14/07/2023
LET REVIEWERS
Note: This is included last LET March 2023, some of the items in the exam are all about taxonomy in Gen Ed and Science major.
TAXONOMY (CLASSIFICATION OF ORGANISMS)
Taxonomy is the branch of biology that classifies all living things. It was developed by the Swedish botanist Carolus Linnaeus, who lived during the 18th Century, and his system of classification is still used today. Linnaeus invented binomial nomenclature, the system of giving each type of organism a genus and species name. He also developed a classification system called the taxonomic hierarchy, which today has eight ranks from general to specific: domain, kingdom, phylum, class, order, family, genus, and species.
DOMAINS
A domain is the highest (most general) rank of organisms. Linnaeus did invent some of the taxonomic ranks, but he did not invent the domain rank, which is relatively new.
Three Domains of Life
1. Eukarya
2. Archaea
3. Bacteria
**Archaea and bacteria can also be classified as one called MONERA.
KINGDOM
In biology, kingdom is a taxonomic rank that is composed of smaller groups called phyla (or divisions, in plants). Supplement. Historically, the kingdom is the highest taxonomic rank or the most general taxon used in classifying organisms
Four Kingdoms
1. Animalia
2. Plantae
3. Fungi
4. Protista
PHYLUM
Phylum (plural: phyla) is the next rank after kingdom; it is more specific than kingdom, but less specific than class. There are 35 phyla in the kingdom Animalia, including Chordata (all organisms with a dorsal nerve cord), Porifera (sponges), and Arthropoda (arthropods).
CLASS
The class was the most general rank proposed by Linnaeus; phyla were not introduced until the 19th Century. There are 108 different classes in the kingdom Animalia, including Mammalia (mammals), Aves (birds), and Reptilia (reptiles), among many others. The classes of Animalia that Linnaeus proposed are similar to the ones used today, but Linnaeus’ classes of plants were based on attributes like the arrangement of flowers rather than relatedness. Today’s classes of plants are different than the ones Linnaeus used, and classes are not frequently used in botany.
ORDER
Order is more specific than class. Some of Linnaeus’ orders are still used today, such as Lepidoptera (the order of butterflies and moths). There are between 19-26 orders of Mammalia, depending on how organisms are classified—sources differ. Some orders of Mammalia are Primates, Cetaceans (whales, dolphins, and porpoises), Carnivora (large carnivores/omnivores), and Chiroptera (bats).
FAMILY
Family is, in turn, more specific. Some families in the order Carnivora, for example, are Canidae (dogs, wolves, foxes), Felidae (cats), Mephitidae (skunks), and Ursidae (bears). There are 12 total families in the order Carnivora.
GENUS
Genus (plural: genera) is even more specific than family. It is the first part of an organism’s scientific name using binomial nomenclature; the second part is the species name. An organism’s scientific name is always italicized, and the genus name is capitalized while the species name is not. Genus and species are the only taxonomic ranks that are italicized
SPECIES
Species is the most specific major taxonomic rank; species are sometimes divided into subspecies, but not all species have multiple forms that are different enough to be called subspecies. There are an estimated 8.7 million different species of organisms on Earth, but the vast majority have yet to be discovered and categorized. While each genus name is unique, the same species names can be used for different organisms
Source: https://biologydictionary.net/taxonomy/