What term is used for a group of animals or plants that have natural relations?

The term "taxa" refers to groups of organisms that are classified together based on shared characteristics and evolutionary relationships. This classification can range from broad categories, such as kingdoms or phyla, to more specific levels like families, genera, and species. In the context of natural relations, taxa encompass all levels of biological classification that help scientists understand the diversity and relationships among different living organisms.

The other terms listed have specific meanings within biological classification. "Genus" refers to a rank in the hierarchy of biological classification that groups together species that are closely related. "Species" is the most specific level, identifying individuals that can interbreed and produce fertile offspring. "Subclass" is a higher classification level than genus but lower than class. Each of these terms denotes a specific relationship or hierarchy, but when considering the broader concept of a group of organisms with natural relations, "taxa" is the most appropriate term.