topic 3 Flashcards
3.1
classification?
Why is a classification system needed?
Classification is the process of naming and organising organisms into groups based on their characteristics.
- provides a catalogue of past + present species
- An internationally recognised way of referring to particular organisms = allows scientists around the world to work together
- use classification to look at evolutionary patterns + makes ancestral relationships clear
What’s Taxonomy?
origins of taxonomy?
Taxonomy is the science of describing, classifying and naming living organisms.
-Carl Linnaeus used physical features (morphology) to group organisms
-devised a hierarchical structure for classification - still used today
-naming organisms using Binomial system.
-split all life into taxonomic groups = 2 kingdoms - animal + plant
-split them further to phylum and then species
- technology + DNA analysis = realised there was 2 distinct groups (eukaryote / prokaryote)
=new taxonomic group added above kingdom - Domain
=3 Domain system introduced
(Archaea, Eubacteria, Eukaryota)
3 Domains (largest taxonomic groups)
- Bacteria
contains 1 kingdom:
Eubacteria - true bacteria
- Archaea
contains 1 kingdom:
archaebacteria - ancient bacteria that can withstand extreme conditions/environments.
- Eukaryota
contains 4 kingdoms:
- Protista
- Fungi
- Plant
- Animal
The 3 domains?
Evidence for the 3 Domains?
3 Domains: Archaea, Bacteria, Eukaryota.
Evidence:
- Differences in sequences of nucleotides in Cell’s ribosomal RNA
- Cell membrane lipid structure
- Sensitivity to antibiotic + toxins
The binomial system?
originally used by Linnaeus, but now universally among biologists.
every organism given 2 names : genus name and species name. [ Homo sapiens]
-must use italics
-genus name UPPER CASE LETTER and species lower case
-after first use, its abbreviated/shortened to initial of genus and then the species name. [H. sapiens]
What are the levels of classification?
Domain (Drunk/Dead)
Kingdom (King)
Phylum (Phillip)
Class (Came)
Order (Over)
Family (For)
Genus (Goat)
Species (Stew)
The Eukaryota Kingdoms
- Plantae
- Autotrophs : make own food through photosynthesis using chlorophyll in chloroplast
- have cellulose cell wall
- Animalia
- Heterotrophs: eat others for food
- no cell wall
- capable of whole body movement
- Fungi
- Live of dead organisms using extracellular digestion
- Chitin cell wall
- reproduce by spores
- Protista
- strange set of microscopic organisms that can have features of the other kingdoms.
Sexual dimorphism?
Molecular phylogeny?
Species?
Sexual dimorphism: when there’s a big difference in the appearance of the male + female of a species.
Molecular Phylogeny: The analysis of genetic material of organisms to establish their evolutionary relationships.
Species - group of organisms with similar characteristics that can interbreed to produce fertile offspring.
Problems with this definition of species?
- sometimes they can be geographically separated + cannot interbreed…Despite being same species
- Plants often interbreed with different species and produce fertile offspring
- sometimes fertile hybrid offspring are produced
- many organisms cannot reproduce sexually
- Fossil organisms cannot reproduce sexually + lack DNA
Improvements to the definition of species?
Groups of organism with similar characteristics that are all POTENTIALLY capable of breeding to produce fertile offspring.
Problems with identifying NEW species
- is it just new in the area?
- has it been previously identified but thought to be extinct?
- is it completely new species or just a variation of a current species?
- some species look very different but are acc the same
There are many different methods of defining a species.
- Morphological species model?
limitation?
based solely on the morphology/ appearance of the organism.
-Sexual dimorphism may make different genders of the same species look very different (peacocks)
-appearance if organism can be affected by different things such as environment/ predators as some change appearance to escape predators
- Biological / reproductive concept?
limitation?
a group of organisms with similar characteristics than interbreed to produce fertile offspring.
- Not all organisms in a species can attempt to interbreed to produce fertile offspring as they may be geographically isolated.
- earlier limitations on species definition
Ecological species model?
limitation?
