Arizona State University (ASU) BIO360 Animal Physiology Exam 1 Practice

The characteristic of being multicellular is true for all animals and is a fundamental aspect of their biological organization. Animals are complex organisms made up of multiple cells that work together to perform various functions essential for survival. This multicellularity allows for specialization, where different cell types can develop to take on specific roles within the organism, such as muscle cells for movement, nerve cells for signaling, and epithelial cells for protection and absorption.

In contrast, the other characteristics listed do not apply across all animal species. For instance, while many animals do consume other organisms, not all have diets that exclusively include other animals—some may be herbivores, detritivores, or omnivores. Additionally, while sexual reproduction is common among animals, there are many species that can reproduce asexually. Lastly, being triploblastic, which refers to having three primary germ layers (ectoderm, mesoderm, and endoderm), does not apply to all animals, as some, like sponges and cnidarians, are diploblastic with only two germ layers. Thus, being multicellular stands as the unifying characteristic for the kingdom Animalia.