Module 4.3 Flashcards
Classification and evolution
Order of biological classification of species
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
How to write binomial names
Genus names then species name
Genus name 1st letter capitalised
Species name not capitalised
Written in italics or underlined if handwritten
What are the 5 kingdoms
Prokaryotae
Protoctista
Fungi
Plantae
Animalia
Features of Prokaryotae
No nucleus
DNA not associate with histone proteins
DNA in a loop not chromosomes
Smaller cells
smaller ribosomes
No cell bound organelles
Features of Fungi
Chitin cell wall
Eukaryotes
Multinucleate
Saprophytic
Features of plantae
Eukaryotic
Cellulose cell wall
Chloroplasts
multicellular
autotrophic
Features of animalia
Eukaryotic
multicellular
heterotrophic
No cell wall
Features of protoctista
Eukaryotic
All they have in common is that they don’t belong in another kingdom so take a wide variety of forms
What are the 3 domains
Archaea, Eubacteria, eukaryote
Evidence for the 3 domains
Eubacteria and Archaea have
Different cell membrane
Flagella with a different internal structure
different enzymes for DNA synthesis
Different mechanisms for DNA replication and RNA synthesis
Comparison of 3 domain system to kingdom system
What determines phylum
Body plan e.g. having a backbone
What determines class
General traits e.g. number of legs
Order
additional information e.g. carnivora or herbivora
Advantages of the binomial naming system
names are the same in all countries
so no confusion will occur if the same common name is used for different species or if common names vary for the same species
Evidence used in classification
Cytochrome C and DNA sequencing
What is cytochrome C
A protein used in the process of respiration
Means all organisms that respire must have cytochrome C
It is not identical in all species
How cytochrome C sequencing helps classification
The amino acids in the protein can be identified
Compare how closely related species are
If the sequences are the same the species are closely related
If the sequences are different they are not so closely related
The more differences there are the less closely related the species are
How DNA sequencing helps classification
Comparisons of DNA sequencing help classify
The more similar the sequences are the more closely related the species are
If the sequences are very different the species have evolved separately for a long time allowing them to develop more mutations from the common ancestor
What is a common ancestor
An ancestor shared by 2 species that is no longer living
What similar features do Archaea and Eukaryotes have
Similar enzymes for RNA synthesis
Similar mechanisms for DNA replication and RNA synthesis
Production of some proteins that bind to DNA
Who suggested the 3 domain system and why
Carl Woese in 1990
Argued the differences in DNA and RNA synthesis were fundamental and that Archaea and Eukaryotes are more similar than Eubacteria and Archaea and an accurate classification system should represent this difference
What is artificial classification
Bases on only a few characteristics
Does not reflect evolutionary relationships
Provides limited information
Is stable
Done for convenience e.g. appearance
What is natural classification
detailed study of the individuals in a species
Uses many characteristics
Reflects evolutionary relationships
Provides lots of useful information
Mya change with advancing knowledge
What is phylogeny
The study of evolutionary relationships between species
Involves how closely related the are
Relates to how long ago their common ancestor was
What do common ancestors tell us
How much time the species have had time to evolve separately to adapt and mutate
More recent common ancestors = more closely related species
What does monophyletic mean
A group of organisms descended from one common ancestor - they belong to the same phylogenetic group
Evidence for natural selection - Darwin
proposed the mechanism of natural selection
At the Galapagos islands discovered variation between the same species on different islands
Finches - wide variety but were all actually closely related
concluded 1 species arrived and evolved into many different species
Evidence for natural selection - Wallace
Independently came to the same conclusions as Darwin
Darwin’s observations
Offspring appear genetically similar to parents
No two individuals are identical
Organisms have the ability to produce large numbers of offspring
Populations in nature tend to stay fairly stable in size
Darwin’s conclusions
There is a struggle to survive
Better-adapted individuals survive and pass on their characteristics
Over time a number of changes may give rise to a new population
Evidence for evolution - Fossil evidence
in the past the world was inhabited by species that were different from those present today
Old species have died out and new ones have arisen
The new species that have appeared are often similar to the older ones found in the same place
Evidence for evolution - biological molecules
certain biological molecules are found throughout the living world suggesting all species arose from one original ancestor
2 closely related species will have separated only relatively recently - their biological molecules are likely to be identical or very similar
In species that took separate evolutionary paths a long time ago the biological molecules are likely to differ more
Cytochrome C and DNA sequences show this pattern of changes
What is variation
The presence of differences between individuals
What is intraspecific variation
Variation within a species
What is interspecific variation
Variation between species
What is continuous variation
There are 2 extremes and a full range of intermediate values between the 2 with most individuals close to the mean
How is continuous variation caused
Often by more than one gene and environmental factors
How is continuous variation graphed
Histogram
What is discontinuous variation
When their are 2 or more distinct categories with no intermediate values
What causes discontinuous variation
Usually regulated by a single gene
Not influence by the environment
How is discontinuous variation graphed
bar chart
Causes of variation
Inherited/genetic and environmental
What is genetic/inherited variation
Genes we inherit from our parents used to define our characteristics
Combination of alleles we inherit is not the same as in any other living thing
What is environmental variation
Characteristics affected by the environment e.g. overfeeding leads to obesity and exposure to sunlight darkens skin tone
Combined effect
Many characteristics are caused by both environmental and genetic variation
humans have become taller because of a better diet but you are still unlikely to grow tall if the rest of your family are short (limited by genes)
Not all genes are active at one time e.g. puberty changes in the environment can directly effect which genes are active
What is adaptation
A variation that helps the organism to survive
What is anatomical adaptations
structural adaptations
e.g. long roots rolled leaves in xerophytes
What are behavioural adaptations
Behaviours an organism exhibits to survive
e.g. when earthworms are touched they rapidly contract and withdraw into a burrow as they think it is a bird about to eat them
Physiological/biochemical adaptations
Ensures the correct functioning of cell processes
e.g. guard cells
What is convergent evolution
When two unrelated species living in similar environments evolve similar adaptations
despite separate evolution they may look and behave similarly
What is natural selection
A individual that had a characteristic which helps it to survive is more likely to live long enough to reproduce therefor passing on these adaptations to the next generation
process of natural selection
Mutation creates alternative alleles
creating genetic variation (intraspecific) -
selection pressure selects variations that give an advantage
Individuals with advantageous characteristic survive and reproduce successfully
They pass on their advantageous characteristic
The next generation will have a higher proportion of individuals with the successful characteristics
environmental variation does not get passed on to offspring
pesticide resistance
pesticides are a very strong selection pressure
if an insect is susceptible it will die
if it has some sort of resistance the individual may survive
Individuals with some resistance reproduce and pass on the resistance characteristic
Resistance quickly spreads throughout the whole population
Problems with pesticide resistance
Can cause pests to accumulate in the food chain
If they survive the application of the pesticide their predators may eat them and receive a larger dose of the insecticide
Antibiotic resistance
Powerful selection pressure
if a bacteria is susceptible it will die
if it has some sort of resistance the individual may survive (especially if the full course of antibiotics is not taken)
Individuals with some resistance reproduce and pass on the resistance characteristic
Resistance quickly spreads throughout the whole population
