TOPIC 3: CLASSIFICATION Flashcards
What are the stages of classification system according to the hierarchy? (Include an example)
- Domain (Eukaryota)
- Kingdom (Animalia)
- Phylum/division (Chordata)
- Class (Mammalia)
- Order (Primates)
- Family (Hominidae)
- Genus (Homo)
- Species (Sapiens)
What does the binomial name tell you about the organism?
First part of the binomial name tells us the genus, the second part tells us the species.
Define species.
A group of living organisms with similar characteristics which interbreed to produce fertile offspring.
Ecological species model
Based on the ecological niche occupied by an organism.
Limitations: Niche definitions vary and many species occupy more than one niche
Mate-recognition species model
Based on unique fertilisation systems, including mating behaviour
Limitations;
Many species will mate or cross-pollinate and produce fertile hybrids but be of the same species
Genetic species model
Based on DNA evidence
Limitation: Some people find it hard to decide how much genetic difference makes two organisms members of different species.
Evolutionary species model
Based on shared evolutionary relationships between species/organisms.
Limitations: Sometimes there is not always a clear evolutionary pathway for a particular organism
What are the limitations of the species model?
- Finding evidence – many living species have never been observed mating.
- Plants of different but close species frequently interbreed and produce fertile hybrids
- Many organisms do not breed sexually but asexually so definition involving reproductive behaviour is irrelevant
- Sexual dimorphism – There is a great deal of variation between males and females of the same species
Distinguish between analogous characteristics and homologous characteristics.
Analagous characteristics have a similar structures but different evolutionary origins.
Homologous characteristics are structures of a similar origin but different functions
Outline allopatric and sympatric speciation.
Allopatric speciation is caused by geographical separation whereas sympatric speciation occurs within the same habitat caused by different niches (behavioral/courtship/feeding differences)
Both processes lead to the isolation of sub populations
Define Speciation
Speciation is the formation of a new species by the splitting /separation of an existing species
How can gel electrophoresis be used to distinguish between species and determine evolutionary relationships?
DNA AND RNA SEQUENCING
- DNA sample + restriction enzymes
- DNA is cut into fragments
- DNA fragments loaded into wells in agar gel
- DNA molecules negatively charged
- DNA molecules move when potential difference
- Lighter molecules move further up gel
- Compare sample from organisms – more closely related organisms will have similar band patterns
List the ways in which scientists check validity of investigations
- Scientific journals
- Peer review
- Conferences
Describe the differences between the 5 kingdoms
- Prokaryotae – Bacteria and cyanobacteria, unicellular, reproduce asexually.
- Protoctista – Eukaryotes, mostly unicellular, mainly reproduce sexually.
- Fungi – Eukaryotes, mainly multicellular, non-motile, heterotrophic nutrition, sexual and asexual reproduction.
- Plantae – Eukaryotes, multicellular, non-motile, autotrophic nutrition, sexual and asexual reproduction.
- Animalia – Eukaryotes, multicellular, motile heterotrophic nutrition, mainly sexual reproduction but some reproduce asexually.
Describe the differences between the 3 domains.
See image
Define the term ecological niche.
How an organism feeds, where it lives and how it behaves in relation to other organisms in a habitat.
Define Anatomical adaptions
form and structure of the organism e.g. thick layer of blubber on whales
Define Physiological adaptations
the way the body of the organism works and differences in biochemical pathways e.g. diving mammals can drop their heart rate to conserve oxygen
Define Behavioural adaptations
change to programmed or instinctive behaviour e.g. ectotherms orientate themselves to maximise sunlight keep warm
Define the term natural selection.
The process by which organisms that are best adapted in a particular environment are most likely to survive and reproduce, passing on their advantageous alleles to their offspring
Define the term evolution
The development of new types of living organism from pre-existing types by the accumulation of genetic differences over long periods of time
What are selection pressures? (give some examples)
The pressure exerted by a changed environment or niche on individuals in a population. E.g. availability for resources, availability of a mate, predation, competition, disease
Predators Availability of resources eg shelter and water Nutrient Supply eg food source Disease/Pathogenic spread Accumulation of wastes
Phenomena eg natural disasters
Abiotic factors
Weather conditions
What are the arguments to support natural selection and evolution?
- The DNA molecule is the same in all organisms this supports darwins idea of descent from a common ancestor
- The individuals in a species are not all identical
- Natural selection results in offspring with favourable characteristics
What are the isolation methods?
- Geographical isolation – a physical barrier such as a river/mountains separate individuals
- Ecological isolation – two populations inhabit the same region but develop preferences for different areas
- Seasonal isolation – changes occur in the courtship ritual, display or mating pattern so that some animals do not recognise others as being potential mates
- Mechanical isolation – a mutation occurs that changes the genitalia of animals, making it physically possible for them to mate successfully.
How does isolation lead to allopatric and sympatric speciation? (please provide an example)
- Allopatric speciation – When two populations are physically or geographically separated from each other by a barrier. This prevents interbreeding and mixing of their gene pools.
- Sympatric speciation – when two populations are still able to mix freely in the same area but accumulate changes in their gene pools, which are sufficient to prevent interbreeding.
Giving a named example, explain stabilising selection.
Where conditions are favourable and not changing, so pressures to change in one way are less. E.g. birth weight
Giving a named example, explain directional selection.
Where environments are changing and there is a clear advantage in the population changing in one direction. E.g. antibiotic resistance
Describe the evolutionary race between pathogens and the development of medicine.
- Bacteria cause a wide range of disease
- 1940s introduction of antibiotics
- Signs of resistance emerged rapidly
- New antibiotics e.g. methicillin produced to counteract evolutionary race
- Further signs of resistance to multiple antibiotics
What is biodiversity?
The variety of plant and animal life in the world or in a particular habitat
Why is biodiversity important?
- Provides genetic variation – greater variety of crops
- Food security
- Protection of water resources
- Medicinal resources
- Recovery from unpredictable events
- Research and education
Define species richness
The number of different species in an area
What equation would you use to calculate an index of diversity?
D = N(N-1)/∑n(n-1)
N= Total number of Organisms of all species n= Total number of Organisms of each individual species
What are the ethical and economic reason for the maintenance of biodiversity?
- We are denying future generations of the opportunity to use these resources
- Great source of pleasure for many so should be protected
- Biodiversity is lost with extinction losing unique combinations of DNA
- Human activities reducing biodiversity through climate change is considered unethical.
What is ex-situ conservation and what are the limitations?
- Conservation out side of the natural habitat E.g. in zoos
- There is not enough space or sufficient resources in zoos
- Difficult to provide the right conditions
- Reintroduction to the wild can be unsuccessful
- Greater problems adapting to unsupported life
What is in-situ conservation and what are the limitations?
- Conservation takes place in the natural habitat of the organisms. E.g. national parks
- Conflicts between needs for living people and needs of animals
- Some illegal operations occurring
- Non always sustainable
Define Molecular Phylogeny
Molecular Phylogeny is the analysis of the genetic material of organisms to establish their evolutionary relationships
Evidence for the three domain system of classification
Analysis of ribosomal RNA from bacteria, Archaea and Eukarya showed the same nucleotide sequences in Archaea and Eukarya but different sequences in Bacteria
What shows the DNA bands after going through electrophoresis
An Electrophoretogram
