Chapter 10 - Classification and evolution Flashcards
What is taxonomy
The practise of biological classification
What is beneficial about the hierarchal classification system
There’s no overlap
What is each group called in the hierarchal system
Taxon (Plural taxa)
Hierarchal classification - mnemonic
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Difference between higher + lower ranks on classification system
• higher ranks contain more organisms with less similarity between them.
• lower ranks contain fewer organisms with more similarity between them.
Three domains
Eukarya + archaea + bacteria
Define species
a group of organisms that are able to reproduce to produce fertile offspring
How to name a species scientifically
Binomial system = a group of organisms that are able to reproduce to produce fertile offspring
Importance of binomials
allow for species to be universally identified - the binomial for a species is the same across the entire globe
What should be done when writing binomial name
- always typed in italics or underlined when handwritten.
- The genus name should have a capital letter but the species name should not
What type is bacteria
Prokaryotic
What type is archaea
Prokaryotic
What type is eukarya
Eukaryotic
How did scientists realise that prokaryotes where split into two groups / domains
• Based on molecular analyses of RNA genes in particular, and by looking at features such as ribosomal RNA (rRNA), aspects of protein synthesis and the structure of cell membranes and flagell
Features of archaea that are the same as bacteria
No nucleus = same as bacteria + similar size range
Features of archaea that are different from bacteria
o Unique lipids being found in the membranes of their cells
o No peptidoglycan in their cell walls
o Ribosomal structure (particularly that of the small subunit) are more similar to the eukaryotic ribosome than that of the bacteria
DNA transcription in archaea…
is more similar to that of eukaryotes
How do bacterial cells divide
By binary fission
What are the three differences between archaea + bacteria
• Membrane lipids
• Ribosomal RNA
• Cell wall composition
How are membrane lipids different between archaea + bacteria
• Archaea = Consist of branched hydrocarbon chains bonded to glycerol by ether linkages
• Bacteria = consist of unbranched hydrocarbon chains bonded to glycerol by ester linkages
How is ribosomal DNA different between archaea + bacteria
• Both Archaea and Bacteria possess 70S ribosomes
The base sequences + primary structure of ribosomal DNA / ribosomes more similar to eukarya in archaea
How is cell wall composition different between archaea + bacteria
• Bacteria = peptidoglycan
• Archaea = some have peptidoglycan walls + others do not contain peptidoglycan
Overall comparison table between archaea / bacteria / eukarya = cell type / chromosome / cell membrane lipids / ribosomes / cell walls / histones
List the 5 kingdoms
o Prokaryota
o Protoctista
o Fungi
o Plantae
o Animalia
What are the key features of prokaryota
- generally unicellular
- have cell walls + cytoplasm
- vary in size
- divide by binary fission
- • Can be autotrophic or heterotrophic = nutrients are absorbed through the cell wall or produced internally by photosynthesis.
What are autotrophic feeders
photosynthetic
What are heterotrophic feeders
feeding by decomposing living / dead organisms + nutrients absorbed
Key features of protoctista
- mainly unicellular
- Eukaryotic = nucleus
- Some have chloroplasts
- Some are sessile, other moves by cilia, flagella or by amoeboid mechanisms.
Key Features of fungi
• eukaryotic
• non-cellulose cell walls = normally made from chitnin
• don’t have cilia
- heterotrophs
- reproduce using spores
- no chloroplasts
- • some consist of long threads = hyphae = that grow from fungus body + form a network = mycelium
What are hyphae
Long threads in fungi
What is mycelium
Fungi body = fungus network
Key features of plantae
- cell walls composed of cellulose
o Possess large (and usually permanent) vacuoles = provide structural support
o able to differentiate into specialized cells = tissues and organs
o chloroplasts
o sometimes have flagella - autotrophs
- multicellular
Key features of animalia
- multicellular eukaryotic organism
- able to differentiate
- small temporary vacuoles
- no cell walls
- heterotrophs
How do prokaryota divide
Binary fission
What are the cell walls made up in fungi
Chitnin
Does fungi have cilia
NO
Prokaryota is..
Bacteria
Protoctista i..
Unicellular eukaryotes
Fungi are..
yeast, moulds, mushrooms, etc.
