B15- Genetics and Evolution Flashcards
describe mendel’s discoveries
carried out breeding experiments on peas
he cross bred smooth, wrinkled, green and yellow
suggested there were separate units of inherited material and some characteristics were dominant over others so they never got mixed together
when and why was mendel’s work accepted
16 years after his death (1884) as people then could see chromosomes under a microscope and observed cell division
how was dna discovered
in the 1950s rosalind franklin and maurice wilkins observed dna by xray
what is lamarck’s theory of evolution
the way organisms behaved affected the features of their body- if animals used something over a lifetime this feature would grow and develop, if a feature wsn’t use it would shrink and be lost
what were problems with lamarck’s ideas
no proof
people didn’t like the idea of being descended from worms
what is darwins theory
all living organisms have evolved from simpler life forms which has come about by a process of natural selection
what were darwin’s main ideas
- individual organisms in a species show a range of variation for a given characteristic
- survival of the fittest as reproduction gives more offspring than the environment can support
- when the ‘fittest’ survive they pass on the characteristics that have enabled them to survive
why did darwin take so long to publish his ideas
he was conscious that he needed evidence so he spent years carrying out experiments but he was pushed to publish when he found out that alfred russell wallace had similar ideas
why was darwin’s ‘origin of species’ only gradually accepted in some areas
challenged the religious view that was widely accepted
people felt there was not enough evidence
no way to explain how variety and inheritance happens as genes and genetics were not known of until 50 years after Darwin published
how is alfred russel wallace
had similar ideas to darwin but darwin published before him so he focused on the idea of speciation and developed theories on the role of geographic isolation in the formation of species
what is speciation
when a new species forms as a result of geographical isolation so alleles that allow the organism to survive in the new conditions are selected and variation increases because of natural selection. population changes until they can no longer interbreed with the old population and a new species is formed
how do populations become isolated
new mountain range or river
earthquakes and volcanoes
climate change in only one area
what is an endemic species
when a species evolves in isolation and is found in only one place in the world
what is mineralisation
harder parts of the animal or plant are replaced by minerals
how are animal and plant fossils formed
when an animal or plant does not decay because there is no oxygen or posionous gases kill bacteria needed for decay then animals/ plants are preserved almost intact
what are examples of traces as fossils
footprints, burrows, eggs, droppings
what are the reasons for the fossil record being incomplete
many of the earliest organisms were soft bodied so left little trace
many get destroyed by geological activity
many still to be found
many didn’t form fossils as the conditions for fossil formation were rare
what are natural causes of extinction
change in temperature new predators new diseases more successful competition flooding drought volcanic eruptions asteroid collisions
what causes mass extinction
often a single catastrophic event eg asteroid collision o volcanic eruption
what caused dinosaur extinction
giant asteroid collision in mexico which would have casued fires, earthquakes, landslides and tsunamis. theory is that dust in the atmosphere amde everywhere dark, temp dropped and 50-70% of species died
what is antibiotic resistance
when a bacteria that used to be killed by a drug has a natural mutation meaning they are no longer affected by it
how can you prevent more resistant strains of bacteria forming
don’t overuse antibiotics- doctors cut down on prescriptions
finish course of medicine to ensure there are no bacteria surviving that could mutate and form resistant strains
restrict agricultural use of antibiotics to prevent spread of antibiotic resistance from plant to animal pathogens
who is carl linnaeus and what did he do
swedish botanist born in 1707 who put forward a system of grouping living things based on physical similarities
he proposed diferent levels of oranisation where organisms share more characteristics
what is a species
a group of organisms that can breed together and produce fertile offspring
what is the binomial naming system
a scientific naming system intorduced by carl linnaeus in latin
the first name is the genus of the organism (upper case letter)
the second name is the species of the organism (lower case)
when hand written the 2 names are underlined and in italics if printed
who is carl woese
american biologist born in 1928 who modernised linnaeus’ system to include different types of bacteria
what is the archaea domain made up of
primitive forms of bacteria including extermophiles (organisms that can live in extreme environments) this domain contains one kingdom; the archaebacteria
what is the bacteria domain made up of
bacteria and cyanobacteria that can photosynthesise
contains one kingdom; the eubacteria
what is the eukaryota domain made up of
organisms that have cells that contain nuclei. contains 4 kingdoms; protista, fungi, plants, animals
what are the 3 domains
archae, bacteria and eukaryota
