Final answer:
A bear is classified under the kingdom Animalia. Pluto was reclassified as a dwarf planet because it did not 'clear the neighborhood around its orbit.' Organisms and ecosystems are considered open systems.
Step-by-step explanation:
The question seems to be centered around the topic of taxonomy and the classification of organisms within different categories. According to the information provided, when classifying a bear using the taxonomic classification system, the category that best describes a bear is Animalia. Bears are multicellular organisms that get their energy through ingesting other organisms, which fits the definition of the kingdom Animalia. In contrast, Plantae pertains to multicellular organisms that conduct photosynthesis to acquire energy, and Fungi encompasses organisms that get their energy by absorbing nutrients from their surroundings.
Regarding Pluto's classification, the IAU's decision to reclassify it as a dwarf planet was because it did not meet the criterion of having 'cleared the neighborhood around its orbit,' which is one of the three criteria set for a celestial body to be considered a planet. In terms of understanding whether organisms and ecosystems are open or closed systems, it is accurate to say that they are open systems because they exchange energy and matter with their surroundings.
Finally, in classifying a newly discovered single-celled organism, scientists would need additional information such as genetic material or cellular structure to accurately place it within a domain. Different types of information, such as ribosomal RNA sequences, can be very helpful in determining its classification.