A Level Biology Practice Exam

In biological classification, what does the term 'order' refer to?

1. A type of genetic sequence in an organism

2. A taxonomic group that is a subdivision of the class

3. A grouping of species based on habitat

4. A classification of organisms based solely on physical characteristics

The correct answer is: A taxonomic group that is a subdivision of the class

In biological classification, the term 'order' refers to a taxonomic group that is a subdivision of the class. The hierarchy of biological classification is structured like a ladder, where each level is more specific than the one above it. After domain and kingdom, the next levels include phylum, class, order, family, genus, and species. In this system, the class is composed of multiple orders, each representing a group of closely related families that share a common evolutionary ancestor. For example, within the class Mammalia (mammals), there are several orders, such as Carnivora (carnivorous mammals) and Primates (primates, including humans). This hierarchical structure helps scientists organize and categorize the vast diversity of life on Earth based on evolutionary relationships. The other choices do not accurately describe the term 'order' in biological classification. A type of genetic sequence pertains to molecular biology rather than taxonomy. Grouping species based on habitat falls under ecological classifications rather than taxonomic. Lastly, classifying organisms based solely on physical characteristics misses the evolutionary relationships that the order classification intends to capture.