Test center: Biological Classification and Classification Unit Special topic: Analysis: The commonly used tools for identifying biological species are biological retrieval table, fixed distance retrieval table (also called back format retrieval table and dichotomy retrieval table) and parallel retrieval table, and the answers are all based on this. Biological key table is a professional reference book commonly used in biological research to help identify animals and plants. According to different purposes, the biological retrieval table will be divided into different classification levels. According to some stable and easy-to-observe and identify characteristics, the key table divides a group of organisms into a series of binary levels, and finally points to taxonomic levels such as phylum, class, order, family, genus and species. The key table generally does not provide intuitive pictures, nor does it fully describe the characteristics of different groups of organisms. The text description used for binary division often involves a large number of technical terms, so the use of key tables requires a certain professional background and special training. Otherwise, it is difficult to get the correct result through the key table. However, because the key list is classified with stable and remarkable characteristics, it is generally more accurate to identify biological species by using the key list. When encountering unknown animals and plants, we should look for the taxonomic status of the animals and plants one by one according to their morphological characteristics and the order of the key table. First, determine which phylum, type and target plant it belongs to. Then continue to search the key table of animals and plants by family, genus and species. When using the key list of animals and plants, it is necessary to observe or dissect the animal and plant specimens in detail, and to understand the various organs carefully check one by one according to the key list. For exactly the same items, we should continue to search until the search is over. So we choose: b comments: the common tool for identifying biological species is the biological key table, and we should understand its compilation and application.