Variety of Life Revision

• A species (basic unit of classification) is a group of individuals of common ancestry that closely resemble each other, and are normally capable of interbreeding to produce fertile offspring.

• Species are classified into groups within a hierarchy. In descending order this hierarchy is: 

Kingdom , Phylum , Class , Order , Family , Genus , Species

• Species are named according to a binomial system. The genus name is given first, followed by a species name. For example, Homo sapiens 

• Organisms are grouped into five kingdoms: 

Prokaryotae (bacteria) , Protoctista , Fungi , Plantae , Animalia.

• Prokaryotae - prokaryotic cells, reproduction by division, DNA naked/circular, smaller ribosomes, walls made of peptidoglycan. E.g. rod-shaped bacterium
• Protoctista - eukaryotic, unicellular OR multicellular showing limited differentiation, herterotrophs (Phylum Protozoa) or autotrophs (Phylum Chlorophyta)
• Fungi - eukaryotic, multicellular and some unicellular, consist of hyphae with chitin cell wall, lysotrophs, extracellular digestion. E.g. mould, toadstools, yeast
• Plantae - eukaryotic, multicellular, cellulose cell wall, autotrophs, photosynthetic possessing chlorophyll in chloroplasts. E.g. ferns, mosses, flowering plants
• Animalia - eukaryotes, multicellular, lack cell wall, heterotrophic, digestive system, locomotion. E.g. chordates, arthropods

• A phylogenetic classification is a system that reflects the ancestral or evolutionary relationship between groups

• Modern methods of establishing relationships include comparison of amino acid sequences in proteins and of nucleotide sequences in DNA and RNA. Closely-related organisms possess a high degree of agreement in the molecular structure of their proteins, DNA and RNA

• Unfamiliar organisms can be identified using an appropriate dichrotomous key

• Species diversity can be measured by using the Simpson's index (D). Simpson's index (D) values lie between 0 and 1, with values closer to zero indicating greater diversity

• The 'richness' of a region (such as Northern Ireland) can be described in terms of the diversity of its ecosystems (or habitats)

• Genetic diversity reflects the genetic variability of a species and is important in allowing for the continued adaptability of a species