The Living World Test - 31

Botanical nomenclature is the formal, scientific naming of plants. The principles and rules are listed in international code of botanical nomenclature (ICBN). According to ICBN, the colour of the flower is not a criteria for classification.
A tautonym is a scientific name of a species in which both parts of the name have the same spelling. In the current rules for botanical nomenclature (ICBN), tautonyms are explicitly prohibited. According to ICBN, two genera can not have the same name. Thus, option D is correct.

The botanical name of onion is Allium cepa. It is also known as the bulb onion or common onion and is used as a vegetable. It is widely cultivated species of the genus Allium. The onion is a biennial or a perennial plant. Allium sativum, commonly known as garlic, is a species in the genus Allium. It is a medicinal plant. The garlic bulb is also used in cooking.They belong to family Liliaceae.
Thus, the correct answer is option D.

The branch of biology which deals with the identification and naming of organisms or in simple words in the classification of organisms is known as taxonomy. Biological classification is arranging the organisms into various categories on the basis of their structure, development and evolutionary history and the basic and the smallest unit of this biological classification is species.
Family, class, and genus come in a higher order of hierarchy in taxonomic classification hence, they cannot be the smallest and the basic unit of classification. Species are the smallest unit of classification.

Carl Linnaeus, also known as Carl von Linne or Carolus Linnaeus, is called the father of systemic botany. His system of naming, ranking and classifying organisms is in wide use today. He devised the formal two-part naming system. During his career, Linnaeus named about 13000 life forms and classified them into suitable categories. Linnaeus hierarchical classification and binomial nomenclature, much modified, have remained standard for over 200 years. His writings have been studied by every generation of naturalists.

The botanical garden is the collection of a diverse range of species which are a major source of biodiversity. IUCN classifies 2,700 of these as rare, threatened or endangered. The species are conserved in a natural habitat. 

A plant taxonomist doing research has to study type specimens in order to ensure that names associated with plants are correct. The most important specimen is the holotype. The holotype designated by the researcher is the specimen to which a name is permanently attached. There can be only one holotype. Isotypes are duplicates of the holotypes. The holotype is deposited in a museum of the author's choosing and isotypes are usually distributed to major botanical institutions, such as the New York Botanical Garden and the Smithsonian. This ensures that there will be additional specimens available in case the holotype is lost or destroyed. When a holotype is not available, other kinds of types must be designated. Syntypes are specimens cited by the author, when a holotype was not designated or has been lost. A lectotype is a specimen designated by a later investigator, when no holotype is available. It is selected from the isotypes or syntypes.

• A taxon is a taxonomic group or taxonomic unit. Each category is referred to as a unit of classification in fact, represents a rare and is commonly termed as taxon. Many modern systematics, such as advocates of phylogenetic nomenclature, use cladistic methods that require taxa to be monophyletic. 
• The term taxon is a collection of more than one population of the organisms or organism seen by the taxonomists for forming a unit. There are seven main taxanomic ranks: kingdom, phylum or division, class, order, family, genus, species.
  
• The term taxon was first used in 1926 by Adolf Meyer for animal groups, but the term taxon was coined by Linnaeus. 

So the correct option is taxon.

• "Species Plantarum", a book written by Carolus Linnaeus (Swedish naturalist), contains nearly 5900 species of plants and it is the starting point for the nomenclature of flowering plants (spermatophytes) and ferns i.e, plants. 
  
• Species Plantarum was the first botanical work to consistently apply the binomial nomenclature system for the large group of plants.

Family, class and phylum are names of different taxon in which groups of organisms are arranged. In contrast, taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit in biological classification.

The taxa are the hierarchical ranks which are used for the classification of the organisms. The correct sequence of groups from most to least inclusive is Kingdom- Phylum- Class- Order- Family- Genus- Species. The taxa which are placed below family are the genus.