Based on the ecological niche (role they play in their environment) occupied by an organism.
-Niche definition vary + many species occupy more than 1 niche
Mate-recognition species model?
limitation?
Based on unique fertilisation systems - including mating behaviour.
-Many species will mate with or cross-pollinate with other species - but are never the less different species
Genetics species model?
limitation?
Based on DNA evidence
-Time consuming and expensive to collect data and study them -historically
-need to decide how much genetic differences make 2 organism different species?
Evolutionary species model?
limitation?
Based on shared evolutionary relationships between species
-Not always a clear evolutionary pathways for a particular organism = not always easy to apply
What is DNA sequencing?
DNA profiling?
Why are they useful?
DNA sequencing - process where the base sequences of all or part of the genome of organisms are worked out. [it leads to DNA profiling]
DNA profiling - process where the non-coding areas of DNA are analysed to identify patterns.
These patterns are unique to individuals, but similarities of patterns can be used to identify relationships between individuals and species even.
What is bioinformatics?
why is it useful?
Bioinformatics - the development of the software + computing tools needed to organise and analyse the large amount of biological data (that wouldn’t be possible to be done by humans as there’s too much data).
Allows us to make sense and use the many information generated by DNA sequencing and profiling to identify species and the relationships between them.
Examples of when DNA profiling was used
[don’t need to know]
-external conditions result in major differences in appearance = red deer in one area looked very different to another area (much longer + broader) = thought different species = DNA evidence showed they’re same.
- A plant disease thought to be caused by a single fungus = DNA evidence showed that there was at least 6 different species of this fungi pathogen which had same effect on crops.
-Caviar tin - DNA profiling found that 25% of tins contained eggs of other species that weren’t caviar.
-DNA analysis used in ethics of marketplace - DNA analysis found horse meat in European beef, chicken, pork products.
DNA barcodes?
[don’t need to know]
large group of scientists (IBOL - International Barcode of Life Project + others) developing DNA barcoding as a global standard of species identification.
Involves looking at short genetic sequences from a part of the genome common to particular groups of organisms. Fast and cheap ad numbers of species barcoded increasing all the time.
Important that every specimen used to produce the definitive bar codes is preserved for reference.
Will not replace taxonomy - support it.
Makes it easier to identify plants with no flowers/fruit, immature animals.
Quick identification of invasive species eg makes it easier to deal with threat.
Gel Electrophoresis?
A way of separating DNA / RNA fragments / proteins / amino acids according to their size and charge.
- Chemicals to be compared placed in gel medium in pH buffer solution, with the known DNA / RNA.
- The DNA molecules being identified are cut into fragments by restriction enzymes at specific sites.
- The DNA fragments added to a gel with dye which binds to the fragments + makes them fluorescence under UV light. fragments are inserted into a well at the end of a piece of agar gel.
- Electric current passed through apparatus and DNA fragments move towards the positive anode as their negative charge on the phosphate group in DNA attracts.
- Fragments move at different rates depending on mass and charge. The smaller mass / shorter pieces of DNA fragments move faster through gel matrix and therefore further from the wells than the larger fragments
- plate is placed under UV light after. The DNA fluoresces and shows up clearly so pattern of different bands can be identified
(Probes are single-stranded DNA sequences that are complementary to the regions of interest)
How does the scientific community evaluate and validate data and theories?
- Peer review - data sent to experts in their field so they read and review to check the validity of it. If its valid enough, data will be published in scientific journals.
- Scientific conferences - scientists working in same field get together to discuss ideas and analyse and challenge the validity of results that are being presented.
[also allows exchange of ideas/data/techniques between scientists around the world] - peer reviewed scientific journals
For many years biologist divided organisms into 2 large domains (eukaryotes or prokaryotes).
The theory was that eukaryotes had evolved from prokaryotes billions of yrs ago - how?
- cell engulfed prokaryotic organism capable of
A. aerobic respiration + B. photosynthetic organism. - They’re not digested by chance, A. allowed for efficient respiration so cells grow and reproduce more and B. provided cell with food through photosynthesis giving cell adv to grow and reproduce more.
