Flashcards in Mod 4 Chap 10: Classification and Evolution Deck (46)
The act of arranging organisms into groups based on their similarities and differences.
Describe the method of the biological classification of species most commonly used today.
The Hierarchal Classification System:
- contains 7 taxonomic groups ordered into hierarchy:
A mnemonic to help remember this:
BUT: now Domain is used above Kingdom in the Hierarchal classification system.
Describe why we classify organisms / species.
- to identify species
- to predict characteristics
- to find evolutionary links
- convenience + more manageable
Describe how we classify organisms / species (today, after using just five kingdoms in past).
- organisms split into 3 different domains:
Archae / Bacteria / Eukarya
Describe how we name species.
The Binomial System of Naming Species.
- developed in 18th cent by Carl Linnaeus
- aka 'Binomial Nomenclature'
- works by giving all species a scientific name of two parts
- First word: indicates organism's genus (the genetic name), has a capital letter
- Second word: indicates organism's species (the specific name)
- whole name always written in italics
Give some advantages of using the Binomial Naming System of Species.
- helps to avoid the confusion of using common names
- ensures scientists the world over and discussing same organism
Describe the features that classify organisms into the kingdom of Prokaryotae.
- no nucleus / other membrane bound organelles
- a ring of naked DNA
- small ribosomes
- no visible feeding mechanism, nutrients absorbed through cell wall / produced by photosynthesis
Examples: bacteria: Bacillus anthracis
Describe the features that classify organisms into the kingdom of Protoctista.
- mainly unicellular
- a nucleus + other membrane bound organelles
- some have chloroplasts
- some are sessile, others move by cilia / flagella / ameboid mechanisms
- nutrients acquired by photosynthesis (autotrophic feeders) / ingestion of other organisms (heterotrophic feeders) / both
Examples: Algae, Protozoa
Describe the features that classify organisms into the kingdom of Fungi.
- unicellular / multicellular
- a nucleus + other membrane bound organelles + cell wall mainly composed of chitin
- no chloroplasts / chlorophyll
- no mechanisms for locomotion
- most store food as glycogen
- saprotrophic feeders - acquire nutrients from absorption, mainly from decaying material
Examples: mushrooms, mounds, yeast
Describe the features that classify organisms into the kingdom of Plantae.
- a nucleus + other membrane bound organelles + cell wall composed of cellulose
- all contain chlorophyll
- most don't move
- nutrients acquires by photosynthesis - autotrophic feeders
- store food as starch
Examples: mosses, ferns, flowering plants.
Describe the features used to classify organisms into the kingdom of Animalia.
- a nucleus + other membrane bound organelles
- no chloroplasts
- move w/ aid of cilia / flagella / contractile proteins, sometimes in form of muscular organs
- nutrients acquired by ingestion - heterotrophic feeders
- food stored as glycogen
Examples: reptiles, birds, mammals
Describe recent changes in leading to new classification systems.
- early classification systems used observable features to classify organisms into groups
- but, problems caused as scientists didn't always agree on relative importance of diff features, + groups based solely on physical features may not show how related organisms are
- SO, classification systems now based on observable features along w/ other evidence telling us how closely related organisms are
Describe the evidence that is used in and has lead to new classification systems.
- embryological evidence used (similarities in early stages of an organisms development)
- fossil evidence
- molecular evidence (involves analysing similarities in proteins and DNA, more closely related organisms = more similar their molecules are)
Describe how this evidence has lead to new classification systems such as the three Domains of life, which clarify relationships.
- three domain system groups organisms using differences in sequences of nucleotides in cells' ribosomal RNA (rRNA), + cells' lipid structure + sensitivity to antibiotics
- observation of these differences made possibles through advances in scientific techniques
- under this system: organisms classified into three domains and six kingdoms
Three domains: Archaea / Bacteria / Eukarya
- organisms classified into these domains by their form of rRNA and diff ribosomes
Old Prokaryotae kingdom divided into two: 1) Archaebacteria and 2) Eubacteria
Then other 4 are: 3) Protoctista, 4) Fungi, 5) Plantae and 6) Animalia.
Describe the features of the rRNA and ribosomes used to classify organisms into the domain of Eukarya.
- have 80s ribosomes
- RNA polymerase (responsible for most mRNA transcription) contains 12 proteins
Describe the features of the rRNA and ribosomes used to classify organisms into the domain of Archaea.
