(b)explain the relationship between classification and phylogeny

By grouping things into their evolutionary relationships in natural classification phylogeny, which studies the relationship, we can see what organisms are closely related to each other with common ancestors and determine using genetics which organisms belong where and help identify organisms which should be classified in certain areas.

(e)outline the binomial system of nomenclature and the use of scientific (Latin) names for species

The binomial system uses two names to identify each species: the genus name and the species name. Latin was a universal language, which means that species are given a universal name. For example, Homo sapiens is the binomial name given to humans. Homo refers to the genus to which humans belong. The genus name is always given a capital first letter. The species name is sapiens. Thus humans are Homo sapiens, which can be abbreviated to H. sapiens. In printed text it is in italics, in handwritten text it is underlined.

(f)use a dichotomous key to identify a group of at least six plants, animals or organisms

A dichotomous key uses a series of questions with two alternative answers to help you identify an organism. Each question have two answers – yes or no – and will lead you to another question. Eventually the answers will lead you to the name of the specimen. A good dichotomous key will have one question fewer than the number of species it can identify.

(g)discuss the fact that classification systems were based originally on observable features but more recent approaches draw on a wider range of evidence to clarify relationships between organisms, including molecular evidence

Using Biochemistry in Classification:

Evidence from biochemistry can help to determine how closely related one species is to another. Certain large biochemical molecules are fund in all living things. But they may not be identical in all living things. The differences reflect the evolutionary relationships.

(h)compare and contrast the five kingdom and three domain classification systems

In 1990, Carl Woese suggested a new classification system of domains, basing his ideas on detailed study of RNA. In the three domain system, organisms with cells that contain a nucleus are placed in the domain Eurkarya. Organisms that were in the kingdom Prokaryotae (unicellular organisms with no nucleus) were separated into two domains: Bacteria (Eubacteria) and the Archaea (Archaebacteria).

The three domain system was proposed because of new molecular evidence. This evidence showed that Bacteria was fundamentally different from Archaea and Eukarya:

  • Different cell membrane
  • Flagella with a different internal structure
  • Different enzymes (RNA polymerase) for building RNA
  • No proteins bound to their genetic material
  • Different mechanisms for DNA replication and for building RNA

Evidence also showed that Archaea was similar to Eurkaryotes:

  • Similar enzymes (RNA polymerase) for building RNA
  • Similar mechanisms for DNA replication and building RNA
  • Production of some proteins that bind to their DNA

Most scientists now agree that Archaea and Bacteria evolved separately and that Archaea are more closely related to Eurkarya than Bacteria.