A3.2 Classification and Cladistics Flashcards
Define “taxonomy”
is the science of classifying organisms.
List the levels of classification in the traditional hierarchy of taxa.
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
(dear king phillip came over for good soup)
Define clade.
groups of organisms (or viruses) with a common ancestry and shared traits.
draw a clade
question 4
State that DNA and amino acids sequences can be the basis for constructing cladograms.
Within a clade, some species will be more closely related than others, because they diverged relatively recently. They will have fewer differences in base or amino acid sequence. Species that diverged a longer time ago are likely to have more differences.
Define “parsimony” as used in a biological context.
a principle used in phylogenetics to choose the simplest explanation or tree that accounts for the observed data, such as genetic sequences or morphological traits.
Outline how the principle of parsimony relates to evolutionary divergence between the members of a clade.
Parsimony does not prove how a clade evolved but it indicates the most probable pattern of divergence.
Define “cladogram”.
Cladograms are tree diagrams which show the most probable sequence of divergence between clades
Outline what is represented by a “root”, “node” and “terminal branch” on a cladogram.
Root: The starting point that represents the most recent common ancestor of all organisms in the diagram.
Node: A point where a branch splits, indicating a common ancestor of the descendant groups.
Terminal Branch: The ends of the cladogram that represent individual species or groups, showing current descendants.
Outline the reason and evidence for the reclassification of the figwort family.
Reason:
Molecular Data: DNA studies showed that the traditional classification based on appearance was incorrect.
Evidence:
DNA Sequencing: Many genera were found to be closer to other plant families, like Orobanchaceae and Plantaginaceae.
Phylogenetic Analysis: Genetic trees revealed different evolutionary relationships that didn’t match the old classification.
Taxonomic Revision: As a result, some genera were moved to different families for a more accurate classification.
List the three domains of life.
Archaea (archaeans)
Eubacteria (bacteria)
Eukarya (eukaryotes)
Discuss evidence from rRNA base sequences that led to the reclassification of life from two cell types (prokaryotic and eukaryotic) to three domains.
The three-domain model is based on the differences in sequences of nucleotides in rRNA between eukaryota, eubacteria, and archaea. It was also based on the lipid structure of the cell membranes and their sensitivity to antibiotics.