- become permanent features in cell and copies are made and passed to daughter cells in reproduction.
A. as mitochondria B. as chloroplast
But then new theory about 3 domains not 2?
-looked at internal structures of prokaryotes + eukaryotes and compared + used bioinformatics to process the data generated.
-2 prokaryote domains: Archaea + Bacteria
-Eukaryotes
-All probably had a common ancestor
-some evident suggest that Archaea are more closely related to eukaryotes than bacteria.
why was the 5 kingdoms under scrutiny and more biologist use the 6 kingdom classification system instead?
due to the work done using biochemical and DNA evidence.
The prokaryotes are no longer regarded as a single mass of bacteria - the archaea and Eubacteria are 2 very different groups of organisms.
- Archaebacteria (survive extreme conditions)
- Eubacteria (true bacteria)
- Protocista (single celled organisms)
- Fungi
- Plantae
- Animalia
Why is the three-domain model of classification more accepted by the scientific community
Takes into account research of a particular ribosomal unit.
More accurately represents evolutionary relationships than five-kingdom.
3.2
What is evolution?
A gradual change in the genetic composition of a population of organisms over several generations, as a result of natural selection acting upon variation, leading to a different phenotype overtime.
Darwin’s theory of evolution?
- there is genetic variation amongst a group of organisms /specie due to mutations = alleles
- there is competition within species for food/mate/space/predators [selection pressure]
- organisms with better adapted characteristics (alleles) for this change in environment survive whilst those with disadvantageous genes die
- Survivors pass on the advantageous allele to offspring + overtime it becomes more common in population.
Why did people not accept his theory straight away?
As they didn’t have knowledge about chromosomes /DNA / genetic bases of variation at the time
Ecology?
What are niches?
Adaptations to niches?
what are the 3 types of adaptations?
Ecology is study of interaction of organisms with each other and with the environment in which they live in.
A niche is the role of an organism within the habitat in which it lives.
A successful species is well adapted to its niche = have characteristics that will increase its chances of survival and reproduction.
- Anatomical adaptations
- Physiological adaptations
- Behavioural adaptations
Anatomical adaptation?
Adaptation involving the form and structure of an organism.
EG:
-sticky hair on sundew plant allowing it to capture insects
-thick layer of blubber on seals + whales to keep them warm
Physiological adaptations?
Adaptations involving the way the body of the organism works.
EG:
-Diving mammals can stay under water much longer than non-diving mammals without drowning. once underwater = heart rate drops dramatically = blood pumped around body less = o2 in blood is used up less quickly.
-Snakes make venom to protect themselves from predators
Behavioural adaptations?
Adaptation involving changes in programmed or instinctive behaviour making organism better adapted for survival.
EG:
- many insects/reptiles orientate themselves to get maximum sunlight when temp is cool to warm up and move fast enough to get food and avoid predators.
- when warm, they change their orientation to minimise exposure to sun / shelter from it.
-birds migrating to warmer area / avoid harsh conditions.
What is directional selection?
Selection pressure?
Directional selection - natural selection showing a change from one dominant phenotype to another in respond to change in environment - one phenotype is favoured over all the others.
Selection pressure - pressure exerted by a changed environment / niche on individuals in a population, causing changes in population due to natural selection.
Bacteria resistance v antibiotics
-origins
-1st antibiotic - Penicillin - worked rly well
-did not kill ALL bacteria = penicillin resistant bacteria 1 yr later due to mutations - enzyme (penicillinase that split penicillin molecule = no longer worked)
2nd antibiotic made - methicillin
-methicillin resistance increased
= there’s constant race between bacteria resistance and development of medicine used against them
evolution of antibiotic resistance by natural selection?
- original population has variation due to mutations
- Antibiotic given
(acts as selection pressure) - Bacteria with resistant alleles more likely to survive
- Pass advantegous allele to offspring and new population has more resistant bacteria
- repeat = only resistant bacteria survive so new population almost entirely resistant to that antibiotic
Reasons for increased antibiotic resistance?
