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Classification and Biodiversity - Five Kingdom and Linnaean Classification

Grade 9IB

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

🔑Concepts

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Classification is the process of grouping organisms based on shared characteristics to study them systematically. This branch of science is known as TaxonomyTaxonomy.

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The Linnaean System, developed by Carl Linnaeus, uses a hierarchical structure: Kingdom→Phylum→Class→Order→Family→Genus→SpeciesKingdom \rightarrow Phylum \rightarrow Class \rightarrow Order \rightarrow Family \rightarrow Genus \rightarrow Species.

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Binomial Nomenclature is the two-part naming system where every species is given a name consisting of its GenusGenus (capitalized) and speciesspecies (lowercase), both written in italics or underlined, e.g., Panthera leoPanthera\ leo.

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The Five Kingdom Classification (Whittaker, 1969) categorizes life into: MoneraMonera (prokaryotic, e.g., bacteria), ProtistaProtista (eukaryotic, mostly unicellular), FungiFungi (heterotrophic, chitin cell walls), PlantaePlantae (autotrophic, cellulose cell walls), and AnimaliaAnimalia (heterotrophic, no cell walls).

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Criteria for classification include cell structure (ProkaryoticProkaryotic vs. EukaryoticEukaryotic), body organization (UnicellularUnicellular vs. MulticellularMulticellular), and mode of nutrition (AutotrophicAutotrophic vs. HeterotrophicHeterotrophic).

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Biodiversity refers to the variety of life on Earth. It is often measured by species richness (number of different species) and species evenness (relative abundance of each species).

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Dichotomous Keys are tools used by scientists to identify organisms based on a series of choices between two contrasting physical characteristics.

📐Formulae

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

D=1−(∑n(n−1)N(N−1))D = 1 - \left( \frac{\sum n(n-1)}{N(N-1)} \right)

💡Examples

Problem 1:

An organism is found to be multicellular, eukaryotic, has a cell wall made of cellulose, and performs photosynthesis. To which Kingdom does it belong?

Solution:

Kingdom PlantaePlantae

Explanation:

The presence of a eukaryoticeukaryotic cell structure and a cellulosecellulose cell wall, combined with the ability to perform photosynthesisphotosynthesis (autotrophic nutrition), are defining characteristics of the Kingdom PlantaePlantae.

Problem 2:

Correct the formatting of the scientific name for a house cat: 'felis Catus'.

Solution:

Felis catus\textit{Felis\ catus}

Explanation:

According to the rules of binomial nomenclature: 1. The GenusGenus name must start with a capital letter (FelisFelis). 2. The speciesspecies name must be lowercase (catuscatus). 3. The entire name should be italicizeditalicized (or underlined if handwritten).

Problem 3:

Calculate the Simpson's Index of Diversity (DD) for a sample where N=10N = 10 (total individuals) and the counts for two species are n1=6n_1 = 6 and n2=4n_2 = 4.

Solution:

D=1−(6(5)+4(3)10(9))=1−(30+1290)=1−4290≈0.533D = 1 - \left( \frac{6(5) + 4(3)}{10(9)} \right) = 1 - \left( \frac{30 + 12}{90} \right) = 1 - \frac{42}{90} \approx 0.533

Explanation:

The formula D=1−(∑n(n−1)/N(N−1))D = 1 - (\sum n(n-1) / N(N-1)) is used. First, calculate n(n−1)n(n-1) for each species, sum them up, divide by the total N(N−1)N(N-1), and subtract from 11. A value closer to 11 indicates higher biodiversity.