- have 70s ribosomes
- RNA polymerase of diff organisms contains 8 - 10 proteins + is v similar to eukaryotic ribosomes
Describe the features of the rRNA and ribosomes used to classify organisms into the domain of Bacteria.
- have 70s ribosomes
- RNA polymerase contains five proteins
Describe the new kingdom of Archaebacteria derived from the old of Prokaryotae.
- aka ancient bacteria
- can live in extreme environments: e.g. Hot thermal vents, anaerobic conditions, + highly acidic environments
Describe the new kingdom of Eubacteria derived from the old of Prokaryotae.
- aka true bacteria
- found in all environments
- most bacteria are of eubacteria kingdom
- name given to evolutionary relationships between organisms
- the study of the evolutionary history of groups of organisms.
- reveals which group a particular organism is related to + how closely related these organisms are
Describe the relationship between classification and phylogeny.
- classification can occur without knowledge of phylogeny
- but it is objective of many scientists to develop a classification system that also correctly considers phylogeny of organisms
- phylogeny can be done without reference to classification
- classification uses knowledge of phylogeny in order to confirm classification groups are correct or causes them to be changed
Describe evidence for the theory of evolution by natural selection.
A number of sources used to study evolution:
- palaeontology - study of fossils + the fossil record
- comparative anatomy - study of similarities + diffs between organisms' anatomy
- comparative biochemistry - similarities + diffs between chemical make up of organisms
- molecular evidence: DNA - organisms that diverged away from eachother more recently should have more similar DNA, as less time passed for changes in their DNA sequences (evolution) to occur, + this what scientists found
- molecular evidence: Proteins + other molecules - similarities in molecules also provide evidence, sequence of amino acids in proteins, and antibodies, are compared. More recently diverged organisms from eachother have more similar molecules
(So is mainly evidence for divergent evolution)
Describe the different types of variation.
- Interspecific variation: variation between members of different species, the widest type of variation
- Intraspecific variation: variation / differences between organisms within a species
Describe genetic causes of variation, and give examples of genetic variation.
This is an organisms genetic material - differences in the genetic material (genes + alleles) an organism inherits from its parents leads to genetic variation. Several causes for genetic variation in a population:
- Alleles: genes have diff alleles. W/ a gene for a particular characteristic, diff alleles produce diff effects, so individuals in a species population may inherit diff alleles of a gene
- Mutations: changes to DNA sequence + so to genes can lead to changes in proteins that are coded for, this can affect physical + metabolic characteristics, resulting in variation
- Meiosis: gametes (sex cells: ovum + sperm) produced by meiosis in organisms reproducing sexually. Each gamete relieves half genetic content of parent cell, this genetic material inherited = mixed up by 'independent assortment + crossing over', leading to gametes showing variation
- Sexual reproduction: offspring inherits alleles from each of parents, so each individual produced differs from parent. (This why = much more greater variation in sexually reproducing organisms than asexually, (asexual = clones, so variation only happens through mutations))
- Chance: result of chance as to which two gametes combine in sexual reproduction (aka random fertilisation) , so individuals produced differ from siblings as each contains unique combination of genetic information
- tongue rolling ability
- eye colour
Describe environmental causes of variation, and give examples of environmental variation.
- all organisms affected by environment, but plants may be affected more than animals by environment in which they live, due to lack of mobility
- presence of scars on your body
- ability to speak diff languages
- tattoos / piercings
Describe environmental AND genetic causes of variation, and give examples of genetic and environmental variation.
- in most cases variation = caused by combination of both environmental + genetic factors
- 'nature vs nurture argument': many characteristics caused by both, so diff to investigate + conclude about causes of a variation, e.g. Cause of variation in intelligence = genetics / environment?
- skin colour
- hair colour
State the two ways variation can be described, and give variation examples of both.
- Discontinuous Variation: A characteristic that can only result in certain discrete values. Variation determined purely by genetic factors is discontinuous.
E.g. An animals sex / gender; either male / female only, human blood groups
- Continuous Variation: A characteristic that can take any value within a range. Variation determined by both genetic factors environmental factors are continuous
Describe palaeontology as evidence for the theory of evolution by natural selection.
- fossils of the simplest organisms e.g. Bacteria are found in oldest rocks, but fossils of more complex organisms e.g. Vertebrae are found in more recent rocks - this supports evolutionary theory that simple life forms gradually evolved over an extremely long period of time period into more complex ones