End Of Topic 5th Form Test Flashcards
What is the Linnaean system
- developed by carl Linnaeus in 18th century
- based on visible characteristics of organisms
Hierarchy of classification
- kingdom
- phylum
- class
- order
- family
- genus
- species
Binomial naming system
- uses genus + species (Homo sapiens)
- used worldwide to avoid confusion
Modern classification name
Three-domain system
Who was 3-domian system system developed by
- carl woese in 1990 based on biochemical and genetic evidence
Three domains
- archaea: primitive bacteria found in extreme environments
- bacteria: “true bacteria”, including common pathogens
- eukaryota: all organisms with a nucleus (protists, fungi, plants, animals)
Evolutionary trees
- shows how species are related
- based on fossils and genetic data
What is evolution
The gradual change in inherited characteristics of a species over time due to natural selection
Who was evolution proposed by
Charles Darwin in 1859 on the origin of species
What is natural selection
Individuals with the most advantageous traits survive, reproduce and pass of their genes
Key evidence for evolution
- Fossil record: shows gradual changes over millions of years
- Comparative anatomy: similar body structures suggest common ancestry
- Genetics & DNA evidence: similar DNA sequences in different species suggest they evolved from a common ancestor
- Antibiotic resistance in bacteria: a real-time example of evolution happening today
What are fossils
Fossils are preserved remains or traces of organisms from millions of years ago
How fossils form
- Lack of decay: some organisms don’t decay due to oxygen, moisture or extreme temperatures
- Mineral replacement: hard part of organisms are replaced by minerals
- Preserved traces: footprints, burrows and rootlet traces remain in rock
Why are fossils important
- show how organisms have gradually changed over time due to
- provide evidence of extinct species
- help scientists understand transitional forms (eg. How fish evolved into amphibians)
Limitations of the fossil record
- soft bodied organisms rarely fossilise
- geological activity can destroy fossils
- some species may have existed for short time, leaving few fossils
What is extinction
Extinction occurs when a species completely dies out and no individuals remain
Causes of extinction
- new predators: humans hunting dodos
- new diseases: could wipe out a species
- competition: a more successful species may outcompete another
- environmental: climate change, rising temperatures,loss of habitat
- catastrophic events: asteroid impacts, volcanic eruptions (dinosaurs)
What is a mass extinction
Periods when a huge number of species become extinct
Why do bacteria evolve quickly
- bacteria reproduce as quickly as every 20 minutes
- mutations lead to new traits, including antibiotic resistance
How antibiotic resistance spreads
- Mutation occurs, making bacterium resistant
- Antibiotics kill non-resistant bacteria, but resistant ones survive
- Resistant bacteria reproduce, passing on resistance
- New strain spreads, making infections harder to treat
How to reduce antibiotic resistance
- doctors should avoid over prescribing antibiotics
- patients must finish their full course to kill all bacteria
- limit antibiotic use in farming to stop resistance spreading to humans
Why is antibiotic resistance a problem
- developing new antibiotics is expensive and takes decades
- bacteria evolve faster than new antibiotics are created
Non specific defence mechanisms
- skin - waterproof barrier with anti microbial secretions
- nose - mucus and hairs trap microbes
- trachea & bronchi - lined with cilia that sweep mucus and pathogens away
- stomach - produces hydrochloric acid to kill bacteria
Role of immune system
- Phagocytosis: white blood cells engulf and digest pathogens
- Antibody productions: special proteins that recognise and destroy specific pathogens
- Antitoxin production: neutralise harmful toxins
