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Diversity - The Need for Classification

Grade 9CBSE

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

🔑Concepts

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Biodiversity refers to the vast variety of life forms found on Earth, ranging from microscopic bacteria of size 1μm1 \mu m to blue whales of about 30m30 m.

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Classification is the process of grouping organisms based on similarities and differences in their characteristics such as cell structure (prokaryotic vs eukaryotic), body design, and mode of nutrition.

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Charles Darwin first introduced the idea of evolution in his book 'The Origin of Species' in 18591859, linking classification to evolutionary relationships (Phylogeny).

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Taxonomic Hierarchy: Organisms are classified into different levels. The sequence from highest to lowest is: Kingdom→Phylum (for animals) / Division (for plants)→Class→Order→Family→Genus→SpeciesKingdom \rightarrow Phylum \text{ (for animals) / Division (for plants)} \rightarrow Class \rightarrow Order \rightarrow Family \rightarrow Genus \rightarrow Species.

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Species is the basic unit of classification. It refers to a group of organisms that are similar enough to breed and perpetuate.

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The Five Kingdom Classification was proposed by Robert Whittaker in 19691969. The kingdoms are: Monera, Protista, Fungi, Plantae, and Animalia.

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Binomial Nomenclature, introduced by Carolus Linnaeus, provides a unique two-part scientific name to every organism consisting of a Genus and a species name.

📐Formulae

Kingdom→Phylum→Class→Order→Family→Genus→SpeciesKingdom \rightarrow Phylum \rightarrow Class \rightarrow Order \rightarrow Family \rightarrow Genus \rightarrow Species

Scientific Name=Genus+species\text{Scientific Name} = \textit{Genus} + \textit{species}

1μm=10−6m1 \mu m = 10^{-6} m

💡Examples

Problem 1:

Write the scientific name of a Mango plant and identify the genus and species.

Solution:

Scientific Name: Mangifera indica\textit{Mangifera indica}

Explanation:

In the binomial system, the first word Mangifera\textit{Mangifera} represents the Genus (starts with a capital letter) and the second word indica\textit{indica} represents the species (starts with a small letter).

Problem 2:

Arrange the following taxonomic categories in increasing order of specificity: Class, Kingdom, Species, Genus, Order.

Solution:

Kingdom<Class<Order<Genus<SpeciesKingdom < Class < Order < Genus < Species

Explanation:

Specificity increases as we move down the hierarchy from Kingdom to Species. Species is the most specific level where organisms share the maximum number of common characteristics.

Problem 3:

Calculate the difference in magnitude between the size of a bacterium (1μm1 \mu m) and a blue whale (30m30 m).

Solution:

Difference=30m10−6m=30×106=3×107Difference = \frac{30 m}{10^{-6} m} = 30 \times 10^6 = 3 \times 10^7

Explanation:

A blue whale is approximately 3×1073 \times 10^7 times larger than a bacterium, illustrating the extreme range of diversity in living organisms.