Plantae is
Plants
Animalia is
Animals
Which kingdoms have nuclear envelopes
Protoctista / fungi / plantae / animalia
Which kingdoms have cell walls
Prokaryota / some protoctista/ fungi / plantae
What is the cell wall made of in prokaryota
Peptidoglycan
What is the cell wall made of in plantae
Cellulosw
What is the cell wall made of in fungi
Chitnin
Which kingdoms have organelles + fibres e,g microtubule
All but prokaryota
type of nutrition - prokaryota
Autotrophic + heterotrophic
type of nutrition - protoctista
Autotrophic + heterotrophic
type of nutrition - fungi
Heterotrophic
Saprophytic feeders
type of nutrition - plantae
Autotrophic
type of nutrition - animalia
Heterotrophic
Are prokaryota mobile
Some bacteria have flagella
Are protoctista mobile
Come have flagella / cilia
Are fungi mobile
No
Are plantae mobile
Gametes of some plants have flagella
Are animalia mobile
Yes = muscle
Which kingdom has nervous coordination
Just animalia
Examples of prokaryota
Bacteria
Examples of protoctista
Amoeba / algae / moulds
Example of fungi
Mould fungi
Example of plantae
Liverworts / flowering plants / mosses / ferns / conifers
Examples of animalia
Jellyfish / coral / worms / insects / vertebrae
Define homology
old biological classification systems grouped organisms based on shared features
What does it mean if features are homologous
• Features are homologous if they are shared by organisms that have evolved from a common ancestor
Why is using physical features bad classification
has many limitations and can often lead to the wrong classification of species
Define phylogeny
the evolutionary history of organisms
Define phylogenetic tree
diagrams that show the evolutionary relationships between different taxa
What are the types of data used to investigate evolutionary relationships
o DNA
o mRNA
o Amino acids (of a protein)
More similar sequences…
More closely related
More different sequences
Less closely related
• Species that have been separated for longer have had a greater amount of time to accumulate mutations and changes to their DNA, mRNA and amino acid sequences
If your looking at proteins for phylogeny what needs to be present
the protein used needs to be present in a wide range of organisms and show sufficient variation between species
How to compare DNA
extracted from the nuclei of cells taken from an organism
Where can DNA be extracted from
from blood or skin samples from living organisms or from fossils
Read notes on using antibodies in classification = module 4 = results / interpretation
from blood or skin samples from living organisms or from fossils
They are not a species
What is a sister group?
Groups with a recent split, the two groups that diverged most recently
What is a node? (in relation to phylogenetic trees)
Divergence of a species
What is a tip? (in relation to phylogenetic trees)
Present day organisms
If two species have a recent divergence, are they closely related?
Yes. The more recent the divergence, the more closely related organisms are
Under the 3 domain system, how many kingdoms are there?
6
Under the 3 domain system, what are the 6 kingdoms?
Eubacteria
•Archaebacteria
• Protoctista
• Plantae
• Fungi
•Animalia
Give 3 similarities between the domains of Bacteria and Archae
circular chromosomes
• no nucleus
• 70s ribosomes
• no membrane bound organelles
Give a similarity between the domains of Bacteria and Eukarya
normal phospholipids in membranes
Give 3 similarities between the domains of Eukarya and Archae
similar DNA replication
• histones bound to DNA
• No peptidoglycan cell walls
• not susceptible to antibiotics
• similar RNA polymerase
Darwin’s evidence
Evidence for evolution
Fossils (palaeontology)
• - DNA
• - Molecular evidence
How can the relative age of fossils be determined?
over time sediment is deposited to form rock strata
• recent rock strata are found at the top and older rock strata are found at the bottom
• radioisotope dating can be completed on fossils to date rock strata
How do fossils provide evidence for evolution?
fossils of the simplest organisms are found in the oldest rocks
• fossils of more complex organisms are found in more recent rocks
• allow relationships between extinct and living organisms to be investigated
• sequence in which organisms are found matches ecological links
What is comparative anatomy?
The study of similarities and differences between organisms’ anatomy
How does comparative anatomy provide evidence for evolution?
