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Biology - Diversity in Living Organisms (Five Kingdom Classification, Bacteria, Fungi)

Grade 9ICSE

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

🔑Concepts

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Five Kingdom Classification: Proposed by Robert H. Whittaker in 19691969. The criteria include cell structure (prokaryotic vs eukaryotic), complexity of the organism (unicellular vs multicellular), and mode of nutrition (autotrophic vs heterotrophic).

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Kingdom Monera: Comprises unicellular prokaryotic organisms. They lack a defined nucleus and membrane-bound organelles. Examples include BacteriaBacteria and CyanobacteriaCyanobacteria (Blue-green algae). Their cell wall is composed of peptidoglycan.

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Kingdom Protista: Includes unicellular eukaryotic organisms. They possess a well-defined nucleus and membrane-bound organelles. Movement occurs via ciliacilia, flagellaflagella, or pseudopodiapseudopodia. Examples: AmoebaAmoeba, ParamoeciumParamoecium, and EuglenaEuglena.

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Kingdom Fungi: Multicellular (except YeastYeast), eukaryotic, and heterotrophic (mostly saprophytic). They absorb nutrients from decaying organic matter. Their cell wall is made of a tough complex sugar called Chitin (C8H13O5N)n(C_8H_{13}O_5N)_n.

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Bacteria Morphology: Bacteria are classified by shape: CocciCocci (spherical), BacilliBacilli (rod-shaped), SpirillaSpirilla (spiral), and VibrioVibrio (comma-shaped).

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Binomial Nomenclature: Developed by Carolus Linnaeus. Every organism has a two-part scientific name: GenusGenus (capitalized) and speciesspecies (lowercase), both written in italics or underlined separately.

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Economic Importance of Bacteria: Useful in curdling milk (via LactobacillusLactobacillus) and nitrogen fixation (via RhizobiumRhizobium in root nodules), but also cause diseases like Typhoid (via Salmonella typhiSalmonella \ typhi).

📐Formulae

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

Photosynthesis (Plantae specific): 6CO2+12H2O→SunlightChlorophyllC6H12O6+6O2+6H2O\text{Photosynthesis (Plantae specific): } 6CO_2 + 12H_2O \xrightarrow[Sunlight]{Chlorophyll} C_6H_{12}O_6 + 6O_2 + 6H_2O

Cell Wall Composition (Fungi): Chitin=(C8H13O5N)n\text{Cell Wall Composition (Fungi): } \text{Chitin} = (C_8H_{13}O_5N)_n

Surface Area to Volume Ratio in Bacteria: SAV=3r (where r is the radius of a spherical bacterium)\text{Surface Area to Volume Ratio in Bacteria: } \frac{SA}{V} = \frac{3}{r} \text{ (where } r \text{ is the radius of a spherical bacterium)}

💡Examples

Problem 1:

Identify the Kingdom of an organism that is unicellular, contains a nucleus, and moves using a whip-like structure called a flagellum.

Solution:

Kingdom Protista

Explanation:

Since the organism is unicellular and eukaryotic (has a nucleus), it belongs to ProtistaProtista. The flagellum is a characteristic locomotory organelle found in protists like EuglenaEuglena.

Problem 2:

Write the scientific name of Modern Man according to the rules of Binomial Nomenclature.

Solution:

Homo sapiensHomo \ sapiens

Explanation:

The first word HomoHomo represents the Genus and starts with a capital letter. The second word sapienssapiens represents the species and starts with a small letter. Both are italicized.

Problem 3:

Distinguish between the cell walls of Kingdom Monera and Kingdom Fungi.

Solution:

Monera: Peptidoglycan; Fungi: Chitin.

Explanation:

Bacteria (MoneraMonera) have cell walls made of peptidoglycan (amino acids and sugars), whereas FungiFungi have cell walls composed of Chitin, a nitrogen-containing polysaccharide.