B15- Genetics and Evolution Flashcards Preview

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Flashcards in B15- Genetics and Evolution Deck (30):

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

1. individual organisms in a species show a range of variation for a given characteristic
2. survival of the fittest as reproduction gives more offspring than the environment can support
3. 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
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