- over prescription of antibiotics when not needed
=the more antibiotics = higher chance of resistance in future if ppl keep taking antibiotics when not needed (EG when they have virus) - Don’t complete dose of antibiotics
=doesn’t kill all bacteria if u don’t finish dose = leaves more bacteria to be resistant - Most antibiotics (2/3) are used in agriculture/farming to help them grow faster + prevent animals from getting ill. = leads to resistant strains = we eat them = pass resistance to us?
What is speciation?
main cause for it?
different ways this can occur?
Speciation is the formation of a new species.
Reproduction isolation is main factor in speciation.
Isolating mechanisms:
- geographical isolation
- ecological isolation
- seasonal / temporal isolation
- behavioural isolation
- mechanical isolation
- Geographical isolation?
A physical barrier such as river/mountain separating individual from original population
- Ecological isolation?
2 populations from original species inhabit same region but develop preferences to different parts of habitat
- Seasonal isolation / temporal isolation
the timing of flowering / sexual receptiveness in some parts of a population drifts away from norm of a group = lead to the 2 groups reproducing several months apart
- Behavioural isolation
changes in the courtship/ ritual / mating pattern so some animals no longer recognise each other as potential mates.
eg due to mutations changing colour/pattern of markings.
- Mechanical isolation?
Mutations occur that change the genitalia of animals - making it physically impossible for them to reproduce anymore as their genitalia no longer fit.
what are the 2 types of speciation?
Sympatric speciation
Allopatric speciation
Sympatric speciation
Speciation that takes place between populations of a species living in the same place,
they become reproductively isolated through
-mechanical isolation
-behavioural isolation
-seasonal isolation
=reproductive isolation reduced breeding + gene flow between population.
Allopatric speciation
What is frequently followed after allopatric speciation?
Speciation that takes place when populations are physically or geographically separated
=no interbreeding or flow of gene between the populations.
Allopatric speciation is frequently followed by adaptive radiation.
Adaptive radiation?
The process by which one species evolves rapidly to form a number of different species that are all fill different ecological niches.
- Species arrives into a geographical location + it disperses (spreads) throughout area.
- Ecological niches filled depending on the different selection pressures of each area
- New species formed in each areas they displaced to as they adapt to the areas they’re living in.
3.3
What is biodiversity?
The variety of living organisms in an area.
can be assessed at different levels
-within a habitat at species level (index of biodiversity)
-within species at genetic level (variety of alleles)
Why is biodiversity important?
Organisms in an ecosystem are interdependent = rich biodiversity allows large ecosystem to function better and self-regulate.
provides genetic variation that will help us cope with problems such as findings new medicines / climate change.
assessing biodiversity at the species level
1. Species richness?
2.The relative abundance?
2 main factors when measuring biodiversity at species level
- species richness -number of different species in an area
- The relative abundance of the different types of organisms that make up the species richness -the evenness of distribution of the different species
Biodiversity hotspot?
An area with high level of biodiversity.
wet tropics generally have highest biodiversity
Endemism?
number of endemic species in an area.
species that are found no where else.
Relative species abundance
Relative species abundance - refers to the numbers of species in an area.
measuring biodiversity formula?
D = N (n-1) / {n(n-1)
D= diversity index
N = total number of organisms of all species
n = total number of organisms of each individual species - the abundance of the different species
{ = the sum of all values that follow (need to calculate n(n-1) for each species then add them together)
How biodiversity varies.
High biodiversity is seen in..
- areas where photosynthesis rates are very high, as this can support more niches
- areas where organisms can grow and reproduce rapidly
- very stable ecosystems as this allows many complex relationships to develop between species
areas of extreme conditions = low biodiversity as cannot support all life
less hostile environments = higher biodiversity
why is biodiversity not constant?
not constant
- can vary with the time of the day
eg bats flying on warm evening wont be seen the next morning - vary in distinct seasons = so it will change throughout the year
eg number of plant species in summer is much higher than in winter
how can biodiversity be measured WITHIN a species?
gene pool?
allele frequency?