-Homologous structures provide evidence for divergent evolution and that from a common ancestor different species have evolved
How does molecular evidence show evolution
Differences in nucleotide sequence shows how closely related species are
• - Ribosomal RNA has a very slow rate of substitution so is commonly used with fossil info to determine relationships between ancient species
Define variation
differences that exist between two or more things
Define genetic variation
variation with genotypes between or within species
Define phenotypic variation
variation in phenotypes = any other features apart from genes e.g weight mass shape colour blood type
Define interspecific variation
variation between species
Define intraspecific variation
variation within species
What is Discontinuous variation
- Falls into distinct groups = blood groups
- differences in phenotypes
What is continuous variation
- Forms from quantitative differences in phenotypes
- Does not fall into distinct groups = mass / height
Causes of Variation
• Genetic or environmental
Causes of discontinuous variation
Result of inheritance of one gene with 2 or more alleles
• Solely due to genetic factors
• Phenotype = genotype
Causes of continuous variation
due to the inheritance of 2 or more genes
- interaction between genetic + environmental
What are the 5 causes of genetic variation?
presence of a different allele
• random fertilisation/random fusion of gametes
• random mating
• melosIs
• mutations
What are the two types of mutations?
Point mutations and chromosomal mutations
What are point mutations?
Change in the base sequence of DNA
How do chromosomal mutations arise?
From crossing over
What are the two sources of variation in meiosis?
•crossing over
- independent assortment
Is continuous variation influenced by the environment?
Can be
Is discontinuous variation influenced by the environment?
No
Define polygenic
A characteristic is controlled by two or more genes
Define multifactorial
Involving both genetic and environmental factors
If a mutation occurs in a somatic cell
just the individual is affected.
If a mutation occurs in a hamate
could pass to offspring.
Define selection pressures
Environmental factors that affect the chance of survival of an organism
What do selection pressed effect
the allele frequencies of a population through natural selection
Example of natural selection - lions = refer to allele frequency
o The lions with the advantageous alleles are more likely to catch prey and survive
o These lions will produce more offspring
o The allele frequency will increase in the population
o The resulting adaptation will become more common in the population
o The species will be better suited to their environment
Three types of adaptation
Anatomical
Physiological
Behavioural
Anatomical adaptations
o Structural or physical features
Example of anatomical adaptations
white fur of a polar bear provides camouflage in the snow so it has less chance of being detected by prey
Physiological adaptations
o Biological processes within the organism
Example of physiological adaptations
Mosquitos produce chemicals that stop the animal’s blood clotting when they bite, so that they can feed more easily
Behavioural adaptations
o The way an organism behaves
Example of behavioural adaptations
Cold-blooded reptiles bask in the sun to absorb heat
What is evolution
change in adaptive features of a population over time as a result of natural selection
What is convergent evolution
species that do not share a recent common ancestor = live in different parts = show very high levels of similarity in terms of adaptations
When does convergent evolution occur
when the two habitats, in which the two species have evolved and to which they have become adapted, are very similar
Example of convergent evolution - spec
• marsupial moles = Australian desert + European mole
Similarities between the two moles
• Both species burrow through soil and very rarely emerge in daylight.
