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Evolution and Biodiversity - Classification of biodiversity

Grade 12IBBiology

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

🔑Concepts

The binomial system of nomenclature, devised by Carl Linnaeus, identifies species by two names: the GenusGenus (capitalized) and the speciesspecies (lowercase), both written in italics or underlined.

The hierarchy of taxa for classifying eukaryotes follows a nested order: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Organisms are classified into three distinct domains based on 16S16S rRNArRNA sequences: ArchaeaArchaea (extremophiles), EubacteriaEubacteria (true bacteria), and EukaryotaEukaryota (complex cells with nuclei).

Natural classification groups organisms that share a common ancestor; this allows for the prediction of characteristics within a group and reflects evolutionary relationships.

Plant phyla are distinguished by vascular tissues and reproductive structures: BryophytaBryophyta (non-vascular, mosses), FilicinophytaFilicinophyta (vascular, ferns), ConiferophytaConiferophyta (woody stems, cones), and AngiospermophytaAngiospermophyta (flowering plants).

Invertebrate animal phyla include PoriferaPorifera (no symmetry, pores), CnidariaCnidaria (radial symmetry, stinging cells), PlatyhelminthaPlatyhelmintha (bilateral, flat bodies), AnnelidaAnnelida (segmented worms), MolluscaMollusca (muscular foot, mantle), and ArthropodaArthropoda (jointed appendages, exoskeleton).

Vertebrate classes are categorized by skin covering and reproductive methods: ActinopterygiiActinopterygii (bony fish with scales), AmphibiaAmphibia (moist skin, eggs in water), ReptiliaReptilia (dry scaly skin, leathery eggs), AvesAves (feathers, hard shells), and MammaliaMammalia (hair, milk production).

Taxonomists sometimes reclassify groups (e.g., moving the Figwort family based on DNADNA evidence) when new evidence suggests a different evolutionary pathway.

📐Formulae

D=N(N1)n(n1)D = \frac{N(N-1)}{\sum n(n-1)}

N=Total number of organisms of all species foundN = \text{Total number of organisms of all species found}

n=Number of individuals of a particular speciesn = \text{Number of individuals of a particular species}

💡Examples

Problem 1:

Classify a Grey Wolf using the full taxonomic hierarchy from Kingdom to Species.

Solution:

Kingdom: AnimaliaAnimalia; Phylum: ChordataChordata; Class: MammaliaMammalia; Order: CarnivoraCarnivora; Family: CanidaeCanidae; Genus: CanisCanis; Species: lupuslupus.

Explanation:

This follows the Linnaean hierarchy where the binomial name is CanisCanis lupuslupus.

Problem 2:

An unknown plant has vascular tissue, does not produce flowers, but produces seeds in woody cones. Identify the phylum.

Solution:

ConiferophytaConiferophyta

Explanation:

Plants with vascular tissue (xylemxylem and phloemphloem) that reproduce via seeds in cones rather than flowers are classified as ConiferophytaConiferophyta.

Problem 3:

Calculate the Simpson's Diversity Index (DD) for a sample where Species A has n=10n=10 and Species B has n=20n=20.

Solution:

N=10+20=30N = 10 + 20 = 30. n(n1)=[10(9)]+[20(19)]=90+380=470\sum n(n-1) = [10(9)] + [20(19)] = 90 + 380 = 470. D=30(29)470=8704701.85D = \frac{30(29)}{470} = \frac{870}{470} \approx 1.85.

Explanation:

The Simpson's Diversity Index is a measure used to quantify the biodiversity of a habitat, where a higher value typically indicates a more stable and diverse ecosystem.

Classification of biodiversity - Revision Notes & Key Diagrams | IB Grade 12 Biology