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The Living World - Concept of species and taxonomical hierarchy

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Taxonomy is the branch of science dealing with the identification, nomenclature, and classification of organisms based on their characteristics.

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The Biological Concept of Species, proposed by Ernst Mayr, defines a species as a group of potentially interbreeding natural populations that are reproductively isolated from other such groups.

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Taxonomical Hierarchy is the process of arranging various organisms into successive levels of biological classification in either a decreasing or an increasing order from kingdom to species or vice versa.

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Each level in the hierarchy is referred to as a taxonomic category or 'taxon' (plural: taxa).

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Binomial Nomenclature, developed by Carolus Linnaeus, follows specific rules: the first word represents the Genus (starting with a capital letter) and the second word represents the Specific Epithet (starting with a small letter), e.g., MangiferaMangifera indicaindica.

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As we move from Species to Kingdom, the number of common characteristics decreases, while the complexity and number of organisms included increase.

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Suffixes are often used for plant categories: −aceae-aceae for Family (e.g., SolanaceaeSolanaceae) and −ales-ales for Order (e.g., PolymonialesPolymoniales).

📐Formulae

Scientific Name=Generic Name+Specific Epithet\text{Scientific Name} = \text{Generic Name} + \text{Specific Epithet}

Kingdom→Phylum/Division→Class→Order→Family→Genus→Species\text{Kingdom} \rightarrow \text{Phylum/Division} \rightarrow \text{Class} \rightarrow \text{Order} \rightarrow \text{Family} \rightarrow \text{Genus} \rightarrow \text{Species}

Common characteristics∝1Rank in Hierarchy\text{Common characteristics} \propto \frac{1}{\text{Rank in Hierarchy}}

💡Examples

Problem 1:

Identify the taxonomic hierarchy of a Housefly.

Solution:

Kingdom: AnimaliaAnimalia, Phylum: ArthropodaArthropoda, Class: InsectaInsecta, Order: DipteraDiptera, Family: MuscidaeMuscidae, Genus: MuscaMusca, Species: domesticadomestica.

Explanation:

The scientific name of a housefly is MuscaMusca domesticadomestica. It belongs to the order DipteraDiptera and class InsectaInsecta because it possesses three pairs of jointed legs and two wings.

Problem 2:

Write the scientific names for Potato, Lion, and Leopard using the rules of Binomial Nomenclature.

Solution:

Potato: SolanumSolanum tuberosumtuberosum, Lion: PantheraPanthera leoleo, Leopard: PantheraPanthera parduspardus.

Explanation:

In PantheraPanthera leoleo and PantheraPanthera parduspardus, PantheraPanthera is the genus name common to both, indicating a close evolutionary relationship, while leoleo and parduspardus are distinct specific epithets.

Problem 3:

Which taxonomic category contains organisms with the maximum number of common characters?

Solution:

The category is Species (SpeciesSpecies).

Explanation:

Species is the lowest/most basic level of classification. Organisms within a species are most similar to each other and are capable of interbreeding to produce fertile offspring.

Concept of species and taxonomical hierarchy Revision - Class 11 Biology CBSE