4.3 - Classification And Evolution - New Flashcards
Why do we classify living organisms
- for our convenience
- to make the study of living things more manageable
- to make it easier to identify organisms
- to help us see the relationhsip between species
List the eight different taxonomic levels
Domain Kingdom Phylum Class Order Family Genus Species
What are three domains
- Archaea
- Eubacteria
- Eukaryotae
List the five kingdoms
Animalia Plantae Fungi Protoctista - (all eukaryotes)
Prokaryotae
Species def
A group of organisms that can interbreed to produce fertile offspring
What is the phylogenetic definition of a species?
A group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics
Where, in an ecosystem, do members of the same species live?
The same niche
Kingdom - Prokaryotae info
- no nucleus
- loops of DNA not arranged in linesr chromosomes
- have naked DNA in cytoplasm (not associated with histone proteins)
- have no membrane-bound organelles
- have smaller ribosomes than in other groups (70S, compared to 80S in eukaryotes)
- have cells smaller than that of eukaryotes
- may be free-living or parasitic (some cause diseases)
Kingdom - Protoctista info
- are eukaryotic
- are mostly single-celled (many algae are multicellular, though)
- show a wide variety of forms (all dont belong to other 4 kingdoms
- show various plant or animal-like features
- are mostly free living
- have autotrophic or heterotrophic nutrition, some photosynthesise, some are parasites, etc.
Kingdom - Fungi info
- are eukaryotic
- can exist as single cells - called yeasts
- or have a mycelium that consists of a hyphae
- have cell walls made of chitin
- have cytoplasm that is multinucleate
- are mostly free-living and saprophytic - cause decay of organic matter
Kingdom - Plantae info
- are eukaryotic
- are multicellular
- have cells surrounded by a cellulose cell wall
- are autotrophic (absorb simple molecules and build them into larger organic molecule)
- contain chlorophyll - for photosynthesis
Kingdom - animalia info
- are eukaryotic
- are multicellular
- heterotrophic (digest large molecules to form smaller molecules for absorption)
- are usually able to move around
Heterotroph def
Autotroph def
Saprophytic def
Different biological molecules that can be used as evidence for classification
- cytochrome C
- DNA - base sequences and comparison between species
What is convergent evolution?
Where two unrelated species adapt and ecolve in similar ways, and therefore look very similar
How is cytochrome c used for classification of a species?
- if the sequences are the same, the two species must be closely related
• if the sequences are different, the two species are not so closely related
• the more differences found between the sequences, the less closely related the two species.
How is DNA useful for classification?
- DNA codes for same sequence of amino acids in all organisms - DNA is universal
- can compare DNA base sequences between species
- more similar base sequences show a closer evolutionary relationship - a common ancestor, etc.
Phylogeny def
The study of the evolutionary relationships between organisms
Pros and cons of artificial classification
- based on a few characteristics
- does not reflect any evolutionary relationships
- provides limited information
- is stable
Pros and cons of natural classification
- uses many characteristics
- reflects evolutionary relationships
- provides a lot of useful information
- may change with advancing knowledge and technology
How can we use an evolutionary or phylogenetic tree to evaluate the evolutionary relationship between humans and gorillas (for example).
- Humans and gorrilas (both mammals) share many features and are closely related
- We have a common ancestor in the recent past
- We can call humans and gorillas monophyletic - they belong to the same phylogenetic group
- Humans and gorillas can be placed/classified in the same taxonomic group
How are archaea similar to eukaryotes
Contain similar enzymes - RNA polymerase to synthesise RNA in transcription
Similar mechanisms for DNA replication and synthesising DNA
Production of some hi stone proteins that bind to DNA
Natural selection def
Explains how features of the environment apply a elective pressure/force on the reproduction of individuals in a population and the a populations’ characteristics
Different evidence for evolution
Fossil evidence
Biological molecules - DNA and Cytochrome C
Different observations made by Darwin about evolution
- Offspring generally appear similar to their parents
- No two individuals are identical
- Organisms have the ability to produce large numbers of offspring
- Population in nature tend to remain fairly stable in size
Continuous variation def
Variation when there are two extremes and a full range of values in between
Discontinuous/discrete variation
Where there are distinct categories and nothing in between
Genetic variation
Variation caused by possessing a different combination of alleles
Environmental variation
Variation caused by a response to environmental factors
Interspecific variation
Differences between species
Intraspecific variation def
Variation between members of the same species
Variation def
The differences between individuals
What can our physical characteristics be caused by
A mixture of genetic and environmental varuation
Standard deviation def
A measure of the spread around the mean
Students T test
A test used to compare the significance between two means
Normal distribution info
68% of data should lie within one standard deviation of the mean
95% of data should lie within two standard deviations of the mean
Any value outside two standard deviations might be viewed as anomalous
Spearman’s rank coefficient
Adaptation def
A characteristic that enhances survival in the habitat
Anatomical adaptations
Anatomy/Structural features
Behavioural adaptations def
The ways that behaviour is modified for survival
Physiological adaptations def
Physiology: affect the way that processes work
Examples of good adaptations of an organisms to an environment
Find enough food/photosynthesise we’ll
Find enough water
Gather enough nutrients
Defend itself from predators and diseases/grazing
Respond to changes in its environment
Have sufficient energy to allow successful reproduction
Survive physical conditions of its environment, e.g. changes in temp, light, water availability, etc.
Anatomical adaptations of xerophytes
Physiological adaptations of marram grass
What is convergent evolution
When two species with different ancestral origins develop different characteristics
What is divergent evolution
When two species diverge from a common ancestor to develop different charctefistcis
Examples of natural selection in modern times
Evolution/natural selection occurs most obviously in organisms with a short life cycle:
Pesticide resistance in insects
Antibiotic resistance in microorganisms - e.g. MRSA
