4.3 - Classification and Evolution Flashcards
Define species.
A group of organisms with similar characteristic and alleles and can breed to produce fertile offspring.
What are the basics of the taxonomical hierarchy?
Organisms are classified into groups, which are subdivided into more groups.
Organisms are classified in terms of similar or shared features, these may be obvious or determined by biochemical or genetic tests.
There is no overlap between groups, it can either be one or the other and cannot fall halfway between groups.
What is the taxonomic hierarchy?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
What are the rules for naming a member of a species?
Genus part of the name has an upper case first letter, species part of the name has a lower case first letter.
Compare the new 3 domain system with the older 5 kingdom system.
Kingdom – organisms placed into one of the following groups: Animalia, Plantae, Fungi, Protoctista & Prokaryotae.
Domains - Prokaryotes (cells without a nucleus) are now divided into 2 domains – Archea and bacteria. Eukaryotes (cells with a nucleus) are placed in the domain Eukarya.
Why was the classification system changed & the 3 domain system introduced?
New evidence, mainly molecular showed large differences between Archea & Bacteria – evidence suggests that these two groups evolved separately. The classification system changed to reflect this new evidence.
What is phylogeny and what can it tell us?
The study of the evolutionary history of groups of organisms. All organisms have evolved from shared common ancestors. It tells us who’s related to whom and how closely related they are.
In what ways can we compare organisms other than observable (anatomical) features?
Molecular evidence. Compare amino acid sequences in common proteins e.g cyctochrome c or Hb. Compare DNA base sequences between species.
Behavioural evidence – similarities in behaviour & social organisation.
Why are organisms adapted to their environment & how do they develop?
To increase their chances of survival and reproduction. Adaptations develop because of evolution by natural selection – best-adapted individuals survive, reproduce & pass on their adaptations to their offspring.
Describe behavioural, physiological & anatomical adaptations.
Behavioural - the way an organism acts increases its chance of survival.
Physiological – processes inside an organism’s body increase its chances of survival.
Anatomical – structural features of an organism’s body increase its chances of survival.
Why do the marsupial & placental mole look similar but are not closely related?
Due to convergent evolution – they have evolved similar characteristics independently of one another due to adapting to similar environments & ecological niches – in two different continents.
What is an ecological niche?
The role of an organism within its habitat, e.g. what it eats, when & where it feeds.
Which two scientists contributed in formulating the theory of evolution by natural selection?
Charles Darwin & Alfred Wallace.
Why are people more aware of Darwin than Wallace?
Interest in this subject by the public came only after the book ‘On the origin of species’ was published by Darwin.
Describe the theory of natural selection.
Individuals within a population show variation in their phenotypes. Selection pressures create a struggle for survival. Individuals with better adaptations (to the selection pressures present at the time) are more likely to survive, reproduce & pass on their advantageous alleles to their offspring. Over time the frequency of the advantageous allele increases in the population.