Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

Which of the following identifies organisms with a backbone?

1. Invertebrates

2. Vertebrates

3. Prokaryotes

4. Eukaryotes

The correct answer is: Vertebrates

The identification of organisms with a backbone points directly to vertebrates. Vertebrates are a specific subgroup within the animal kingdom that possess a vertebral column, commonly referred to as the backbone. This structural feature provides support and protection to the spinal cord, which is a critical part of the nervous system. Vertebrates include classes such as mammals, birds, reptiles, amphibians, and fish, all of which share this key characteristic. In contrast, invertebrates are organisms that do not have a backbone, making them a distinct category. Prokaryotes refer to single-celled organisms without a nucleus, such as bacteria, and are unrelated to the classification of organisms based on the presence of a backbone. Eukaryotes encompass a broader group of organisms, including those with and without backbones, as they are characterized by cells with a nucleus. Therefore, the understanding of vertebrates as organisms with a backbone highlights their unique position in biological classification.