classification

• Species have similar patterns of development and occupy the same ecological niche.
• Species are capable of breeding, meaning when a species reproduces, any of the genes of its individuals can be combined and belong to the same gene pool.
• The binomial system, devised by Linnaeus, is a universal system based on Greek or Latin names.
• The first name in the binomial system, the generic name, denotes the genus to which the organism belongs.
• The second name in the binomial system, the specific name, denotes the species where the organism belongs.
• The binomial system is used in scientific writing, with the names printed italics or underlined, the first letter of the generic name in upper case, and the specific name in lower case.
• Artificial classification divides according to differences such as colour, size, number of legs etc, these are analogous characteristics where the have the same function but not the same evolutionary origins.
• Natural classification is based on evolutionary relationships between organisms and classifies species into groups sharing features derived from ancestors.
• Each group in biological classification is called a taxon, positioned in a hierarchal order called taxonomic ranks, with the largest group being a kingdom within each kingdom the largest groups are known as phyla.
• The phylogeny of an organism reflects the evolutionary branch that led up to it, represented by a tree like diagram called a phylogenetic tree.
• Species are not fixed forever and change and evolves over time, within a species is a lot of variation, many species are extinct, some species rarely reproduce, and members of different groups of the same species may be isolated and never meet or interbreed.
• DNA hybridisation depends upon a particular property of the DNA double helix, when DNA is heated, its double strand separates into two complementary strands, when cooled, the bases on each strand recombine with each other to reform the original double strand.
• The degree of similarity in the amino acid sequence of the same protein in two species reflects how closely related they are.
• The greater the amount of H bonds the stronger the hybrid strand.
• The stronger the strand the higher the temperature to separate it.
• Adaptation is when organisms adjust to suit the changing environment in which they live, increasing the long-term reproductive success of a species by helping members survive long enough to breed.
• Immunological comparisons of proteins involve injecting serum albumin from species A into species B, which produces antibodies specific to antigen sites on the albumin from A.
• The process of courtship behaviour helps ensure that mating is successful by enabling individuals to recognise members of their own species, identify a mate that is capable of breeding, form a pair bond, and synchronise mating.
• Diversity in organisms arises from changes to its DNA, which can occur in two ways: changing the quantity or structure of DNA of an organism (mutation) or recombining the existing DNA of two individuals (during sexual reproduction).
• Any differences in the base sequence of a DNA molecule results in a different amino acid sequence being coded for which will lead to a different polypeptide, a different protein which can disrupt the metabolic pathway leading to production of other substances.
• Mutations are changes in DNA that result in different characteristics, which can arise in many ways such as some bases may be added, deleted or replaced during replication.
• The Royal Botanical Gardens, Kew devised a new classification of the families of flowering plants based on the DNA sequences of three genes found in all plants.
• The higher the temperature where it splits, the more related the two species are.
• During courtship, animals use signals to communicate with mates and members of their own sex, with males carrying out actions which acts as a stimulus to the female, who responds with a specific action of her own.
• DNA base sequencing is used in classifying plants, with monocotyledons having a single seed leaf and dicotyledons having two seed leaves.
• DNA hybridisation can be used to compare the DNA of different organisms, extracting, purifying, cutting DNA from two species, labelling one with a radioactive or fluorescent marker, mixing, heating to separate the strands, cooling to allow the strands to combine, separating out hybrid strands, increasing temperature to measure the degree that the two strands are linked, and if the species are closely related they will share complementary bases and more H bonds linking them in the hybrid strand.