The Living World Test - 4

• Classification is the arrangement of organisms into convenient categories or groups on the basis of their similarities and differences in certain easily observable but fundamental characters.
• A hierarchy of categories is raised keeping in mind the affinities or relationships of various groups. The various taxonomic categories represent distinct biological entities and not merely morphological aggregates.
• The various categories are kingdom, phylum (or division in plants), class, order, family, genus and species.

• Hierarchy of categories is the classification of organisms in a definite sequence of categories (taxonomic categories) in a descending order starting from kingdom and reaching upto species or an ascending order from species to kingdom.
• The number of similar characters of categories decreases from lowest rank (species) to highest rank (kingdom).
• The taxonomic hierarchy includes seven obligate categories kingdom, division or phylum, class, order, family, genus and species.

Fig: Taxonomical hierarchy showing arrangement in ascending order

From the given representation of taxonomical hierarchy, it is clear that family is interpolated between order and genus. Some subcategories like tribe, subfamily, subspecies are also used whenever required.

The correct hierarchy of classification of various taxons in descending order is given by :
Kingdom → Phylum → Class → Order → Family → Genus → Species
The kingdom is the highest level of classification while species being the most specific.
Since Class occupies the highest level amount all options, it has most generalized characters and organisms share least similar characters at this level.
So, the correct option is 'Class'.

Given plant is Helianthus sp. which can be classified as:
Kingdom - Plantae
Division - Angiospermae
Class - Dicotyledonae
Order - Asterales
Family - Compositae (= Asteraceae)
Genus - Helianthus

Species occupies a key position in classification and it represents the lowest taxonomic category. A species is the basic unit of the biological classification of the organisms. According to the definition of the biological species, it is a group of organisms living in a particular area at a particular time and are capable of interbreeding.

As per the definition given by Ernst Mayr in 1964:
"A species is a group of actually or potentially inbreeding populations that are reproductively isolated from other such groups.''
A species may have subgroups, called subspecies or varieties, showing certain distinct features of their own.

• Family is a taxonomic category which contains one or more related genera. All the genera of a family have some common features and they are separable from genera of a related family by important characteristic differences.
• The family Solanaceae includes a number of genera like Solanum, Petunia, Atropa, etc. due to certain similarities.
• They are distinct from the genera of the related family Convolvulaceae such as Convolvulus, Ipomoea.
• In the same way, the family Felidae which includes the genus Panthera of lion, tiger, leopard and genus Felis of cats is distinctly separated from the family Canidae which includes dogs and foxes.

Musca domestica (Housefly) belongs to class-lnsecta of phylum- Arthropoda.

Birds or Aves is the taxonomic class all flying chordates with four-chambered heart and feathers on their body are placed in.

Taxon is a unit of classification which may represent any level of grouping of organisms based on certain easily observable common characteristics.

May (1964) has defined taxon to be a taxonomic group of any rank that is sufficiently distinct to be worthy of being assigned to a definite category.

• Tautonyms are the scientific names in which both generic and specific epithets are same.
• Tautonyms are used in zoological nomenclature.
• However, in the current rules for nomenclature of living organisms, tautonyms are explicitly prohibited.
• Examples of tautonyms are Rattus rattus (Rat), Catla catla (Catla), Gorilla gorilla (Western gorilla), etc.

Order includes one or more related families e.g. the family Solanaceae is placed in the order Polemoniales along with four related families (Convolvulaceae, Boraginaceae, Hydrophyllaceae and Polemoniaceae). Name of a plant order usually ends with 'ales'.

hence, the correct option is Option B i.e. '-ales'

Phylum Arthropoda is the largest phylum of kingdom Animalia. It includes the largest number of animals with about 900,000 species.

Phylum Mollusca is the second largest animal phylum, which includes over 60,000 species.

Euplectella is classified under the phylum Porifera. They belong to the class Hexactinellida, characterized by the skeleton of six-rayed triaxon spicules. The common species of Euplectella is Euplectella aspergillum.

1. Sapiens is the species name of the human being whose scientific name is Homo sapiens and it is one of several species categorized into the genus Homo, but it is the only one that is not extinct. Homo sapiens are the species belonging to highly intelligent primates. Humans are the only existing members of the subtribe Hominina and they belong to the family of Hominidae. They can be classified by their characteristics of erect posture and bipedal locomotion.
2. Americana is also a species name whose scientific name is Ficus americana. So, the genus is Ficus. It is commonly known as West Indian laurel fig or Jamaican cherry fig. Ficus americana is a tree that belongs to the family Moraceae and it is commonly found in the Caribbean, in the north of Mexico, Central, and South America, and southern Brazil.
3. Rotundus is a species name of Desmodus rotundus which is commonly known as the common vampire bat. They are small, leaf-nosed bat and native to Latin America. They are mainly feeding on the blood of livestock. These bats are the carrier of rabies.
4. Hemidactylus is the genus of the common gecko family. The species are typically known as a common lizard. They are generally found in all the tropical regions of the world.

As sapiens, americana and rotundus are the specific names and Hemidactylus is the generic name, therefore Hemidactylus is the odd one.

The International code for Botanical Nomenclature gives a set of rules and recommendation for the scientific names of plants.

According to it, the suffix 'oideae; is used for the taxonomic names of subfamilies of plants, algae and fungi. 

The suffix used for the tribe is '-eae', for the family is '-aceae' and for the class is '-opsida'. 

Thus, the correct answer is option D.