interfere with the growth or metabolic activities of the microorganisms being cultured, ensuring that any growth observed is due to the organisms themselves rather than the medium.