o short and powerful limbs, with large, strong front claws for shovelling soil out of the way
o no external ears = not necessary underground + have simple ear canal openings in their fur
o limited eyesight = not needed
o very similar, highly silky and fine fur that allows them to move efficiently underground
What is genetic variation
• differences in DNA base sequences between individual organisms within a species population
What happens if genetic variation is passed on through generations
results in genetic diversity
What is genetic diversity needed for
Natural selection
How does selection pressures impact natural selection
increase the chance of individuals with a specific (more advantageous) phenotype surviving and reproducing over other
What is fitness
ability to survive and pass on its alleles to offspring
What does it mean to have a higher fitness
individuals with the favoured phenotypes = better suited to their environment
Example of selection pressures
Environmental factors
What would happen if all the offspring of every individual survived to adulthood and reproduced
population would experience exponential growth
How does natural selection happen = refer to alleles
• Random mutation can produce new alleles of a gene
• the new alleles may benefit their possessor, leading to an increased chance of survival and increased reproductive success
• The advantageous allele is passed onto the next generation
• As a result, over several generations, the new allele will increase in frequency in the population
GCSE natural selection exam answer
• Within a species, there is always variation and chance mutation
• Some individuals will develop a phenotype (characteristic) that gives them a survival advantage and this allows them to:
o live longer
o breed more
o be more likely to pass their genes on
• Repeated over generations, the ‘mutated’ phenotype will become the norm
• If genetic differences accumulate and the population is isolated then a new species may evolve
What are antibiotics
• chemical substances that inhibit or kill bacterial cells with little or no harm to human tissue
Natural selection in bacteria - refer to antibiotic resistance
• variation caused by mutations = bacteria
• A chance mutation might cause some bacteria to become resistant to an antibiotic
• When the population is treated with this antibiotic, the resistant bacteria do not die
• means the resistant bacteria can continue to reproduce with less competition from the non-resistant bacteria, which are now dead
• Therefore the genes for antibiotic resistance are passed on with a much greater frequency to the next generation
Mutations in bacteria - what would change
o mutation may change an existing gene within the bacterial genome, causing it to give rise to a nucleotide sequence that codes for a slightly different protein that is not affected by the antibiotic being used
Why do mutant genes have an immediate effect on bacteria
o As bacteria only have one copy of each gene, a mutant gene will have an immediate effect on any bacterium possessing it
How do bacteria inherit resistance - 2
• Vertical transmission / Horizontal transmission
Vertical transmission
• Bacteria reproduce asexually by binary fission
• reproduce like this very rapidly (on average, every 20 minutes)
• If one bacterium contains a mutant gene that gives it antibiotic resistance, all of its descendants (millions of which can be produced in a matter of hours) will also have the antibiotic resistance
• This form of transmission enables antibiotic resistance to spread within a bacterial population
Horizontal transmission
• plasmids often contain antibiotic-resistant genes
• plasmids are frequently transferred between bacteria = even from one species to another
• occurs during conjugation – DNA from the bacterial chromosome can also be transferred in this way
• bacterium containing a mutant gene that gives it antibiotic resistance could pass this gene on to other bacteria
Conjunction
when a thin tube forms between two bacteria to allow the exchange of DNA
Key process in vertical + horizontal
Vertical = binary fission
Horizontal = conjunction
Difference between vertical + horizontal transmission
Vertical = resistance spreads within bacterial population
Horizontal = resistance spreads between or within bacterial populations
Is vertical or horizontal more dangerous and why
Horizontal = o how ‘superbugs’ with multiple resistance have developed = MRSA
What has effected this natural selection of bacteria
Humans
How have humans helped to develop this natural selection in bacteria
• Incorrect use of antibiotics
o Treatment of non-serious infections
o Routine treatments in animals in agriculture
o Failure to finish prescribed course
Types of pesticides
• Insecticides (kill insect pests)
• Herbicides (kill plant pests)
• Fungicides (kill fungal pests)
• Molluscicides (kill slug and snail pests)
• Rodenticides (kill rodent pests)
Insecticides that are sprayed on crops act as…
selective agents
Selective agents
any environmental factor that influences the survival of a particular species and so drives natural selection in that species
Example of how selective agents work
any insect that has a mutation making them resistant to the insecticide will survive and reproduce, passing on the resistant gene
Consequences of antibiotic resistance
• New resistant strains are constantly emerging due to the overuse of antibiotics
• Commonly prescribed antibiotics are becoming less effective for many reasons.
- development of superbugs - MRSA
Why are new resistant chains of bacteria constantly emerging
o By using antibiotics frequently, humans exert a selective pressure on the bacteria, which supports the evolution of antibiotic resistance
Why are antibiotics becoming less effective
o Overuse of antibiotics and antibiotics being prescribed when not necessary
o Large scale use of antibiotics in farming to prevent disease when livestock are kept in close quarters, even when animals are not sick
Consequences of pesticide resistance
problem for the security of future food supplies
How are we planning to fix the pesticide resistance problem
armers are also encouraged to use other forms of insect pest control, such as:
o Biological control (introducing a natural parasite or predator of the pest insect)
o Using crops that have been selectively bred or genetically modified to be pest-resistant
behavioural adaptations example
courtship
migration
hibernation
physiological adaptations example
poison production
antibiotic production
water holding