Genetic diversity is a measure of the level of difference in the genetic make-up of a population.
They look at the gene pool of a species - all of the genes in the genome, including all the different variants of each gene.
Mutations increase the gene pool of a population by increasing the number of different alleles available.
= allele frequency - is the frequency which a particular allele appears within a population.
Ethical reasons for maintaining biodiversity
- if we destroy biodiversity of ecosystem = denying future generations the opportunity to use these renewable natural resources
- if biodiversity is lost when species become extinct = unique combinations of DNA lost = unethical for this to occur dur to human behaviour/competition for habitat
- natural world + biodiversity is great source of leisure for many ppl + should be protected + maintained
- human activities have potential to cause mass extinction through global climate change and this interfere with biodiversity on massive scale = very unethical
Maintaining biodiversity for economic reasons
(ecosystem services)
ecosystem services are services provided by the natural environment that are of benefit to people
Provisioning services
ecosystems provide provisions we need:
- food
- fibres for clothes
- building materials
- fresh water
- medicine
=greater biodiversity = more available for us
regulating services
ecosystem helps us maintain or regulate our environment.
-water purification
-sewage treatment
-maintaining air quality
-pollination
-climate of our planet
supporting services
biodiverse ecosystems provide support for other ecosystems services we need
-soil formation
-nutrient cycling we need to grow food to eat
cultural services
A biodiverse and health ecosystem important for human health and well being
- improve mental health by taking nature walks
- recreational purposes such as ziplining
- education by visiting to observe animals and plants
economic expense of biodiversity problems
if biodiversity lost - not easy to regain - expensive
if biodiversity neglected/destroyed = expensive
human activities causing environmental disasters such as flood/forest fires =costs lots of money to put it right
soil erosion = cant farm = no food = malnutrition + loss of money for farmers
What is conservation?
2 methods for it?
Conservation - refers to maintaining and protecting a living and changing environment.
- Ex-situ conservation - conservation that takes place outside their natural habitat ( eg in zoos / seed banks )
- In-situ conservation - conservation of living organisms that takes place in the natural habitat of the organism.
Ex-situ conservation for plants + problems
plants
- seed banks collect and conserve seeds = maintain genetic diversity
-preserve many plants as many seeds remain capable of germination for up to 200 years
-seeds usually small = large numbers can be stored relatively cheap in small space
-potential new plants for future, if get extint, can plant the seeds
-some seed do not store well (coconut/mango/avocado)
=conserved differently - field gene bank
-but field gene banks take lots of space and work
Ex-situ conservation of animals + problems
if conditions of wild put them under threat of extinction = conserved in zoos /wildlife parks / breeding programmes.
- breeding programmes - endangered species bred in zoos and park in attempt to save them from extinction
- goal is to reintroduce them into wild after
-
- not enough space/sufficient resources in zoos/parks for all endangered species
- often difficult to provide perfect conditions for breeding in artificial habitat
- reintroduction into wild can be very expensive and time consuming + will fail unless original reason for species being at risk of extinction has been removed
- animals bred in captivity may find it difficult adjusting to unsupported life in wild
in-situ conservation + problems
in natural surrounding - primary conservation stratergy
- national parks protect large areas in UK = conserve animals + plants living together within their natural relationships
- land is protected from human use such as development + deforestation
- protect native species
- genetic diversity of ecosystem + threats to biodiversity monitored such as exploitation of resources
- habitat restoration + recovery, + management recovery programmes for threatened/endangered species
-
- however poachers may still kill animals for money for their skin/horn
- conflicts about the land being protected = needs of ppl living there and needs of animals/plants
- money spent on conserving areas should be spent on education / health care etc
How sustainability can help
habitats can be conserved with less conflict by encouraging sustainable methods of land use
- harvest trees selectively and replant for future
=biodiversity maintained whilst human needs met - use organic fertilisers + biological pesticides + planting in rotations to avoid soil erosion
allows humans to use the forest for income and needs whilst not harming biodiversity
